Popular Mechanics Complete Car Care Manual: Updated & Expanded

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MANUAL

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COMPLETE

MANUAL Updated and Expanded Illustrations by LEONELLO CALVETTI, RON CARBONE , PAUL DIMARE, STEVE KARP, DON MANNES , RUSSELL J. VON SAUERS AND JEFF TRISH HEARST BOOKS A Division of Sterling Publishing Co. , Inc. NEW YORK

COMPLETE CAR CARE MANUAL Updated & Expanded Copyri ght © 2003, 2005 by H earst Communications, Inc. All rights reserved. The written instructions, illustrations, and photographs in this volum e are intended for the personal use of the rea der and ma y be reproduced for that purpose only. Any other use, especia lly commercial use, is forbidden under law witho ut the wr itten permission of the copyright hold er. Eve ry effort has bee n made to ensure that a ll the in fo rmation in this book is accurate. However, du e to differing conditio ns, tools, and indi vidual skills, the publisher cannot be respo nsible for any injuries, losses, and/o r other damages that ma y result frol11 the use of th e information in this book. Produced by Bi shop Books 777 Westchester Avenue, Su ite 100 White Pl a ins, New York 10604 Th e Library of Congress has cata loged the first hardcover edition as follows: Popular mechanics comp lete car care manua l / Illustration s by Russel]. Von Sauers, Ron Carbon e, and Don Mannes. p. cm. ISBN 1-588 16-260-5 1. Automob il es-Maintenance and repairAmate urs' manu a ls. I. Popular mechanics. TL152.P625 2003 629.28'72-dc21 2003050841 10 9 8 7 6 5 4 3 2 1 Published by H earst Books A Division of Ster lin g Publishin g Co., Inc. 387 Park Avenue South, New York, NY 10016 Popul ar Mechanics is a trademark owned by H earst Magazines Propert y, Inc., in USA, and H ea rst Comm unications, Inc., in Canada. Hearst Books is a trademark owned by Hearst Communications, In c. www. popularm echanics.com For info rmati on about cu stom editions, specia l sa les, premium and corporate purch ases, p lease contact Sterling Special Sa les Department at 800-805-5489 or specialsa les@sterlingp ub. com. Di stributed in Canada by Sterling Publishing G/o Canadian Manda Group, 165 Dufferin Street Toronto, Onta rio, Ca nada M6K 3H6 Di stributed in Austra li a by Caprico rn Link (A ustrali a) Pty. Ltd. P.O. Box 704, Windsor, N SW 2756 Austra li a Manufactured in China ISBN 1-588 16-439-X

Contents Maintenance Basics

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88 138 158 214

Engine

Drivetrain

Electrical and Electronic Systems

Chassis

Interior and Exterior

Appendix

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254

314

Foreword

or almost 100 years, the editors of Popular Mechanics have made car care and maintenance a central component of the magazine . From the very beginning, we understood just how passionate readers were abou t their cars, and just how far they would go to protect, repair, and maintain their beloved vehicles . How else to explain an exec uti ve trad ing in his workday suit for a pair of overalls and spending his Saturday afternoons hunkered down under the hood of his car? For some of our readers, saving money is no doubt a major motivation . But for most, working on their cars is a labor of love, pure and simple. That, and they want to make sure the repair is done right. The cars may have changed over the years, but the dedication of readers has been a constant. And Popular Mechanics has been a partner all the way, delivering the hand s-on information car enthu siasts need to get the job done right. We understand th at the key to any successful piece of advice is clarity. So we strive to make sure o ur instructions and our illustrations are legible and to the point. We hope yo u'll find those qualities in evidence in the pages that follow. You'll find chapters on all the basic car componentsengine, chassis, electrica l system, drive train, and interior/exterior-as we ll as an opening chapter on the essential maintenance information that every owner sho uld know. Each project is la beled "easy," " modera te," or "d iffic ult " to allow yo u to make yo ur own decision as to whether yo u have the requisite expertise, not to mention the time and energy, to undertake a given procedure. So, whether yo u're breaking out the brand-new wrenches from your first tool set, or sliding under a car on yo ur creeper for the umpteenth time, yo u'll find this book to be an indispensable reference source, packed with easy-to-fo llow, step- by-s tep instructions that take the mystery ou t of auto maintenance and save yo u money. And , should yo u decide that a given repair is a bit too tr ick y for you, the book will arm yo u with the knowledge necessary to discuss the work intelligently with your professional mechanic. Our goal is a simple one: We want to provide yo u with the information yo u need to keep that treas ured car of yo urs in peak condition regardless of its make, model, or age . We know how much yo u love yo ur car and how dedicated yo u are to maintaining it. We're hoping our book provides you with a way to put that dedication into action .

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THE ED ITORS

Popular Mechanics

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CHAPTER ONE

Replacing Wiper Blades / 4 Replacing Your Air Filter / 7 Changing a Tire / 10 Replacing Your Tailpipe / 13 Repairing Power Antennas / 16 Replacing Your Spark Plugs / 19 Replacing Spark Plug Wires / 21 Maintaining Your Tires / 24 Jumpstarting Your Car / 27 Repairing a Leaky Radiator / 30 Curing Pulsing Brakes / 34 Getting Your Car Ready For Winter / 37 Repairing a Flat Tire / 40 Servicing Your AlC / 44 Maintaining Your Battery / 48 Replacing a Battery / 51 Maintaining and Repairing Your Suspension / 54 Replacing Shock Absorbers / 58 Maintaining Your Exhaust System / 62 Replacing Your Belts / 65 Replacing Hood and Hatch Struts / 69 Resetting Your Emissions Maintenance Reminder (EMR) / 73 Passing an Emissions Inspection / 76 Changing Your Oil and Filter / 79 Search Engines / 82 Charging Your Battery / 85

3

EASY

Replacing Wiper Blades

hro ugh the monsoonli ke ra in , yo u see some sort of flashing lights ahead of yo u. But despite the best efforts of your w indshi eld wipers, all yo u can see are blurry blo bs of ye ll ow, am ber and red. Slow ing to half speed, yo u continue to press fo rwa rd thro ugh the deluge. Sudd enly yo u rea lize that those fl as hing blo bs are the warning lights of a sto pped school bus, and children are running across the road in front of yo u. Fortu nately, your brakes work infinitely better than yo ur windshi eld wipers.

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Once it's dry and sunn y aga in, grab a tape measure and hea d for the garage. Lift one of the wiper arms (it's usually easier to grab the driver's-side arm ) off the windshield against its spring tension and keep lifting unti l the pivot point locks the arm upright (Fig. 1) . Look for contaminated rubber inserts, which can be ca used by road film or ca r-was h chemica l adhesion. Inspect the wiping edges for "park set rubbel;" the term used to describe hardened finely-cracked inserts that have been exposed to the sun too long in a

(Fig. 1) In 10 minutes, you can replace your streaky view of the world through a windshield with fresh wiper blades.

parked position. This will cause chattering and skipping. Check for a rubber insert that has been partially torn away fro m its metal sup port. It will slap the windshield with each wiping pass. Pla in o ld dr ied o ut, cracked rubber inserts mea n they've seen better days . Yo u a lso may find rub ber inserts that are a brasio n-worn from w inter co ndi ti ons, in frequ ent car washes and/or a

MA I NTENANCE

BASICS

HOW IT WORKS

Windshield Wipers

(Fig. 2) Measure your old blades before heading down to the parts store.

lack of preventive maintenance. And rear-wind ow wiper blades are subjected to a lot more roa d grit than front blades. In th e rear, you get aerodynamic backwas h, with th e rear tires kicking up a ll sorts of debris. And do n't rul e out an improperl y insta ll ed refi ll. Maybe someo ne else had tried to replace the in serts before yo u got to them . Bu y a pair of full-bl ade assemblies to get a fac tory fit. Also check the wiper anTIs. If they're okay, proceed to replace the blades .

Blade Runner But first, measure the length of the wiper blade to the nearest inch (Fig. 2) . Most vehicles today use blades anywhere from about 16 to 21 in. in length. H owevel; so me cars or minivans w ith very large windshields may exceed that by a few inches. Parts ca ta logs, even those for simp le items li ke w iper blades, are fu ll of all sorts of extraneo us information. You may find three different types of re fills and three different types of blades for almost every vehicl e listed .

REPLACING WIPER BLADES

As the rubber insert of a wiper blade sweeps across your wet windshield, a wedge of water builds up in front of the rubber-a squeegee effect-and the wiper displaces that water elsewhere_ What's left is clean, clear glass that allows you to continue on your way safely_ That's the way it's supposed to work. The illustrations to the right show some of the reasons why it may not. Other reasons may involve components that work behind the scenes-actually, behind the cowl or dashboard of your car. They include the splined shafts that the wiper arms pivot on, the mechanism that creates the back-and-f orth pivoting motion and the electric wiper motor that drives the whole system. A small nut under a cosmetic plastic cover jams the wiper arm onto the splines of its shaft. The splines keep the shaft from slipping in the arm as it turns in one direction and then the other, over and over and over. This reciprocating motion is created by a metal cranktype linkage assembly that's attached to each wiper arm's splined shaft, and to the wiper motor with another splined shaft. Picture the chugging action of a steam locomotive's piston and drivewheels and you 'll get the idea. Rear wipers-found on minivans, SUVs and some sport coupes-work the same way, except the reciprocating mechanism is much smaller and built into the motor. Wiper speed depends on the amount of voltage that's sent to the motor from the wiper switch-low voltage equals low speed, high voltage equals high speed. Intermittent wiper action is created by a separate electronic module wired between the switch on your dashboard or steering column st alk and the motor. Some cars even have electronically controlled roadspeed-sensitive wipers that wipe faster the quicker you go.

TORN RUBBER

PARK SET RUBBER

DAMAGED SUPERSTRUCTURE

ABRASION-WORN RUBBER

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(Fig. 3) Release the tab to disengage the the straightened arm.

If yo u do n 't kn ow w ha t bra nd of bl ade your ca r has, do n't bu y r ubber insert refi ll s. The refi ll s may not fit the bl ades properl y, and yo u' ll get lo usy wiper p erfo rmance . If yo u do kno w w ha t bra nd of bl ade is currentl y o n th e car, refill s are okay as lo ng as yo u bu y th e sa me bra nd a nd type. Experi ence has shown that m ixing bl ade and refi ll bra nd s doesn't lea d to o ptimulll w iper performa nce. But rea listica ll y, yo u're still better off just buying a p a ir o f bl ade asse m bli es no ma tter w ha t t he bra nd . Th e few extra bu cks get yo u new, ma tched co mpo nents th at mo unt q ui ck ly a nd eas il y.

Fresh Rubber Now that yo u've got new bl ades in ha nd , it's tim e to determine w hat method to use to mo unt th e w iper blade to th e wiper ar m. T here a re ma ny varia ti o ns: hook-s lot conn ecto r, pin -type a rm , wide-stra ight end , na rrow-s traight end , side sa ddl e, pin-type bl ade, narrow-dea d loc ke r, fla t hook a nd rock to lock. At the very least, yo u'll need a sm a ll screwd r iver to gentl y p ry t he blade off th e arm o r to unl ock a ta b of so me sort. Som etim es a pa ir of needl e- nose pli ers helps too, but th e pli ers tend to ma r the w iper-arm fi nish mo re th a n a screwdr iver. Bear in mind that m ost wipers will stay ra ised in an upright positio n away from the w indshield so yo u ca n work

6

unit may simply lock o nto the pin. o n them. O thers w ill not. Sometim es, the box w ill contain an So if thi s is th e case, yo u'll adapte r that locks in to t he blade op enha ve to ho ld the bl ade off ing and accepts pins in di fferent sizes . the glass w hile yo u wo rk . T he stra ight-en d connector ca n be If yo ur ca r has w ipers tha t tricky. So metimes yo u need to lift a park behind a cow l or the ta b o n top o f the existing blade with a lip of the hood, turn on the ignitio n, turn on th e wipers screwdri ver to clear the lock ing nub o n the a rm . Yo u m ay also need to and then shut off the igni cock t he o ld bl ade a few degrees o utti on when the w ipers are in o f-pa ra ll el w ith t he a rm to slide it off mid stro ke so yo u ca n have t he arm 's end . access to them. Once th e old bl ade is off, ap plying Al ways r em e mber to a little a nti seize co mpo und to th e lay a cl ea n rag o n to p o f ar m's end couldn 't hurt. The new the w ind shield to p ro tect bl ade m ay come w ith a n adap ter to fit blade from the glass in ca se th e ba rethe a rm 's end o r it may just slide o n . meta l w iper a rm su d Aga in , give a firm shove until th e denl y snaps do wn o n th e blade cli cks in to place. w inds hi eld 's glass. If yo u' re replacing a rubber insert, For the hook-s lot co nnector, yo u just grab it with needle-nose pliers at the generally need to raise the arm off the open end . T he other end genera lly has windshield to a working height. T hen , some sort of deadstop that prevents the swing the blade perpendicular to the insert fro m sliding o ut. Yo u may need arm so tha t you have more light on the connecto r. Yo u'll find some sort of ta b to unlock a ta b o r squeeze together the locking ta ngs of the in se rt before yo u at the connector that either needs to be lifted or pushed to release the lock that ca n begin pulling. Th en, just ho ld the holds the blade p ivot in the hook slot. blade firm ly w hil e yo u pull th e insert O nce the ta b is released, a firm shove o ut like a p iece of sp ag hetti. Gra b th e new insert-m a ke sure that yo u've got to wa rd the base of the a rm will slide the blade right out of the hook slot the right end if they're different-line (Fig. 3) . Then, simpl y line up the new it up w it h the fi rs t set of g uides o n the bl ade's mo unt (there may be a n adapter bl ade, th en fee d it in ca refull y. Ma ke sure to engage eac h set of g uides as in the box to crea te this mo unt ) w ith the hook slot and sli de it in until it yo u go. Sometimes t here are as ma ny clicks. This mea ns it's locked in place. as eight guides . O nce th e in se rt is a ll Fo r the pin-type a rm , ra ise th e arm the way in , make sure it is locked in p lace. fj to a working height and ta ke a close look a t the type of lock(Fig. 4) With pin-type wiper blades, push down on the ing ta b th at holds the pin lock to release the wiper blade from the wiper arm bl ade o nto the p in. with a sideways motion. Yo u'll either have to p ush the ta b up fro m undern ea th the bl ade o r Iift the ta b from th e top wi th a screwdri ve r (Fig. 4) . Once th e tab " unco llars" the pin , p ull the blade assembl y with a sid eways m otio n away fro m the a rm. (Try to imagine p ulling t he blade up the w indshield, to picture th e motio n. ) Depending on the bl ade manufacturer, the new

MAINTENANCE

BASICS

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Yo ur mil eage has been dropp in g stead ily for mo nths. A tun eup is in order, so a fin e Sa turd ay morn ing find s yo u on a deserted stretch of roa d . Yo u fig ure a few miles of sp irited dri ving should blowo ut tb e cobwe bs a nd restore tha t ponycar performance. Bu t w hat happe ns in stead is a lot of no ise a nd no t much performa nce a t a ll . Time to check th e air cl ea ner-w hi ch is p lugged w it h d irt, bugs a nd lea ves . Every engine ha s an a ir fi lter, a nd althoug h t here have been ma ny types of air-fi lter ing materials tried over

REPLACING

YOUR

AIR

FILTER

t he years-in cluding o il -we tted plastic foa ms a nd w ire m es h-dr y, p lea ted "paper" (actu all y res inimpregnated , hea t-cured fiber ) co ntinu es to be t he mater ia l of cho ice for filter elem ents in eve ryt hin g from cars to heavy-duty trucks a nd offroad equip ment .

Housing Project C hec k yo u r a ir filte r at leas t o nce a yea r. All air-filte r ho usin gs are so mewhe re und e r the hoo d (Fig. 1) . The housing cover ma y be held by w ingnuts or spr ing clips- prett y

(Fig. 1) Check your old filter element for dirt, oil or moisture, cracks and proper sealing at the gasket.

stra ightforward stuff. Separa te the cove r from the hous ing a nd yo u ca n li ft t he filter o ut for inspec ti on. Ma ny fil te rs, particu lar ly t he na rrow cyli nd ers use d o n o lde r rea rdr ive ca rs a nd eve n on many of toda y's tru cks, ca n be rotated. If th e re's a dirt y area nea r th e a ir intake , tap th e filter agains t a ta ble to remove loose dirt, then turn it 0 180 and expose a fresh surface t~

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(Fig. 2) If a conical filter has a dirt buildup on only half the circumference, it can be rotated 1800 to equalize dirt pickup, extending service life. Clean the housing's interior before assembly.

th e a ir inta ke (Fig. 2) . So m e con ica l fil te rs a lso can be r o ta ted , but o t hers ca n 't. Neve r tr y to clean a "paper" a uto motive filter in detergent a nd wa ter. So m e hea vy-duty filter s a re d esigned to be cl ean ed severa l times, but a utom o t ive filters are not. Before yo u reuse a fi lter, ho weve r, in sp ect it fo r crac ked p lea ts. Th e best way is to hold th e dirty sid e of th e fi lter in fr o nt of yo ur eyes with good lighti ng on the oppos ite sid e (w ith a cylindrica l fi lter, ho ld a troub le li ght in the middle of the openin g). O f co urse, yo u shou ld see some tra nslucence (if yo u do n't, the filter is p lugged ). But if yo u see even a single li ne of li ght, w hich ind ica tes a ha irline crac k, discard t he fi lter. A lo t of unfiltered a ir ca n get t hro ugh a c rack, a nd it's the a bras ive d ust in th e air t hat wears engines . Sure, that wea r ta kes p lace over time, but if yo u're in a du sty area th a t time ca n be a lo t sho rter th a n yo u'd li ke. Buy a q uality rep lace ment fil te r. T he top bra nd s are d iffere nt fro m th e no-nam e cheapies yo u may see. There a re ma ny grades of fi lter " p aper " a nd th e m o re expensive ones used by th e to p bra nd s have more consistent

po res, so they do a better jo b of t ra pp ing dirt. In additi o n, their p lea ts are more prec ise ly spaced so the fi lter has t he maxim um surface area fo r th e size of t he ho using.

Metering the Air Ju st downstream of t he filter ho usin g, perha ps conn ected by a duct, w ill be the engin e's a irfl ow meter, or sensor. (So me engines have no airflow meter. Instea d, their computer calcu la tes air intake using rpm , intake vac uum a nd baro metri c press ure.) Conta min ati on of the a irflow meter w ill give yo ur engine's co mp uter inacc ura te in forma ti o n a bo ut the a mou nt (mass) of a ir the engin e is burnin g. Th a t coul d mea n poo r d rivea bility, p oo r m ileage a nd hard sta rting. Don 't, however, tr y to clea n th e a irflo w se nsor, save fo r blo w in g loose d irt a nd co bwebs wi th yo ur brea t h. T he ca libra tio n of th ese in stru ments is fr ag il e, a nd yo u sta nd a good cha nce of muc kin g yo ur sensor up irrepa ra bly.

Duct Hunting Before yo u install the new fi lter, in spect the duct fr om the th ro ttle

body to t he fi lter ho using. Sprea d the flu tes of t he du ct, look in g fo r cracks. If th e d uct is cracked, it may be closed a t idle but sprea d o n acce leration, w hen t he engine torq ues. Th at not o n ly brin gs in unfi lte red air, but o n today 's engines with m ass a irfl ow senso rs, the dirty a ir also is " unmea sured ." T he am o unt of fuel sprayed by the inj ectors is determin ed by how much a ir is fl ow ing in , so if some of t ha t a irfl ow isn't meas ured by the senso r, not eno ug h fuel w ill be inj ected . T he engine w ill run lea n and hesita te and/or stum ble . Th e sam e th ing ca n occur if th e d uct isn 't properly fitted a nd cla mped a t each end . Find a crack ? Well , it's a duct, so yo u ca n repa ir it w ith duct tape (Fig. 3) . Th at's a move that no professiona l would ma ke, beca use in time th e tape w ill lose its grip in the hea t of the engine co mpartment, as the duct flexes. Bu t it's your cal; and if yo u a re w illing to rec heck periodica ll y a nd retape as necessary, yo u ca n save the cost of th e new pa rt, or a t least postpone the expense.

Fit Is Important Ca refull y ch eck th e fit betwee n th e lips of th e ho using a nd the rubber ga sket rimm ing th e filter. Thi s gas ket no t o nl y sea ls the filter ho usin g's tw o ha lves togeth er, but a lso p rov id es a n a irtight a nd dirt-ti g ht sea l betwee n th e fil ter a nd the cl ea n sid e of th e ho using . Look carefully a t th e old filter's gasket. It sho uld show a smo ot h , cl ea n line 360 ar o und a t the sea ling fa ce o n bo th sid es. The rim of th e filter ho using w ill have co mpressed th e rubber gas ket if every thin g is correct . If no t, a little detecti ve wo rk is in o rd er. Is t he fil ter the co rrect pa rt ? If not , is yo ur replacem ent fil ter th e co rr ect p a rt? D on't re ly o n just a visual compariso n-l oo k up th e correct pa rt number a nd cross-refe rence. Ad it 's p oss ible a no t her bra nd w ill fit better. Are a ll of th e sp ring cl a m ps p ro perl y latched ? So me air cl ea ners use screws to hold them shut, whi le others use a large w ingnut. All of the fa steners need to be ti ght, even that one 0

MAINTENANCE BASICS

8

(Fig. 3) Check the air cleaner 's ductwork for leaks and splits, especially if you 're having driveability problems. Temporary repairs can be made with ordinary duct tape.

DUCT TAPE

byp ass th e f ilter and a llow dirt into the engin e.

Buttoning Up

yo u can hardl y see or reach next to th e battery. On a few ve hicles, the ho us ing is attached by a bo lt or spring clamp that can be removed to a ll ow the hous ing to be di splaced an inch or two, permitting big hands to fit into a na rrow space. Rea d y to install the filter element ? C lea n out th e housi ng first , wi ping

th e inn er surface w ith a cloth lig htl y m o istened w ith solve nt. In sert the element so it seats properl y. A filte r has a specific side up or toward the throttle bod y, and yo u h ave to in stal l it correc tl y so the e nd seal lines up w ith the shape of the hou sing or its cover. If it doesn't, yo u won't get a good end sea l, and incom ing air ma y

It's time to fini sh up. In sta ll th e cove r or th e ha lves of t he filter hou sin g. In additi o n to the sprin g clips a nd w ingnurs that ho ld th e pans togeth er, there also may be alignment ta bs in areas yo u ca n't reac h w ith yo ur fingers. Be sure the tabs are engaged as yo u fit th e halves together, so the two parts of the ho using for m an airtight joint w hen you tur n the w ingnuts or engage th e spring clips. Be sure that both encl s of any ductwork are properly sea led to both the air cl eaner body and the airflow meter or throttle body, including hose cl a mps or retaining clips. ~

HOW IT WORKS

Your Air Filter The resin-impregnated , heat-cured "paper" element looks like a pleated sheet, and most of the dirt particles are stopped at the outside surface. A light coating of dirt actually improves the filtering ability of the paper. But soon the dirt builds up and even starts filling the bottoms of the pleats , restricting airflow. The paper also has multiple layers, and if you looked at it under a microscope, it would look like a forest with an irregular crisscross of vines and limbsthe fiber strands of the " paper. " It all looks random, but the premium-priced filter "papers" are more consistent in the sizes of the pores than it seems, and a quality material is a mathematically predictable barrier to dirt particles. In actuality, the layers of fibers form a maze and some of the dirt also is trapped within the layers of the paper. The inrushing air produces

REPLACING

YOUR

AIR

FILTER

some static electricity, which also causes some smaller dirt particles to adhere to the surfaces of the paper fibers. A point comes when not enough voids remain to pass the air needed to supply your engine. The result is inadequate oxygen to burn the fuel at wide-open throttle. With carbureted engines, this used to mean rich running. Modern fuelinjected engines meter the air admitted to the intake and add appropriate fuel-making for a clean-running engine that eventually won 't get out of its own way. At least carbureted cars coughed and sputtered to let you know that you had a problem. But with today's engines, a filter has to be really bad to restrict acceleration . A bigger hazard is an overloaded filter rupturing and dumping 20 miles of bad road into your engine.

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~ . EASY

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Changing a Tire la t tires a re never a fun thing-but this o ne takes the cake. It's late, of course, and in the middle of a frog-choking rain. You're stuck in the a nkl e-deep mud on the sho ulder of a deserted road. How deserted? Our-of-cellphone-coverage deserted, or yo u'd be sittin g in the cab of a serv ice truck w hil e so mebod y else gets drenched . That's how deserted. Yes, yo u could drive a lo ng the should er 0 11 th e rim for a few miles to civili zation, but in sura nce wo n't cover the damage to you r expens ive a ll oy rim. It's tim e to kn uck le d own an d put o n th e spare. A pressu re ca n of fl at-fix foam ca n get you ho me if the problem is a simple puncture, and that may be a viable option, especially for smaller individuals or the elderly who would have a tough time changing a tire . .lust reme mber two things: This stuff is a temporary soluti on, and the fl a t will need to be attended to by a tire technician at the earliest opportunity. Be sure to wa rn the technicia n that you've used this stuff. The propel lant is fl ammable, and unless he's wa rned, he sta nds the chance of causing a nasty explosion. Aeroso l fl atfix, however, is no help if the problem is a tire un seated from the wheel rim after an encounter with a pothole.

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(Fig. 1) Be sure to check the air pressure in your spare tire periodically. jack isn't rusted in to imm obility. C heck the manual and find the ve hicl e's jacking poi nts. You ' ll proba bly need to lie o n the grou nd to find them, but this will be a lot more palatable now in yo ur driveway than later on the sho ulder of some mud bog.

Grunting Helps

Furthermore, yo u' ll never be able to cha nge a tire if yo u do n't have the basics-a jack and a lug wrench (Fig. 2) . Go back into their hid y- ho le and confirm their existence (Fig. 3) . W hile yo u're there and you have enough light to read the owner's manual , fi gure Ollt how to un sh ip them and make sure the

The most co mm on difficulty in c ha nging a tire is lugs that are tighten ed far too tightly. A cas ual rattle w ith a mechani c's air wrench can deli ver a tightening torgue that o nl y a pro wres tl er could remove w ith the stock lu g wrenc h. Wheel lugs need to be ti ghtened to no more th a n t he manufacturer's recommended torgue to ens ure the y won't loosen. C heck yo ur (Fig. 2) loosening lug nuts calls for a lot of upper-body strength. An inexpensive 4-way lug wrench can substantially increase your leverage and break loose overly tightened lugs.

Be Prepared First of ail, remember to check the pressure in your neglected spare tire (Fig. 1) w henever yo u check tbe pressure in the other four, which yo u do faithfully every mo nth or so, ri ght? A flat spare is no help. An d if yo u' re like most people w ho save a plugged or nearly worn tire for the spare, it's likely that the spare has a slow lea k, which would leave yo u stranded.

10

MAINTENANCE BASICS

LUG WRENCH

(Fig. 3) Locate the jack and other tire tools and make sure you know how to use them.

owner's manual, but the fi gure wi ll be 75 to 100 ft .-l b. of torq ue. Do the math-that mea ns a 200-pound adult should be a ble to tighten th e lugs by placing all his weight on top of the wrench only 6 in. away from the fastener. A few drops of engine oil or grease on the threads and the lug chamfer (where the lug touches th e whee l, not th e threa ds) wi ll prevent ga lling and seizing. When removing a wheel, first loosen all of the lugs in a crisscross pattern a half-turn or so. It may be necessary to use the mechanic's favorite cheater bar (Fig. 4)-a piece of water pipe or thick wall pipe about 4 ft. long- to add enough leverage to break the lugs loose. Remove them one at a time and lube them if they squeak . Retighten them in three stages, again in a crisscross pattern.

Black And Round Many carmakers, in a n attempt to reduce vibration by making sure the wheels are more concentric with the hub, use a protruding lip that mates closely with the centerhole on the rim. This works wel l for a

CHANGING A TIRE

(Fig. 4) A cheater bar helps loosen lugs. Never use it to tighten them.

coup le of years, but eventua lly corrosion from road grim e can make it imposs ibl e to budge the w hee ls, even after you've loosened all the lugs. Correct this now, and you won't need to try it in the field. Jack up the corner of the car to take the load off the wheel and kick the whee l, alternating sides until it pops loose. No joy, and now yo ur feet hurt? Be sure the lugs are only a single turn frol11 tight, lower the car and move it a foot forward and back, rapping the brakes smartly to break the wheel loose. A shot of penetrating oil may help in an

hour or two. Clean up the corrosion with emery paper (Fig. 5) and coat al l th e surfaces li ghtly with wheel bearing grease, Va se line or, best of all, antiseize compound. You' ll need a few things besides the on-board tools for your emergency tire change. Pack a flash light with good batteri es or, better yet, a cigarette-lighter-powered trouble li ght, an emergency triang le, a coup le of road flares, some gloves and a poncho or ground cloth. Toss in three pieces of scrap 2 x 4 as well, each about a foot long, and a piece of thick plywood 2 x 2 feet.

That Fateful Day Wh en changing a tire the fir st, and most important, thin g to do is to get the vehicle to a safe area, far enough from the road to save you from becoming road pizza-particularly if tbe flat is on the left side and your back sid e wi ll be poking out into traffic whi le you work. Set your triangl e or (Fig. 5) Remove corrosion from the centering hole with emery cloth or a wire brush.

11

jack, and there's probably flares 100 ft. o r so upstream. eno ugh to p ut a smidge n on the Leave the ve hicle in Park and lugs w ith your finger. Be sure to set the hand brake. Block th e get it on the mating chamfer as whee l di agona lly opposite the we ll as on the threads . flat with two pieces of wood Lower the vehicle and pull the (Fig. 6) . Loosen all the lugs on jack out. Now yo u can tighten the flat a full turn. Take the the lugs to their correct torque. spare out of the trunk and put it Check the owner's manual for halfway under the car near the the torgue specification. Measure jack. In the unlikely event the carefull y. If the lug is dry and car fa ll s off the jack, it will onl y unlubrica ted, it may take a lot fall onto the spare-not your more force to tighten the lugs. foot or head-and will leave ,/' The only accurate way to you a fighting chance of raising WHEEL CHOCKS torgue the lugs is to use a the car and continuing. If the mechanic's torg ue wrench. car falls to the gro und, yo u'll T hese can be purchased for 20 (Fig. 6) Block the opposite corner of the car to keep have no way to raise it. bucks or so . If you have expenRaise the jack from its stowed it from rolling off the jack. sive all oy wheels, yo u may want position to nearly higb eno ugh to bu y one and keep it in the trunk. wrench, aga in in a crisscross pattern. to contact the bottom of the car. If Be sure you don't have anything As yo u're putting away yo ur tools you've got a different style of jack th an (like a stone or mud) trapped and jack, be sure yo u haven't left the one pictured here (Fig. 7), check your owner's manual for specifics. between the rim and hu b, or the rim them covered with mud or moisture, which might ca use them to rust while If the ground isn't firm, put the 2 x 2 w ill wobble. In fac t, if the mud COI11presses later, th e lugs co uld lose their stored . If they're a mess, clean them piece of pl ywood under the jack point, and the jack o n top of th e wood. Be torg ue and the whee l co uld fly off. If and relubricate at your earli est opporyo u need to, remove th e whee l aga in tunit y. Don't forget to pick up yo ur sure everyt hing is level. Jack th e car up until the fl at clears the ground by in th e m orning to remove the debris, safety tria ngle. severa l inch es, beca use the spare isn't corros ion a nd ru st fro m a ll th e matNext Morning flat and will need more cl earance. ing faces and between the w hee l an d Remove the lug nuts, and put them hub, a nd then li ghtly lube. This w ill Take yo ur fl at to a competent tire technician for repair ("Repa iring A . inside the hubcap or in some other have th e added benefi t of mak in g the place where they won't get lost in the w hee l easier to remove the next tim e. Flat Tire," page 40 ). And don't let dark, or accid enta ll y sca ttered into him overtighten your lugs with hi s Hint: There sho uld be so me grease to the weeds by yo ur fee t. be found o n the jackscrew of yo ur fancy-dan air wrench. 9 Pull the flat off and put it halfway under the car. Hang the spare on the studs. No studs? You've got lug bolts (common on many Europea n ca rs) and you'll need to juggle the w heel w hil e yo u get the top one started. The easy way is to sit down on the ground facing th e hub a nd ba lance th e spare on yo ur legs w hile yo u start the first lug bolt. If yo u begin with the top bolt, the wheel will hang gracefull y from it and yo u can start the rest. Finger-tighten a ll the lugs a nd then lightl y ti ghten them w ith the lug (Fig. 7) The correct jack point on the frame of your vehicle may be difficult to reach.

12

MAINTENANCE

BASICS

EASY

Replacing Your Tailpipe

rakelights flicker sudden ly in fro nt of yo u, fo llowed rapidly by the screeching of tires. Cars before yo u swerve to the left and righ t as you slow as safe ly and rapidl y as practical. Despite yo ur best efforts, th e so urce of the pandemon ium , what appears to be half of a cement block, di sappea rs directl y under yo ur front bumper at a high speed. Thump. And as it exits from yo ur rear bumper, yo u

B

REPLACING

YOUR TAILPIPE

follow it in your rearview mirror for a few seconds. It has company. Your muffler- or at least most of yo ur muffl er-ha s apparently developed a lasting relationship with the aforemen ti oned ce ment bl ock. They' re elop ing at high speed toward the curb, in extricabl y intertwin ed. The next thing you notice is the sound of what seems to be a B-29 landing in the next lane as you press

back down on the gas. Actu all y, it's your engine-minus its mufflerwaking LI p again as yo u try to negotiate through the traffic, back home to sa fety, family and so mething ta ll and co ld th at w ill make yo ur ha nds stop shak in g. To add insult to injury, yo u replaced yo ur ex ha ust sys tem from the cata lytic converter back only la st spring. Inspection of the und erside

13

of yo ur car revea ls good , so lid p ipe most of th e length of the ve hi cle, ter min atin g in sha rd s of muffl er. H ere's yo ur chance to rep lace a few fe et of pipe and th e missin g muffler yourse lf.

pipes it's connected to at both ends have been crimped by cl a mps. How do yo u remove the Sw iss-c heese pipe witho ut ruining the o th er two ? By using a power cutting whee l and a very steady hand (Fig. 1). The preferred too l is an air-powered di e grinder w ith a cutoff w heel, but a hi gh-speed electric drill will work, a lbeit more slowly.

oi l, so yo u can get th em o ut, pry the fl a nge from its r usty partne r and sec ure the new fl ange with a new gasket and fres h bo lts. Use antiseize compound on everything to ease removal the next time . T he other type of co uplin g is made up of a larger pipe slipped over a small er one o r a small er pipe slipped into a larger one, dependin g on wh ich

Now That You 're Home Actua ll y, it may not be road debris that removes yo ur muffler and tailpipe. Rust never sleeps, and cars in short-trip serv ice m ay rust out the farth est, coolest portion s of the exha ust system in as little as 18 months. Th e following scenario is typical of vehicles that have had part of th eir exha ust system repl aced at least once. T he saga begin s with a section of the origina l exhaust plumbing behind the catalytic converter rusting o ut and m aking a ruckus. Beca use th e original exhau st pipes are welded together, however, a ll th e p ipes from th e cat back need to be (Fig. 2) Peel up the corners of the old pipe to slide in the new piece. repla ced. T here's no practical wa y to remove just the rotted section because of all the weld s. If you had the wherewith a l, you cou ld probably cut out just th e rusted portion and have a pipe custom-fitted. But th at would be extremely labor' . . intensive and not particularl y econom ica l over the long ha ul. Also, exhaus t work just isn't don e that way. So , generally, two or three aftermar ket pipes and th e muffler a re clamped togeth er behind the converter (Fig. 3) After installing all the parts, adjust for fit and tighten the clamps. to repa ir the exha ust. T hen yo u dri ve aro und for way the coupling is facin g. Both may Sizing It Up another yea r or two in peace and be present in the same exha ust sysGet the back of the car up on jackquiet-unaware that the repl acement tem. The importa nt thing to rememw ith chocks securing the front stands, pipes hangi ng under you tend to rust ber is that yo u may need to save the w heels. Be sure to wear safety gogat different rates. Sometimes, th e midpipe, so use a gentl e to uch w ith inn er exha ust systems tend to drop gles, as dl e pipe of th e three you insta ll ed goes the cutting wh ee l. If th e outer pipe razo r-sharp flakes of ru st that a re first . Other times, the muffl er at the needs to be saved, there's nothing you seemingly attracted to your eyes . end fa ll s off before the other two. Still do to keep fro m cutting it. But can Get under the ve hicl e to see what other times , the fl anged pipe bolted to why yo u're going to use a cutthat's kind of co uplings yo u' re dea ling the cat is the first to go bad. In a ll ting wheel instead of an impact chi se l. with. The fl anged type is easy. Just cases, though, yo u want to replace It ma kes for a nea ter, smoother cut. spray the rusty bolts with pen etrant onl y th e bad pipe. Problem is, the

14

MAINTENANCE BASICS

o uter p ipe lik e a tin ca n. That w ill g ive yo u enough play a t t he crim ped area to w iggle the pipes apart.

Spread 'em

(Fig. 4) Smear muffler cement over the joint after you install the clamp.

Slice, Don't Dice To begin, remove the bad pipe's cla mps. Then, ma ke a lengthwi se mark 'I to 2 in. lo ng where yo u want to sli ce open th e outer pipe. Put on a pa ir o f gogg les, get a good doubl eha nd ed grip on th e cutte r too l a ncl sta rt it up . Slow ly ra ise the spin nin g w hee l to the mark o n the pipe. With gentle pressure, score the mark.

REPLACING Y OUR TAILPIPE

If yo u're saving the inn er pipe, repeat this step until you're throug h the outer p ipe. It's okay for the inner pipe to get a li ttle score groove in itjust as long as you don't c ut it a ll the way th ro ugh. [f yo u' re sav in g the o uter p ipe, the second cut ca n take yo u a ll the way throug h the inner pipe. With th e cut made, use a screwdri ver or a c hi sel to pry ope n the

Fitting a new pipe over an o ld o ne is no problem. Fitting a new pipe in to a n o ld o ne sometimes is, because of the crimp fro m t he o ld clamp. If you' re hav ing trouble, use a n exhaust-pipe expa nder to gai n so me ext ra cl ea ra nce . Then, simpl y fit the pipes together as if they were both new after smeari ng a little muffler cement on the joi nt. If yo u saved th e outer pipe, it now has a 1- to 2- in . slice at th e encl. Make sure to slide th e inn er p ipe in past the end of the cut, so there's no ho le between t he pi pes (Fig. 2) . in sta ll a new muffle r cl a mp, but do n 't tig hten it until the rest of th e system is hung from th e ha ngers a nd a ligned properly (Fig. 3) . Once every thin g is back together a nd c la mped dow n tight, a littl e mu ff ler ceme nt strateg ica ll y a ppli ed w ith yo ur thumb over th e c ut wi ll take care of a ny tin y res idu a l gaps (Fig. 4) . Lower yo ur car a nd enj oy th e sil ence. t;

15

MODERATE

Repairing Power Antennas

(Fig. 1) Scratchy radio reception might be caused by poor ground or antenna connections. Use an ohmmeter to chase high resistance pOints.

t's time to kick out some jams, so you reach into the console for your favorite MC5 CD. Popping open the jewel box, yo u reac h for the CD, only to find o ut that Juni or ha s liberall y lubri cated it with peanut butter and jell y. After making a mental note to give Junior a good ta lk ing-to, you dec id e to surf the a irwaves for some good oldtime rockand-roll. Punching the FM button, yo u hope that at least one of the radio presets ha s so me Bob Seger tun es hiding behind it. But no, th ere's nothing to be heard o n any channe l except a great rushin g no ise, not even so much as CONELRAD. Time to come back to this mill ennium and find out what's wrong w ith yo ur antenna.

I

16

Manual Or Power? Fixed antennas have on ly a couple of fai lure modes, and generally they in vo lve mechanical damage to the antenna mast or the ca ble. If part of the mast is still there, yo u'll generall y get so me sort of signa l. A poor connection between the antenna ba se a nd the fe nd er also cou ld be a problem. Unscrew the antenna mounting nut and check for corrosion. A cleanup w ith a w ire brush and reassembly might re-estab lish a good gro und. Powe r antenn as are more coy. If they're too shy to come o ut of the fender, yo u're li stening to static.

No-Show The iss ue could be either electrica l or purely mechanical. Go back to yo ur

(Fig. 2) If water that leaks down the mast can't escape, the mechanism may freeze up.

antenna and tr y to pull the mast o ut with your fin gers. If it moves out readily, pull it out all the way, and then cycl e the radio power w ith the key on. If the mast moves even the slightest amo unt, or yo u can hear the motor running at a ll, the prob lem is mechanical. If the motor seems deceased, go back to basics-check the fuse. Determining which fuse protects the antenna motor may require so me detective work . It may be the radio fuse, or it may be a separate fuse, perhaps shared with the rear-window defroster grid or a trunk-mo unted CD changer. (Finding something else that doesn't work often is a good clue.) Fuse is okay? Check the antenna's mounting, as described previous ly, for

MAINTENANCE BASICS

(Fig. 3) A sticky or damaged antenna mast can often be replaced without accessing or disassembling the mechanism. As we show here, this can be done without removing the interior trim.

assembly sho uld have o ne hot w ire o n, a nd a di ffere nt w ire hot when th e key or rad io is off. Good huntin g.

Stubborn a good gro und pathway, a lth o ug h there ma y be a separate gro und w ire to a spec ific chassis gro und point. You may want to use a n o hmm eter (Fig. 1) to hunt for resistance. Inci denta ll y, if yo u tr y to meas ure th e res ista nce of th e a ntenn a cable's RF lea d between the mas t a nd the radio connector, it ma y check out as infinite. Some a ntenn a assemb lies use a capac itor in series w ith the RF lead , some don 't. T he ground shell of the a nten na cab le shou ld have a low resistance to chassis gro und , normally 5 o hm s or less . You' ll need to find a schema ti c of the a ntenna w iring to tro ubles hoot a ny deeper. But with the radio and key on, the harn ess to the antenna

REPAIRING

POWER

ANTENNAS

Does the antenna motor run briefl y but not ac tu ally move the mast up a nd down? Or does it move a few inches a nd th en grind to a ha lt? One prob lem we've seen is a kinked o r pinched drain tube. (Fig. 2) The mechanism ca n fill with water, w hich then freezes solid in cold weather, or corrodes the works and causes a jam. C heck the tube, espec ia ll y if yo u can pull th e mast o ut manually a nd it's wet. If the tube is compro mi sed an d the works are full of water, you may need to disassemble the thing, dry it o ut, and put it back together with fresh lubrica nt. Ca n yo u help the mast along in and out? If so, the sliding sections

of th e mas t may be corroded or bent. Careful bending by ha nd may resto re mo ve ment, a nd po li shing with 600-grit sandpaper or rubbing compound ca n smoo th th e action. At the ve ry least, run the mast compl etely out a nd cl ea n it th oro ug hl y with a soft cloth, re lu bri cating w ith a spa rse a mo unt of silicone grease or pas te wax.

What's That Funny Noise? Modern power a ntennas use a simpl e, fl exibl e rac k-a nd-pinion mecha ni sm. It's pretty reli able, but a buse and the ravages of time a nd weather ca n litera ll y st rip the gears . So if yo u hear noises that sound li ke interru pted gear meshing, there's probably some section of the rack or pinion th a t's in need of denta l work. It's poss ible to fix thi s w itho ut replacing the a ntenna asse mbly o utright (Fig. 3) . (You m ay not even have to access the mecha nism .) ~

17

FERRULE

(Fig. 4) Remove the outer nut and collar as a first step to removing or replacing the mast.

Visit yo ur dea lership 's parts department. GM, for one, offers a repair kit fo r p ower a ntennas . T hi s consists of a new mast a nd rac k asse mb ly, rea d y to in sta ll. You may need to order it, as the two dea lers we tri ed didn 't have it in stock . Th ere are afte rmarket antenna pa rts to be ha d, but finding th e ri ght pa rt is going to be di ffi cult unl ess yo u have better lu ck than we did interroga ting the staff behin d the pa rts co unter a t the loca l ware ho use di stributor. H ere's how the system works: Th e limi t switc hes that stop th e motor at bo th end s of th e antenna ma st's trave l a re built in to the mech a nism , a nd yo u ca n consider them un se rviceab le. T he limit switches rely on th e a ntenn a bo ttoming o ut o r topp ing out to ro ta te a sw itch drum , a t which po in t th e c urrent to the motor turn s off. At the top of the antenna mechanism is a large nut that holds the who le wo rks onto the fender. Remove this nut. T his isn't as easy as it sounds if it doesn't have flats that yo u ca n turn with a wrench. Yo u may need to use a spanner w ith pins- a ltho ugh a pair of snap rin g pliers may work if the nut isn't w icked ly tight. At the potentia l expense of the chro me fini sh, yo u may need to fa ll back on the mechanic's friend, locking pliers. Under the nut and perhaps a plastic spacer or two there wi ll be a ferru le (Fig. 4) , which

18

is the stepped sleeve that the mast actua ll y bumps into at the end of its travel upward. Pul l o ut thi s ferru le. Now have someone else turn on the radio. The mast should elevate itself comp letely out and flop over, so you have to be there to catch it. Carefull y notice which way the teeth of the rack point as the mast clears the fender. Note the state of the teeth. M issing teeth proba bl y mea n yo u sho uld disassemble the ho using and clea r a ll the bits o ut, but teeth that are simply worn shou ld be okay. The new mast's rack has been cu rled up lik e a p ig's ta il in th e package, and it will be difficu lt getting it to mes h with th e gea rs. With yo ur fin gers or pli ers, bend th e bottom 2 or 3 in. backward to remo ve the c url. The end sho uld be stra ight now. After ma king sure tha t the ra di o is turned o ff, take a look at th e last too th-you may need to remove a sm a ll a mount o f castin g fl as h. A pocketknife does th a t job we ll. Tak e th e new ma st, wit h th e teeth of its rack a ppropri a te ly oriented, a nd in se rt it in to th e ho le unti l it bottoms . Rota te the mast a littl e to the left and ri g ht to get th e teeth to mesh w ith the pinion gea r (Fig. 5) . H ave yo ur helper turn th e rad io o n a nd off w hil e yo u pu sh th e new m as t firm ly down. Thi s wil l ca use th e limit switch to cycl e in sid e th e mecha ni sm. Now have yo ur help er turn the radi o o n, a nd if a ll is we ll , the mas t w ill suck itse lf very nea tly in unti l it bottoms o ut. All yo u need to do now is reinsta ll the ferru le, space rs a nd nut. Ligh tl y lu be the mast sectio ns w ith sili cone grease o r pas te wax.

runnin g aga in. The sw itch co nsists of a pl as tic drum w ith wiper fin gers a nd electri ca l traces, so it's vu lnera bl e to moi sture a nd dri ed-out lu bri ca nt. If yo u ca n't fi x it, or th e motor itse lf is toasted, yo u'll n eed to replace t he w ho le shootin' ma tch. An afterma rket a ntenn a w ill set yo u back about $60 to $75 at th e loca l a uto p arts store, or mo re than a hundred a t th e dea lermaybe mo re for a lu x ury impo rt. The OEM parts w ill , of course, dro p in. Aftermark et pi eces m ay require a certain a m o unt of a daptation to mount properly, a nd perhaps even some crea ti ve w irin g to make th em wo rk prope rl y. Don 't forget to chec k for used pa rts a t the loca l scrapyard o r auto recycl er. t)

NEW MAST

Outer Limits If the limit switch mechanism stops work ing, yo u m ay be a bl e to d isasse mble it, cl ea n up a n y fore ign matter o r corrosion, a nd get it (Fig. 5) It may take a little fumbling to get the rack to mesh with the drive pinion, but when it does the mast will run completely home by itself.

J MAINTENANCE BASICS

,- 0

EASY

l~~PlaCing Your Spark Plugs es pite the heavy traffi c-peri ods of slow-go inte rsp ersed w ith lo nger per io ds of no-go-thin gs a re okay. Yo u've gOt tha t new Ya nni disc in th e playe r a nd yo ur java is still piping ho t. H o w eve r, as yo ur dri ve wea rs on , the CD starts skipping and th e co ffee in yo ur cup sta rts spilling ove r th e to p. Suddenl y yo u rea li ze th a t yo ur engin e is no lo nger idlin g w ith its a cc ustom ed silk y sm oothn ess. In fac t, it's getting as lumpy as cold oatmeal. Th e engin e's deve loped a ba d misfire. As yo u sit a nd jiggle a lo ng in th e ro ugh-runnin g car, yo u fi gure th a t it ca n't be the spa rk plugs. After a ll , w ith today's unl ea ded gaso line th ey can last twice as long as they used to. And th e engine's high-o utput electronic igniti o n system produces eno ugh vo ltage to fir e even a wo rn plug. Well , think aga in.

D

Fair is foul Altho ug h plu gs w o n 't lea d- foul w ith today's unl ea ded gasolin e, they can o il-foul , ca rb o n -fo ul o r even be fo ul ed by so m e fue l a dd iti ves. So if yo u 've go t a mi sfire, th e re's a fa ir c ha nce a plu g is th e ca use . In fac t, it's mo re like ly a plu g th a n th e fue l inj ec tor. So, back ho me, it 's tim e to take th e plugs o ut. Loo k fo r oil y- bl ac k or soo t y ca rbonbl ack dep os its. The fo rm e r us ua ll y are fro m defec tive in ta ke va lve stem sea ls, th e la tter fr o m a n ove rl y ri c h fu e l mi x ture, o r a lazy o r d e fec ti ve oxyge n (0 2 ) se nso r. T he oxygen se nso r is wh a t s ig na ls th e co mpute r to a dju st th e fu e l mix ture. It ca n be tough to hear a misfire, which is o ne reason w hy emissi o ns-

REPLACING YOUR

control sta nd a rd s require the engin e computer's o n-boa rd di agnostics (O BD ) to log tro ubl e codes fo r each o f th e cy linders. H o weve r, th e first ca rs equipped with that setu p (ca ll ed O BD 1I) we ren't produ ced until 1994 , a nd most cars didn 't have it until 1996 . Even w ith a n ea rlier model , yo u sho uld c heck fo r tro ubl e co d es indi ca tin g a pro bl e m with th e eng ine, pa rti c ul a rl y th ose in vo lvin g th e oxyge n se nsor. But if eng in e pe rfo rma nce is d o wn a nd yo u ' re no t seeing tro ubl e co des, a nd th e plu gs have gon e a co upl e o f yea r s o r a bo ut 30,00 0 miles, it's wo rth pullin g the m fo r a loo k. But no t so

fas t-thi s ma y not be as ea sy as in yo ur las t ca r. F irst, it may be ha rd e r to di sco n nec t th e plu g wires. If th ey' re recesse d , yo u ca n ' t ju st pull o n th e w ire. Wo rse, m ost of th e s impl e spa rk plu g pull er s w e've tri ed wo n ' t w ork o n a stuck boot. You need plie rs th a t grip th e end o f th e boo t a nd g ive yo u so me thin g so lid to ho ld. Th ese pull e rs cos t $20 o r so . In a n y case, t w istin g th e boo t to brea k th e heat sea l ofte n is necessa r y, eve n w ith p li er s. Neve r tr y to p ull o n the plu g wire itself, o r yo u'll prob a bl y cau se a se parati o n in th e res ista nce wire.

SPARK PLUGS

19

A second thing to watch for is whether yo ur spa rk -p lug socket really fits. To meet th e lates t standard of th e Society of Automo ti ve Engineers, many new plugs are about Ys-in. longer than yo u're pro ba bl y used to. An o lder, margina l soc ket may not fit the hex properl y and co uld slip off and break the p lug. It also helps to use a socket w ith a rubber in sert to sec urely ho ld the plug.

Finally, the elbow grease Start wi th a warm engine. Clean the plug ho le recesses with compressed air, crack a ll th e p lugs loose one-quarter turn, and let the engine cool. Removing plugs from a ho t cylind er hea d ca n damage the threa ds. Once yo u have the plugs out, check them ca refully before yo u dec id e they've got a lo t of li fe left. Use a ma gnifying glass and fee ler ga uge to be sure . If the ga p is worn .005 in. over the specs, an d yo u can see ro undin g off of th e ce nter electro de and wear o n th e sid e electrode, in sta ll new p lu gs. Forget trying to fil e the plugs . If yo u're reinstalling the old p Iugs, smear a film of antiseize on the threa d s near th e tip. New p lu gs have a coat in g th at w ill lu bricate th e threa d s o n th e way in a nd preve nt the p lu g from se izin g on their next removal, but it 's o nl y good for one stab. If a ny sp ark plu gs are dry-soot black, that's from carbon-a richfuel mixture problem. If there's a trouble code indi ca ting the oxygen se ns o r is incorrectl y sign a li ng lea n, the sensor co uld be responsible. If it's correc tl y indicating a rich mixture, then yo u have to look for a cause, such as leaking fuel inj ectors or engi ne misfire, perha ps ca used by defecti ve plug wires. It wou ld seem th at mi sfire wo uld thro w a lot of raw gas into th e exha ust, whic h it does. But it also th rows in a lo t of oxygen, and th at's w hat th e sensor sees, and in thi s case it just tells the comp uter to add more fuel. No t sure or no code? Then check th e oxygen sensor, w hi ch resemb les a

HOW IT WORKS

The Right Plug The correct plug for your engine is, of course, the exact part number that the manufacturer installed at the factory. When it's time to retire them, you'll be forced to choose from several manufacturers' offerings, and they're all pretty much alike, right? Wrong. There are subtle differences in a plug's ability to dissipate heat that belie what would otherwise be an exact physical match. A "hot" plug has a long path through the ceramic to the (relatively) cool cylinder head. A "cold" plug has a shorter heat-conduction path and tends to run cooler. Plug manufacturers cross-reference their product lines to other manufacturers' lines, and you should be able to find a plug to fit almost anything in the cross-reference chart. More important than heat range are things like thread diameter and length, and the type of tip . Installing the wrong plug can ruin your engine instantly if the plug is too long and whacks the top of the piston, especially in today's aluminum heads. Too short a plug not only won't fire, carbon will quickly fill the threads on the cylinder's head, preventing you from installing the correct plug.

spar k p lu g threa ded into the ex hau st manifold . If there's an O 2 trouble cod e a nd no apparent ot her ca use, yo u cou ld just rep lace the sensor. O r, before yo u in vest in a new one, test the se nsor yo u' ve got. You ca n do this using one of the inexpensive testers made for Saturday mechanics. With a warmed-up engine (necessar y to get the O 2 se nsor work ing) a nd the throttl e cracked open (so th e engine is running at abo ut 2000 rpm), the tes ter's indicator lights t ypica lly wi II fla sh o n and off (or w ill both glow stead il y) if the O 2 sensor is working properly. If yo u don't get the lights, or as an extra check, let the engin e coo l. Remove th e sensor w ith a tight-fitting wrench and bench-test it. The typ ica l sensor ha s a closed but slotted end and is a heat battery of sorts. If you envelop the senso r end w ith the flame of a propane torch (so it gets hot but not cherry red ), it should produce

over OAv with a high-impedance digital vo ltmeter hooked up, or turn on th e tes ter li ghts. If the sensor is good, th e vo ltage should drop or the lights go o ut w ithin 3 second s after yo u pull away th e fl ame. Occasiona ll y a vehicle has a different type of sensor, and in some designs it has an open tip. This is a varying-resistance device that doesn't respond to these vo ltage-generating tests, so yo u'll have to rely on the on- board diagnostic system fo r openers, and a shop manual checko ut procedure to find out if it's bad. T hi s type (widely used on new cars) also was used on 1987-90 Jeeps, an occasional Toyota in the late 1980s and a lot of N issa ns. These days yo u shou ld ha ve access to factory service information (or a good afterma rket eq ui va lent) for yo ur car, so refer to it. Whether yo u install a new sensor or refit the one you've got, coat the th reads of the 0 , sensor wi th anti seize compound.- ~

MAINTENANCE

20

BASICS

EASY

Replacing Spark Plug Wires (Fig. 1) Dampen the wires with a spray bottle and clear water, and look for arcs with a grounded, insulated screwdriver.

(Fig. 2) Inexpensive boot pliers allow you to remove stuck plug wires without damage.

efore easing o ut of the fas tfoo d 's parking lot, you gra b a sip of the hot coffee you picked up at the drive-thru. You take yo ur time as you p lace the cup in its ho lder in the center co nso le. No hurr y. Th e a pproaching traffic may be mo ving fas t, bu t it's far enough away for you to accelerate up to cruising speed. Good thing, beca use at a bo ut half-throttl e you fee l the engine mi s-

B

REPLACING

SPARK

PLUG

WIRES

fire. The cl osing traffic ha s time to back off and let yo u sputter up to road sp eed . But n ow yo ur engine sputters like a H arl ey idling at the curb, eve n at norma l tra ffic speeds. And there's coffee a ll over the co nso le fro m the vibrati on.

What's Up? A brief underhood inspection co nfirms that all th e vacuum hoses are o n

and that none of them have been burn ed open by lea ning against th e exhaust manifold . Yo u've touched every sensor connection to see if it's o n tight, you 've even checked for troubl e codes . H owever, not everything ca ll s fo r high-tech di agnosti cs a nd the latest scan tester. Engin e mi sfire often is ca used by lea king spa rk plug wires, so visu al inspection could re veal what's wrong . Th e jackets may be damaged fr om the outside by a brasion ca used by engine vibra ti on (p articul arl y at the plug-end boots), a hot engin e compartment, spill ed fluid s or battery acid , multiple disco nnectio ns and reconnections for other service, o r even a fa mil y of nesting rodents. Run the engine in near darkness, and then look and listen. If you see littl e electrical arcs, or hear a snapcrac k, th ere is hi gh-vo ltage electrica l leakage. Of co urse, running the engine at idl e doesn 't exercise the igniti on system ve ry hard , so yo u ca n add so mething to the test by spray in g the plug wire ends with clean wa ter fro m a ho usehold spray bottle. Another test: With a jumper w ire, ground the metal shank of a screwdri ver that has a well -in sul ated handl e. Then, run the tip of the screwdriver along th e length of each wire and a ll around at the coil and plug boots. Thi s w ill often produce an arc from the wire to th e screwdriver (Fig. 1) . Now look at the wi res und er good lighting. If they are da maged by a brasion, o il-soa ked, cut, burn ed fr om contac t with the exha ust, or have a dried-o ut look with hea t cracks, it definitel y shouldn't be a surpri se if yo u see arcs in the dark under so me conditi ons. H owever, if they loo k bad

21

but th ere a re no arcs, do a res ista nce chec k. A conve nti o na l plug w ire has a res ista nce of 10,000 to 15,000 o hms per foot of length-if it's meas ura bly high er, t he w ire probab ly is bad. An a bso lutely failed w ire w ill have a ha irline brea k so mew here, a nd t he res ista nce wi ll be infinity.

affect th e operatio n of underhood e lectro nics by not co nta in ing radio waves. T he ac tual method of removing the o ld wire is not a lways " ju st pull it off." Pulling o n th e w ire itse lf is sure to cause an intern a l separa tion (see p. 19). Of course, if yo u' re replacin g a ba d wire , it may no t ma tter, but if anyone of th e o ld w ires is Out With The Old, st ill good, it's bes t to kee p it as In With The New a spare . Once yo u've found a bad w ire, Grasp the plug wire by the the so luti on should be simpl e: boot at the plug end. If it's in a (Fig. 3) Some wires are secured inside the cap by Rep lace the plug w ires . recess or is difficu lt ro access for spring clips. Use needle-nose pliers here. First, yo u have to decide some other reason, use a spa rk whether yo u want to bu y from a plug wire too l. There are specia l car dea ler a t Iist price o r get A word of ca uti o n : You may no t pliers of a ll sorts designed ro reach in a qua lity aftermark et bra nd, if you have wa nt " hig h- perfo rmance" wires, even a nd grasp the boot (Fig. 2) . They' re no t that cho ice. Prices for 198 0s models if th ey fit yo ur ca r (and they may be expensive, and having them could prove ma y be under $35 for a popular make cheaper th a n a conventional type) . useful if you ever have ro discOlUlect at the parts srore. For a late-model V8 , Some high-performa nce w ires are not w ires for other underhood service. Twist be prepa red to pay the dealer up to th e resistance type, and a lth o ugh they the boot if necessary ro break the heat $200 o r mo re, even for a popul ar car. m ay do well o n racing cars, they can sea l to the plug, then pull . As yo u do this

HOW IT WORKS

Spark Plug Wires The spark plug wire has a seemingly simple job: Carry the high-voltage electricity produced by the ignition coil to the terminal of the spark plug. Once at the plug, the electricity travels to the other end of the plug, and jumps a gap between electrodes to produce the "spark" that ignites the fuel mixture. Because high-voltage electricity looks for an easier path to jump across than a pair of electrodes in a spark plug, containing the electricity within the wire takes a thick jacket of insulation, and some wires have an outer jacket to resist cuts, high underhood temperatures , etc. If that outer jacket is damaged, the electricity may leak out to follow the easier path. In addition, high-voltage electricity produces radio waves,

with all types of on-car electronic devices, from sensors and computers to radios and other entertainment systems. So, a simple length of solid wire can create problems. The electrical conductor typically has a carbon-impregnated core of a

THICK RUBBER INNER INSULATOR

CONDUCTOR IS CARBONIMPREGNATED NYLON STRING [AVOIDS RADIO

suitable fiber, and everything from nylon to Kevlar has been used by different makers. That conductor (often covered by a second layer of a nonconductive material such as synthetic rubber) has enough electrical resistance to suppress radio interference without unduly weakening the spark. Some premium wires may have copper or stainless steel wire wound around the carbon core to reduce resistance. In some special applications in which minimum resistance is needed for engine performance, a solid metal wire has been used as a conductor, but over the inner layer of insulation is a layer of wound wire as a shield. On other types of wires, the outer f h' h jacket 0 t e wire may ave a metallic shield to prevent

D

L-_W _h_i_c_h_c_a_n_c_a_u_s_e__in_t_e_rf_e_r_e_n_c _ e ________________A _N _D __TV __I_N_ TE_R _F _E _R _E_N _C _E _l____________i_n_te_r_f_e_re_n_c_e_._______________

22

MAINTENANCE

BASICS

(Fig. 4) Replace plug wires one at a t ime to maintain the exact same routing as original. Use silicone grease on the boots to allow easy removal in the future.

take note if you fee l some looseness at the connection (it may have been ca used by engine vib ration). The plug w ire usua ll y is more accessibl e at the co il end , but it m ay not be a sim ple p ush-on. Si nce th e ea rl y 1980s, C h rys ler plug w ires o n engi nes w ith distr ibutors have been held in the cap by spring c lips. Co mpress t he tan gs of the clip with pliers a nd pu sh out to di sengage t he wire (Fig. 3) . Some Japanese makes have t h read-in" boots." Foll ow th e r o uting of a spa rk plug wire as if it were th e road to success, beca use when it com es to engin e opera tion, it really is. Every ma nufacturer includes li tt le plastic guides, and altho ugh they may cost pe nni es to make a nd in sta ll , they're used to locate each wire so it doesn't cause crossfire (a tra nsfer of high-vo ltage electricity from o ne cy linder's w ire to th e o ne that's next in the fir ing o rd er) (Fig. 4) . If yo u see o ne wire crossing over or under a no ther a t nea rl y r ight ang les, t ha t's a n example of the ro uting strategy used to avoid crossfi re. Of co urse, o n so me engin es w ith co il -on-p lug igniti o n (COP), th ere is no w ire and the boot is o ut of sig h t, out of mind. Al th ough t hi s type is immun e to hungry rodents, a boot m ay suffer interna l d a m age from hi g h-vo ltage e lectric ity o r crack in g from engi ne hea t. It's eve n possibl e for spill ed o il to fl ow und e r th e cover a nd ge t d ow n o nto the boots o n some cars, so ha ve a rag ha nd y w hen yo u 're ad dlI1 g eng lll e Oil. It's

th e engi ne running, so you've got to remove th e igniti o n cover a nd li ft t he COP modules to make a physical in specti on. T here are so me " hyb rid " des igns, w ith o ne coi l o n o ne plug t o serve two cy linders (Fig. 5) . The co il directly feeds a plug in a boot und ernea th , a nd th ere's a plug wire (rep lacea bl e) to a seco nd p lug. T he COP boots a lo ne are usua ll y (Fig. 5) Many newer cars have individual coils mounted on the plugs. Short wires connect opposite-firing cylinders.

und er $25 a set, a nd are stri ct ly a d ea ler part. Ju st pu ll the co ille lectronics modu le off the plug a nd t hen pull the boot off th e mod ul e. If th e boot is integra l to the electro ni cs th e price co uld be $ 100 each. There's no mainte na nce you ca n perform to extend the li fe of plug w ires. However, before yo u insta ll th e boot o n th e p lug, coa t th e in side wit h boot re lease lube (a silicone grease) to make it eas ier to re move next time. And w henever yo u wo rk und er t he hood , avo id nic kin g th e w ires, sp illin g so lve nt on them, or mishandlin g if you have to set them as ide w hil e yo u work o n something else. And if yo u see a w ire da ngling ve ry close to t he ex ha ust ma ni fo ld, reposit io n it in its g uid e to ga in so me clearance. A penny of prevention can be worth a co upl e of hundred

L-_i_nl_p_[_'a_c_ti_c_a_l _to__c_h_e_c _k _t_h_e_se__b_o_o_ts__w_i_t1_1._______________________________________________d_o_I_la_I_ ~s_0_f_c__ure.

REPLACING

SPARK

PLUG WIRES

~~ 23

EAS"i

Maintaining Your Tires

(Fig. 1) Always check your tires cold. Driving even a few miles will heat them up and change the internal pressure, possibly masking underinflation.

ably when the tires are overnight cold, or when it has been at \east 6 hours y kind of tire failur e- even a since the vehicle was driven (Fig. 1) . sirnp\e flat- is a h uge hassle. D on't try to "eyeba\l" a tire for norload, not what the tires are physiBut this can be avoided with mal inflation. You can't te\l the differcally capable of withstanding. careful tire maintenance. It the recent ence between a properly inflated tire Although tire pressure specificatire reca\ls and reports ot tread sepaand one that'S even 10 psi under. usually peak at 32 to 36 psi, buy tions ration have alerted yoU to the imporSome tires always look underinflated. a tire pressure gauge that reads to at tance of regular tire inspection and Some have stiff sidewalls and always ust \east 60 psi. That'S a typical pressure care, you're ready to go beyond i a look nOrlllally inflated. specificati on tor a compact spare. 1£ quick look to make sure the tires R ead the tire specification label, the vehicle manufacturer specifies a aren't flat. Most fa ilures are caused which usually is on the driver's tront pressure range, such as a minimum by underinflation, overloading your doori a or the matching surface on and a maxin"\llm, alwayS use the maxmb vehicle, or damage trom debris, curbs the pillar (Fig. 2) . T hese pressure imum. The higher the pressure, the and potholes. These are things yOU specs usually are lower than the greater the load-carrying capacity of maximum pressure allowed on the can check yourself. the tire, the more stable the vehicle's tire's sidewall, but they' re based on pref\\ght inspection each particular vehicle and its rated At least once a month, check your ertire pressures- in your driveway, pref -

A

24

Inspecting Tires

to a sharp edge at one or both sidesor mu ch grea ter o n o ne sid e is a sign of mi sa li gnm ent. sha rp rock, of course yo u' re going to If yo u see cuplike wear in th e look as soon as possib le for damage. But remember, even if th e exteri o r trea ds, typ icall y along one side, th e possibl e ca uses are wheels that are o ut looks fine, the tire may be damaged inside. Although it may not slow-lea k, of balance, worn -out shocks or struts, a nd loose suspen sion components. it co uld fai l suddenl y. You'd be wise The class ic sign o f unbal a nced w hee ls to get th e car to a tire shop so th e tire is high-speed (50 mph and up) vibraca n be demou nted a nd given an interti on, and it usuall y surfaces before th e nal inspection. Th e few doll a rs is a cuplik e wear becomes noti cea bl e. Susgrea t in vestment in peace of mind, pensio n problem s usuall y p roduce and if there is interna l da mage, fo rget shake at lower speeds. abo ut a pa tch. Inves t in new rubber. Look for any cuts on the surface of the tire that expose th e steel belt o r fa bWEAR ric cord. This is gro und s for INDICATOR BAR immedi ate replacement. Tires w ith un eve nl y worn trea ds sh ould be replaced , unl ess the problem is ca ught ea rl y and there 's pl enty of trea d dep th left . In tha t case, th ey co uld provid e a moderate amou nt of life o n the rea r wheels, particu la rl y on a fro nt-dri ve car. Ho w(Fig.3) Check the tread for cuts, foreign objects ever, if yo u have an a lland abnormal wear. The wear bars will indicate w heel dri ve that yo u pu sh when the tire is worn out. pretty hard, invest in an enti re set of new tires . Wheel a lignment a lso pl ays an important ro le in tire perfor ma nce. If Wheel Balancing the w hee ls are mi sa ligned , they don't Most shops have off-ca r electronic ro ll tru e down the road. T he side sli pbalancers that allow the wh ee ls to be page produces friction, which raises rotated to any position wi th out affecttire temperatures and not only ing their balance. The disad va ntage is, increases tread wear but ca uses the if there's any unbalance in the w heel wear to be uneven . So in spect the tire treads. As yo u hub, it won't be corrected. If thi s doesn't cure the vibratio n, it's wort h find do, pry o ut pebb les from the grooves . T hey reduce traction and can damage ing a shop with on-ca r equipment th e tread a rea . before yo u try something else . In add iThe tread s sho uld be deepest at ti on, make sure the shop has weights designed for your wheels. It ta kes at midpo int-at least Ys in. thick . That's )\6 in . above the tread bars th at are the least a half-dozen differentl y shaped official "replace them " indi cators weights to fit properly on th e rims of (Fig. 3) . H oweve r, yo u need tread all the p opular w heels . There are severa l so-ca ll ed "u ni versa l" we ights, but a bove th ose bars o r the tire wi ll do a poor job of shedding any water a nd th ey may not fit yo ur rim , a nd co uld slu sh it runs into o n the road. The pop off or ca use rim dama ge. wear pa ttern sho uld be rela tive ly even If the w heels a re balanced and yo u at each side, a lth ough it might be have wheel shake at medium speeds somew hat grea ter in the middle. on up, or the tires ha ve cup wear, Trea d wear th at is "fea th ered"-worn check the sh ock s and struts.

If yo u hi t a road hazard such as a

(Fig. 2) Appropriate tire pressures are listed on a sticker on the doorframe or the matching door pillar.

hand ling w ill be, and the coo ler the tire will ru n at speed. All tires leak air press ure over tim e. Th e closer the tires are to the recom mend ed maximum press ure, the greater th e safety ma rgin for a ll op eratin g parameters. A no rm al tire lea ks about .5 to 1 psi per month. In additi o n, as ambient temperatures drop wit h th e changes of sea so ns, so do the ti res' air pressureone psi per 10°F. It might seem th at th e temperature-related drop is marched by lower operating temperatures of the tires in cold weather. But the key to tire safety is adequate pressure to carry yo ur ve hicle's load . Although hi gher rire pressures sti ffe n th e ride so mew hat, it's a small price to pa y for th e ex tra safety and the a bility of the ve hi cle to accommodate greater loa ds. Ma inta ining proper tire press ure a lso improves fuel economy, altho ugh not by much. Ca ution : Overinfl atio n increases center tread wea r. Do n't forget th e sp are. And note o ur ea rli er wa rning abo ut the higher spec ified pressure for a compact spare. If yo ur spare is carri ed in the underbody, as it is on man y minivans, yo u' ll need to craw l underneath with a pressure ga uge and air hose.

MAINTAINING YOUR TIRES

25

HOW IT WORKS

Reading A Passenger Tire Sidewall RADIAL

A "P" or "LT" stands for passenger car or light truck tire. The 3-digit number (215 on this diagram) is the tire cross-section width in millimeters. The 2-digit number that follows (65) is the aspect ratio-the height of the sidewall relative to the cross-section. A lower number indicates a wide tread area relative to the sidewall-today's sporty look. The letter "R" means radial tire construction. The next 2digit number (15) is the wheel rim diameter in inches. A 2-

~

.• ':..

digit number following the size information is a load-versus-pressure rating. A letter that follows that 2-digit rating is a speed rating. Example: "S" is for a tire rated for speeds up to 112 mph. You'll also find maximum pressure (in psi and kilopascals), and maximum load (in kilograms and pounds). In addition, there are numerical or letter grades for relative tread life, traction and temperature (UTQG). The layout of the information may vary accordingto make.

LOAD INDEX AND SPEED RATING DOT SAFETY CODE

UTQG RATINGS

.

(Fig. 4) Minor scraping on the rim's lip is okay, but a bent bead surface may cause a leak or vibration.

Sidewall Check Us ing a tire and w heel cleaning product wi ll give yo u a cl ear loo k at both th e tires and whee ls. Yo u shou ld be ab le to fin d crac ks in th e whee l, damage beyo nd surface nicks to th e tire sid ewa ll s, and dam age to th e bea d area that cou ld be res pon si bl e for pressure lea kage (Fig. 4) .

Tire Rotation Every owner's manu a l has a tire rotation diagram, and tire ro tatio n ma y seem lik e motherhood and appl e

26

WHEEL RIM DIAMETER

(Fig. 5) To avoid warping brake discs, tighten the lugs in a crisscross pattern with a torque wrench.

pi e- a lways good. H oweve r, thi s subj ect is not so simpl e. Cost of ro ta t io n vers us longe r tire li fe is not a prec ise equation. It depends o n th e tires, th e driving, wheel a lignm ent a nd suspension cond itio n. Further, professiona l service is n ot always exp ertly done. Un less th e lu g nuts a re ti ghtened to specificat ions in three eve n sta ges, using a crisscross pat tern (Fig. 5) , the rotors may become warped, w hi ch add s to main ten ance costs. If yo u let the mil eage stretch o ut a bit, suc h as to 10,0 00 mil es or more , tires ma y deve lop

a lm ost imperceptible wear patterns that w ill affec t rid e w hen th ey' re moved to a new p ositi on o n th e car. If yo u ca n 't ro tate th e tires often, yo u m ay be better off leavin g them in place and accepting the somewhat sho rter tread life. Some tire treads are directi o nal. Th ey should rotate in on ly one directi o n a nd should not be rota ted excep t by a profess iona l who can demou nt them. H ow ca n yo u tell if yo u ha ve thi s type of tire? Look for a directiona l ar row on the sidewall .

fI

MAINTENANCE BASICS

(

I

'~

EASY

Jumpstarting Your Car

t hits yo u like an electrica l shock just as the airliner door sla ms a nd the flight attendant oh-so-poli tely instructs yo u to turn off yo ur cellphone. Less th a n an hour ago, you parked your car in the middle of a lO-acre a irport parking lot, expecting the vehicle to take YO Ll home when you return in five da ys. Except yo u reali ze that yo u forgot to turn off tbe headlights after your predawn departure from ho me and t he warning bLlzzer hasn't worked for eons, if yo ur car has one. And if it doesn't, there's no surpri se- yo u've done thi s before. G reat. Now w hen YO Ll get home yo u'll have to ca ll the a irport-approved towing service and drop close to a hundred bucks for a jump.

I

JUMPSTARTING YOUR

CAR

Neglect Is Abuse Lead-acid a utomo ti ve batteries are ac tuall y remarka ble a t de livering extremely high current for the few seco nds it takes to sta rt yo ur engin e, even in extremes of heat a nd co ld . What t hey are no t good a t is being able to recover after delivering mo re modest a mounts of current for a long time. Irreversibl e chemi ca l changes ta ke place. Specifica ll y, sulph a te need les t hat bridge the separator between the positive a nd nega ti ve pla tes for m w hen a battery is deep ly discharged. T hese needles no t on ly intern a ll y short the plates, ca using a hi gh self-d ischarge rate, they also coat the plates a nd interfere w ith the norma l lea d/s ul-

(Fig. 1) Make the last connection to a ground point not on the battery to prevent creating a spark near any venting, explosive hydrogen gas.

furic acid reactio n th at makes electricity to spi n your starter motor and run yo ur fu el inj ectio n and ignitio n long eno ugh to coax yo ur engine into life. Before yo u do anyt hin g else, check to see tha t the dead ba ttery isn't frozen. Whi le a fu ll y cha rged battery is a lmost freeze-p roof, a hig hl y disc harged battery ca n freeze w hen temps hit the low 20s. If the battery has them, remove the fi ller caps and look for ice crysta ls in the electrolyte. Don't try to charge a frozen battery. It wo n't

27

CHECK FOR IMPRINTED POLARITY MARKS

work, a nd will damage the battery furth er. If you need a boost start to get home, well ... life's like that.

Safety First

(Fig. 2) Make absolutely sure you've got the polarity correct whenever you work on a battery. If your battery has side terminals, use these adapter bolts (right) when jumping it or use jumper cables with clips shaped for side terminals.

HOW IT WORKS

Deeply Discharged Batteries A lead-acid car battery, like any battery, has an internal resistance, normally a few tenths of an ohm. This means that a charging voltage only a little higher than the battery's normal 12.6 volts will provide enough current to actually charge the battery at some decent rate, say, 10 to 12 amps. But as the battery discharges, its internal resistance goes up. And the curve is steep. When the battery is almost totally discharged, internal resistance can be high enough to prevent the 13.5 to 14 volts your alternator puts out from doing any significant charging. Charging current in this instance can be as little as only a few hundred milliamps until the battery's resistance goes down-and that might take many hours, or even days of charging at normal voltages. The answer is a high-voltage, high-rate professional charger that can supply as much as 25 to 30 volts for a brief period to give the battery a kick in the pants. This will generate a lot of heat, enough to cook a battery within a few minutes. Leave this business to a professional, and follow up with a normal 6- to 10-amp charge.

28

Your first task is to get jumper cables. Preferably nice fat ones with a quality, heavy-duty set of clamps . This is more than just tool envy- there'S a lot of current passing along those wires, more than an arc welder, at least for a few seconds. Resistive losses in the cable can reduce the voltage available to your stalled car's electrical system to the point at which it will still be difficult to start, even with a healthy donor battery and alternator adding their all to the mix . It's important to use fat cables and to have good electrica l connections to reduce these losses to a minimum. A set of 6-ft. cables won't do you much good if you're parked nose-in to a parking space-wlless you feel up to pushing a 3-ton SUV back a truck length to make the engine compartment available. Twelve or 15 ft. is better, which makes using heavy-duty cables more important because resistance losses are proportional to the length of the cable. Keep your cables clean and dry to prevent corrosion from becoming a high-resistance factor.

Doing The Deed It's nitty-gritty time. You've got cables, you've got a healthy donor car available. Open the hoods and position the donor car nearby, so that your cables will reach. Some cars, like the one illustrated on the previous page (Fig. 1), have a remote positive terminal someplace in the engine compartment. The battery is mounted in an inaccessible area or with its terminals inaccessible even in the engine compartment. As for where to attach the jumper cable, this junction will be clearly marked and covered in a red plastic sheath. If in doubt, consult yo ur owner's manual. Wear eye protection, even if it's only a pair of sunglasses. Once in a blue moon, a battery will explode

MAINTENANCE BASICS

(Fig. 3) If your car or RV is in storage and chronically needs help starting, a trickle charger will keep it ready and improve your battery life as well.

TRICKLE CHARGER

in tb e reverse ord er. Was h yo ur ha nd s if possibl e to prevent a ny ba ttery ac id fr om bleac hin g yo ur cl othes or getting into yo ur eyes .

when yo u try to jump it. Options Exp lode? Yes, explod e. If yo ur RV or second car is It's ca used by hydroge n in storage for extended gas, w hich is norm a lly periods of time, the battery vented by a ba ttery th at's will self-di scharge . The being charged or dissimplest solution is to use charged at a high rate, a trickle, or maintenance, say, when you 're trying charger (Fig. 3) . These to start a car, the battery chargers will automaticall y runs down and yo u need LEADS FOR PERMANENT adjust their charge rate to a jumpstart. H ydrogen is INSTALLATION CLIPS FOR TEMPORARY CHARGING a safe level, low enough to expl os ive, and a sp ark keep the battery at 100 fro m making a connecpercent charge without cooking it. more wh en the dead car starts, but it tio n can ignite it . It won't be a big They're not recommended for charging will help tbe donor car's battery sta rt expl os io n, but it can cer ta inl y blow dead batteries-just maintaining them. yo ur engine a little if you give it a the top of the plastic battery case off If you're not in a cra shing burry, quick shot of charge. If the dead car's and spray acid into your eyes . battery had enough charge left to make yo u might find cigar-lighter ca bl es Co nnect the red clamp on one end will get yo u sta rted (Fig. 4) . T hese of th e jumpers to the positi ve termina l the soleno id click and run th e interi or and in strument lights, then a minute or ga dgets just plug into th e two ve hion the dead ca r. Verify th e pol a rity of cl es' li ghter p lugs, p rov iding a modest the terminals by the plu s sy mbo l so is enough. If the battery was dead , leve l of ch arging, but not carr yin g molded into th e battery case (Fig. 2) . dea d, dea d, give it 5 minutes or so . Don't just use the red terminalenou gh current to start a car with a someone may ha ve insta lled an incortrul y flat battery. But if the engine w ill Crank, Zoom rect, red-colored termin al onto the almost start, a 10- or 20-minute N ow you ca n actu ally try to start your dea d car. When the car starts, let it run negative pole of the battery. Do the charge will get you o n yo ur way, out same on the p os iti ve terminal of the at fast idle for another few minutes still of th e wea ther and with cl ea n hand s. donor ca r. Start the d on or car and let connected to the donor ca r to continue Remember that the lighter socket on it idl e. Lights, bea ters, stereos and cha rging by both alternators. Idling the dea d car mu st be electricall y hot rear-w indow defrosters- all electr ica l provides onl y a modest charge rate, so with th e key off, or yo u' ll need to drains- should be off. after a few minutes the best thing is to turn o n the key in the dea d car to If possible, cover the dead battery dri ve the car at normal speeds for 30 compl ete the circuit. with a shop towel or a sheet of cardto 60 minutes. (Fig. 4) Minor board. Any acid that man ages to bubRemove the jumper ca bl es cases of won 'tble out o f th e vents will wind up on quite-start will the cl oth instea d of o n yo ur cl o th es or answer to simple-to-use the pa int on the fe nder. lighter-plug Connect to the negative terminal of starters and the donor car's battery with the black jumper cables. clamp. Verify the polarity. N ow connect the remaining black clamp to the dead car's engine block, an accessory mounting bracket or a p rotruding ear on a manifo ld. Use the battery's negative termina l as a last reso rt. This procedure will generate any sparks far fr om any hydrogen gas venting from the battery and reduce the risk of explosion. Now wait. This will let the dea d TO DONOR CAR battery recharge slightly. It will charge

fI

JUMPSTARTING YOUR CAR

29

MODERATE

Repairing a Leaky Radiator

Y

o ur radi a tor is lea king . Well , it happens. If yo u have n 't cha nged the coo la nt o n a reaso na bl e schedul e, it ca n beco me corrosive a nd eat thro ugh the ra dia tor. Even normal shaking a nd vibra ti o n w ill eve ntu a ll y ca use se pa ra ti o ns bet wee n th e pa rts th at a re connected by so ld er, ep oxy or mecha nica l crimps. Therm a l forces fr om engines heating up a nd coo lin g down ca n ca use c rack s in stressed a reas . Sea lin g gas kets ca n co mpress a nd a ll ow lea kage . And if yo u have a rea r-drive ca r with a mec hanica l fa n and wea k engine mounts, the engin e ca n lurch forw a rd und er braking far eno ug h for th e engin e-mounted fa n to " ki ss " th e radi ato r. O r it co uld be ju st p la in bad lu c k-a rock gets thrown up a nd pun c hes a ho le in a tube. Wh a tever its root ca use, a lea k is genera ll y o bvious. But w hat to do about the radiator? Repl ace it? After all , today's ra di ators a re supposed to be unrepaira bl e. Thi s is no t tru e at all , a nd th e best thing yo u ca n do is ta ke o ut t he radi ator a nd bring it to a radi ator sho p fo r a free consulta ti o n. If it ca n be repa ired, you ' ll not o nl y sa ve mo ney, but th e repa ired origin a lequipment (OE) radi ator p ro ba bl y will be a lot better tha n a new disco unt pa rt. It's no di ffe rent fr o m a ny rebuilt a uto mo bile co mponent, except th a t th e radiator has no mov in g p arts. Everyt hin g star ts w ith re mov ing th e lea kin g ra di a tor. Altho ugh do in g so ta kes some ca re, it's a stra ightfo rward job. In the ea sier cases, yo u can lift it o ut w ith shro ud a nd fan s attach ed, th en compl ete the strip-

30

(Fig. 1) Loosen and slide the hose clamps on the hoses clear of the radiator necks. Then, disconnect the hoses.

prepared to do a co mpl ete dra in-a nd-refill , thi s prelimin a ry step ca n help prevent trapping a lot of a ir in th e system. Air bubbl es lea d to engin e ho t spots a nd ping in summe r o pera tio n, a nd p oor hea ter o utput in the w inter. If there's an underbod y pl astic cover a t the fr o nt, remove it, even if it's not necessa ry to do so to drain the coola nt. With the cover off, yo u'll surely be a ble to collect the draining coo la nt w ith less splas h . You'll also be abl e to get to th e lower radiator hose more easil y, a nd you ca n inspect th e lowe r end of th e radi ator as well. Yo u might see a bolt-on connectio n to the cond enser o r the support member that yo u wo uldn 't otherwi se no tice . And w ith most Ja pa nese cars, which have downflow radi ators (tanks at the top

down o n the garage floor. And eve n in a rea lly ti ght engin e compa rtment yo u can usua ll y get it o ut w itho ut tou chin g the alc lines, or at w orst yo u wo uld o nl y ha ve to unbolt the radi ato r from th e sa me module th a t ho lds the alc co ndenser. Begin by di sco nn ecting th e battery gro und strap (even if th e ca r has beltdri ve n, ra ther th a n electrica l, fan s) . The next step no rmally is to drain th e radia tor, but befo re you do, in spect both radi ator ta nks (Fig. 2) If you have an electrical cooling fan, you'll carefull y. If you find a need to disconnect the wiring to it. hea ter hose co nn ecti o n, as o n a few ca rs, pinc h off th e hose just a few in ches fr o m the nec k, using loc king pliers . (If necessary, use a pa ir of tongue depressors or popsicle sticks between th e jaws to get a good squeeze .) With th e hea ter hose pinched , yo u w o n 't lose coola nt fro m th e hea ter during th e drain . It can be tough to get coolant to compl etely fill the heater o n som e cars, so unl ess you 're

MAINTENANCE BASICS

a nd botto m ), yo u' ll be abl e to reac h a ny hoses or w ires th at yo u must di sconn ect from the bo tto m ta nk. Rea d y? ow remove the press ure cap, even if it's on a separa te ta nk or on the engine. R emove th e radiator drain p lug (or open th e dra in cock ) and let the radiator dra in. Move tb e cl a mps off th e necks towa rd the mid po ints of th e radi ato r hoses (Fig. 1) , then di sconn ect th e hoses-in cluding th e hea ter hose if there's a co nnectio n at the radiator. If th e hoses are hea tsea led to the rad iator necks but in

.. ..

. .

REPAIRING

A LEAKY RADIATOR

good conditi o n, slip a thin sc rewdri ve r between th e hose and nec k, a nd wo rk it aro und to free the hose, th en twist th e hose a nd wo rk it off. D o n't pry w ith a large screwdri ver or yo u could distort a meta l nec k or even crack a plastic o ne. You may find it necessary to ca refull y slit th e hose w ith a sharp kn ife to get it to let go . Don 't sc ratc h th e neck, or it' ll lea k in th e futur e. As yo u di sco nn ect th e lowe r hose, a fa ir a mo unt of engin e coo la nt is like ly to fl ow o ut, so ma ke sure yo u have a la rge ca tc h pan und erneath.

Eva lu a te th e ra di a tor in sta ll a tio n a nd begin th e wrench work to fr ee it up. A typica l app roac h is to remove t he uppe r mo untlreta iner o n each side, or the single support member across the front. If there's eno ugh clearance for th e ra diator to come up a nd o ut with its shro ud and e lectri c fans intact, just unp lug th e electri ca l conn ectors for eac h fa n (Fig. 2) . If no t, yo u' ll o ft en be a ble to just unbo lt the shro ud a nd fa ns from the radiator a nd tilt th em back to provide c lea ra nce to lift o ut th e ra diator.

.

.

31

(Fig. 3) A radiator shop can replace a leaky O-ring seal, one or both end tanks or the core relatively inexpensively.

tanks crimped onto the core. Your nex t step is to take the rad iator to a radiator shop that actu a lly repairs plastic-tank ra diators. Th e Nationa l Autom oti ve Radiator Serv ice Associati on (NARSA) has been giv ing its members intensive training in the repair of these radiators, whether with copper/brass or al uminum cores , for several years (215/541-4500 ). So a radiator shop sho uld know how to fix it, and not simpl y try to unbox a cheap new radiator and se ll it to yo u. The chea p radi ators just don 't transfer hea t as well, and unl ess yo u can get a spectacular price on a well-made replacement, you're usually better off with a repair.

Can it be repaired?

Disco nn ect th e overflow hose and if th e reservoir is in the way, take it out. T hi s can give yo u your first close look at the reservoir. Many reservo irs develop hairline cracks that allow hard- to-t race lea ks, so if yo u have a lea k here, yo u just ma y have saved a bundle. If not, keep working. If yo u have an au to matic transmi ssion, th e radiator usuall y conta in s an autom ati c transmiss ion cooler. Disconnect the cooler lin es, a job that isn't always a simpl e wre nch operation. In th e easiest cases, there's a hose connecti on and a cl amp. In the most difficult, tb ere's a quick-disco nnect fittin g th at requires a specia l (but inexpe nsive) tool to separate. If YO ll have a quick-disconnect, as on most Ford products, and YO ll can't get the tool , yo u'll find tb at the radiator end of th e q uick-disconn ect has fittin gs

32

that threa d into the cool er. So a fittin g ca n be unscrewed , but be ca reful. Use a tight-fitting wrench and unthread slow ly, so yo u don't dama ge the quick-disconnect coupling. W hatever type the cooler connections are, be prepared to plu g them. Yes, yo u want to a void transmissionfluid leakage. But more critica ll y, if any amount of coo lan t gets into the cooler or its lines, it can be sayonara for the a utomatic transmission. You can plug a hose end with a bolt. Plug a fitting with a rubber eraser, vac uum hose plug or so me other cl ea n, soft, flexible materi a l th at will stay in place (but also come out easil y w hen yo u're read y to reinsta ll the radi ator). All clear ? Lift o ut the radi ato r and strip off an y parts you were a ble to leave in place. Virtually all late-model ve hicl es have radiators with plastic

Almost a ll car, light-truck and sport/ute radiato rs ha ve plastic tanks, eith er with a luminum or copper/brass core sections. They're precisely engineered to cool. And given today's tin y grille openings or no-grille underbody breathers, a cheap radiator is a bad ga mble. It ma y look shiny new, but it cou ld corrode and fail a lot faster th a n a properly repaired unit. When a radiator leaks, the most conunon causes usually are readily repairable at far less than the cost of a new quality radiator. It certainly has been true with the copper/brass radiators largely out of use. It's even more likely with today's designs, particularly aluminum-core radi ators, which can run $200 to $400 for a first-rate replacement. H ere are some repair examples: • Leaking gasket between plastic tank and core: Th e shop uncrimps the tank, install s a new gasket and reet·imps the tank (Fig. 3) . It should cost less than $75. • Damaged tube (perhaps from a stone): These can be fixed for an extremely modest labor charge with special epoxy or solder. Even aluminum radiator tubes can be soldered.

MAINTENANCE

BASICS

• Cracked plastic tank (per haps from therma l st resses): A new tank today is re lati ve ly in expensive for most makes, so th e jo b should cost less than $150. • Leak ing header: The headers are the metal pl ates at each end of the tubes. The radi ator ta nk s attach to the headers, eith er by crimping a gas ket joint or by so ld ering. O ld er Ford radiators have epoxy sea ling between th e hea ders and th e tubes . If leaks occur from cracked epoxy, a radiator shop can remo ve the old epoxy and insta ll a new sealing film using specia ll y shaped guns and other tools. Th e cost is typ ica ll y a bo ut $175 to $200 for bo th ends of the r adiator, abo ut half the pr ice of a new Ford radi ator. • Fan " kiss" or corroded radiator: the core is smashed in or leak ing from corrosion pinholes. If the tanks are good, the shop can install a new core-perhaps even an OE one- and reuse the old tanks, saving abo ut 25 to 30 % on the cost of a new radi ato r. And the resu lt shou ld be equal to a new OE radiator. If the OE rad iator is an inexpensive design, then there won't be much of a difference (perhaps less than $75), and you might as well buy new if it's in stock . However, one core fits

REPAIRING

A LEAKY

RADIATOR

many different sets of tanks, so stocking cores is simpler for a shop. Resu lt: T he cho ice may come down to a new co re that's availa ble now versus wa iting for a new radiator and having to spend up to $100 more besides.

Putting It All Together When yo u're ready to insta ll , inspect the rubber support bushings for the rad iato r. Ma ny of today 's radi ato rs are held by mounting systems that allow them to shake at a frequency tha t absorbs engine vibration. Replace heat-cracked or oil-soaked bushings. Otherwise, engine idle w ill be rough a nd the radi ator may shake itself into a leak . Clea n the threa ds of o il-coo ler quick-d isconn ect fitt ings a nd app ly Tefl on pipe sea ler before reinstallati on. If yo ur drained coolant was rela tively fres h, it's okay to put it back in if it's not contaminated with dirt, oi l or tran smi ssion fluid . Otherwise, use a 50/50 coo lant/water mi x . If yo u've ta ken thi s opportunity to flu sh the system with water, th en add ha lf the system's capacity of pure coo lant a nd top off with wa ter. Always check the carmaker's instructions for filling a radiator-and

th en go beyo nd that an d add a littl e more. Today's coo ling systems are notorious for convo luted passages th at ba lance heat transfer if the system is full, but trap air bubbles if not completely fill ed. If there are air bleeds, they must be open duri ng the fi ll -up. Jack up the front of th e car to raise the press ure-cap fill neck before yo u pour in coo la nt. Even if the fi ll neck isn't on the radia tor itse lf, the higher it is, the better the system wi ll burp air as yo u pour in coo lant. Make sure the reservo ir level is correct and that the air-sea ling gasket in the pressure cap is in good condition, so the system won 't draw in air as the coo la nt cools. And " thermocycle " the system, wh ich simpl y mea ns to warm it up, then let it coo l down. Check the radiator coolant level when the system is coo l, and top it off if necessa ry. Once is not eno ugh. Keep check ing eve ry day or so for a few weeks. Some air purging w ill continue, a nd the system shou ld draw in add itiona l coo lan t from th e reservo ir. The reservo ir level drops modestl y? Hey, th at's th e way it's sup posed to work. Top it off when necessary and you ca n conclude that all has gone we ll. (;

33

MODERATE

Curing Pulsing Brakes he driver in the left la ne suddenl y rea li zes he's abo ut to mi ss hi s ex it, so he cuts in fro nt of yo u. Yo u mas h the brake peda l, and it vibra tes like a runnin g cha in saw as th e a ntil ock brak ing system (ABS) keeps yo u o ut of a skid. Th a nkfull y, you don't rear-end the jerk 's car, as he al so bra kes to slow down. H e's o n th e off ra mp a nd go ne, so yo u do n 't get th e cha nce to pull a lo ngs ide a nd express yo ur feelings w it h universa l sign la nguage . But that's pro ba bl y a good thing. W hil e it can be reassuring to fee l that ABS-co nn ected bra ke pedal pulsa tin g beneath yo ur firml y p la nted foo t, it's reaso n to suspect a prob lem if yo u ge t th e sa me peda l pul sa ti o n with a li g ht to medium brak in g app li ca tion.

T

th e titl es of a ll bull etin s fo r yo ur specific ma ke a nd m o del ca r.

ABS-esque

Lug Nut Torque

If the brake feels like the ABS is

The No .1 ca use of brake ped a l pul sa tion is uneve n lug nut torqu e. T he usua l reaso n is th a t so me m ec ha nic overtightened the w hee l lu g nuts w ith a n impac t wrench, di sto rtin g th e brake di sc. How d o yo u kn o w if yo ur torq ue

cyc ling, but yo u k now th a t it's no t, check the indi vidu a l axle trigge r w hee ls in fro nt (a nd o n some ca rs a lso in back ) a nd the adj ace nt w hee l speed sensors. If yo u see a damaged w irin g co nnector, bent sensor mo unting brac ket or stone-damaged t rigger whee l, that's a likely cause. But on a lm ost a ll cars, th e ca use norma ll y is something in t he service bra ke itself, a nd the primary pro blems a re o nes yo u usua ll y ca n check a nd correct yo urself. Befo re yo u check eve n th e most likely pro bl ems o n a late model, m a ke a bso lutely sure there isn't a factory probl em with a specific fi x . Sure, this is low o n the " likely" li st, but it's a lo t eas ier to look for a bull etin th a n to pull w heels, etc. One poss ibility: th e AIID a ta Web site, a lea din g sup pli er of informati o n for profess io na l mechanics (www.alldata.com ). If yo u work yo ur way th ro ugh its consumer information section and techni ca l se rvice bulletin s (TSBs), yo u ca n check

34

(Fig. 1) There's no proper alternative to torquing the lug nuts in a crisscross pattern, by stages and with a torque wrench. Oil the threads and chamfer with engine oil.

w re nc h is acc ura te? Well , if it's by a na me- br a nd too l co mpan y and hasn ' t been throw n aro und o r ha d a ce ment bl ock dr opped o n it, it sho uld be o kay. C heck th e torque a t eac h wheel a nd comp a re th e read in g w it h m a nufac tu rer's spec if icat io ns. If th e re's a diffe re nce o f 20% betw ee n a n y t wo lu g nuts, th a t 's too mu ch. Tr y loosenin g a ll th e lu g nuts, c lea nin g th e stud thread s w ith

MICROMETER

(Fig. 2) A micrometer is needed to check that each brake disc (new ones as well) is a consistent thickness. Check about 1 in. in from the outer edge, at six or eight equally spaced places.

MAINTENANCE

BASICS

(Fig. 3) Borrow or rent a dial indicator to measure brake disc runout. Even a scant thousandth of an inch of wobble will make your right foot dance on the pedal.

'Miking' A Disc

a wire bru s h, lightl y coa tin g t he m and the nut c h a mfe r w ith cl ea n engine o il , a nd th e n re in stallin g th e nuts finge rtight. Nex t, usin g a cri sscross pattern , (Fig. 1) ti g hten all of th em to a bo ut o ne-third th e sp ec ifi ed rea din g, th en to two-third s a nd fina ll y to the spec ifi ed torq ue.

Basic Diagnosis If simpl e reti ghtenin g doesn 't fi x th e prob le m , particu la r ly if a ll w h ee ls were o ff to rqu e s pecs, yo u ' ll h ave to pu ll th e wh ee ls for a c lose r in s p ecti o n. F irst, iso late t he pro bl e m to th e fro nt o r rear w hee ls. Tr y dri vin g the car a nd then s low in g or stopping w ith t h e parkin g brake leve r li ghtl y pu ll ed up and yo ur fin ger o n th e ratc het 's re lease button . If th e ca r has a peda l parkin g brak e, tr y app lyin g th at lightl y, but be su re to pick a safe, d eserted parking lo t w ith s m oo th pave m ent. If the car s lows d ow n smooth ly to a stop, th e brake p ro bl e m is in th e fro nt whee ls . If th e car d ece lera tes in

CURING

PULSING

BRAKES

s urges , o ne o r more of t he rea r brakes m ay be o ut-of- tru e.

Full Inspection Ac tu a ll y in s pect ing th e w hee l a nd b ra ke is th e nex t step. Make a lig nment m arks for th e w hee l and a lu g stud before rem ova l so yo u ' re a b le to in de x the rim to th e sam e stud . W ith th e w hee l off, inspect th e ma tin g surfaces of the w heel and di sc hub surface . If th ey're packed w ith dirt or bad I y rusted , c lea n th em th o ro ug h I y (use 100-grit sa nd paper o r emery cloth ). Rem ove sa ndin g res idu e w ith a cloth and b ra ke solve nt. Lu be sparing ly w ith a nti se ize . Look c lose ly a t both sides of th e bra ke linin g contact surfaces o f t he d isc . Moderate scores (too sm a ll to snag yo ur finge rn a il on) are no t norma ll ya concern, but ru st o r o th e r m ateria ls are (typica ll y brak e li ni ng tra nsfer ). R ust o ften occu rs o n ca rs t ha t sit for extended pe ri o d s in damp clim ates w ith n o t-so-cl ea n a ir. Use a fin er abrasive (2 00 grit) o n t he di sc co ntact su r fa ces.

C hec k th e di sc for un eve n th ic k ness, using a mi c ro m eter (Fig. 2) a t six to e ig ht evenl y spa ced locati o n s on th e di sc, and co mpare th e read in gs wi th ma n u factur er 's specs. As littl e as .0005 in . (th at's fi ve tenthou sa ndth s!) is th e m ax imum , a nd yo u ca n believe t ha t yo u ' ll fee l a lo t o f d isc pu lsation a t .0008 in. Sho uld yo u get th e disc m ac hin ed? A lot of ev id ence says u n less a sho p do es a good jo b of m a inta ining its brake lat he, the res ults often a re poor. And if the di sc is cut too thin , it w ill war p eas il y in se rvice . A bra n d-new di sc is th e best ch o ice, but eve n th at sh ou ld be chec ked for eve n th ick ness .

Measuring Disc Runout M eas ure la tera l run o ut w ith a di a l indi cator (Fig. 3) o n the linin g co ntac t surfaces , on both sides, wit h the lug nu ts reinstall ed and tig htened to appro x imate ly 30 ft.- lb . T he ma x imum a mount o f run o ut shou ld be .00 3 in . If it's m o re, ind ex- ma rk th e ca li pe r to th e hub, a nd rem ove th e ca liper a nd th en th e di sc. Ins pect th e m a tin g surfaces of the disc a nd hub and if there 's ru st , remove it w ith ge ntl e us e of 200-g rit paper. A lso rem ove an y d eb ri s a nd cl ea n th e surfaces w ith bra ke so lve nt. Rota te th e di sc c loc kwi se o n e stud , rein st a ll , tig hten th e lu g nuts a nd rec heck. D o th is a coup le of tim es to see if yo u ca n brin g rLlIlout down to an accep ta ble le ve l (th e prob lem m ay ha ve been produc ed by

35

plastic or metal sleeves. W hen yo u re move the ca liper (Fig. 4), inspect everythi ng. If the guide bo lts or p ins a re corroded , rep lace them with brand-new ones, lubed with silicone grease (don't tr y cleaning them ). D itto (incl uding silicone lu be) for the sleeves if they're corroded or crack ed, and the bushi ngs if they a re deteriora ted.

PISTON

Rear Drum Brakes (Fig. 4) Sloppy, corroded or deteriorated pins and their mating bushings on some calipers can cause wobble and pu lsation.

fai lure to make a nd fo ll ow a li gnment ma rks a ft er so me ea rli er serv ice procedure). If yo u ca n't bring runout down eno ugh, check the hub for runout.002 in . is the maxi mum. The thought of repl acing the hu b may not be appea ling, but unl ess run out is fa r beyo nd reason and pu lsa ti o n is intolerab le, keep it in mind if noth ing else surfaces as a possibility. A p rofession a l shop w ith an o n-car lathe may (we repea t, ma y) be a ble to mach ine a disc so th at it's referenced to the hu b, to compensa te fo r a sma ll amo unt of excess ive hub runo ut.

Brakes Not Releasing W hen there's an uneven t hickness

pro bl em o n the d iscs at re lative ly low mileage (under 50,0 00 ), acco mpa nied by short lin ing li fe , it's poss ible the bra kes aren't relea sing fu ll y, a ll owing the shoes to stay in contact w ith the di scs. A defective caliper piston (sti cking when yo u try to p ush it back ), a bad p iston sea l (no t retracting th e pisto n ) a nd a stick ing ca liper are a ll poss ibili ties . W hen th e ca liper does n't slid e smoothly bac k a nd fo rth, th at's tro ubl e, and short lin ing life from fa ilure to retract the shoes completely is just o ne consequence. T he bra ke shoes may a lso slap unevenl y aga inst the di sc, anoth er ca use of pu lsa tio n. Most ca li pers slide a long guide bolts or pins, through bushings with

The rear drums are not as freq uent a cause of pulsation as rear discs, but if they're warped, or if the linings are no t making good contact, they certainly ca n be responsible. Un less a drum contact surface is bad ly grooved (grooves here are not as acceptable as on a disc ), you 'll need a dru m gauge to check for taper or o ut-of-ro und. Or as k a machi ne shop to measure it fo r yo u, as the typica l shop will do it fo r free or a nominal charge. Linings that are worn very un evenly are a tip-off to a drum that should be measured. Also check fo r bro ken springs, or springs that show obvio us signs of weakness by allowing shoes to move easily. Invest in a good torq ue wrench, keep it in the trunk and use it to ti ghten the lu g nuts in stea d of the lug wrench w hen yo u have a fl at. Yo u sho uld enjoy smooth modera te stops fo r the life of the car. fI

HOW IT WORKS

Tire Imbalance Tire imbalance, per se, shouldn 't cause a pulsating brake pedal. Brake pedal vibrations are almost always caused by an outof-true condition somewhere in the braking system. But on rare occasions it can happen. Normally, each tire has to be balanced statically first-i.e., so no part of the tire is heavier and always sinks to the bottom. Then they all need to be balanced dynamically, so the rim doesn't wobble at higher speeds. Any imbalances from either of these conditions normally will manifest themselves as steering-wheel vibration,

36

,

not brake pedal vibration. Even a tire with a high or low spot will normally be felt through the wheel. But once in a great while you'll find a tire that has inconsistent stiffness. Some parts of the tire's sidewall will be more or less easy to deflect under load than others. This won 't show up on the wheel balancer, but will make a brake pedal pulsate at a rate proportional t o your road speed. The diagnosis is to swap for a different tire and see if the problem goes away.

J

MAINTENANCE

BASICS

MODERATE

Getting Your Car Ready For Winter especially during damp winter days. This m o isture ac ts as a conductor a long a path th at normall y does n't condu ct electricity at a ll, and can leak enough current between the battery posts to prematurely drain yo ur battery. In fac t, co nsid er rep lacing yo ur battery if it's mo re tb an 4 yea rs o ld . Newer cars tend to use sma ll er ba tteries to red uce weight and improve mileage , and, combined w ith high und erhood tempera tures, th at spell s Winter Takes Its Toll an ear li er demise th an The traditiona l tuneup is yo u may have gotten 10 gone. Newer cars are large ly to 15 years ago . self-tuning, and do n't have igniWhile yo u're at it, tion points or carburetors to check all tb e electrica I tweak . Factory-fill radiator conn ections for loosecoolant in some new cars is ness and corrosion. That rated for five yea rs or far lo nger (Fig. 1) Use warm water to clean the battery posts and clamps. Use baking soda for stubborn sulfate deposits. may mea n getting und erthan many peop le keep a car in neath the ca r to see the this age of low-monthly-payground strap a nd so leno id/s tarter melted snow w ill infiltrate d irt deep ment leases. motor connections. into th e fibers, th ere to remain forCars are still imperfect, m echa ni Check all light bulbs a nd repl ace ever. Dump the as htray. Clea n the cal contrivances, howeve r. Although any that aren't wo rking. The d ays w heel we ll arches and und ercarriage many m a intenance re qui rem ents are are short during the winter, and reduced, there's still plenty of stuff of mud a nd road dirt, so that sa lty yo u' ll depend on th ese bulb s for visislush does n't soak into th em, providthat can break or fall off. An afternoo n of preventi ve ma intenance will bilitya much larger propo rti o n o f ing a perfect en vironm ent for rust. grea tly reduce the possibility of bad the day. things happening. It 's a utumn-th e Electrical leaves are fa lling, but the weather is While yo u' re cleaning, clean the batUnderhood in General still relatively warm. A couple of tery with warm w ater. Remove th e Still in an electrical mode, check the ho urs of maintenance w ill be a lo t terminals and w ire brush them and alternator connections and mo unts easier to take now than a couple of the battery posts with warm water fo r looseness and evidence of overhours of repa irs when yo u have to and ba kin g soda (Fig. 1) . Reattach hea ting. High electrical demand s for shovel yo ur wayan ext ra 50 ft . to th e termin als and coa t a ll exposed lights, hea ter fa ns and rear-wind ow work in an unh ea ted garage. metal with petrol eum jell y. Yo u're defrosters, as we ll as recharging a batnot do ne yet-u sing so me sort of tery ab used by coaxing a reluctant The Easy Stuff ho useho ld cleaner, clean a ll traces of engine to life, can make a margina l Clean. Clea n out the interior and the dirt and o il from the battery's top connection overheat. trunk . Shampoo the carpets and the a nd sides, particu larly near the termiCheck accessory belt condition and seats , beca use a winter of slush an d nals. Traces of dirt can tra p moi sture, tension, beca use that extra electrical

now covers yo ur car. After 10 minutes of shoveling snow and ice from the roof and w indows (not to menti on 30 minutes of shoveling the dri veway), yo u' re rea dy to go to work. Twisting the key languidly brings the engine to life, much to yo ur relief. But ... th e windshield wipers leave strea ks, th e washers drizzle fluid inches short of the glass, the battery light flickers and the heater fan blows little a ir of any temperature. Not a particularly good da y for even a late-model car that's been neglected.

S

GETTING

YOUR

CAR

READY

FOR WINTER

37

(Fig. 2) Check belts for proper tension using a tension gauge. Serpentine belts can also be checked with a gauge, although they aren't as likely to be loose.

dema nd will strain a ma rgina l belt (Fig. 2) . Man y modern ca rs have a single se rpentine, a utomatica ll y tensioned belt, but it still can fr ay a nd come off. C heck a ll rubber hoses . Five years, in th ese t im es o f a ir po llut io n a nd hi g h und erh oo d tempe ra tures , is a leg itim ate life spa n fo r a rad ia-

to r hose. If o ne seem s sq ui sh y, brittl e o r ju st s uspect, now wou ld be a goo d tim e to replace th e m a ll. C heck th e d a te o n the coo la nt. (Re membe r many new cars have ex tended dr a in inter va ls-but no t p e rm a ne nt coo la nt. Rea d th e ow ner's ma nu a L) [f it's du e to be rep laced ,

use a 50 -50 mi x of fr es h coo la n t a nd wa te r (Fig. 3) . Co nsider cha ng ing yo ur tra nsmission fluid, differenti a l lu brica nt a nd brake fluid if yo ur ca r is more th a n 3 yea rs o ld. Lubri ca nts brea k d ow n, a nd brake fluid a ttrac ts mo isture a nd d eteri o ra tes . At a ny ra te, check th e leve ls, and d o n't forge t the p ower steer ing rese rvo ir. F ill the w ind shield was her ta nk w ith was her fluid. C heck the pump a nd nozzles fo r a hea lth y, we ll -a im ed sp ray pattern. Ma n y nozzles ca n be re-a imed b y in se rt ing a pin into th e nozzle to use as a ha nd le. Winds hie ld w ipers are esse nti a l for w inter driving, a nd afte r a SUJllm er of sun shin e, th e rub ber sq ueegees are probab ly in so rr y shape . Pl ay it safe a nd replace th em. Be sure th e w iper arms a nd sp rin gs a re in good shape,

HOW IT WORKS

Oil Viscosity Fall is a good time to change oil and filters. Check your owner's manual for the rating and viscosity, but most cars nowadays use an SL-service rated oil. This rating is some measure of the oil 's longevity and resistance to oxidation and evaporation. SL oil is fine for older engines that specify an SG- , SH-, or SJ-rated oil, because the rating always improves when a new one is introduced. The SAE viscosity rating is a measure of how thick the oil is. All modern cars should use a multigrade oil, probably a 5W-30 or lOW-30. The W in these ratings stands for a winter viscosity. A multigrade oil will be as thin as the thinner (5W- or lOW- rating) when the engine is first started. This will allow oil to flow more rapidly and lubricate parts that have had all the oil drain off of them overnight. A thicker oil might not be pumped to remote parts of the engine rapidly enough. On the other hand , a thicker oil (the second number in the rating) will resist becoming too thin when the engine reaches operating temperature. The American Petroleum Institute is an industry watchdog and oils bearing the API emblem can be expected to meet their specifications.

38

In spite of what your brother-in-law the shade-tree mechanic tells you, don't use a heavier grade of oil just because you used to in your older car. Modern cars were engineered to use 5W-20, 5W-30 or lOW-30 oil yearround. Check the owner's manual to be sure. The lighter oils are also better on fuel consumption and can significantly improve mileage.

When buying engine oil, check for API certification and SAE rating.

MAINTENANCE

BASICS

a nd th a t th e bl ad e is held squ a re to th e w indshie ld surface . You may need to bend it sli g htl y to keep everyt hing sq ua re. C hec k th e a ir cl ea ner, a nd consider replacing it and the fuel filt er (if yo ur ve hicl e has a repl ace ment type, no t the perm a nent one in the gas tan k) . Th e fu e l filte r w ill tend to trap wa ter, and o nce it tra ps eno ug h, it w ill fai l a nd may dum p so me accumu la ted dirt into yo ur fu el inj ection system . And winter, o f course, is w hen yo u tend to find the most wa ter in gaso lin e at th e pump.

bial dared 6-yea r-o ld's tongue sti cks to a frig id fl agpo le.

Rust Never Sleeps

Befo re the sa lt tru cks come o ut is a good tim e to ge t out th e to uch up pa into Use it to cover a ll th e bare metal at the bo tto m o f a ny sto ne c hips a nd parking lo t dings. C lea n rh e c hipped a rea thorou g h Iy, a nd use a too thpi ck or a ma tch to ap pl y a touch of zin c- rich primer to the bare metal. All ow this to dr y, a nd chase a ny overlap back to th e lip of th e scratch with lacquer thinn e r. Th en ca refull y fill (Fig. 3) In spite of long-life coolant in many new cars, eventually you'll need to drain and refill with th e chip w ith to uc h up paint. fresh coolant mix. It' ll shrink, so yo u may need Where The Rubber Meets seve ra l a ppli ca ti o ns to build up The Road th e leve l of pa int to flu sh . ca lipers a nd sliding pins. Wh il e th e Dri ving in snow d ema nd s goo d tires. Be sure yo u ha ve a d eq uate tread w hee l is off, pu ll th e pa d s out of the ca lipers and be sure everythin g is slid- On the Road d ep th, a nd consid er changing to ing free ly. Wire brush sliding-key snow tires if yo u li ve in a heavy snow Even a perfectly running car ma y w ind up stu ck in a snowbank. So put a rea. Go a hea d a nd pick up a set of ways a nd pin s that let t he pa d s pull bac k from th e di sc when yo u remove in expe nsive stee l w hee ls a t th e loca l together a kit of essenti a ls for yo ur sa lvage ya rd for yo ur snows in stead yo ur foo t from the brake. Exerc ise trunk. This should includ e flar es, a of hav ing yo ur tires remounted and the p isto ns b y push in g t hem back fl as hli g ht, jumper cables (if only to ba la nced eve ry fall a nd sprin g. And into th e ca lipe rs and th en press in g o n help so me unfo rtun a te so ul w hose car whi le th e ca r is up on th e sa fet y the bra ke p ed a l once o r tw ice to was n't winterized li ke yo urs), a fo ldsta nds, inspect th e suspension bushbreak up corrosion between th e pising ca mp shovel, kitty litter for tracings, control a rms, ba ll jo ints a nd tie ton a nd the ca liper. ti o n, a ca n of gaso line anti-freeze, a nd rods, a nd th e brakes. Now wou ld be Again, it's a lo t eas ier to look a t tire chains if th ey ' re lega l in yo ur a good tim e to replace t he bra ke pa d s thi s stuff o n a c ri sp a utullln da y than sta te. If yo u eve r tra ve l outs ide o f if they are more than 60 percent it is to try to fi x it so me sub ze ro urba n a reas, a co up le of blankets a nd worn. Even if th ey a re no t, chec k mornin g when a ll of yo ur wrenches a ce llph o ne or CB rad io o ug ht to be carefu ll y fo r co rrosion around th e stick to yo ur fin gers li ke the proveron boa rd as wel l. ~

GETTING YOUR CAR READY FOR WINTER

39

EASY

Repairing a Flat Tire pressure or flat. Driving m ore than a few feet w ith the tire at zero inflati on pressure may ca use the rim to go uge th e inner liner, damaging the body cord . Driving at mo re tha n a wa lk w ith th e tire a t very low pressure ma y build up eno ugh heat to damage the sidewall beyond servicea bi lity (Fig. 1) . The portion of the nail or wire that entered th e ti re's interior may have fl ailed aro und and ripped the inner liner or plies (Fig. 2) . After in specting the tire, th e technici a n may app ly a proper patch , remount the tire a nd rei nfl a te it.

Here's How

here's rarely a more welcome sight tha n the insid e of a warm garage late at night, as yo ur door ro ll s open to we lco me yo u and yo ur fam il y ho me after a t rip o ut of ' town. Partic ul arly to night, beca use you're far la ter than expected. Fla t tires are genera lly no more tha n a nui sa nce-but t hi s time yo u found yo ur spare tire to be as flat as yesterday's beer. Fortun ately, a nice yo ung gentlema n working in a gas station o nl y a ha lf mile up the road man aged to plug yo ur tire w ithin a few minutes. Yo u watc h the inflati o n pressure of the tire for a week or so, a nd everything seems fine. Until a few weeks la ter. Then the sa me tire disintegra tes suddenl y o n th e intersta te in heavy traffic. You ma nage to ma intain control of yo ur SUV by lifting partway off the thro ttl e a nd gingerl y steerin g ove r to the sho ulder, ignoring the cacopho ny of th e fa iled tire as it fl a ps violentl y in the w heel we ll , shedding parts as it tears into pieces . It's not just flat, it's a smoking ru in , and there's substantial

(Fig. 1) This damaged area inside the sidewall was caused by driving the tire when it was flat.

da ma ge to yo ur w heel well 's sheetmetal to boot. Obv io usly, th ere was mo re damage to yo ur tire than met the eye-and the ni ce fellow w ho repaired it for yo u didn't necessaril y do yo u any favors.

The Right WayAnd The Wrong Way The tire indu stry has a rule a bo ut externall y pl ugging a tire w ith a worm. Don 't. It's a qualified exclusio n, a nd we ag ree with it, for good reasons. An externa ll y a pplied worm might be an acceptable emergency get-home-tonight quick fix, but a properl y trained tire techni cia n must late r co mplete th e repa ir by remov ing the tire fro m th e rim a nd do ing a co mplete inspecti o n of th e tire for additio nal p unctu res and damage. Damage ca n come from no t o nly th e na il o r w hatever caused the air loss, but a lso fro m runn ing the tire at low

Okay, we doubt many readers w ill ever repa ir a flat them selves beca use it in vo lves some pretty exp ensive tools. However, we've done it w ith nothing m o re t ha n hand too ls and a 12-vo lt portabl e compressor, a nd more than once, too . Once, it was late a t night a nd we didn't wa nt to wa it for the ti re shop to open. Ano ther time, it was beca use we were in a very re mote area, a nd a trip to tow n was nearly a two-d ay hike.

Busted Wheel/tire assemb ly off the ca r ? (We've do ne it with the rim still bo lted to the axle of a trail er but it 's to ugh work.) Start by inflating the tire a nd subme rgin g it in water to look for bubbl es . Now ro ll the tire a long th e gro und in a good li ght to look for the pun cture. Cha lk a ny suspic ious ho les in the trea d, even if there was no stream of tin y little b ub bles associated w ith it. You'd be a ma zed at how m a ny times tires a re take n in for repa ir w ith multipl e punctures . Make a c ha lkm ark o n th e ti re sid ewa ll next to the va lve stem , because the ti re sh o uld be reinstalled in the sa m e ind ex. Now yo u can remove the val ve core to completely

M A IN TEN A NeE BAS I C S

40

DAMAGE NOT VISIBLE FROM OUTSIDE OF TIRE

(Fig. 2) An innocuous-looking nail through the tread may have damaged the inside of the tire.

deflate the tire a nd demo unt it . Next, with a bright light, carefully inspect every sq uare inch of the inn er lin er. Pay particular a ttention to the areas inboard of th e cha lkmark s yo u've mad e. Look fo r damage caused by the fore ign object. Such a ho le may be p atched if the object has n 't d amaged any cord, although a ny exposed cord usually mea ns t he tire shoul d be scrapped .

Also look for p eripheral damage ca used by the tire being pin ched between th e rim a nd the pavement. Any da mage to the inner lin er th at came a bo ut as a resu lt of friction by being p inched a nd then dr ive n makes the tire a likely ca ndidate for immediate rep lacement. Any punctu re through th e sidewa ll of the tire a utomatica lly means the tire needs to be scrapped.

Remove any fore ign o bj ects in the tread by grasp ing th em wi th p liers a nd ya nkin g th em o ut. Make no te of t he angle the objec t ma de to t he surface of th e trea d . In fac t, yo u sho uld take a thin probe, lik e an aw l, a nd probe the ho le stra ight through in to t he ins id e of the tire. Look for evidence of cut cords or separated pli es, beca use they' ll be sti ck ing o ut of the ho le.

HOW IT WORKS

Run-Flat Tire A few late-model cars come equipped with tires that can be run without any air at all, at least far enough to get to a place where they can be repaired. These tires, available from several different manufacturers, can be retrofitted to any car that uses an appropriate size tire. The sidewalls of these tires have an extra piece of molded rubber near the bead. This rein forcement is stiff enough to keep the rim from contacting the inside of the tire, even under cornering and braking. The tire and auto manufacturers specify an upper

REPAIRING A FLAT TIRE

Run-flat tires' bead reinforcement provides stiffness to keep the bead seated on the rim and prevent sidewall damage.

TREAD

BEAD

limit on speed-usually 50 or so miles per hour-and a maximum range-often 50 or 100 mileswhen the tire is deflated. Because the performance of these tires with zero air pressure is so good, tire manufacturers require any car fitted with them to have a tirepressure monitoring system that will alert the driver to the fact that he's driving on a flat.

41

(Fig. 3) A tubeless t ire puncture can be properly repaired only by breaking the tire off the rim and pulling a stem-type patch through the t read from the inside.

Straight Holes If the ho le ma kes a 25 " or sma ll er a ngle to th e tread , t he correct p a tch to use is a " mushroom " pa tch (Fig. 3) . The head of the mu shroo m provi des a good a dh es ive sea l to the tire's inn er liner for pro per a ir retenti o n . Th e stem o f th e p a tch se rves severa l p urposes . It plugs th e ho le to a nchor th e p a tch a nd , in concert w ith the c hemi ca l vulca nizing cem en t, prevents wa ter fro m entering th e ho le and w orking its way into the tire's trea d . Using a proper tire rea met; clean out the hole fro m the inside o ut (Fig. 4) . Aga in , look carefull y fo r evidence of wire o r tire cord . T he rea mer w ill remove any road dirt o r o il and all Yda maged rubber fro m the ho le, leaving a fresh rubber surface for bonding the cement. Center the p atch over the ho le inside t he tire, a nd mar k a ha lf-inch

42

(Fig. 4) Thoroughly ream t he puncture t o clean the rubber and provide a good bond.

a ro und its perip hery w it h cha lk. Use a tire bu ffin g too l to remove t he surface of t he ru b ber a nd leave a sm ooth texture. A power buffin g too l is best, but a ha nd sc raper w ill wor k . Do n't b uff

thro ugh the lin er into the p ly rub ber or th e cord . Bru sh, blow or vac uum t he ru b ber dust a w ay from the buffed area . D o n't to uch this area w ith yo ur fi ngers o r a rag .

MAINTENANCE BASICS

Coat yo ur awl liberall y with cement and run it in and out of the hole several times to carry the cement throughout the hole. Leave the awl in the hole until just before installing the patch so the cement stays liquid. Remove the peel-off tab from the patch, and put a single coat of vulcanizing cement on the head of the patch and the buffed area. Allow this to dry thoroughly, and don't touch the cemented areas because the moisture and oil in your fingerprints will prevent good adhesion. Lightly coa t the stem of (Fig. 5) Oblique punctures require a different plug. the patch with cement. Pull our the awl , and pull the stem of the patch through the hole. Stitch patch. This involves reaming the hole the patch (using a tire patch stitching and installing a rubber stem with tool) to the tire from the middle out to cement. The stem is then trimmed prevent any a ir bubbles fro m being flu sh with the inner liner, the area trapped under the patch. Now cut the buffed and a patch is cemented over protruding stem off nearl y flush with the top of the stem. the surface of trea d rubber.

Back On The Road Oblique Holes If the hole isn't within 25 ' of vertical (Fig. 5) , yo u' ll need to use a two-piece

REPAIRING

A FLAT TIRE

Before remounting the tire on the rim (a jo b for a professional with specia l equipment), take a hard look at the

rubber va lve stem. If it's weather-beaten, damaged o r just more than about 5 years o ld, pop it o ut and pu ll in a new one. Use the correct diameter and length, and a valve core that matches. Valve stem caps aren't there to simp ly backstop the valve core's air retention-they keep moisture and dirt out of the stem and out of yo ur tire. Reinfla te the tire. Use soapy w ater to check the beads, va lve stem and the repair for leaks . And keep a close eye o n yo ur tire for a few weeks, both by monitoring the a ir pressure a nd looking for evidence of delam ina tion or a belt failure. A failed belt usually will cause an out-of-round condition and the ride will often indicate it. Ca n you adequately repair speedra ted tires? So me ti re ma n ufacturers di sagree, but at leas t o ne (Goodyear) says yo u ca n . They do specify th at there can be on ly a single r epair, less than one-q uarter inch in diam eter, per tire. (I

43

MODERATE

Servicing Your Ale t's hot, so hot yo ur car's interior juice is getting to the clutch by probHowever, after the system has been shimmers. Getting into the car is ing its wiring connector with a 12shut off for a few minutes, pressures clearly out of the question, at volt test light (Fig. 2) . If the light equa lize, so you can check pressure at least until the air conditioning hau ls doesn 't go on, there 's a break in the both of the service valve ports (one out a few million BTUs. You lean in circuit. If it does go on brightly, attach low-pressure, one high-pressure). and twist the key, being careful not to a jumper wire to the ground side of They should be the same-rough ly raise blisters by touching the steering the clutch circuit. If the clutch sti ll equal to the ambient temperature. wheel. The engine fires If pressure is less, the and idles smoothly, then refrigeration system is low you punch the max cold on refrigerant, and that button on the dashcould account for the failnothing happens. ure of the compressor to Great, you think, at engage. Have a profesleast in the old days, ordisional trace the leak and nary folks used to be able then recharge the system to purchase R -12 refrigerwith refrigerant. Incidenant to punch up a tepid tally, if the service va lve air cond iti oner. Not anyca ps are missing, they more. And it won't be too could be the cause of your long before R-12 is off the loss, as they provide the GAP market completely- a vicreal sea l, not the valve tim of federa l regulations itself. Warning: Do not try that restrict the manufacto seal leaks withalc sea ler ture of ozone-depleting prod ucts-period. chlorofluorocarbons. (Fig. 1) Gap between hublplate and pulley should close when Important: Use only Ralc is turned on. Fortunately, it's still 12 in an R-12 system, Rpossible for the average 134a in an R-134a system; Saturday mechanic to fix some of what won't engage, it's bad. never mix the two! Right now, there's ails his air conditioner without having It takes special tools to change a still some R -12 around, so you might to open up the system. To keep you in compressor clutch. Unless you can want to keep the system on R-12. However, if you ever have a compressor the service picture, let's consider just a rent them, leave this job to a pro. few of the common causes of poor-or If the clutch engages when you jump failure, the replacement will likely be compatible with R-134a, which would it, there's a problem with the ground zero---cooling that you can diagnose make changing over to the new refrigand cure. Start by acquiring the alc ser- circuit, which may be wired through to erant simpler. But th is is not do-it-yourthe engine computer. Both circuit probvice manual and electrica l schematic self work. It takes special equipment. lems require straight electrical diagnofor your vehicle. You'll also need a 12The alc pressure is normal? Apparsis and a good wiring diagram. volt test light. A volt-ohmmeter comes ently, the problem is purely electrica l. However, the refrigeration system in handy as well. And in this case the first step is to may also be involved. There's a lowcheck for a computer trouble code. pressure switch in the current-feed No Cooling The engine computer? You bet. On circuit that is designed to keep the If the compressor doesn't engage, compressor from engaging when pres- most American cars and some there will be zero cooling. An electroimports, turning on the air conditionsure is low. magnetic clutch shou ld lock the drive ing at the dashboard is just a request See if there's enough refrigerant hublplate on the compressor (Fig. 1), to the engine computer to provide the pressure to close that switch, which with the belt-driven pulley to spin the electrical ground to complete the comrequires pressure gauges, and hoses compressor shaft. pressor clutch circuit. If the engine The clutch circuit is fused, so check that attach to your system. When the system is running, one half operates at computer sees a reason not to, the alc the fuse. The fuse is good? With the won't come on. Possible reasons, in low pressure and the other at high. engine and the alc on, check to see if

I

44

MAINTENANCE BASICS

addition to low refrigerant, include warning signa ls from certa in engine sensors . The coo lant-tempera ture sensor may be signaling a very high coolan t te mpera tu re, and a ll owing the ale to come on could ca use overheating. O r a power-steering switch may be signaling high pressure (as in a parking maneuver ), and all owing the alc to come on could add to the engine load fro m the belt-drive n accessories and sta ll the engine . Of course, some of these signa ls may be wro ng, and yo u' ll need to investigate the so lu tion to these engine pro bl ems to get the alc online aga in. No comp uter tro uble codes? C heck fo r a bad alc clutch relay. Also, note

SERVICING YOUR

AIC

tha t some of the comp uter sensors are not covered by tro uble codes-the power-steering sw itch is a common exa mple. If yo ur car has one, bypass it for tes ting. If th e compressor now comes on, rep lace the switc h. No cl ues in th e comp uter circ uit ? Refer to an ale circ uit diagram to see what ad ditional switc hes or relays are in th e co mpresso r-c lu tch circ ui t. On many cars of a ll makes (particul arly R-12 systems), there's a sw itc h that cycles the compresso r clu tc h on and off to co nt rol performa nce. You ca n fin d out if the switch is ba d by un p lugging it and attac hing a jumper wire across its connector. If the compressor now comes on, the switch

(Fig. 2) Use a 12-volt test light to probe the alc compressor's clutch wiring. If the clutch isn't pulling in, there's no cooling.

apparent ly isn't clos ing. Confi rm thi s with an ohmmeter acr oss the sw itc h ter minals. O n GM and Ford ve hicles, the switch us uall y is on a large cy li ndrica l can ca ll ed the acc umul ator. On ma ny C hrys ler prod ucts, it's in a block at the fi rewa ll. Ba d sw itc h? O n late-models, the sw itch is mo unted on a Schrader va lve. As yo u unt hread the switch, the va lve closes so yo u wo n't lose any refrigerant. Grease the new O-ring w ith minera l o il, gently pos ition it on

45

the port and then thread the new switch in to pl ace. 1£ the switch has a plastic body, a firm hand-tightening is enough . With metal, a gentle nudge w ith a wrench does it, beca use the O-ring makes the sea \. Note: Your circuit diagra m ma y show other pressure switches. The variety is almost endless, depending on the type of vehicle, so without a diagra m, yo u're in Guess City. Among the most common va riety are a high-pressure cutout and a dedicated low-pressure cutout (often in addition to the cycling clutch switch). If the basic pressure check showed nothing awry, unplug and bypass these switches

for testing. In most cases, the bypass is achieved with a jumper wire acrosS the wiring connector terminals-but read the wiring diagram details, as some switches are normally closed and open

up as a signal. If so, simply unplug these to bypass. Double-check each switch with an ohmmeter. Ma ny cars-particularl y Japa nese models and many late-model Chr ys ler products-use a temperature sensor o n the evaporator (th e in-car hea t exchanger that cools the inter ior a ir) in conjunction w ith an electronic module to cycle the clutch. The shop m anual should provide specifications for a resistance check of the tempera ture sensor and w here to connect a voltmeter to test for an output signa l to operate the clutch. Make these checks under the das hboard .

Poor Cooling

.. -- ..... - .... ..

_-

The temperature of the air coming o ut of the registers w ill not necessarily be very low on a humid, hot day. The alc may expend all its effort just wringing humidity out of the air, and the air blowing out of the registers easily could be as high as 60° to 65°F. If there is some cooling, but clearly not a normal amount, make this simple check: Is the front of the condenser (the heat exchanger in front of, or alongside, the radiator) free of bugs, leaves, road film and other debris? If it isn't, airflow is restricted. Clean the condenser with a soft brush and a detergent-andwa ter solution (Fig. 3) . (Fig. 3) Use a soft brush and detergent to clean leaves and dead bugs from the condenser.

MAINTENANCE BASICS

46

ma nce as a nyt hing. If th e If yo u've got a car that has either no grille or a tiny o ne, bl ower simpl y won't reac h you've got a n " underbod y high speed, check the circuit diagram for a hi gh-speed brea th er." Inspect a ny underbody a irdams a nd covers. bl ower rela y. You might be a ble to fix a bad connecti o n If they're damaged or missing, by simply plugging in th e they could be responsible for w iring connector properl y. Or reduced airflow and poor coo lyo u may find a broken wire ing. And on a lmost all cars, by pro bin g tb e w ir in g co nn ecwhen t he a ir cond iti o ning is tor wit h a test light. turned on, a radiator/conAnotber common ca use of denser electric fan should a lso poor performance: the hea ter come o n. If it doesn't, th at also core's bigh temperature is red uces airflow and a/c perform a nce, particularly in slowbleeding into w hat sho uld be driving conditions. purely chilled air from th e Of course, if the a irfl ow is evap orator. Some hea t tra nsfe r is normal if yo u move the temnorma l, you'll wa nt to make (Fig_ 4) Bubbles in the sight glass may mean the air pera ture lever or turn t he knob sure a parti a l loss of coo la nt conditioner is undercharged. Have a professional (using from the max co ld pos itio n. is no t responsib le fo r a drop special equipment) recharge. in performance. Some o lder However, a t max cold, t here Japanese-made a nd some should be no hot-air bleed . Chrys ler systems (with R-12 C la mp off a hea ter hose to refrigerant) have a sight block t he h o t-coola nt fl ow glass- a tin y w ind ow into the (Fig. 5) . If ale performa nce refrigera tion circ ui t . C hec k it improves cons iderab ly, o ne to see if there are a ny bubbles of tb e fo ll ow in g co uld be w hen t he clurc h is engaged occ urring: (bubbling w hen it's di sen• A hea ter coo lan t-flow va lve gaged o r in th e first few sec(used on many bur not a ll onds after engagement is norve bicl es) is stuck in the open mal ). Bubbles with th e clutch p ositi on. engaged may- repea t, may• The flap door that's indica te a low c harge (Fig. 4) . supposed to reg ul ate the a ir'., ' Also, check ope rati ng presflow t hroug h th e hea ter or sures wi th a pressure ga uge evapora tor isn't opera ting a nd co mpare them w ith facproperly. If it's a manu al, tory specifications. You must cable-controll ed type wit h a use the specs beca use preslever, tr y slamming the lever sures vary w idely with amb i(Fig. 5) Clamp off the heater hose with padded Vise-Grip aga inst the max cold stop. ent tempera tures. pliers to check for a leaky flap. H yo u don't hear a flap doo r As exp lained ea rlier, a hit a stop inside the underd as h p ower-steering switch may mi sbetio ning system has an eva pora tor-te m- case, the ca ble ma y have, signa li ng " high press ure" w ith perature sensor, take a ca reful o hmneed adjustment. W ith a n electric just a sli ght rise in pressure, t hu s meter read ing a nd convert it to motor-driven design, check the case for killing th e a/c. If yo ur system runs fine degrees by consulting the table in the a bad wiring connection a t the mo to r. with the car parked, but stops as soo n manual. You ma y find that the sensor And, of course, there ma y be co ld as yo u pull away, either a bad powert hin ks it's co ld w hen it's really not. air, but in the wrong place. If the co ld steering sw itch or a mi sbe hav ing H t he air blow ing in your face air is going to your fee t or o ut of the thro ttle-position sensor (TPS ) is poss iis coo l, but t here isn 't eno ugh a ir defrost ducts-but not to yo ur facebl e. T he TPS is supposed to signa l blow ing, opera te th e blower sw itc h that's an a ir-d istributio n problem. Air "ki ll the alc " o n full thro ttl e to proa nd see if th e a irflow picks up . A nondistributio n is controlled by operating vide improved pass ing performance, running bl ower fan a nd a slow-runflap doors inside the hea ter/a ir-condibut the sen sor ma y come in w ith thi s ning blower motor are purely electritioning case, a nd it's done either by vacsigna l when yo u're just bare ly touchca l problems, and are as likely to be uum or electricity. H it's vac uum-operin g the gas peda l. Or if the a ir-cond irespo nsible for poor system perfora ted, look for a leak. tI

".>,c.";"">""""'«l\>_'".'",~<.,,,, ", , , , ,., ,_, , .,"

SERVICING YOUR A I C

47

EASY

Maintaining Your Battery

~II I "I I I I I

t's th e second time this week that you've had to jumpstart yo ur ca r. Bad eno ugh first thing in th e morning, when you can use the battery in yo ur RV to give you a startbut standing in a rainy Wal-Mart parking lot w ith yo ur hood open and jumper ca bles in yo ur drippin g hands is just plain humiliating, not to mention uncomfortable and inconvenient. The standard solution: Install a new battery- which mean s cough ing up enou gh mon ey to bu y a new one and have it installed. A few minutes of attention once or twice a yea r can perh a ps do ubl e the life of yo ur battery, sav ing yo u co ld , ha rd cash. And, just as importantl y, keep rain from running down your neck in shopping mall parking lots on storm y nights.

I

48

(Fig. 1) Always remove the negative connection from a battery first and reconnect it last to prevent shorting the wrench out on nearby metal objects.

Would You Like Fries With That, Sir? First, you need to determine if yo ur battery is indeed fried or not. Other reasons for a no-start or barely start cond iti on include, for openers, a marginal starter motor and high- res istance wiring in th e primary (starter motor) CirCU It. Open the hood. If your top-post battery terminals are covered with green fur that looks like it belongs in a bad sci-Ii mo vie, yo u'll need to cl ean that up'. Start by pouring some wa rm water over the terminals to di ssolve the sulfation. Thi s accretio n is normal, but it can prevent good contact between the battery posts and the clamp, w hich in turn keeps your battery from providing enough vo ltage to start or prevents it from charging

properly. Remove the terminals, and brighten up all the metal with a wire brush-style battery post termina l cleaner and a baking soda paste. Don't splas h li quid around the engine compartment or onto the paint, and rinse everything off thoroughl y. Side-terminal batteries rarely look worse than dull, but that's eno ugh to ca use hard starting. Wire-bru sh the contact surfaces to brighten them. (See page 80.) Dirt on the top and sides of th e battery, even greasy dirt, can hold enough moisture to crea te a current lea k from the positive terminal d irectl y to the nega ti ve termina
' making yo ur batter y selfdischarge more rapidly. Lea ve the battery clea n and dry. Now take a close look at the terminal clamps on the cables. If they're eroded too badly to provide good mechanical contact, replace them. Warnin g: Wh en eve r you work o n a car battery, a lways di sconnect th e nega ti ve terminal fir st-not the p os itive (Fig. 1) . Wh y, yo u ma y ask? Simple: If yo u accidentall y brush up against the fen derwell or any o ther grounded metal part of the car w hil e you ' re unho o king the gro und sid e, n o thing wi ll happ en. But if th e gro und is still connected, and yo u're wre nching o n th e positi ve sid e and ha ppen to touch any metal, yo u' ll be holding onto a wrench th at's sud denl y conducting severa l hundred amperes . That's as much current as

MAINTENANCE

BASICS

than a single wire. Yo u have a cho ice here. The best solutio n is to go to the dea ler a nd get the co rrect p iece. T hat may be inconvenient, a nd w ill ce rtain ly be expensive. Also (see page 89) , yo u may be able to get (at an a uto parts store) a "ca ble repair sectio n" (termina l attac hed to a sectio n of ca ble) . It's designed to attach to cab le ends from which the battery connecti ons a nd extra w ires have been amputated . Or yo u can so lder lugs of the appropriate size and ga uge to the extra wires, and then attach the lu gs to the clamp eit her by mea ns of the cl amp bolt or a large sheetmetal screw into the clamp body. Look for a cl a mp w ith an extra terminal if thi s is necessary, a lthough if yo u've got sideterm inal batteries this might be impossible. As a las t resort, sp lice and so lder the cab les together ahead of the terminal. Be sure to use shrink tu bing to cover the splice, espec ially if you ' re sp licing the positive side. W hen yo u rein sta ll the cl a mps, co ver a ll exposed meta l with petrole um jelly, w hite grease o r m y own persona l favorite, Cop-Graf or NevrSeez brand antiseize compo und. This wi ll delay the inevita ble growth of sulfur sa lts on the term inals by keeping mo isture from co llecting on the ba re meta I.

HOW IT WORKS

Maintenance-Free Batteries Like many things in life, the term " maintenancefree" is only partially true. Lead-acid batteries normally consume some of the water in their dilute sulfuric acid electrolyte during a normal chargedischarge cycle. It actually electrolyzes into hydrogen and oxygen and escapes as gas. So adding water periodically is necessary to keep the plates flooded, although it can 't be done Maintenance-free batteries often can have on some batteries. (See their lives extended by proper attention to page 50) Maintenanceelectrolyte level and good connections. free batteries use a cal cium alloy of lead instead of an antimony alloy, which reduces mal service life there should be no need to add water. the amount of electrolysis. In addition, the amount of free-standing Any abnormal electrical system elect rolyte above the plates is condition or high ambient tempdesigned to be much higher in a eratures may boil off more than new ma intenance-free battery. This the normal amount of water, however. Adding water where possible means that there 's enough electrolyte to keep the plates covered may extend the service life of even after a few seasons of normal these supposedly maintenanceuse. So, during the battery's norfree batteries.

a n arc we ld er- w h ich mea ns a large sp ark , lo ts of hea t a nd eno ugh energy relea se d to turn yo ur wrench cherr y red w it h in a fe w seco nd s. Avo id quicki e afterm a rk et unive rsal clamps that simp ly let yo u saw off the o ld clamp and clamp o n the new o ne. Wh il e these have their uses (kee p one in yo ur on-ca r too lbox as a gethom e-to n ight exped ient) they ' ll develop co rros io n betwee n the cla mp and the cab le in a few mont hs and leave yo u stra nded , again . If you feel up to it and have a soldering iron (proba bl y p ro p ane-fired ) ca pa bl e of genera tin g eno ugh hea t, yo u ca n so lder a new cl a mp o nto th e existing cable. Use ros in-co re elec trica l solder, no t p lu mb ing so lder. D on 't have th e Great M other of All So lder ing Iro ns? The simple way o ut is to rep lace the enti re ca ble. If

MAINTAINING YOUR BATTERY

yo u' re luck y, yo u can p ick up an approp ri ate ca ble at the a uto p a rts co unter. Genera ll y, all they stock a re simp le one- lead cables, in positive a nd gro und . Yes, there is a significant difference between the term inals o n th e battery, and you rea ll y o ught to use a black-insulated ca ble on the gro und and a red-in sulated ca ble on the p os iti ve or the p ost w ill fit the clamp poorly, w hich is how yo u got into thi s mess in the first place. Unfortuna tely, it's no t a lways that simp le. So me battery cla mps, bo th p ositi ve and nega tive, are so ldered to mo re (Fig. 2) A built-in hydrometer eye is a good check, but won 't necessarily find a bad battery.

All Hooked Up You've eli mina ted battery ca bles and clamps as the cause of yo ur no-start or almost-start problem . And you figure

CHARGED

DISCHARGED

LOW ELECTROLYTE

49

it's not a problem with guised unde r a label (Fig. 4) . the starter motor, because a jumpstart instantly Open it up and look brings the engine insid e. The electrolyte whirring to life. So far, so shou ld come up to the good. Maybe it really is bottom of the filler cap, the ba ttery. or at least near it. If the Does the battery have level is down, especially a built-in hydrometer if the plates are exposed, eye (Fig. 2) ? This eye add water. Always use has a small plastic ball distilled water in a batsuspended at the bottom tery. There is never any of a clear plastic winneed to add additiona l dow. The ball floats electrolyte. Batteries will when the battery is normally consume water, charged, turning the but the sulfuric acid window green. When the component of the elecbattery is discharged, the trolyte remains behind ball sinks and turns the and never needs to be (Fig. 3) A proper batwindow yellow. If the replenished. tery hydrometer can level of electrolyte is Before you add detect an underbelow the hydrometer, any water, suck charged battery, as then the battery is past enough elecwell as pinpoint a single bad cell. its useful life. trolyte out of One danger of these one cell into the built-in bydrometers: They check only hydrometer to float the bulb. one of the six cells. If you've got a bad Write down the rea ding. cell (tbe normal failure mode for batSquirt the liquid back and teries ), there's only one chance in six repeat with the next cell. All you'll know it from the hydrometer. six cells should have readings that agree within 0.050, or A better check is to use a handheld hydrometer (Fig. 3) . First yo u'll need you've got a bad cell. These to remove the filler caps. Battery clean? readings are temperature sensitive, so if it's very co ld or hot Cover the battery with a rag and pry o ut, yo u may need to correct the caps up. Warning! Battery acid will the readings. The hydrometer remove paint, corrode electrical consca le eq uates the specific gravnections and potentially destroy your ity of the electrolyte with the eyesight. Wear eye protection. state of charge of the battery. First hitch: no battery caps to If all the readings agree, and the remove, it's a sealed, maintenance-free gravity is low, the battery needs battery. Maybe so, but there 's access to be charged. to the individual cells, perhaps dis(Fig. 4) Battery filler caps may be concealed under a tab, a pry-up cover, or even under a large vinyl label.

50

Charge An alternative to the hydrometer test (and one used by professionals): With the battery charged, open circuit voltage should be 12.6 to 12.8 volts with the engine off and all loads off. With the car running and all loads off, the voltage should be between 13.6 and 14.5 volts. Disable the engine by pulling the fue l pump fuse. Measure the battery vo ltage whi le cranking the engine. It should read at least 9.5 to 10 volts while cranking. If the charging voltage is low, suspect some charging system problem. But if the charging voltage is correct and the cranking voltage is low, then the ba ttery is suspect, as you've already troubl eshot the wiring from the battery to the starter and gro und.

(Fig. 5) Battery hold-down clamps are essential to prevent a battery from becoming ballistic.

Strapping In Replacing the battery is straightforward . It's vital that the hold-down clamps be reinstalled properly (Fig. 5) . Some batteries use a wedge/lip arrangement at the bottom of the battery, while others (usua lly in o ld er cars) use a pair of long bolts and a frame or lip to hold the battery down to the tray. A battery is perfectly capable of holing a radia tor or smashing expensive fuel-inj ection components if it doesn't stay put. t;

MAINTENANCE

BASICS

EASY

Replacing a Battery " H oney! T here's a woodpecker in the car!" she says. It's too ea rl y in the morn ing for this, and far toO cold for woodpeckers anyway. Yo u politely suggest to your wife that she do two things im mediately: Let you go back to sleep, and let the woodpecker fl yaway in his own good time. No luck, the kids have to go to hockey practice-now. As you stumble o uts ide, you rea lize the absurdity of it all. Now, you know that there is no woodpecker in your car, or an yw here nearby. The pecking sound your significant other has identified as avian in origin is really just your starter soleno id clacking away merrily as she tries to start th e car. Sleepily, yo u jumpstart the reca lcitrant conveyance, and then try to gra b another 40 winks . After hockey practice, yo u' ll have to find out why your night's rest was suddenly abbreviated .

(Fig 2) Use a battery cutoff switch to diagnose parasitic current drains.

FLOATING BALLS

Time Is On Our Side The useful life span of an average automotive batter y is four to seven yea rs. With th e a uto companies' eterna l quest to make cars and trucks more efficient, two things have consp ir ed to shorten this life span: smaller batteries and h igher under h ood temperatures. Higher temperatures are so dam aging that many cars have insu lating b lankets for t he battery, or t he battery is mounted in the trunk. A single instance of deep-discharging a battery can reduce its life span by half, so avoid running a battery into deep discharge. If you do, then charge it properly as soon as possibl e before the plates inside bu ild up a layer of sulfates. A properly charged battery won't freeze, but a d ischarged battery wi ll freeze at temperatures well abo ve zero. Any battery that's been fro zen is finished.

REPLACING A

BATTERY

(Fig. 1) This battery hydrometer shows a fully discharged cell.

How Can You Tell? Is one cell of the battery visibly different than the others? Look through the side of a transluce nt-cased battery. If one cell has substantia ll y less electrolyte than the rest, or if one cell's lead p lates are much lighter in color, then tha t cell has gone bad and the battery is junk. Charge the battery for an appropriate time (depending on how powerful yo ur ba ttery charger is) a nd then use a hydro meter (Fig 1) to measure the specifi c gravity of the electro lyte. The more charge on the battery, the more su lfuric acid there is in the electrolyte and the higher the hydrometer floa t wi ll be on the scale. A battery tha t shows a low state of charge on the hydrometer after

a long charge is dead. Don't rush to judgment, however, because a deep ly discharged battery will take a charge very slowly at first. Is there some parasitic drain in your vehicle that's discharging your battery ? An easy way to check is to temporarily install a battery cutoff switch (Fig 2) in the ground side . With everyth ing in the car shut off, put an ammeter across the switch, turn the sw itch off, wait at least one hour, and measure the current drain. Up to 40 mill iamperes (ma) is normal to keep the vehicle computers, rad io presets and clock alive. Anything more than 200 ma will run yo ur battery down in a few days .

Transplant Once you've determined the battery is bad and the charging system and the rest of the electrica l system is good, it's time to install a new battery. Start by rinsing the bad battery and the surrounding area with p lenty of water. Th is wi ll wa sh away any sp lattered battery acid, which otherwise would eat through sheetmeta l, electrica l wiring and the seat of yo ur britches. Try not to splash it around. Next, disconnect the battery's neg-

51

ative termin a l. If yo u accid enta lly to uch yo ur wrench to anything nearb y, no bi g dea l. Th en, yo u ca n unhook the positive sid e. If yo u tr y to un hoo k the positive side first, any random contact w ith nearb y meta l, such as the inner fender, will res ult in a welder-like shower of sparks a nd hea t. Remov ing th e ground side first brea ks the circuit and preve nts this. Side-terminal ba ttery hardwa re is notori o us fo r not wanting to turn . Try tapping ligh tl y with a hammer, and rotating the w ire terminal slightl y as you turn the wrench . Top-post battery term ina ls are sometimes very diffic ul t to re lease. Light tapp ing ma y help, but yo u stand the chance of brea king th e pos t off if you app ly any substanti a l force. Yo u may need to use a ba ttery post too l to elevate the clamp loose from the post.

cla mps should not be defo rmed. Light co rrosion can be wire-brushed off, a nd a pas te of baking soda will help neutrali ze any acid. R inse thoro ughl y. If the attachment point of the wire to the metal clamp is good, fin e. If the cl amp o r the connection is nasty-lookin g, you sho uld replace the cable. Reserve the cl amp-on, universa l cableend termi na ls for emergencies-th ey wo n't las t as long as a proper connection and ma y contribute to yet another premature battery failure. Remember that the positive and negative posts on top-post batteries are phys ically, as well as electr ically, diffe rent. Don't interch ange. You may be a ble to rehabil itate an otherwise good term ina l clamp by rep lacing the boltbut be sure to use a lead-p lated ba ttery termina l bolt, not just something left over fro m insta ll ing your screen door.

Nurse! Clamp!

How Dry I Am

Now's the time to ser iously eva luate all of the wiring and clamps. T his hardwa re carries substa nti al am o unts of current- hundreds of amps for short periods when starting the car, and dozens for longer periods when the engine is running. It's imperative that it a ll be in good shape. T he

Most conventiona l batteries are shipped with o ut any electro lyte in them. If yo u have a good auto parts store, they'll keep a supply of ready-touse batteries in assorted sizes on hand . If not, yo u'll have to have one fi lled and charged. Here's the procedure: Fill the dry battery with electrolyte of the

correct specific gravity. Any place that can sell yo u a battery wi ll have this. Fill to the bottom of the filler neck, no higher. Now wa it severa l ho urs while the electrolyte seeps into the spongy lea d plates . T he level will go down, but as long as it covers all of the plates inside yo u can proceed to charging the battery. At this point th e battery p ro bably will start the car- but it's important (Fig 3) A proper battery holddown is necessary for safety and long battery life.

HOW IT WORKS

Built-In Battery Test Windows

GREEN DOT VISIBLE (OK)

DARK GREEN DOT NOT VISIBLE (CHARGE BEFORE TESTING)

LIGHT OR YELLOW (REPLACE BATTERy)

Many maintenance-free batteries have no access to the electrolyte to check the level or state of charge. But many of them have a built-in

TOP OF BATTERY GREEN BALL

tester. This is a Plexiglas wand that sticks down into the battery just below the normal level of the electrolyte. At the bottom of this is a

small chamber containing a loose plastic ball that floats in the dense electrolyte when the battery is charged. When it's floating, you can see the green ball at the top window through the Plexiglas. When the battery is discharged, the ball sinks and all you can see is the dark electrolyte. But when the electrolyte is too low, the plastic wand 's bottom isn't submerged in it, and you 'll notice a light color through the window. This means it's time to replace the battery. Remember, this tester sees into only one cell-there are five others, any one of which could be faulty.

MAINTENANCE

52

BASICS

(Fig 4) Always reattach the battery 's negative H terminal last. that it be fast-charged fo r an ho ur or so. Thi s mea ns being charged a t a higher current than yo ur 4 -a mp ho usehold cha rge r ca n mu stel; so it must be don e w ith at least 1 Y2 ho urs of super highway cruis ing, or by a shop w ith a fast charger capable of putting our 20 amps or so. Failing to do so will shorten the battery's life spa n and reduce its capacity. Now top up the electrolyte, a nd rinse we ll .

Dropping It In You've got the correct battery, right? Check that the positive and negative termin a ls are o n the proper sides, and that the ho lddown clamp is the correct style. You may as well fa sten the

REPLACING

A

(Fig 5) Side-terminal battery posts are easy to overtighten-be careful. holddown first (Fig 3) . Use some a ntiseize compo und on the hardware in case yo u ever need to rem ove the battery in the future. Don 't skip this step beca use vibration w ill shorten the

battery 's li fe by crack ing th e delicate lead p lates away from the internal bu s bars. The worst case would be the ba ttery shooting out of the tra y as yo u bottom out in some p o tho le. ow hook up th e positive terminal. Wh en it's tight, put o n the red rubber cove r. Now hoo k up the nega tive (grou nd ) side (Fig 4) . Side-terminal ba tteries (Fig 5) have a very sma ll bo lt head for a reason. It's to keep overenthusiastic mechanics from overtightening th em and stripp ing the threa ds o ut of th e so ft lea d terminal. Use a sho rt wre nch to keep torq ue down. Now cover the terminals with p etrol eum jell y. This wi ll substantia lly slow down the buildup of corros ion o n the terminals. Finall y, be sure to replace the battery heat insula tor if th ere was one in stall ed. tj

BATTERY

53

MODERATE

Maintaining and Repairing Your Suspension

'~----~~~!

"I

t feels like driving a truck," co mplallls your slglllficant other. Okay, she was the inspiration for " The Princess and the Pea," and yo u point out, "Well, it is a truck." Bur you know th e truth: It used to ride and dri ve a lot more like a car, a nd that's why yo u bought it. T he ca rlike fee l of tod ay's p ick ups and sport utility vehicles is th ere w hen they're new. Bur most pickups a nd some 5UVs have so li d axles (a t the rear a nd even the front of some

54

~

-~---------------

four-wheel -d rive mo dels), and rear suspensions with leaf springs. The tuning is carefully balanced betwee n an accep ta ble ride a t no load (besides passengers) and something to lerable w hen th e pickup bed is stacked high w ith 2 x 4s, pan eli ng a nd decorative brick . 50 it doesn 't take a lot of deterioration to make the ride/drive experience something that even yo u have to admit is somewhat harsh. You can get all kinds of assist

(Fig. 1) Raise the vehicle on safety stands. Then support the axle itself to get the tension off the spring. Remove the center U-bolt nuts, washers, plate and then the U-bolts.

spr ings for the rear axle, including aux ili ary leaves- even air assists th at yo u can deflate or inflate. But the object of th ese is to increase the load carrying capacity of the vehicle. What you want to do is restore the r ide/hand ling of everyday or weekend

MAINTENANCE BASICS

trips after 20,000 to 30,000 miles or so have precipi tated a harsher ride and vag uer hand li ng. There are aftermarket shock absorbers made for p ickups and SUVs used primarily as transportation, and they wi ll help. If yo u want more, there are add itio nal steps you can take to furt her restore the r ide and ha ndlin g.

(Fig. 2) Removing some spring shackles can be tedious, requiring two wrenches.

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()

Springs and Shackles Look at t he leaf spri ngs-at the rear on eac h side, even at the front if yo ur ve hicl e a lso h as them there . Loose center U-bolts are an occa siona l prob lem, and retighten ing wit h a torqu e wrench co uld be helpfu l. But wh en the ride qua li ty is down sign ifica ntl y, look closely for a crack ed leaf (Fig. 1) , and if yo u find o ne, c hange the spr in g, plu s the mountin g bush ings an d shackle in back . In fact, even w ith the leaves intact, there can be eno ug h deteriorat ion in the rear shack les to justify rep lac in g bot h for a rea l ride im prove men t. Take out the bolts t hat ho ld t he spring assemb ly a t front and rear,

w hi ch ca n be easier said th a n done in many cases . Turning the bolts while hold ing the nuts with a second wrench is straightforward stuff (Fig. 2) , but the rear bo lts ca n almost "ma te" w ith the rubber bushings inside the shack le, a nd getting them out ca n be a ted ious job if that happens. You may have to slowly unthread the bolt,

w hi le at the sa m e t ime prying under the bolt head to keep o utward pressure on the bolt. Or yo u m ay be able to tap it o ut w ith a ha mmer and punch. Just keep clear of the top of t he end of the leaf spring, w hich co uld snap up (aga inst the fram e) if there's still some tension on the spring. On some trucks, the shackle's upper

HOW IT WORKS

The Leaf Spring Suspension The leaf spring suspension is a popular choice for the rear of trucks and some sport utility vehicles. It has been used for some heavy-duty truck front suspensions and the rear of passenger cars, but the leading application is the truck/SUV with the nonindependent rear axle. The leaf spring has several leaves-simply adding leaves increases the load-carrying ability of the suspension. The top leaf typically is the longest and each end of that leaf is formed into an eye, into which a rubber bushing is installed. The spring eyes are bolted to the chassis in front and attached at the rear through a hinge joint called a shackle. The shackle permits the spring to effectively change its length as it flexes to absorb impacts. The leaf spring also attaches (through U-bolts) to the solid rear axle, so it locates the axle without the use of arms, an important function. This permits a simple

MAINTAINING AND

REPAIRING

YOUR

SUSPENSION

suspension design with obvious packaging benefits. However, these advantages are offset in passenger cars and some SUVs by the superior ride qualities of the coil spring, which merely supports the vehicle and simply compresses and expands as it absorbs the impacts.

55

the y' re bad ly cracked, p erh aps mi ssing chunks of rubber, insta llin g rep lace ments will help elimin ate bod y shake. Occasiona lly, the meta l fl oor pan of the vehicle is the problem- it's ru sted and weak . A piece of ga lva nized fl at sheetmeta l, thick en o ugh for support, sho uld be welded in place. Even if yo u just have to replace bad bushings, don't simply loosen the bolts and pry to get clea ra nce to in stall replacements, or yo u co uld ca use damage you won't see. Thi s work normally requires loosening radiator mo unts, the steering gear and col umn, and other parts, so check and fo ll ow the fa ctory-prescribed procedure for yo ur ve hicle. Or better still, lube periodically and the bu shings will be fin e. (Fig. 3) Check frame-to-body and suspension bushings. Look for cracks or overly brittle rubber as well as missing chunks.

bo lt is in sta lled o n the inboard side a nd it won 't cl ear the frame to co me o ut. Jack up the rear of the ve hicl e until the shackl e end of the leaf spr ing comes down far enough below the frame. The origina l equipment bushings with those meta l shack les are part of th e reaso n for loss of ride qua lity. To get a long-term smoother rid e, in stall aftermarket shackles th at include sma ll rubber springs with two m eta l

sleeve inserts and meta l arms-a lmost a reverse of th e origina l equipment design. The Dana Ve lvet-Ride series that we in stalled is an example. You a ttach the meta l arms to one meta l sleeve of the rubber sha ckle, insert and tighten th e through bo lt and nut, a nd then install the new sh ack le in place of the original. The meta l arms connect to th e chassis and the rubber spring, and the rubber spring is bolted (through its second metal sleeve) to th e leaf spr ing. In spect the underbody fram e-tobody bushings (Fig. 3) a nd the radius rod bu shings, and apply rubber lubricant as routine maintena nce. If

Steering Stabilizers Is a lot of vibration coming through th e steering wheel? The pro blem cou ld be w heel ba lance or a lignment, even the stee ring gea r's free play ad justment. But if it's a low-speed problem on second a ry roads, look for so mething worn o ut. If yo ur operation has pounded the tightness our of steering p arts, yo u ca n feel the looseness wh en yo u grab (Fig. 4 ) Shimmy can be caused by a worn or loose steering stabilize r. Check t he mounts, and check the damper for a bent rod or leakage.

........

.

:.::: .. : . . .. . . . .

~

."

. ..

: .. .- . : ....... . .

.' . :.....

MAI N TENANCE

56

~

BASICS

the tie rod and idler arms and find yo u ca n flex th em too eas il y. If yo u want to rep lace them just this o nce, get heavy-duty parts specifica ll y des igned for pick ups a nd SUVs. They' ll not on ly be labeled for heavy-duty use, but they' ll have grease fittings, which th e origina l equipment may not. Man y vehicles have steeri ng sta bili zers . If the ve hicle is suffering from vibration and shimm y, look for worn-out stabilizers, bas ica ll y one or two horizonta lly installed " dampers" (shock absorbers) that connect the steering linkage to the frame or axle (Fig. 4) . The dampers mount to the steeri ng lin kage with a bracket (held by U-bo lts) and to the fram e or fro nt axle w ith ano ther bracket, and there are washers and rubber bushings at each end. If they' re loose but the bushings look good, a simp le tightening ma y remedy the probl em. When they have significant mil eage on them , repl ace th e dampers along with mo unting hardwa re and bushings. If you don't have stabili zers, but use the vehicle on bad roads a lot a nd want to get rid of the shimmy, there are kits yo u can install, complete with fra me brackets and U-bo lts. These kits have been a fac tory fi x for otherwise unfi xa ble shimm y for yea rs, and aftermarket kits for trucks and SUVs are avai lable.

Jounce Bumpers Have th e rear axle jo unce bumpers been taking a beating? If the y have, yo u may see that the ends are sc uffed.

MAINTAINING AND

REPAIRING YOUR

However, yo u proba bl y know witho ut even look ing wh ether o r no t th e vehicle has been botto min g. If yo u get stiffer shocks, yo ur norma l rid e will suffer. A better approach is to replace the jounce bumpers w ith ones that rea lly are sma ll rubber assist spr in gs, such as Mo nroe 's Muscle LSE . They look lik e a short stack of thick pan ca kes, a nd when yo u're dri ving on bad roads they make co ntact w ith the jo unce pad on the ax le a nd prevent bottoming o ut. You could perceive this as causing a slight stiffening of the ride, but the bottoms of the "s hort stacks" have a co upl e of inches of clea ra nce to the pads, so they're o nl y in the p icture

SUSPENSION

on bumps . And because they 're springs, they a bsorb impact so th e overa ll rid e qu a lity sho uld be better. On man y trucks, yo u can just unbolt the bracket that holds the o ri ginal jounce bumper, bolt on a universal bracket (with elo ngated holes) a nd attac h the "short stack. " If the jo un ce bumper bracket is riveted to the frame , use a chisel or han d grind er to cut it loose. After installing the bracket and rubber spr ing, tighten the bracket bolts lightl y, then lower the vehicle to the gro und, adjust the bracket height to the reco mmend ed cl earance w ith a normal load in the truck bed, a nd do a fin a l tightening. t6

57

DIFFICULT

Replacing Shock Absorbers

o ur wife has started to so und li ke a detergent commerc ial, bragging about the spilled coffee stains she's gotten out of yo ur shirts. The kids are making excuses about why they'd rather ride their bikes to the mall than get a lift in your car, and even the dog has started to get carsick. Wake up, Bunky, and realize that your vehicle's ride has gone, litera lly and figuratively, downhill. Hey, there are over 60,000 miles on the odometer, and the tires are starting to develop little concave "cups,"

Y

58

sure signs it's time for new shocks. Of course, yo u co uld get the jouncy ride of worn shocks at much lower mileage, perhaps because you drive briskly on bad roads and accelerate the wearing-out process. Or may be the shock mountings have loosened . Occasio nally, a shock produces a visib le leak of fluid, but some hint of weep is normal, and most shocks we've seen that were well worn o ut, also looked bone dry. That's right, we're talking about shock absor bers . The MacPherson

(Fig. 1) Removing shocks is usually straightforward, but getting under the vehicle and applying sufficient torque to remove large-diameter rusted-on fasteners can be daunting.

strut is in wide use, but conventional shocks are on lots of cars, plus almost all those SUVs, pickups and at least the rear suspension of minivans. Isn't replacing them just like changing struts, just easier because yo u don't have to compress and remove the co il spring? No, although some things are

MAINTENANCE

BASICS

simil a r (a st rut is rea ll y a type of shock abso rbe r), th e mo unti ngs-a nd th e refo re th e rep lacement procedure- a re different.

o bvio usly cracked o r ba d ly di sto rted, yo u' ll usua ll y have to rep lace th e shoc ks to get the new bu shings. T ha t's o kay, beca use th e shocks themsel ves don 't fi gure to be in much better shape.

Those Mountings Both shock mo untings o n most la te-mo del ve hi c les a re in the un derbody, so if yo u support th e c hass is o n safety stands, yo u have access to the top a nd botto m. O ne proble m is rea ching them . A noth er is gettin g o ff th e h a rd wa re

Replacement Shocks

Th e afterma rk et m an ufacturers produ ce repl ace ment ARM shocks fo r just about everything, except som e (Fig. 2) If the shock rod spins endlessly as you try to remove electroni call y controlled the upper mount, try Vise-Grips on the flatted end of the rod. (Fig. 1) . d es igns. On Iy a ha ndfu I of T he first thing to d o is electro n ic systems' shocks see if th e mo untings are loose . If yo u stud, so yo u ca n ho ld the stud w hil e a re not a va ila ble fro m th i rd p a rti es, ca n turn th e mounting nut or bo lt a t yo u ti g hten the nut. eith er beca use th ey're a n o ddba ll size th e top or bo tto m without mu ch or beca use th e ti e- in to the vehicl e W hen a nut a nd bo lt loosen, yo u effort, the mounting is loose . O n some may be ab le to just retig hten. Howelectro nics wo uld result in a ride/ shocks there's a stud in a rubber bushever, it will loosen aga in if yo u do n't ha ndling g litch if yo u in stalled noning, a nd if it tears loose, yo u' ll see a nd a pply som e threa d-lockin g compo und electro nic replacements. It mi ght be as fee l it turn as yo u try to ti ghten the to th e threads. li ttle as a tro uble code or wa rnin g nut. T here's typi ca ll y a hex o n the If th e shock bu shin gs' rubb er is li ght, but if th ere's ma jor integra ti o n, UPPER CONTROL

HOW IT WORKS

Shock Absorbers Don't Absorb Shocks A shock absorber doesn't absorb shock (the spring does that, by flexing to absorb the energy of an impact). The shock absorber actually stops the vehicle from bouncing up and down on the flexing spring. It does this by transferring the spring-flexing energy to a piston in an oil-filled

Single- and double-tube shocks are used on either the front or rear end of most vehicles. Struts are simply a shock that includes the spring perch and a bearing that replaces the upper ball joint.

chamber, which dissipates it in the form of heat. Most shocks have twin-tube (chamber) arrangements, an inner chamber with the piston and a calibrated valve at the bottom, which has the entry passage to an outer cham ber-the reservoir. When the piston comes down on compression, it forces fluid through the calibrated valve into the reservoir. When the piston moves up as the shock absorber extends, oil is drawn from the reservoir into the main chamber, and some also flows through orifices in the piston, as part of the ride control calibration. A charge of low-pressure gas in the reservoir reduces oil foaming, which would affect ride control. Many high-performance shocks, including some for heavy loads such as motorhomes, are of single-tube construction, with a high-pressure gas charge in the base. Fluid flow is between the areas below and above the piston, which has a sophisticated valve assembly. The higher pressure of the single-tube design is even more effective against fluid aeration, but at the expense of ride comfort. Strut replacement is sometimes a job for a pro with the right tools and coil spring compressors.

l REPLACING

SHOCK ABSORBERS

59

In most other cases, yo u get a cho ice of shock a bsorber designs.

Getting the Shock Off If th ere's an electrical

(Fig. 3) There are several special tools available for holding the shock rod, in an assortment of sizes, at auto parts stores. Use a box-end wrench to loosen the nut while you hold the rod stationary.

it co uld be mo re th an th a t. Just check th e manufacturer's catalog, a nd if there are shoc k a bso rbers li sted for your exact year, ma ke and mode l, and th e listing says it covers th e electronic control system type, yo u' re cool. You will be giving up the electronic co ntrol , but there isn 't a system that's all th at sophisticated o n anything but a few premium cars, such as Ca dillac, M ercedes, Co rvette and some oth er high-end sports cars. If th e afterm ark et catalog doesn 't Iist a rep lacement, yo u' re stuck with ordering rep lacement shocks from a dealer. On so me Ford products there's an external motor drive, and yo u can unplug it from the o ld shock and in sta ll it o n th e new one.

(Fig. 4) Generally, a socket will spin off the mounting hardware. New hardware is usually included with the shock.

60

connector, sta rt by unplugg ing it. No electron ics problem with in sta llin g con ve ntion a l shocks? You could just cut the w iring, and tape sec urely. But if there's any chance you or a subsequ ent owner will want to re-estab li sh th e system, th at wo n't wo rk. If the co nn ector is in th e trunk, th at's easy (just tape over it). But if it's underneath, find a safe loca tion away from exha ust hea t, pack it with pieces of plastic foa m stuffed aga in st the termin a ls, put it into a heavy p las tic pouch, sea l a nd ho ld it in p lace with a ca ble ti e. Loosening a ru st-frozen nm a nd bolt is o ne of th e ma jor headac hes in

shoc k replacement. If a nut is exposed, yo u sho uld be ab le to loose n it with a nut splitter, a c1 a mp lik e too l yo u o ften can rent from an a uto p a rts store . No space for th e splitter? Penetratin g solvent, followed by hea t from a torch, is a nother possibility. The most diffi cu lt is th e type where the pi sto n rod turn s w hen you try to loosen th e nut. One app roac h is to clamp lock in g p li ers onto th e " do ubl e- D " end of th e piston rod, ho ld it fr o m turning w ith the pliers and loosen the nm w ith a conventional wrench (Fig. 2) . So methin g better (pa rticul a rl y for recessed insta ll ations) is a spec ia l too lkit with a holl ow hex that fits ove r th e rod o nto th e nut, followed by a wre nch (made to fit th e do ubleD ) th a t goes through th e ho ll ow hex onto th e doub le-D end (Fig. 3) . Inexp ensive kits, with three h ollow hexes for most U.S. makes, or even so me for spec ific models, a re r ea dil y ava il ab le in a uto p a rts sto res. It co mes with three ho ll ow hexes for mos t U.S. makes. Th ere's a lso o ne spec ifically for so me Ford products. If the shock p isto n end (or stud en d ) has a conventional hex, yo u can use an ordinary socket, of course (Fig. 4) . Many shocks are mo unted o n studs, and we 've even seen those wh ere th e shock upper m o unt ha s a retaining brac ket held by an additi o nal stud and bolt. It's no t a ma jor difficult y, just extra hardware to remove . Wh en yo u get the nuts off a stu d mo unting, yo u still have to pry off the shock, wo rking evenl y at top a nd bottom so it doesn't cock. If yo u' re not sure of th e cond iti on of a bone-dry shock, just disconnect it from th e bottom mo unt if possible (o r re move it com pl etely if it's o n studs). Then slow ly co mpress th e shock (even low-pressure gas shocks will be eas il y

MAINTENANCE

BASICS

LOWER MOUNTING BOLT

(Fig. 5) Lower mounting bolts are usually, but not always, included in the new shock's box.

compressed ). If you feel a ny lost motion (" looseness" or unevenn ess), th e shock is worn out.

Installing New Shocks If yo u' re o n a budget a nd in sta lling nongas shocks, it's a good idea to m ake sure the y don 't h ave air inside a nd bleed it o ut if th ey do. (Don't try this o n o ld shocks. If the y have a ir insid e, it's from internal wear, a nd bleedin g is not a c ure.) W ith new no n-

REPLACING

SHOCK

ABSORBERS

gas shocks, bl eed by holdin g each shock upright (in sta ll ed positi o n ): Extend it, a nd th en turn it upsid e down a nd co mpress . Repeat t he procedure a few tim es a nd th e new shoc k sho ul d opera te smoot hl y, w ith somew hat grea ter resistance on extension . Us ing adjustab le shocks? So me ha ve soft, norm a l an d fir m p os iti o ns, and a lth ough yo u ca n mak e ad justments after in sta ll a ti o n, sta rt with so ft or nor ma l (firm is best fo r " rid e

restora tion " after tens of th o usa nd s of mil es of use). Th e mounts for rep lace ment shoc ks often are very different from those for th e origina ls. That's okay, so lo ng as you follow the instructions carefull y. A common exa mpl e is th e aftermarket hardware for th e "stud-in-bushing" design used o n ma ny Genera l Motors ca rs. T here's a sp ecia ll y shaped stee l rep lace ment stud assembly that goes into the lower mou nting, an d th e bushing that's in the rep lacement shock just slides onto it (Fig. 5) . If th e shock mounts on studs and the nut is tough to threa d o n, clean th e threa ds w ith a wire brush a nd app ly penetrating o il/so lve nt. If the nut a lm ost sp un off, apply a film of threa d-locking compou nd to t he stud . If yo u ca n ti g hten the shock hardware to specs w ithout distorting the bu shin g, that's ideal. If the nut hits the end o f the threa ds and th e bushings are loose, yo u've got th e wrong o nes- or yo u're mi ss in g so me hardware. ~

61

EASY

Maintaining Your Exhaust System (Fig. 1) Tightening a loose clamp won't help if the bracket has broken loose at the weld line.

T

he sign says " DIP." And it's not advertising a sa mba sch oo lthere's a dip in th e p a vement la rge enough to lose a first-grader in. Yo u to uch the brakes lightl y to keep fro m spilling your ja va as yo u traverse it. But there's a sudden graunching no ise fr o m under yo ur car, fo ll o wed by th e screa m as a bo ut a ga ll o n of fast-food coffee £lenses the skin fr o m yo ur thigh. You pull over to inspect your leg and the underside of yo ur ca r, in that order. There are big, hot chunk s of metal hanging loose under yo ur chass is, a nd th e exha ust system is nea rl y d raggi ng. Tod ay's exha ust systems co nsist of a lo t o f expensive pa rts. Tb ere are o ne o r mo re ca tal ys ts, a n oxygen sensor, ma ybe even a 2-stage muffler. Th ere's piping tha t's not onl y shap ed to cl ea r und erbod y lines, but a lso may be m ade of premium meta ls, in so me cases du a l-wa ll tu b ing. Th ere a re sheetm eta l underbo d y bea t shi elds to prevent tbe exha ust fr o m igniting dry grass . Wb a t's bolding everything togetber? A few clamp joints a nd so me weld s. Wha t's bolding every-

62

thing up? A few pi eces of rubber with some brac kets. Wh a t's keeping everything aligned? Th ose sa me few pi eces of rubber and brackets. Fa ilures are common and they ra nge fr o m cracked rubber to fail ed welds. Before yo u suffer the sa me expensive fate we described ea rli er, ta ke time to perfo rm a reg ul ar und erbod y inspection-it's easy. To get started, jack up the car a nd suppo rt it on safety stands front a nd rear. No w you 're read y for a n in -depth look.

Hangers If a ny ha nger is bro ken, it has to be re placed, w itb o ut delay- eve n if the exha ust system seem s to be ha nging level. One broken ha nger mea ns tba t when the system mo ves up a nd down as you dri ve, a whipl as h effect goes through tbe cl amped a nd welded joints. Eventu a ll y cl a m ps loosen a nd welds crack. Repl acing a broken ha nger used to be simple, beca use most compa nies used some type tb at bo lted to the body and clamped to some p a rt of the exhaust system. Today, the most p opular design uses rods welded to the

p ipes a nd, often, to the ve hicl e underbod y (Fig. 1) . T hese ha ngers a lso have a thick rubber sectio n th at resembles a fl attened foo tba ll or beacb ball , witb bol es fo r a rod a t each apex of th e rubber. Weldin g pos iti vely loca tes a ll the pa rts, a nd a lth o ugh yo u may ha ve to tug a nd pry, rep lacing the rubber piece w hen it becomes crac ked is ve ry stra igh tfor wa rd . Yo u ca n in sta ll a bra nd-new p ipe if t be ro d com es off the pipe, but if th e pi pe itse lf is go od , tb a t's a n unn ecessa rily to ugh a nd exp ens ive r ep lace ment. The altern a tive is to in sta ll a unive rsa l ha nger, th o ugh thi s may require a bit of jury-ri ggin g. First, rem o ve the bro ken ha nger. Then loo k for a nearb y hole, perhaps even fro m th e o ld ha nger. Ta ke a universa l ha nger tha t ca n tw ist a nd tilt a nd has a n adju sta bl e length setup , a nd a ttac h it to th e und erbod y w ith a bo lt (a nd if it isn 't threa ded, a lso with a nut ) throu gh th a t hol e. Nex t, ma ke th e co nnecti o n around tb e pipe- a simpl e cl a mp a nd U-bo lt usua ll y wo rk s (Fig. 2) . D o n't be surprise d if a pa rt of the welded-o n brack et (fro m th e bro ken ha nger) has to be c ut o r gro und o ff to provide space fo r th e cl a mp th a t w ill a ttac h to th e uni ve rsa l ha nger. Yo u sho uld tr y to ma ke a ttachm ents ver y cl ose to th e loca ti o ns of the o ri gina l equi pm ent se tup'. Thi s will m a inta in system a li gnm ent a nd th e ba la nced ha ng o f th e entire system . If t here is no ise fro m exha ust sys tem contact w ith th e underbod y o r a n und er bod y pa rt, yo u sho uld c heck fo r da mage undernea th. Exha ust system cl eara nces are limited , a nd if yo u see th e need to increase o ne, it m ay be p oss ibl e to bend or shim a n ori gi-

MAINTENANCE

BASICS

na l-equ ipm ent ha nger. If a rod -type ha nger is we lded in p lace, see if yo u ca n bend it w it h a p iece o f pipe over the rod 's o pen end. If yo u need mo re tha n Y< in . o r so, loo k fo r a n a ltern ati ve . If t he ha nger is a bo lt-o n to th e bod y, for exa mp le, yo u m ay be a bl e to insta ll was hers as shims. So me o lde r impo rts have rub ber ha ngers tha t rese mbl e thic k ru bber ba nd s. If th e o ld ba nd has bro ken o ff, yo u ca n get a replace ment, but insta lling it is not a ma tter of simp ly st retc hi ng it over t he retaining ta bs. The ba nd is so t hi ck a nd stiff yo u p ro ba bl y w ill ha ve to pry p rett y ha rd to get it o n. Ma ny ex ha ust systems have a bracket to prov ide firm suppo rt cl ose to th e tra nsm issio n. If the bracket cracks- o r if it was removed for se rvice a nd never reinstalled-tha t ca n acco unt fo r a lot of exha ust system fl ex a nd event ua l crac king. If yo u ca n't get a rep lace ment bracke t, yo u may be a ble to get t he old crac ked o ne rewe lded . Bu t replace ment is the bes t cho ice, a nd if t he dea ler doesn 't

ha ve it, th e wrecki ng ya rd ma y.

Shields Exha ust system hea t shi elds a re pro ne to da mage fro m d riving o n ro ugh roads. To a vo id th e possibility of a g rass fi re, repl ace a ny t ha t are m iss ing o r barely ha nging o n. If a shi eld is dented , unbo lt it, a nd check the ex ha ust syste m fo r da m age .

Exhaust Joints If there has been a lot of exha ust system up-down travel beca use of a broken hanger, t he cl amps and joint may be dam aged. If a welded jo int is cracked a t a muffler o r resona to r jo int, yo u ca n rep lace the pa rts. Or to save mo ney, cut away the piping a nd pa rt of the neck jo in t, t hen install a sho rt connecto r pipe a nd secure it w ith clam ps. If a cl a mp ed joint isn 't cracked, but is lea kin g exha ust gas, re m ove the o ld cl a mp. If th e pipe ends a re badl y d istorted , yo u' ll have to rent a p ipe ex pa nder to res hape t hem . O th erw ise, sepa ra te th e p ipes, sa nd th em to remove a ny ru st, t hen a pp ly a coat o f

(Fig. 2) Sometimes a universal aftermarket clamp will fill the bill and let you reattach the OEM hanger.

HOW IT WORKS

Muffler A muffler is a canister with internal tubular passages , shaped in part by baffles, designed to gradually reduce the pulsations of flowing exhaust ga s. The slowdown creates back pressu re in the exhaust system , all the way back to the engine itself. This slows down the exit of exhaust gas from the engine, reducing its performance. To get around this problem , many high-performance engines increase the exhaust flow with larger mufflers and accept some increase in exhaust system noise as a result. With careful design, however, including the use of silencing materials, the systems can be made to meet legal restrictions. Some back pressure is benefi-

MA I NTAINING YOUR

EXHAUST SYSTEM

cial at low speed, because slowing down the flow pattern of intake and exhaust gases improves performance somewhat. Many engines have 2-stage mufflers with an internal springloaded valve. These mufflers maintain a specified amount of back pressure for good low-speed performance. But when the engine is at higher speed and there's more exhaust gas to flow through the muffler, back pressure builds up. Before it can become excessive, it pushes open the spring-loaded valve, and the gases take a far less restrictive flow through the muffler. This "second stage" permits the engine to develop considerably greater horsepower at higher rpm.

63

p

(Fig. 3) Springs on the bolts at the joint at the base of the headpipe allow the exhaust system to flex slightly as the engine moves on its mounts. Replace broken or sacked-out springs to prevent a leak.

ex ha ust pipe sea ler. Reassembl e a nd insta ll a heavy-du ty cl a mp , which ca n tol era te much more torqu e, to provide a leak-free joint. Many sys te m s ha ve a flan ge jo int at the exhaust manifold or at the manifold 's Y-pipe. That joint is held toge th e r w ith sprin g-load ed bo lts (Fig . 3 ). T he hea t m ay weake n the sprin gs, a nd th e jo int w ill loose n. Tr y s impl y ti g htening the bo lts, b ut if the springs ha ve cracked or are weak, repl ace th e bolts . Th ey' r e sold, with new springs, in auto parts sto res .

64

If a flange joint is bad ly ru sted, it's wo rth trying to free it up w ith penetra ting so lve nt. Th en, take it apart and see if it ca n be sa lvaged by sanding it clea n, installing a new gasket with sea ler and rea ssembling with new bo lts a nd nuts (drill

o ut rusted stud s if necessa ry) . C heck at a n a uto parts sto re to see if a cl amp-over rep air fittin g is ava ila bl e.

Damper Weights Some exha ust system s ha ve vibration da mpers (Fig. 4) , which are weights that are a ttached to a pipe or a re part of a fl ange co nn ecti on. If a damper we ight brea ks off or is bent, th e exhaust system wi ll vibrate noticea bly. This not only makes for an uncomfortab le ride, but it can affec t th e life o f we lded a nd cl a mped joints. tj (Fig. 4) When using replacement parts, be sure to reinstall any original vibration-damping counterweights.

MAINTENANCE

BASICS

EASY

Replacing Your Belts

N

Ot aga in! You cra nk the car through a turn and the steering suddenl y gets almost rock hard . Both yo ur heart and th e steeri ng wheel seem to stop. As you apply more muscle to the steering wheel, yo u hear sharp squealing from under the hood. O n the dash , the alternator warn ing light shines brightl y. As your vita l signs normalize, yo u remember that yo u've had this happen before: T he accessory drive belt for the power-steering pump either is slipping badl y or has popped off. Today 's drive belts, p articularly the ribbed belts, are supposed to las t for years. You even know peop le who've

REPLACING

YOUR

BELTS

neve r had to c hange them. Why do yo u ha ve repea ted belt problems? The answer is tha t something'S wrong with yo ur belt's drive. Don 't just put on a new belt, grumble and wait for the next belt failure. Find o ut w hy yo ur car has an appetite for drive belts. T hen make a more durable repair. First, inspec t a II of the bel ts a nd each of the pulleys (Fig. 1 ). Twi st over each belt and c hec k it thoro ughl y. O n a simp le V-belt, look at th e sidewa lls, and if the y're glazed, t hat's a sign of slippage- typically caused by improper adju stment, but poss ibly a sign of a bad pulley, too .

(Fig. 1) A belt that's installed improperly, or one riding on improperly aligned pulleys, will not last long.

On a multi ribbed belt look carefu lly for mi ss ing chunks of rubber. Specifically check for gaps at least a ha lfinch or longer on ad jacent ribs. If the belt hasn't lasted long, the reason w ill be found during in specti on of th e pu lleys. There are lots of reasons why so me cars eat belts.

Feel The Tension Most cars and trucks use a single, serpentine belt (see "How it Works,"

65

POWER STEERING PUMP PULLEY

CORRECT ROUTING

ALTERNATOR PULLEY

(Fig. 2) Correct routing of serpentine belts is not easy, especially in a crowded engine compartment. Incorrect routings may almost fit, so check the routing diagram or the owner's manual.

page 68) to dri ve a lot of accessories. These belts typica ll y are tensioned by an idl er pulley with an automatic tensioner. Ju st becau se there's an au tomatic tensioner doesn 't mean it's working right. Any of the root causes discussed below can result in a belt getting chewed up fa st, o r popping off th e pull eys . Th e re's a ten sio n indicator o n th e idl er a nd it shou ld be reaso nab ly c lose to midpoint. It shou ld not be resting o n the stop ta b at the " loose" end . If it is at the stop- or very c lose-the belt ha s stretched and sho uld be replaced before it pops off. You just put in a new belt, yo u say? Maybe yo u routed th e belt incorrectl y. Yes, it is poss ibl e to get th e be lt wrapped arou nd all the pu ll eys in w ha t seems to be the right way but have it wrong . Check the belt- ro uting diagram (Fig. 2) , which on many cars is o n an und erhood la bel.

66

Are yo u sure yo u have the right belt? Just because the tension indicator is in the right place doesn't mean yo u have th e correct belt. It's hard to eyeba ll th e difference between 7-rib and 8- rib belts, and if the pu ll eys have more or fewer grooves, the belt won't sit right. Even if th e number of grooves matches, it's possibl e to insta ll th e belt too far inboard. While yo u're look ing at the tensioner, also check for cracks in the housing w hi ch wou ld a ll ow it to fle x enough for trouble. Noth ing obviousl y wrong ye t? If the belt is still on the pulleys, run the engine and eyeball th e accessory drive. If th e tensioner is vibrating a lo t but the pulleys are running smoothl y, the damper bL.lshing is bad a nd yo u' ll have to install a new tensio ner. Put a wrench on th e spring te nsion er (Fig. 3) . Usually there 's a square hole for a ratc het or breaker bar drive, and occasiona lI y yo u can use o ne of those. If the tensioner on

yo ur transverse-engine car is buried so deep down between the pulleys and th e suspension tower that you can bare ly see it, c heck o ut the asso rtment of specia l long, thin wrenc hes designed for those in stall ation s at yo ur loca l a uto parts store . The lea ding m akers of th ese specia lty too ls will have theirs o n display (Lisle Too ls, K-D/Dannah er a nd Schley/SP). With th e wrenc h o n th e tens ioner, app ly so me lig ht torg ue in the disconnect direction, and if th e wrench moves very easily a short distance and th en gets stiff, th e tensioner ho using spring eith er is out of position or broken. This co nditi on often causes th e te nsio ner and its idl er p ulley to vibra te. Not today? Keep app lyin g effort w it h the wrenc h, a nd yo u sho uld feel uniform spring ten sion a ll the way to the belt-off position. If yo u feel bindin g or lost motion at a ny point,

MAINTENANCE

BASICS

a noth e r o ne, howeve r, t he o n ly fix is to shim o ut th e accesso r y w ith was he rs, w hi c h is a b it o f c ut-a nd -try. Do some to uchy-fee ly o n th e idler p ull ey. Try to turn it, a nd if it's se ized, the tensio ner has to go . jf it turns, fee l fo r roughness (w hi ch in d ica tes a ba d bea rin g) a nd if yo u come up w ith a da b o f grease from th e bearing a rea , th a t indi ca tes a grease leak past a bad sea l. Try to rock th e pull ey : In -a nd-o ut m ovement m ay be TENSIONER a sign of a loose bolt, but Playing With Pulleys '" mo re lik ely a da maged p ull ey. If t here's wo bbl e in th e idl er If a pu ll ey is stee l and it's o r a n yo ne of th e o th er accescl ea rl y rusted , th a t not o nl y so ry pu ll eys, th e pulley co ul d indicates t he coa tin g has be cracked or worn loose . wo rn o ff (no rm a l, in tim e), Just o ne da m aged pull ey a nybut tha t it is da maging th e where in the accessory drive (Fig. 3) Most automatic tensioners provide a square hole und erside of the belt a nd yo u also ca n affect th e o peratin g for a 'h-in. ratchet. have to rep lace it. appeara nce of th e tensio ne r. Pull ey a li gnm ent o kay a nd Repl ace th e w o bbling pul roo m , lay a stiff m ec h a ni c's strai g h tmo untin gs a re so lid ? No matter how ley- eas ier sa id th a n d o ne o n so me accesso ri es . Bes id es th e prob lem s of ed ge o r a thin stee l ro d across th e ba dl )' th ey' re buri ed , in spect a ll t he p ulleys . Look for chips a nd other pull eys to he lp yo u d ec id e if t he p ul nea r-impossibl e access o n a fro ntph ys ica ll y d a maged secti ons th a t a lso driv e's engin e, yo u may need to rent a ley o n that n ew accesso ry is mi sspec ia l p ulley-p ull er tool if yo u do n 't a li gned. Un less yo u wa nt to take co uld co me in contact w ith the belt. If own o ne. back that accessory a n d check o ur a ny of th e g rooved pu ll eys are packed If t he pu ll eys a ren 't wobw ith road film , belt d ebris, blin g but th e be lt isn 't tracketc., w ire-brus h th em clea n. •• I' in g we ll-see m s to twist If t he sm oo th p ull eys (idl e r s li g htl y o r m ove in a nd o ut a nd wa ter pump) are obv ias it sp in s t he accesso ri eso usly worn o n th e belt-t rac kALTERNATOR th ere may be pull ey mi sing a rea, you' ll have to a li gnm ent. That is, one p ul in sta ll new o nes or a new ley is just too far forward or ten sio ner asse mbl y. behin d a n other. Thi s happens o n new cars w hen m a n Doing It By Hand u factu r ing tol era nces a re A lot of o lde r eng in es-pa rexceeded , but it d oesn 't just ti c ul ar ly o n J a pa nese ca rs"deve lop" unl ess yo u d id sti ll have simpl e V-belts. so me fro nt-oF-e ng in e wor k Ma n y a lso have ribb ed be lts a nd fa il ed to tig hten a ll th e w it h manual ad justers. Th e accesso ry mountin gs caretypica l adj uste r is a full y. It a lso co uld h a ppen if jac ksc rew ; just loosen th e a n accesso ry rece ntl y was lock bo lt a nd turn t he cha nged , a nd th a t accesjac kscrew, co unterclockw ise so ry's pull ey does n ' t lin e u p. to loosen th e belt, cl ockw ise (Did yo u just p ut in a new to t ig hten. a ltern ato r ? Power steer in g Eve n if th e pulley is for a p um p? Air-condi ti o nin g simpl e V-be lt, it can acc u compressor? Water p um p?) mul a te d e bri s in the g roove. If th ere's enou g h access So c lea n it o ut w ith a w ire rep lace th e ten sion er. Neve r " let go" of a tensioner. As ide fro m th e possib le phys ica l da nge r, t he sudd en release ca n ca use intern a l parts of th e tens ioner to snap (includ in g th e spring ). R e lease it ve ry gra dually. If yo u do need a new tensioner, d o n 't thin k yo u have to ge t it fro m a dea ler. Reputabl e afte rm a rket tensione rs a re ava ilab le fro l11 a uto m o t ive parts stores .

;:: ~~~~~G

REPLACING YOUR

BELTS

67

(Fig. 4) Don't check for correct tension with the time-honored one-thumb method. Use a gauge.

bru sh, ju st as yo u wo uld a multig roove. T he d ays of gettin g a n acc ura te sense of belt tensio n by pressing down o n a belt wit h your thum b are lo ng gone . It takes a tens io n ga uge (Fig. 4) . Although there are expensive professiona l ga uges, we' ve found th e Ga te Kr ik- It ga uges do a good job a nd fi t in to rea ll y tig ht pl aces. Look for the lo nges t belt sp a n yo u ca n reach, preferab ly at least a foot. Just lay the Krik- It gauge at midspan, press down slow ly on the center until yo u hear a cricketlike click, then stop pressing. The ga uge bar ri ses as it enco unters

belt tension, a nd stops when yo u stop pressing. You ca n lift th e ga uge away a nd read the po int of a lignment of the edge of the bar w ith th e linear dial o n the gauge ho using. Just turn down the jackscrew to get the spec ifi ed tens ion , then tig hten th e lock bo lt. You 're probab ly familiar wit h " belt dress ing," a n aeroso l spray for belt sq uea l. Use it o nl y to make a q uick check of the belt as a source of noise . Repea ted use r uin s most belts. ~

HOW IT WORKS

Serpentine Belt The serpentine belt is so named because its routing resembles the shape of a serpent. Carmakers developed the system so one belt would drive several, if not all, underhood accessories. A single belt, no matter how long, saves space under the hood since all the pulleys and accessories are on the same plane and there's no need to stack or stagger them. The ribbed side of the belt fits into grooved pulleys (each one a "mini" V) , and the smooth back side of the belt often wraps around the water pump pulley and one or more idler pulleys. An idler is used to route the belt so there's

plenty of " wrap" around each accessory pulley for good power transfer. To maintain adequate tension for good power transfer, and still eliminate the need for periodic adjustment, an automatic tensioner is usually used. There's a nearly infinite variety of tensioner designs, but they all have a powerful coil spring inside. The poly-V belt design used on serpentine belts is capable of transmitting more power with less frictional loss than traditional V-belts. A properly installed and automatically tensioned serpentine belt system could remain troublefree for four to five years or 100,000 miles.

L 68

MAINTENANCE

BASICS

•

ASY

Replacing Hood and Hatch Struts hil e toppin g off yo ur tra nsm ission fluid o ne Satu rd ay mo rnin g-hunch ed ove r th e fro nt of th e engin e, dog a t yo ur sideyo u fee l th e to uc h of co ld stee l o n th e back of yo ur neck. Yo u've rece ived a weak "sta b " from t he car 's hood la tch. Time, weig ht a nd wear have consp ired to forc e a n un expected surrender of th e gas-cha rged hood suppo rt stru ts . Un fort un ate ly, gas struts do wea r o ut-a nd so metim es at th e mos t inopportun e moments. Weak o nes a re more likely to fa il in co ld weat her,

W

..

REPLACING

when th e gas pressure ins ide drops a little. Co nsequ ently, yo u' ll find that th ese sa me weak struts work perfectly we ll o n a ho t sum mer day. But th ey sho uld still be rep laced fo r safety'S sa ke. T he good news is th a t o ne manu fac turer recen tl y introduced a tempera ture-compensating gas strut that sho uld elimin ate seasona l perfo rma nce va ri ation s.

Sizing up the job Large, m o dern a uto pa rts sto res ofte n have parts ca ta logs dang li ng a t the e nd of eac h a is le. So yo u ma y

be ab le to look u p strut ap p licati o ns o n yo ur ow n. If n ot, ju st go to the parts cou nte r a nd as k fo r he lp. Be ca reful e it he r way. H oo d a nd ha tc h st ruts come in man y diffe re nt sizes a nd w ith seve ra l differe nt m ounting ends. Some emp loy a ba ll- joint mount at eac h end . O th ers make d o w ith a ny comb in a ti on of th e fo ll ow in g at eith er end: a ball jo int, a no na rt icula tin g ha rd mou nt w ith a n integ ra l hinge o r a Aa ttened pi ston-rod end tab th at ma tes w ith a stationar y mountin g peg. Some hood struts eve n

..... :

HOOD

AND

HATCH

STRUTS

69

wo rr yin g t hat t he ot he r str ut is go in g to let go .

Doing the double-joint strut

(Fig. 1) Slide the locking clip away from the mount ing leg to allow strut removal. You might have to push or pull the clip to release it.

W it h a ll th e prep wo rk do ne, replacin g th e o ld st ru ts sho ul d tak e a ll of a bo ut 10 minu tes. T ho se ba ll -jo int en d s a re usua ll y he ld t oge th e r w ith so me sort o f c li p : eit he r a flat C-cli p th at m o unts t h ro ug h t he bac k o f t he so c ket a nd g ra bs th e un d ersid e o f t he ba ll , o r a w ire C-c li p t ha t sli d es thro ug h th e bo tto m of the soc ket a n d und er th e ba ll to p r eve nt relea se. Wedgi n g a b ig screwdr iver betwee n th e shee tm eta l a nd t he ba ll jo in t fo r leve rage is no t th e bes t way to po p t he st ru t. A li tt le fin esse, p lea se. Use e it he r nee dl e-no se pli er s or t he sma ll es t screw d ri ve r yo u o w n to ge ntl y p ull o r p r y c li p awa y fr o m the socke t (Fig. 1 & 2) . Th en, simp ly pu ll t he soc ket off t he ba ll . Do t he sa me thi ng a t th e o th er end. Sa ve th e c li ps if t hey' re no t b roke n. So met im es a n ext ra o ne co mes in ha nd y. Be car eful w hen wo rkin g o n ha tc h stru ts m o unted nea r th e rea r-

have two sta ges . On t he Vo lvo 960, be t he o n ly t hin g kee p in g th e li d fo r examp le, u nl ock in g a p la st ic c lip fr0 111 mee t in g yo ur head w it h a th ud . o n eac h st r ut a llows th e hood to conO n a 2 -s tr ut d ea l, t he wood a ll ow s t inu e openin g past ve rti cal for easier yo u to w o rk on eit her sid e wit ho ut engIn e servIce. M ea sure th e f ull- open (Fig. 2) This clip holds the socket onto the ball stud. Carefully remove the clip to release the lengt h of yo u r ex ist in g st ruts sockets so you can pop off the struts. befo re hea di ng o ut t o t he p a rts store. T hen , c hec k t he lengt h of th e new o nes befo re go in g home . Or, tak e on e of th e o ld str uts w ith yo u for co m par iso n . It ma y sa ve yo u a r etur n tri p . Be awa re t ha t so me su ppo rt st ru ts fo r o ld e r cars may no longe r be ava il a ble in t he tra diti ona l aft er ma r ket. (T he 198 1 D a tsun 310GX is o ne exam p le.) If th a t's the case, you' ll have to visit a d ea le r. O r m a ybe yo u' ll ge t lu ck y a nd fin d th e st ru ts yo u need in the .J. e. W hitn ey cata lo g. W ith the co rrect uni t (s) in ha nd , open t he ho o d or h atc h and p rop it up w ith a sto ut p iece of w oo d. O n a STRUT I- str ut se tu p, th e woo d will

70

MAIN T ENANCE

BASICS

(Fig. 3) Insert the new strut's integral ball stud into its mounting hole and fasten it with the nut.

-

w indo w defogger g rid. If yo u slip w ith the sc rew dri ve r or pliers, yo u could ruin the defogge r e lement.

Pop 'em in To ease in stallation of the new unit , m ount th e clip(s) in a partially open position on the new soc ket, and put lube on the in sid e of the soc ket with a littl e silicon e grease . St ick the soc ket over th e ball , then sna p th e clip home. Repea t th is for th e ot her end (and th e o ther s id e, if app licabl e) a nd yo u' re don e. If yo u co me across a ba II jo int tb at's not held togetber with a c lip, see if th e ba ll end of the jo int is sc rewed in to the sheetmeta l (Fig. 3) . If so, it's very likely t hat a hex is includ ed for removing th e o ld ball w hil e it's still attac hed to th e strut a nd screwing in the new strut's ba ll with a n open-end wre nch. Look a t the new str ut for guid ance. For th e ha rd -mo unt t ype of strut end , just undo th e bolt, screw o r nut t hat ho ld s the old strut in place, rem ove it a nd attach the new p iece (Fig. 4) . If yo u're dealing with a peg-style mount, you sho uld find a n E-cl ip of some sort or a cotter pin preventing the strut end from slidin g o ff the peg. E-cl ips genera ll y need to be pulled or pushed in one di recti on or another in order to release th em . Sometimes just a gentl e nudge with th e tip of a screwdri ver is

NUT

enough to pop them off. Oth e rw ise, yo u may need to grab o ne of th e clip's end tabs w ith need le- nose p li ers a nd pull the c lip o ut of position. Th en, remove tb e o ld strut, mount the new o ne a nd slid e the E-clip back ho me until you fee l it click or can see that it is locked in. Altho ug h th e str ut 's piston rod

has a ha rd ened corros io nproof a nd weat herproof finish, yo u sho uld still take care not to ni ck or sc ratch th e po li shed surface . Thi s wo uld res ult in th e marred metal ruinin g t he str ut's ma in sea l. If th e sea l is damaged, the nitroge n gas wo uld lea k out and yo ur bra nd-n ew strut wo uld be tras h.

HATCH

(Fig. 4) Unscrew the hinge from its mounting point on either end to remove this type of strut. You may even be able to use a ratchet wrench and socket.

REPLACING

HOOD AND

HATCH

STRUTS

71

Al so, do n't inad ve rtentl y m o unt the new unit piston-side up, especia ll y if the o ld o ne was piston-side down. Most applica ti o ns-those th at contai n some hydra ulic o il as well as nitroge n gas-

perform mo re smoothl y if o ri ented with th e rod end down. Thi s a ll ows the mo re effecti ve o il compressio n da mping to occur later in the strut's st roke for ni fty end cushi o ning upo n opening.

With the in sta ll a tio n co mpl ete, pull o ut th e wood p ro p a nd enj oy th e conven ience a nd safe ty of yo ur hoods a nd ha tc hes stay in g o pen o n t he ir own. f*

HOW IT WORKS

Support Struts PISTON ROD MOUNT

PISTON ROD

SEALING ASSEMBLY

PISTON STOP GROOVE

NITROGEN GAS

PRESSURE CASING

In the old days, your heavy metal hood and trunklid required beefy, space-robbing, spring-loaded hinges to stay open. Then the carmakers tried flimsy prop-rods for holding up the hood. But they invariably get in the way during service and tend to wear out and break at the pivot point on the radiator support. So, as a result, gas-charged hood and hatch support struts, or gas springs, have steadily infiltrated the market. They're compact, light, durable and relatively inexpensive-key for auto manufacturing in the '90s. One of the slickest applications around is on the Chrysler Cirrus/Dodge Stratus trunklid. No bulky suitcasecrushing hinges here, thanks to two stubby gas struts that open the lid past vertical to allow for easier trunk access.

72

PISTON ASSEMBLY

How do they work? Like tiny shock absorbers really. But instead of being filled primarily with fluid for 2-way damping, they 're charged with nitrogen gas for 1-way expansion. One end is fastened to the inner fender or cowl, the other to the hood or hatch. When you lift the lid a little bit, it extends the strut's piston rod enough for the gas to push on the piston and keep expanding the strut. The lid has nowhere to go but up. On closing, you're actually pushing against the gas pressure to compress the strut back to its original size and position. A typical gas support strut is designed to last for at least 50,000 operations. They're maintenance-free throughout their life cycle but must be replaced when worn out.

MAINTENANCE

BASICS

ODERATE >-------

Resetting Your Emissions Maintenance Reminder (EMR) o ur o ld er m inivan has bee n a tru sted me mber of the family. It has helped you move yo ur sister across town, kept yo ur kid 's Litt le League van p oo l ro lling a nd faithfu ll y transpo rted th e belo ved dog to the vet. But it sure caused havoc last wee kend . Leaving a t 5 am wit h yo ur budd ies a nd a week's worth of fishin g gea r, it sputtered,

Y

spewed black smok e from the ex hau st a nd wo uldn 't eve n idl e. Wa lleye w as ho ut! It's bad eno ug h yo ur fishing pals wo n't ta lk to yo u, but now th e truck's go t to go in for ser vice. And the on ly way to get to work is by munic ipal bu s becau se your wife needs th e Bimm er to ma ke a ll her sa les ca ll s. Peachy.

Your Dash Is Talking To You H o ld o n. Ha ve yo u bee n ignoring that wa rnin g Iight on th e das h beca use your "ca r gu y" brother-in-law sa id it's no t importa nt? We ll, maybe it is. You see, that warn ing light, wide ly used on (Fig. 1) Press button on EMR relay to reset reminder light for another 30,000 miles. This is an older Nissan engine.

SERVICE REMINDER RELAY

RESE T TING YOUR

EMR

73

pre-O BDII ve hicl es (befo re va lve sea t opens a nd c loses 1996), is des igned to co me o n smoothl y. O n la te-model co ma t abo ut 30,OOO-mil e interputer-contro ll ed EGR sys tems, va ls, depend in g o n th e ve hicl e. th ere may be no way to c heck (Chec k yo ur ow ner's manu a l the so leno id/val ve mec ha ni sm for the spec ifi cs.) It's ca ll ed an w ith out sp ec ia l tool s. If yo u emi ss ions ma intena nce haven't heard a n y engine p ing rem ind er, or EMR, a nd it defi or kn ock late ly, id le qua lity is nitely sho uldn 't be ignored . okay, a nd if th e CH ECK ENG I E When the EMR in d ica to r li ght has n 't come o n, th e EG R glows, it doesn't necessa ril y system is probably fin e. mea n tro uble. But each time Other operation s you ca n the light comes o n, the emischeck include the smog pump sions system should be checked. (o r p ul se-a ir system ) on eng ines The idea is to work o n the that use them . Exam ine th e engine before the engine works pump belt for cracks, wea r an d yo u over. After giving yo ur proper tensio n. Foll ow the okay, the light has to be reset (Fig. 2) Stick a pen or pencil in the back of the mileage tubes fr o m the pump to the counter in the cowl tray on Audis and Volkswagens to so the system starts counting d ive rter va lve and down to the reset EMR system. down for the next EMR cycle. exha ust manifold a nd ca tal ytic Th ere's a different reset co nverter. l'v1ake sure th e rubprocedure for just about every ber hoses a re intact and th e MAINTENANCE EMR system . Some indica meta l pipes and check va lves REMINDER tors, such as those o n most a ren 't rusted o ut. You mig ht CONTROLLER C hrys ler light tru cks since even be a ble to reac h under th e 198 9, ca n be reset o nl y by ve hicl e a nd rap th e ca ta lytic ta pping a sca n too l into t he converter with a ma ll et or ham o n-board computer co ntrol s. mer. A ra ttling no ise mea ns the If yo u do n't ha ve a sca nn el; cat has broken down interit's off to th e repair shop or nall y- a nd its better days are th e dea ler for ass ista nce. Some behind it. setups are reset by repl ac ing a If yo u can see th e fu el-sysmodule. After a certa in num tem c ha rcoa l-vapor ca ni ster ber of mil es, the modu le is (sometim es it's buri ed in a sim pl y le ft d isconnected. front fender), in spect t he There's no resetting prov isio n integ rity o f its ru bber lin es a nd a t a ll o n som e ve hicl es. Ju st fittin gs . And whil e yo u' re at it, disco nnect th e plug o r conneclook at th e a ir filter, a ir-box tor to shut off the li ght. (Fig. 3) You'll find Volvo's mileage counter under dash. breather element and t he Press reset switch to turn off light. Still other EMR li ghts, engin e's vac uum lines . Make such as th e sensor wa rnin g o n sure th e pos iti ve cra nkcase mos t N issa ns (Fig. 1) , require no thing Checking Emissions System ve ntil atio n va lve sti ll rattles w hen yo u more t ha n a screwdri ve r a nd a bout 5 Th e key element in )'o ur emi ss io ns sha ke it. C heck th e spa rk p lu gs a nd system is the oxygen senso r th a t's minutes of yo ur time to either pu sh a wires and th e di stributor cap a nd rotor (if app licable) for wear. Ultibutton o n a relay or pull apa rt a conmounted in t he exha ust ma nifo ld . It nector-that is, after yo u've given the senses if th e eng ine is runnin g too ma tely, a ll powertra in components rich o r too lean. When the O 2 senso r ma ke up the em iss ions system , so emiss io ns contro ls a o nce-over. On ly und er th e fo ll owi ng three check w ha teve r yo u ca n get to . gets la zy a nd stops reportin g acc ura te cond iti o ns shou ld yo u consider resetinformati o n to th e electron ic engin e Finding the Reset Location control s, dri vea bility troubl e ca n ting t he EM R li ght w ith o ut in specting th e emi ss io ns system: 1. You've had begin-a nd fis hing trips can be ruin ed . Alt ho ugh it var ies, reset-switc h locano drivea bi li ty troubl e a nd no CH ECK tion s can genera ll y be broken down So check o ut th e O 2 operatio n first. ENG IN E li ght, 2. You've noticed no Next o n th e li st is the exhau st gas into three a reas: th e speedo meter , appreciable cha nge in fu el eco nom y, rec ircu latio n (EGR ) valve, if yo ur ca bl e/fir ewa ll a rea, the kick panel/under-dash a rea a nd the instruengine has o ne. Apply a vac uum to :::d 3 . Your vehicle a lways passes the the va lve's nipp le a nd make su re t he L te emi ss io ns tes t w ith fl ying colors. ment panel a:a. Th e position s ofte~

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74

MAINTENANCE

BASICS

In DOn d

MAINTENANCEREMINDER CIRCUIT BOARD INSTRUMENT PANEL

(Fig. 4) On Chrysler minivans, you must remove the fuel gauge or tachometer to get to the emissions-maintenance-reminder reset switch.

change from model year to model year across the same vehicle make, so a lways a pproach yo ur search with an ope n mind . And check yo ur o wn er's ma n ua I. T he speed o cab le resets are usua ll y the eas iest beca use th e ca bl e sticks o u t li ke a sore thumb, and there's usua ll y p lenty of room to work. Veh icles in this category incl ude many models from the early 1980s. Aud is and Vo lkswagens are a breeze. Yo u' ll find the mi leage counter in th e cow l tray a t t he base of th e w in dshi eld (the speedo cab le leads right to it). There's a ho le on the back of the counter. Stick a pen or pencil in the hole and press in the rese t button (Fig. 2) . You'll fee l the button lock in place . T ha t's it. On Volvos, th e mil eage counter is a lso in line w it h the speedo ca ble. Once yo u've found th e co unter, press its reset button w ith your fin ger (Fig. 3) . Still o thers are do ne from the insid e. Drop the lower steering-column cover. Feel for the sensor reset cable to the left of the speedo cluster. Yank on the

RESETTING

YOUR

EMR

ca ble until yo u see the fla g reset itself o n the left of the odometer.

Hunting for Switches Vehicles tha t fa ll in to the seco nd ca tegory number too ma ny to ca llo ut separa tely, but t hey a ll have some so rt of EMR module, relay, connecto r o r pair of conn ectors . On some models, you 'll find a cancell ation switch on the right side of the fuse panel. Press the switch to the O FF positio n. O lder Fords hide EMR modules behind the passe nger kick panel o n t heir tr ucks. Stick a small rod in the hol e marked RESET. W hil e ho lding th e button down w ith the rod, turn the key to RUN and continue to depress the button for 5 second s. On o lder Jaguars, the mileage counter is behind t he trim in th e trunk. Press th e w hite button w it h the key on to reset the light.

Pulling the Instrument Panel Thi s third ca tegory can get complicated beca use yo u usuall y have to dismantle p a rt of the da sh to remove tbe instrum ent cluster o r a ga uge to

get in behind th e clu ster, as o n C hr ys ler's mini va ns (Fig. 4) . Acco rd in g to a dia gnosti c hot lin e we a re friendly w ith, th ese va ns a re th e ca use of th e most EMR reset ca ll s. T he c ircuit-board-mo unted sw itch is tri cky to fi nd if you don 't know wh at to look fo r. It's mo unted behind th e fu el ga uge o n th e sta nd ard c lu ste r or behind th e tac ho meter on th e op ti o na l clu ster. Someti mes yo u' ll find a 9-vo lt battery in th ere, too . It mu st be rep laced w ith an a lka lin e battery. Some C hrys ler captive impo rt li ght trucks ha ve a reset switch o n the bac k of th e clu ster nea r t he speedo juncti on or o n th e lower ri g hth a nd co rn e r of t he cluster, behind the face pane l. On ea rl y- mod el GM ve hi c les, pull the instrum ent cluster lens a nd use a sma ll tool to p ush on the stem of the orange plastic fl ag th a t pops up near the odomete r. An al ignm ent mark sho uld a ppear in th e left ce nter o f th e odometer w ind ow w hen th e fl ag is proper ly reset. Late- model GMs use no spec ific EMR indica tor. Th e CHECK ENG I ~E light illumin a tes if th e re's a problem. Earl y-model non-turbo Audis have a cancel switch labeled oxs on the back of the instrument cluster that must be removed fro m the pod to ga in access. La te- model turbos hide a mil eage counter w ith a reset button under the rea r seat. Some late-model BMWs use a resettable mi leage counter. On 1989-93 Geo Trackers, locate the 3-w ire ca ncella ti o n switch in the ma in w iring ha rness behind the instrument clu ster or in the steering-column lower-access pa nel. You ' ll find th e reset o n th e bac k of the speedo o n IsuZLI Troopers. Pu ll th e tape from Ho le B and swa p the screw from H o le A to Hol e B. Tape over Hol e A. Mazda MPVs are simil ar. Swap th e screw from H o le N O to Hol e NC. Late- model M ercedes-Ben z ca rs use no EMR in dicator. H oweve r, 1980-85s, o ther th a n th e 280, requ ire bu lb remova l. On VW Rabbits a nd Pickups, remove the instrum ent pan el cover trim p late to get to the mileage counter re lease a rms at the top left of th e speedo hou sing. Good luck!

G

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DIFFICULT

Passing An Emissions Inspection

the pintle of the EGR valve with a screwdriver while the engine idles. If the EGR valve passages aren't blocked, the engine should stall immediately.

our car is running beautifully, and all seems right with the world. You have no trepidation whatsoever when the time comes to take it in for your state or loca l em issions test. After an interminable wait in line at the inspection station, a smiling, snappily dressed functionary shoves a probe up your tailpipe and asks yo u to gun it. Moments later, the in spector sm il es wea ril y as he hands you an envelope-not a new inspection sticker for your license plate, but an envelope that says "FAIL" in bright red letters. You have only a month to do your hom ework and

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pass inspection. Heck, getting into college wasn't this hard. Wasn 't your car designed to meet these emissions standards? Haven 't you done your best to maintain it with regular oil changes and tuneups? What's gone wrong? And, most important, how ca n you make it pass? Take a minute to read the rejection slip carefu lly. Typically, it will give you the test results for your car a long w ith the acceptab le limits. Note which of the " terrib le trio"-hydrocarbons (HC), carbon monoxide (CO) or oxides of nitrogen (NOx)-is o ut of bounds.

Raw Gas Hydrocarbon emissions are simply unburned fuel being pumped raw into the exha ust system. Misfiring is the most likely culprit, and that can come from an ignition problem, or an internal engine failure that reduces compression. Another possibility is a mixture that's too lean to catch fire dependably because of either a fuel system malfunction or a vacuum leak. If a high HC number isn 't from a miss, it's probably due to an overly rich mix. So, worn or fouled spark plugs are the first things to suspect. If you can

MAINTENANCE BASICS

Older cars might benefit from tweaking the idle mixture screw no more than a half turn in either direction to get the idle mixture setting correct.

C rankca se Ventil a ti o n system a nd in to the intake ma nifo ld. Sme llin g th e d ipst ick may tip yo u off to thi s, a nd a n o il cha nge w ill correct th e prob lemtem poraril y.

Killer Compound

feel a dea d mi ss a t idl e, use in sul a ted pli ers to pull p lug wires one a t a time to see if o ne in particular does not have a ny effect o n smoo thn ess (don't do thi s o n '96 a nd newer cars w ith OBD II, as it w ill set a mi sfire code a nd turn o n th e Ma lfu nctio n Indicator Lamp o n the dash) . Remove a nd in spect t hat spark plug. If it's okay, use a n o hmm eter to find o ut if t he plu g w ire is op en-yo u sho uld meter 5000 to 20,000 o hms, t hen exa min e the di stributor cap fo r heavy co r rosion in th e sockets, cracks, etc. W ith the p lu g o ut, do a compress io n testTIMING a nythin g muc h less than LIGHT 100 psi sho uld be suspect (a va lve m ay be burned ). Also, look over the intake manifold to see if t here's a vac uum tap in the runn er lea ding to the prob lem cy linder. A leak here can lea n o ut th e mi x to th e

po int of mi sfire at id le. T here a re a couple o f other t hings that ca n supp ly eno ug h extra gaso line to put hydrocarbo ns above t he lim it. O ne is the evapora tive-em issions cont ro l system th at trap s gaso li ne vapors that wou ld otherwise escape into the atmosphere. It t hen meters the vapors in to the intake during off-idle modes to be burned. If it fl ows at id le, t he mix w ill be too rich. Another potentia l cu lprit is engin e o il tha t's diluted wi th gaso lin e. Fuel vapors are drawn through the Positive

Many cars no longer have adjustable ignition timing, but you should check it with a timing light nonetheless.

PASSING AN

EMISSIONS

Ca rbo n mo noxide is prod uced by incomp lete co mbusti o n-th e a ir/hie! c ha rge is ignited, but isn't burn ing properl y o r entirely. In most cases, thi s is due to fuelsystem tro ubl es th a t make the engine r un ri ch, but inta ke a ir restricti o ns co uld affect it too. It's impor ta nt to no te t hat so me combu stion is requ ired fo r CO to be created. So, yo u won't see a high CO rea din g if there's no spark. W ith a carburetor, richness mig ht be due to a n idl e mi x ture screw that's open too mu ch, a heavy fl oat (the foam type may absorb gaso line, a nd the brass po ntoon type ca n develo p holes a nd fill up wi th fuel), a c hoke th at stays o n a fte r the eng ine has warmed up , or a power va lve that sticks in the open positi o n. Wi th fuel in jection, perh aps th e fue l p ress ure in the ra il is too hi gh du e to a fau lty fuel-press ure regul ator, or th ere may be a cracked vac uum hose to th e regul ator. Of course, just a bout a ny car built wit hin the last two deca des w ill have a n electroni c engin e man age ment system th a t contro ls th e a ir/fuel mi x ture (a mo ng other thin gs), so co nsider the sensors that _ _ _ _ _ _ feed informa ti o n ~

INSPECTION

77

VACUUM LINE

A cracked vacuum line can cause the charcoal canister to malfunction, increasing emissions. A misfiring cylinder may have bad rings or valves, which can be spotted with a compression test.

to the computer. This, ho wever, graduates into professional-level troubleshooting. On a precomputer carbureted car, one way to get under the H C and CO limits is to retard the ignition timing. This w ill slow the idl e and provide a longer, hotter burn. Then, bring the idle speed back up to specs with the throttle stop screw or idle stop solenoid , which will ad mit more air. Perfor ma nce will be off, but yo u' ll probab ly pass th e test .

Hard NOx NOx is a tough one. It forms when nitrogen (78 percent of the air we breathe) combines with oxygen (21 percent of the atmosphere), which can happen onl y at very high combusti on tempera tures. The tro uble is, many of the things that were initi all y done to cut H C and CO involved dra matically increas ing the heat inside a car's cylinders. That heat created plenty of NOx. Fortunately, it was found that only the peak temps (over 2500°F) produced this smog-promoting gas, not the long, hot burn th at oxidized the other two pollutants. Introducing Exhaust Gas Recirculation (EGR) knocked the top off the tempera ture curve, thus putting NOx within bounds. One of the main

78

reasons electronic engine management systems were developed in the late 1970s was to allow a 3-way catalyst, which adds rhodium to the 2-way cat's platinum and pall adium to further diminish NOx. The first things to suspect are an inopera tive EGR valve (perhaps the vac uum line is cracked, or the in te rn a l diaphragm has ruptured) and carbonclogged EGR passages. Try app lyin g vacu um to the va lve at idle. If th e engine starts to r un ro ughl y or stalls, the valve is okay and the passages are at least partially open. Remove the va lve and di g o ut all the depos its yo u ca n. There's a good cha nce th at th e cata lytic conve rter is no longer capab le of reducing NOx, but determini ng that requires high-tech diagnos is best left to a professional. There's another distinct possibility that yo u can dea l with, however: heavy carbon deposits in the combustion chamber and on the backs of the intake va lves. These can raise the compression ratio eno ugh to ca use the hot fl as h that forms NOx, and will also interfere w ith the carefully engineered swirl pattern of the incoming mixture that

makes it burn evenl y. N umerous trea tments have been devised to avo id the huge job of removing the hea d and manually clean ing the combusti on chambers, piston tops and valves, but the only one suita ble for the do-it-yourselfer is chemi ca l treatment. The most basic approach is to po ur a suita ble additi ve into the gas tank. A more thorough jo b can be achieved by adding detergent- or solvent-based cleaners directl y into the intake stream. Too much hea t is another thing to thin k about. Is the engine running hot? Is the inta ke air overheated due to a jammed Ea rl y Fuel Evaporation va lve, or is a Thermostatic Air Cleaner door in the snorkel stuck closed? Ignition timing that's too far ad va nc ed can result in deto nation tha t ca uses NOx to rise. A sw itch to pre mium fue l may reduce it. A final no te: Moisture-l a den a ir ca n lower NOx o utput by as much as 30 perce nt, so yo u might consid er visiting the emissions station on a rain y da y. fj

MAINTENANCE

BASICS

MODERATE

Changing Your Oil And Filter

T

he lin e at the quick-lube goes around the building and nea rly to th e street. But the a uto parts store parking lot is empty-now's your cha nce to show the wife that it rea lly is cheaper a nd easier to cha nge yo ur own oil. Especially after watc hing the grease-stained qu ick-lube mechanic through the ba y doors for a couple of oi l cha nges . Air wrenches o n the oil -dra in plug? Even though yo u rea lize that cars have cha nged since yo u got out of the hab it o f

changing yo ur own, they haven't cha nged tha t much.

All Jacked Up J ack ing up the front of the car and p utting it o n safety sta nds is still t he first step, a nd placing the drain pan under the oi l-dra in plug is the seco nd. Okay, yo u're rea d y to loosen the p lug, but it's rea ll y ti ght . That mechanic w ith hi s a ir wre nch apparently was the las t o ne to tighten it. Dra in plugs typically have a soft metal was her or

a sea ling was her w ith a rubber insert. Use a properly fittin g box wrenc h or a 6-po int socket wre nch to remove the plug. Be carefu l not to rock the socket to th e sid e as thi s co uld damage th e f1 a ts on th e bolt. If putting the ca r up on stands doesn 't leave you eno ugh underbody space to get adeq uate leverage, yo u ca n use a 4-way lu g wrench prov ided it has the proper end . Th is w ill allow yo u to twist the bo lt w ithout add ing a ny side thrust, and yo u' ll be ab le to

This permanent filter with a replaceable element is becoming more common on late-model cars. You need to replace only the inner filter element, not the entire cartridge.

CHANGING YOUR

OIL AND

FILTER

79

use both hand s a nd a ll of yo ur upper-body strengt h. Remain ca lm , have pati ence a nd yo u' ll get it loose. But of course, li fe isn 't easy. The threa ds in the pan a nd o n th e plug are damaged, perhaps from partial crossthread ing. What to do now? Forget the drain plug a nd get a repa ir kit. A t ypical kit has a rep lacement fitting tha t cuts deeper threads, a nd when ti ghtened, it sea ls against a washer and remains in p lace. So me kits cut fresh, deeper threa ds for a new plug . A hexhea d brass cap w ith a n 0rin g sea l threads onto th e end. W hen it's time to c ha nge t he o il, yo u unthread the cap. O th ers (for odd-size, severe ly damaged ho les) are fa t, coneshaped synth eti c rubber plugs large r th a n the drain-plu g ho le. You fo rce a spec ia l rod into a n ope ning in th e cone, w hi c h tempora ril y stretches it A simple band wrench may be all that's necessary to remove a canister filter. Make sure a nd reduces its diam eter, you have enough room to swing the wrench. a ll ow ing it to fit in t he ho le. Withdraw the rod, and the course). If th e drain plug is okay a nd pan is dra in ed, unthrea d the hose fitcone relaxes and sea ls t he ho le-the ting (the va lve sp rin gs shut), rein sta ll yo u want to reuse it, rep lace th e cone won't come out until yo u force th e fin ge rti ght cap a nd you' re good to was her a nd t hen tig hten the p lug to in th a t rod to stretch it. If th e dra in p lug looks marg in a l, go (a fter c ha nging the fi lte r a nd spec ificati o ns-20 ft.- lb. to perh a ps co nsid er insta lli ng a Fra m o il-dra in putting fres h o il in th e engine, of 35 ft.-lb.-depe nding o n th e size of va lve kit. These are avai la ble the plug. Empty the drained o il for the most com mo n types of drain-p lug ho les. Thread a into a suitab le container. spring- loaded va lve asse mbl y (In my area, th e county w ith a copper was he r in to the gives away flat jugs w ith a ho le a nd tighten. Th e va Ive is giant built-in funnel.) th e primary o il sea l, a nd a When the jug is full , take knur led cap threa ds on finth e o il to the store w here ge rti ght aga in st an O-ringyo u bought the new o il to thi s keeps out dirt. be emptied into a n o il-recyWhen it's tim e to dra in o il, c ling tank. Ma ny sta tes unthrea d the cap and threa d req u ire service sta ti o ns to o n a fittin g w ith a drain hose, take small q ua ntiti es of o ld w hi ch you can a im rig ht into o il. Dump ing o il in th at th e pa n (no splatter and no low spot behind the shed or ho t oi l running down yo ur in to the sink is not accep ta rm ). T he hose fittin g has an A spider-style wrench interna l tip th a t push es open may be more suitable for th e spri ng- loa ded va lve, and filters that are not easily the o il dra in s out. When th e accessible.

80

MAINTENANCE

J

BASICS

Sometimes th e end of a fil ter has a hexn ut in the center, so you could use a conventional wrench. If yo u can't find the right size and shape cap wrench, try one of the following: • Ny lon band wrenc h. This universal too l wraps a band aro und the filter ti ghtl y. • Coi l-spri ng wre nch. It '-...... INSERT PLASTIC ROD fits over the end of the conIN OPENING ventiona l spin-on filter, and This filter has a rubberized area to the band coil extends to near provide for tightening by hand. the filter's base. Turn the end ""-- PLASTIC ROD w ith a wrench and the co il s able-and probab ly is ill ega l where tighten around th e entire filThis simple rubber plug can rescue a strippedyo u li ve . ter. This prevents damage out oil-drain-plug hole. Insert the rod to install and separa ti on from the Off With The Filter base . How a bout dri ving a big screwdriver When removing an oil fi lter, what you • Spring-band wrench. This thro ugh the spin-on cartridge and need more than anything is the appro- wre nch fits over the end of the filter using that to loosen a stuck filter? priate wrench. There are many sizes, and extends just past the fI utes, so it You're more likely to destroy the cargri ps th e full circle of the filter bod y. and perhaps the most common tridge and still not loosen the filter. a nswer is the cap wrench, w hich fits • A "spider" has three fluted legs Have the dra in pan in place, sitting that cla mp against the sp in -o n caron the end of the filter. Only probl em: on a spread of newspape rs or an oi ltridge and " di g in, " preventing slipThe wrench fits aga inst a fluted patabsorbent pad- just in case. Once the page. It has an end plate for a ratchet, tern and there are countless fluted filter is loosened, oil ma y start flowin g and because the sp ider legs extend 2 ~ patterns. So not only do yo u need the to th e gro und. right size, but the right internal shape in., they grip well past the o uter end Unthread the filter and carefully to fit the flutes . The one tha t fits the of the filter. This design provides well empty it into th e drain pan. distributed gripping power. filter on yo ur car now, we should It is possible to loosen a badly warn you, may not fit th e replacement Refilling stuck filter with a good filter wre nch. filter yo u buy. App ly a film of cl ea n engine oil to th e gasket of the new filter, then threa d the filter on by hand. Some filters WHAT'S THAT STARBURST? have a rubberized surface to make it easy to turn. Every reputable oil filter You should see two labels on a container of oil. One is a is designed to seal for tens of thou"starburst" with the words American Petroleum Institute sands of miles with no more than a Certified printed on it. This means that the oil has good hand-tightening. You don 't need passed tests for the recommended service in which a wre nch unless yo u have one of those it's to be used-that includes a test by ISLAC (Interdeeply recessed filters with no space national Lubricant Standardization and Approval around it for yo ur hands. (If that's the Committee). Passing the ISLAC oil test enables carcase, the only choice is a cap wrench.) makers to add to their fuel economy numbers. Oils Turn the filter until yo u feel the filter such as OW (a synthetic grade) and 5W (thin) pass this base just make contact with its test, and so do some lOW-30 oils. Heavier oils, including mounting plate. Then use the wrench those formulated for older cars, do not. to tighten a ha lf-turn more. On the second label you'll see the words "Energy Conserving." Real If yo u haven 't bought engin e o il world: Oils labeled this way won't make a noticeable difference in your in a whi le, you may be confused by car's gas mileage. This label also lists the service category. On late models th e choices. For a little fri endl y you want an oil deSignated For Service SL. You may also see some Sl/SJad vice, see "What 's That Starburst? " rated oil on shelves. Read your owner's manual. left. tJ

CHANGING YOUR

OIL AND

FILTER

81

DIFFICULT

Search Engines o ur tempera ture ga uge inches up towa rd the danger p o int. Simulta neo usly, traffic slows eve r closer to mp h-w it ho ut eve r qui te reachin g it-as the ru sh h o ur dee pens. T here's no a ir mov ing th ro ugh yo ur radia tor, a nd an y that does is too da mned h ot. Yo u start to smell that sy rupy-sweet panca kebrea kfas t-in-a-Tu rkish-bath odo r o f nea r-bo ilin g a ntifreeze . You turn off the alc to redu ce the load, but th e needl e does n't d rop. Time to upgra de the coo ling system. After spending a full Sa turday and $4 50, you 've installed a high-perform ance rad iato r and th e pro blem d isa ppea rs. Th en, yo ur fr iend w ith the sa me make o f ca r has the same p ro blem. So yo u tell him the good- if ex pensive-n ews . "1 a lso got the prob lem fi xed," h e tells yo u, " but it cost me onl y $75 at the car dea lersomething a bo ut reprogra mming the co mputer. Th e car was o ut of th e pl ace in a ha lf- ho ur."

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°

Reprogra mm ing toggled the coo lin g fa n on and up to hi gh speed much ea rl ier, usin g a rev ised fan co ntrol a lgorithm . If onl y yo u had known .

Look It Up Now yo u can know. You can do more- and better-wo rk on your car with the spec ia l manu a ls, bull etin s a nd some of the specia l too ls th e dea ler shops have. In fact, yo u even ca n rep rogra m yo ur ca r's co mpu te r us ing yo ur PC and a generic device th at works on a ll makes. Yo u thought all that was secret stuff or incred ibly expe nsive ? Not an ymore-it's ava ila ble to everyo ne fro m fac tory tec hserv ice Web sites. As ide fro m a shop uni fo rm , anyt hing the dea ler tec hs get, yo u can too, in clu d ing o ncesecret me mos . O nl y a few low-vo lu me cars, such as Ferrari, R o lls-Royce, Asto n Martin, etc., are exemp t. Virtuall y every Web site meets or bea ts a cost of $20 per day for a ll in fo rmati on (except BMW at $25 per

day, Porsc he and VW/A udi w ith a per-d ocum ent price). Hyund ai and Kia sites a re free, and others offe r some freeb ies even if yo u don 't bu y anything. We b site informati o n is " professional," intended for service technicians w ith ve hicl e-specific training program s under their belt- so yo u may need to go slow ly to und erstand it. Howeve r, most sites have tutor ia ls, even o nlin e a uto tech co urses yo u can ta ke, as we ll as techni ca l ma nua ls to rea d . T hey're designed for bas ic trainin g, so they won't lose a Sa turday mec hanic. Most of the We b sites h ave p rett y stra ightforwa rd nav igation, but it's still not like o pening a boo k. Always read t he system req ui re ments and freReprogramming your car's engine management computer is only slightly more complicated than downloading music onto your MP3 player. The pass-through device connects the car's OBO II diagnostic connector to your computer.

MAINTENANCE

BASICS

q uentl y as ked questi o ns (FAQ ) fi rs t. High-speed Intern et serv ice ma y be just " reco mm end ed ," but w ith o ut it yo u' re in for rea l frust rati o n, both for downloa ding speci a l so ftwa re a nd using certa in features . Some downloa ds a re over 15MB, and yo ur actu al tra nsfe r speed may be far less th a n th e connecti o n ra te- mea ning litera ll y ho urs of downl oa ding. Th ro ughpu t ra tes mi ght be better in th e wee ho urs w hen there's less traffic o n the Internet . After yo ur days-l o ng subscription to th e Web site expires, yo u ' ll still wa nt access to the da ta yo u've paid fo r. So print o ut the service data as yo u d ownl oa d it, o r a t least keep it o n yo ur hard dri ve a nd backed up to so me o th er pl ace.

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Advice For The Slow Lane If yo u must use a dial-up modem, un dersta nd tha t o nl y stra ightforward wi ring diagra ms (not interacti ve types) a nd no n-PDF repair instructi o ns w ill open w ithin to lera bl e times . Also, yo u sho uld as k som eone w ith a broa dband conn ecti o n to downl oa d needed software a nd store it o n a CD . In sta lling fro m a CD saves lots of time. An a lterna ti ve tha t works reaso na bl y well w ith di a l-up is A ll da tadi y.co m, the Sa turd ay mec han ic's site fro m th e suppli er of p rofess io na l serv ice in fo rm a ti o n . Fo r $25 (one car, $1 5 each additi o na l), yo u get a o ne-year subscriptio n to all th e info rm ati o n Alldata provid es to independent garages as far bac k as 1982, including continu o us upda ting of Tec hnica l Serv ice Bull eti n (T SB) li stings. It's easy to naviga te, a lth o ugh se rv ice ma nu a l info rm a ti o n lags mode l int ro ducti o ns by o ne to two years. Info rma ti o n is edited a nd reforma tted fro m fac tory ma nu a ls, altho ugh so m e specialty inform a ti o n is exclud ed, such as a uto ma tic tra nsmi ssion overha ul. All lea ding m a kes a re covered exce pt H o nda a nd BMW (w hi ch a re o nl y in Allda ta's professio na l system ). T SB postings run o nl y slig htl y behind th e ca rma kers' own li stings. If you ha ve a n o lder car, AIl datadi y.com m ay be yo ur o nl y cho ice, as most facto ry Web sites (except fo r

Tools

A. L L Diagnosti c Trouble Codes ( DTC ) " Codes by Number " Codes by SYstem Relays and l\ Iodul es Sensors and Switches lI. Iaintenance Engine. Cooling and Exha\lst " Engine " Cooling SYstem " Exhaust System PO\\'ertra in l\ Ianagement Transmission and Dri,·etrain Brakes and Tracti on Control Starting and Charging Po\yer and Gro\lnd Distrib\ltion Steering and Suspension Heating and Air Conditi oning

IT'S NOT A HEAP: Alldatadiy.com provides tech info for cars as far back as 1982.

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• ATF level aCCOfding to TSB 03-40.019 Add SPill ATF if necessary. • DIagnostic Ttoubkl Codes In both the "Engine" and "Automatic Transaxlc" mellYs. II OTC are found , repair aCCO«lIng 10 the appropriate TSB or ShOp manual. If no OTe are found, go to "Olagnostic Procedure" DIAGNOSTIC PROCEDURE:

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THE PRICE IS RIGHT: Hyundai's Web site provides service data free of charge.

serv ice bu ll etin s) cover largely latemodel stuff.

Programming Your Car's Computer As more repairs are do ne by repro-

gra mming computers, the Web sites w ill becom e yo ur source for progra ms you can download into your PC, then transfer thro ugh a generic device ca lled a pass-thro ugh to the data bus III yo ur car.

83

"Me? Reprogram my car's computer? If it's anything li ke installing software, I' ll never get to work." T he idea is the same. And there are safeguards to keep yo u from leaving your car dea d in the wa ter. Ford, Chrysler Group, BMW and Mazda already offer reprogramming services on their Web sites. You download a program that checks yo ur car's powertrain comp uter. For other on-board computers, yo u ha ve to check ca li bration charts on the Web site to determine what is avail able. Because of the delays in finishing SAE standard j2534, low-cost, mass-production pass-throughs are not yet ava il ab le. When GM and the lea ding japanese makes offer reprogramm ing software over the Internet, yo u can expect pass-throughs covering most mak es to cost $100 to $300- versus $900 to

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Tech Web Sites Most tech Web sites (take note of the exceptions below) take the form: www.nameofvehicletechinfo.com . Example: www.landrovertechinfo.com. • Alldata Do-It-Yourself: www.alldatadiy.com (excludes Honda/Acura and BMW coverage). • Chrysler Group: www.techauthority.com $20 for a day of TSBs dating to 1992, and all service/diagnostic information to 1996 (a few '95s). Good selection of Chrysler training materials for subscribers. • Ford (and Lincoln Mercury): www.motorcraftservice.com Free selection of OBD II training books, owner's manuals and towing/camping books. It's $10 per day for TSBs from 1988 on and $20 per day for all repair information on a single model/year/car, which includes service/diagnostic information and an e-mail link to OASIS, the Ford factory-tech help line. • General Motors: www.acdelcotechconnect.com Free access to "Tech Link," a monthly professional tech service magazine that covers a wide range of GM service issues, with archives back to 2000. Pay $20 per day for bulletins (from 1980) and all service/diagnostic information (1998 on, with powertrain manuals back to '96). • Honda and Acura: www.serviceexpress.honda.com Buy access separately for $20 for three days. Selecting a subject (such as Fuel & Emissions) gets you information from the service/diagnostic manual, applicable service bulletins and anything on the subject from "Honda Service News," a dealer technician publication.

84

• Hyundai and Kia: www.hmaservice.com Entirely free, includes good training you can download , as well as service/diagnostic information. • Mercedes-Benz: www.startekinfo.com A $20-per-day site loaded with technical information going back to the early 1990s. • Nissan and Infiniti: www.nissan-techinfo.com and www.infinititechinfo.com lt.s $20 per day for access to both sites (bulletins back to 1987, service/diagnostic manuals since 1994). Manuals come up by subject and read like a book. • Porsche: http://techinfo.porsche.com (no www) • Subaru: www.subaru.com (then click on home, and then technical information). • Toyota and Lexus: http://techinfo.lexus.com and http://techinfo.toyota.com (no www) Get both easy-touse, info-packed Web sites for $10 per day. Included are diagnostic/repair manuals, wiring diagrams and bulletins since 1990. • Volkswagen and Audi: https://erwin.audi.de (no www) and www.erwin.vw.com Separate Web sites are run by the same office in Germany. You're charged by the document, so click repeatedly on Search, which gets you to the price and Contents. • Volvo: www.volvotechinfo.com Sells service/diagnostic documents, wiring diagrams and two types of service bulletins for three-day periods. Manuals are $10, diagrams $5 and the bulletins $13. The sales are only for specific models, except wiring diagrams.

MAINTENANCE

BASICS

•

ASY

Charging Your Battery

S

pring has come an d go ne. Wit h th e ya rd fina lly w hi ppe d in to shap e, yo u 've m a naged to sc hedu le a lo ng weekend up in th e mounta in s- just yo u a nd yo ur fa mi ly and a few d ays of a lot of nothing . The motorhome starts w ith the aid of jumper ca bl es, and a fe w hours of fr eeway dr iving sh o u ld fu ll y c ha rge th e ba tte ry. The sa d p a rt is, when yo u fina ll y reach th e camps ite, the kid s ca n ' t watch TV, th e microwave won 't wo rk a nd , horro rs, th e blender is incapa ble of making yo ur favorite froze n concoction. The battery ha sn 't charged much

at a ll. Yo u co uld run yo ur generator o r the motor-h o me engine for power, but yo u ha te to di sturb the untram meled w ildern ess by doing tha t. And bes ides, the ca mpgro und ha s ru les aga inst genera tors after sunset.

Too Close To Home? The prob lem yo u have is common to ma ny RVs, a nd there are many possible reaso ns for yo ur predicament. The RV's deep-cycl e ho use battery was left unc harged over the winter, ftoze a nd is now use less except as an anchor for yo ur boat. Or, you simply forgot to turn on th e battery switch. Or, the

alte rn ato r o n the RV was maxed o ut by running the alc fa n, GameBoy and stereo a nd trying to rec harge th e ba ttery a ll a t the same time.

How Batteries Charge A conventiona l lea d-acid car battery is filled w ith interl eaved p lates of spongy lea d and lea d d ioxide soa king in sul furic acid and water electtol yte. The sulfu ric ac id is diluted to a specific grav ity of about 1.26 to 1.30, depe nd ing o n th e type o f ba ttery. C harging the battery combin es so me of the sulfuric acid a nd lead, reducing the concentra tion of sulfuric acid Motorhomes, tractors, boat s, motorcycles and other occasionaluse vehicles should use a batterymaintainer style of charger to prevent battery damage. The permanent extra wiring harness makes it easy to hook up the charger when necessary.

CH AR GI N G Y OUR

BAT TE R Y

85

With hard-to-access batteries, look for a remote jumper cable post.

FUSE BOX COVER

down to a bo ut 1.12 and coa ting the plates with a la yer of spongy lead sul fate . Reversing this p rocess gives yo u back most of that electricity. This means that checking th e specific gravity of the electrolyte is a very good wa y of finding o ut the actu al state of charge of a battery. It's a lso fu ssy and po tenti all y dangerous if the battery electro lyte end s up someplace it's not supposed to be, like in yo ur eye or on th e lea ther upholstery of your wife's ve hicle. Also, some maintenance-free batteries have no fill er caps a nd there's no way to check o r a dd electro lyte. So, we' re left to estim ate the battery's state of charge by rea ding its in the electro lyte develops a gra dient, voltage. A fully charged 12-volt batbecoming more concentrated next to tery sho uld have an open-circuit vo ltone plate and less concentrated at the age of 12.6 volts. A discharged batoth er. Onl y time wi ll even this out, and tha t's why yo u can't qui ck-charge tery will have a vo ltage of abo ut 11.2 volts-but these numbers need to be a battery to any more than a bout 50 checked w ith no loa d a nd with sevpercent of its capacity. era l hours o f res t after charging. And To charge a battery, a charger or this is at a norma l battery tempera yo ur car's altern ator needs to ra ise the ture of 80°F-colder batteries have a slightly lower vo ltage . An RV parked outdoors is a good candidate for a A battery left disch arged fo r battery maintainer, such as this type. eve n a few ho urs w ill conve rt SOLAR BATTERY some o f its so ft lead sul fa te MAINTAINER depos its-the kind th at rea dil y change back into lea d oxide and sulfuric acid-into hard permanent deposits . These deposits interfere with normal battery operation, and ca n damage the plates. Be ca reful when storin g batteri es in lower temps. A di scharged battery co ntain s mostly water and ca n freeze solid , fracturing th e lea d plates. Always store a battery full y charged and in an area that stays a bove freezing.

Uphill, Downhill As a battery is charged o r discharged , electrolyte needs to diffuse fr om one plate to another. At high or low discharge or charge rates, th e acid

86

voltage across the battery posts. No rmal charging voltage needs to remain below a bout 14.4 vo lts, which is the level at w hich gass ing of hydrogen and oxygen starts. Yo ur ca r alternato r was never intended to charge a tota ll y di scharged battery. H ere's what happened on th at fa teful trip to th e mountai ns. The ba ttery was to tally d ischarged after being left unattended for months. A totally solar discharged battery needs very high vo ltage (ove r 16 vo lts) or a long cha rging time at 14 volts to even begin to acce pt a charge . O nce th at battery started to accept a charge (but in this case it did not ), it wo uld have made the a lternator work very hard to pump current into th e battery, shortening the altern ato r's life. This type of situation ca lls for an external battery charger. The tra ditiona l charger is a simple transformer and diode affair that charges a battery to a constant voltage just below the gassing vo ltage of 14.4 volts. It will sta rt OLlt chargi ng at a good clip, and then tape r off, taking as much as a full day to full y charge a large, dead battery. It's not a candidate for keeping a battery charged, because the voltage it genera tes w ill still

MAINTENANCE

BASICS

HOW IT WORKS

There Are Batteries, And Then There Are Batteries. We commonly think of car batteries as lead-acid flooded wet-cell batteries that haven 't changed substantially since the earliest electric cars used them (the early batteries' cases were made of glass, not plastic). The lead in these is alloyed with antimony to make it hard enough to withstand the vibration it receives in a moving vehicle. In the last few generations, maintenance-free batteries have become the standard. These use an alloy of lead and calcium. In contrast, the antimony used in older batteries promotes the electrolysis of water, lowering the electrolyte level and requiring replenishment. Maintenance-free batteries generally have a higher level of electrolyte covering the plates, and they commonly lack filler caps.

Totally discharging one of these types of batteries even once can permanently compromise its ability to take a full charge. Deep-cycle batteries use a purer lead in thicker plates, and are capable of many cycles of neartotal discharge. They need periodic replenishment of the water in their electrolyte. The newest lead-acid battery technology uses a gel electrolyte that won't run out if the battery or vehicle is upended. Another type becoming popular is the absorbed glass mat (AGM) cell. The electrolyte in this battery is held in a spongy mat and can't move around. AGM and gel-cell batteries internally recombine the hydrogen and oxygen from electrolysis so you never have to add water to them.

A smart charger will rapidly recharge a dead battery without boiling off electrolyte.

ma ke the electro lyte disappea r as gases- an especi a lly bad idea for a maintenance-free battery that ca n't be replenished. Even a small trickle charger will damage a battery over a few months if left on. The more modern battery chargers are smart. They w ill ra ise th e curre nt fl ow hi gh eno ugh to bulk charge th e battery rap idl y, then taper off until th e battery is full y charged . Thi s reduction is necessary to keep below the 14.4-volt ga ssing point . Th e chargers then throttle back to a somewhat lower voltage that w on 't bo il the electrolyte, and peri odica ll y check Voltage is a good indicator of a battery's state of discharge, but not during the charging phase.

BATTERY VOLTAGE AND STATE OF CHARGE

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the vo ltage, occas iona ll y ra ising the voltage for a fe w hours to maintain a full charge . The latest cro p of smart chargers even have a battery-reconditi oning fun cti on tha t is supposed to break up ha rd sulfate depos its by bl asting them w ith p ul ses of high-frequ ency vo ltage spikes, returning a badl y sulfated battery to near-new condition .l spikes, returning a badl y sul fa ted battery to near-new co ndition. ~

87

88

CHAPTER TWO

•

In Today's Tuneup / 90 Smoothing Out a Lumpy Idle / 93 Replacing Your Water Pump / 96 Curing a Clicking Starter / 99 Repairing Cooling System Leaks / 102 Curing Slow Cranking / 105 Finding Oil Leaks / 109 Flushing Your Cooling System / 112 Checking Your Ignition Timing / 116 Replacing Engine Mounts / 119 Cleaning Throttle Bodies / 122 Electric Cooling Fan Problems / 125 Finding Engine Knock / 128 Plugging Leaks / 132 Turning Up Your Heater / 135

89

EASY

Today's Tuneup RETAINING CLIP

T

here's the thruway exit, but you're stuck in the left lane. H ey- a break in the traffic. You fli p up the tu rn signal, floor the gas pedal and try to edge into the right lane. Whoops! Your V8 is embarrassed by a 4-cylinder econobox with the same obj ective. It was behind yo u, but it apparently has better accelerati on. You hit the brakes, crank the wheel to get back into the left lane, cru ise to the next exit miles and miles ahea d , and make the time-wasting U-turn. The Wife suggests a tuneup . But we don't tune up today's engines, right ? They're computerized and there's nothing to adjust. Wrong. It's true we stopped replac-

90

ing ignition points over 20 years ago . If it's rea lly a late-model vehicle, it may not even have a replacea ble fuel fi lter under the hood. The battery is a fill -free des ign. And there's no ignition timing to adjust. H owever, while it has changed signific antly- even in the last seven or eight years-the concept of a tuneup itself is anything but gone. Emissions reg ulations may have tightened, but am bient air is still di rty. So the air filter still plu gs up, and the engine gasps for brea th until a clean new fi lter is install ed (Fig. 1) . Gasoli ne is unleaded, so spark plugs don't lea d-fo ul anymore, and the new prec ious-metal designs last much longer. But they aren't guaranteed to

(Fig. 1) Replacing the air filter will require popping off a couple of clips. Slide the new filter into place, be sure it seals properly, and replace the cover.

last a life time, and engin e performance often ca n improve when p lu gs are replaced well before the owner's manual dictates.

Underhood Checks A good wa y to start today's tune up is to look for tro uble codes, using a scan too l. Th e only codes that turn on a Check Engine light are those th at directl y impact emissions, provided the computer can detect them, to keep people from getting nervous. Most

ENGINE

codes show up o nl y w ith a scan too l. O n th e o th er ha nd , " no code" driveab ility prob lems a re a lso extre mely common. If yo u find a trouble code, yo u sho uld trace the circ uit to pinpoint the problem. Sure, it cou ld be just a bad senso r, but it may be a bad wirin g conn ecti o n, chafed wire o r damaged hose. Yo u'll need t he facto ry se rvice in formation to be ab le to do thi s. No t roub le code? In spect under th e hood. look for dama ged vac uum hoses that sho uld be repl aced, loose connections at a ny of the sensors and soleno ids, tears in th e a ir clea ner du ctwork, a disconn ected duct o r poor spark plug wiring co nn ec ti o ns. Test th e be hav ior of th e engin e co ntro ls a nd th eir sensors. Th ere sti ll a re tim ing m arks on man y la te models an d if yo ur ve hicle is one of them, yo u ca n check ba sic timing (a t idle) w ith a timing light. No mar ks? You still ca n chec k igniti on timi ng o n t he sca n too l by rea din g th e ig niti o n advance data item. look fo r a stea d y in crease in ignition timing as the thro ttle is gra duall y opened from idl e to a mid th rottle position . Even if th e timing is a ll right, check the th ro ttl e position sensor a nd intake airfl ow (mass a irflow ) sensor readings, w hi ch a lso sho uld show grad ua l increases as the accelerato r peda I is dep ressed. At the same tim e, tap o n the mass airfl ow sensor w it h a screwdri ver handle and if th e engine hi ccups or the sca n tool read ing spikes, the senso~' is defecti ve. A coo lant temperature sensor sho uld show a co ntinu ous in crease in th e reading until t he eng in e is full y war m (195 ' F to 230' F). A MAP (manifo ld abso lute p ress ure) engine vacUU111 sensor should show cha nges w hen a pinched-cl osed hose suppl ying vacuum to it is released (Fig. 2) . Th e engine sho uld read a bout 750 to 850 rpm at idle w it h the engin e (Fig. 3) Wiggle the wiring connectors while the engine is running to check for misfires.

TODAY ' S TUNEUP

• , I

1I I I I 1

MAP SENSOR

(Fig. 2) Check the MAP sensor with a scan tool by pinching its hose.

warmed, a nd increase g rad ua ll y as t he gas peda l is dep ressed. Stil l no reason for a dr iveab il ity glitch ? Yo u need to access the powertra in computer. It may be located und er th e hood o r under the dash. T he most comm o n und er-dash loca ti on is behin d the passenger-s ide ki ckpad. Remove t he kickp ad a nd , w hil e a he lper is slow ly acce lerating the engine, flex the computer w irin g connectors a nd tap o n th e co mpu ter ho usin g (Fig. 3) . If th e engi ne hi cc ups, there's a bad connectio n or poss ibly cracked so lder jo ints o n th e circuit boa rd . Yo u may need a rep laceme nt.

Replacing Spark Plugs Time was, spa rk plugs were always vis ible, even if it took a struggle to

reach th em . Now t hey're often recessed into th e hea d, and in m an y cases th ere a re no p lu g wires . A mini igniti o n modu le, perhaps wi th t he co il bui lt in to it (o r into th e plu g boot), is used in stea d. Yo u may have to remove a cove r t ha t ho ld s t he igniti o n modu les a nd plug boots fo r access . W hatever th e des ign, very carefu ll y make a n y necessa ry electrical disconnectio n at the plug prior to plug remova l. If th ere a re plug wires, grasp a nd lift by the plug boots. Never pull o n a plug w ire o r it may separa te internally. Look inside t he boot a nd if it appears soaked in o il or cracked by hea t, rep lace it. If the igniti o n co il is bui lt in , expect it to be pricey. In spect th e p lugs. If th ey a ll have a coa ting of bl ac k carbon, th a t indi ca tes a rich fuel mi x ture and lik ely a bad oxygen sensor. A sca n too l sho uld be ab le to pinpo int a ma lfuncti on ing oxyge n se nso r eve n if it did n't log a tro ubl e code. If th ere's just a single carbonblacke ned plug, yo u probab ly have a leak in g fu e l injecto r. W hen yo u' re ready to in sta ll the new plug, apply a thin film of a ntiseize compound so th e new plug doesn 't hea t-sea l in p lace . Use a torg ue wrenc h to tighte n the plug.

J 91

bru sh bOth contact faces even if they look clean. Make sure the bolt threa ds in with o ut a feeling of looseness, a nd if there is a ny, don 't try to muscle the bo lt supertight with a wrench. You're more likely to m a ke things worse.

(Fig. 4.) You may not be able to clean the pintle on a recessed EGR valve like this one.

Exhaust Gas Recirculation Exha ust gas recircul ati o n (EG R ) va lves may stick o pen, fa iI to cl ose co m pl etely o r just no t o pera te smoothl y. If so, th e engine w ill hes ita te a nd may sta ll , fuel econo m y may d ro p, a nd emi ssio ns may be affected-even if yo u p ass th e sta te in specti o n test. The EGR valve meters so me exha ust gas bac k into th e cy lind ers to lower pea k tempera tures of t he airfuel charge during co mbu sti o n . Thi s not o nl y redu ces a key po lluta nt (ox id es of nitroge n ) but often improves fu el eco no my. Th e EG R va lve, t ypica ll y a di ap hrag m-actu a ted dev ice w ith a pin -type va lve, is pull ed o pen by engin e vac uum , but th a t vacuum mu st be precise ly reg ul ated. Too mu ch vac uum res ults in too much ex ha ust gas fl ow, whi ch ca n ca use the engine to lose power, even sta ll. Late models with OBD II comp uters have sophisticated stra tegies to detect severely ma lfuncti o ning EGR. H owever, this basic check w ill work o n a ll vac uum-contro lled EGR systems. Loca te the EGR va lve a nd if it has a vac uum hose connecti o n, unplug it. Run th e engine at idle, a nd connect a sp are hose fr o m a source of engine vacuum o r use a ma nual vacuum pump a nd a ppl y vac uum to the hose neck. The engine sho uld slow significa ntl y, pro ba bly even stall , if yo u ap pl y full engin e vac uum (17 to 21 in .). If there's no significa nt change in engin e idle-in fact, if the engin e has been idling ro ugh-the valve may be sti ck ing open. Remove it a nd if you can see a heavy acc umulatio n of deposits in the port, a nd if it's a n exposed pin -type va lve, clea n it with a wire brush (Fig. 4) . If the end of the pi n is recessed in the po rt, it ca n't be clea ned. Replace it.

Where To Get Service Information

top-post a nd side-termina l-are subj ect to co ntinu o us drain with the engine off, to keep a live the memories of ma ny computers (from powertra in to car radio). Just a slight coat of corrosionperhaps too subtle to be visible-can reduce battery charge. Disconnect the ca ble terminals. On a top-post battery, bru sh aro und the post and inside the ca bl e termin al (Fig. 5) . If the post o r ca ble terminal is badl y corroded, replace it w ith a premium terminal, the kind that often includes a ca ble secti on. Forget the cheap screw-together terminals-they'll become severely corroded and ca use more problems th an th ey solve. With a side-termin al ba ttery,

Di agnosing fa ilures th a t produce t ro uble codes, a nd findin g o ut normal readings for engin e sensors, is not subject to rul e of thumb procedu res. Yo u need the latest fac tory di ag nosti c sequ ences a nd specifi cati o ns. Ve hicl e ma kers have Web sites w ith t hi s serv ice in fo rma ti o n, a nd yo u' ll be a ble to access the da ta for a day a t a time. Ma ny sites cha rge fo r thi s informa ti on-yo u can pay using a credit ca rd. At present, Genera l M oto rs in fo rm a ti o n is ava il a bl e a t www. acdelco.co m (click o n ACD elco TechConn ect ). O r yo u ca n get a low-cost subscripti o n fr o m ww w.a llda ta .co m (a lea ding so urce fo r p rofess io na ls, w ith infor m ati o n o n all m a kes) . In additi o n, AutoZone offe rs free sca n too l connecti o ns a nd rea do uts a t its sto res. ~

(Fig. 5) Clean the battery posts and cable clamps regularly.

BATTERY POST BRUSH

/

Battery Terminals Clea n the battery terminals, then reinsta ll and tighten. Today's batteries-

92

ENGINE

EASY

Smoothing Out a Lumpy Idle

ea rful p edestri a ns glare at yo u as they pass in front of yo ur bumper at crosswa lks. O ut of embarrass ment, yo u try to igno re them by glancin g aro und no nch alantly, stroking yo ur hair as yo u look in the rearview mirror or tuning the radio. Mea nw hil e, th e size of your right thigh is growing to Dan Jansen proportions from th e force bein g appli ed to th e brake peda l. Your engine's idl e speed is surging up and down, creating crescendos that wo uld make Pavarotti proud : WAAAAaaaah, WAAAAaaaah, WAAAAaaaah! It's all yo u can do to keep yo ur maniacal car from lurching fo rwa rd into a laws ui t. There are a number of ge ner ic steps yo u ca n ta ke to see w hat's a iling yo ur wheels. And if th ere ever was a time to step bac k a nd remember the ba sics, this is it. Pop quiz: W h at is an interna l-combustion engin e? It's basica ll y littl e more than an air pump. T he more a ir that gets in, the fas ter th e engine run s. And a irfl ow contro ls idle. By a ll ow in g a certa in volume of air to bypa ss the closed throttle plate( s), idle rpm can be maintained at a healthy leve l. Even to accelerate, we don 't "step on the

F

SMOOTHING

OUT A LUMPY IDLE

gas," we "step on th e air " by opening th e throttl e plate farth er. Fuel is add ed a nan osecond later, in response to th e grea ter inta ke a irfl ow.

(Fig. 1, left) Make sure all the clamps sealing the intake duct are tight. (Fig. 2, right) Pull back the intake duct to check for hidden cracks underneath.

Check Your Intake Tract If yo ur engine uses a remotely mounted

ho le still needs to be sealed, or else dirt a nd debri s will find its way in . If th e engine uses an airflow sensor, this type of lea k tends to a udibl y revea l itse lf w hen th e engine torq ues forwa rd on its mounts an d opens wid e th e co nvo lute crack . Th en th e engine gets an unmetered gulp of a ir and revs up on its own. The idle speed control may try to ca tch the speed burst by closing down the bypass chann el. Then, when th e engin e ret urn s to its norm a l positio n a nd th e convo lute crack closes, th e idl e speed is too low. In res ponse, th e idl e contro ls may open up the chann el aga in to raise the idle. This scenari o can turn into a cycling condition that produces a lumpy, rolling idle. If yo u don't mind gettin g yo ur engin e ba y a littl e messy, anoth er q ui ck way to go a bo ut chec kin g fo r intake trac t and runner lea ks is to simpl y spray carburetor cl ea ner aro und co nnections and the inta ke manifold w hile the engine is run n ing (Fig. 3) . If yo u get an rpm change w hen yo u spray, it mea ns the vapo rs

air filter in an a ir box, inspect everything fro m there back to the throttle p late(s ). At the air box, check all hose connecti ons and make sure the cl amps are ti ght (Fig. 1) . Replace the air filter if it's so dirty that light fro m a lOO-wa tt bulb doesn't pass through the element. Make sure the new one seats properl y in the air box and that the cover sits flu sh and cl amps down evenly. Follow the intake tract toward the throttle plate, tightening a ll the clamps as yo u go. If there's an inline mass airflow meter in the tract, take extra care to examine its connections for leaks. Big, convoluted rubber tubing-style intake tracts are susceptible to developing cracks between the convolutes on th e und erside of the tube. They' re generall y not visible unl ess yo u remove one end of the tube and bend it back to get a good look below (Fig. 2) . If the engi ne control s meas ure airflow by mea ns of a manifold abso lute pressure (MAP) sensor, this type of leak sho uldn't affect idle q ua lity. But the

93

a re gettin g in so mehow. So yo u have to pl ay spy to find th e lea k. Don't sp ray nea r the d istributo r-if yo u h ave o ne-beca use th ere's a cha nce the solven t wi ll ignite a nd leave yo u minu s yo ur eye brows and nose ha ir.

Keep Your Bore Clean When yo u get to the last clamp a t the throttle bore, unscrew it a nd remove the intake tract. Take a look inside t he bore w ith a fl as hlight. If the muck is so thick that it's a wo nder the throttle plate can move at a ll , you've found a major cause of your lumpy idle. In addition to the idle air-bypass chann el, a sma ll amount of a ir must be a ble to pass aro und the throttle plate itself. When blowby vapors fwm the pev system (a nd EGR exhaust gases) sludge up the bore over time, the idle a ir-bypass functi on is seriouslyaffected. Steal an o ld too thbrush from yo ur kids (so yo ur w ife doesn't b low a gasket) a nd pick up some nonca ustic fu el-i nj ecti o n intake cl ea ner at a n a uto parts store. W it h t he engin e off,

spray some cleane r in th e bore and start sc rubbin g w ith the too thbru sh. Pay pa rti c ul ar a ttenti o n to th e circ um ferent ia l area where the th rottle pl a te sits w hen closed. Also clean both sid es of the plate and its edges. If th e externally mounted idl e airbypass va lve is easil y removed a nd its c ha nn e l eas il y accessed, tr y to get c lea ner to pass thro ug h t he cha nn el into the bore . Be sure to clea n the va lve 's pintle tip, too (Fig. 4) . (Also see page 122.)

Wash Down the Residue With th e bore a nd cha nnel clean, stick t he intake trac t back o n a nd start t he engin e. If the engin e does n't use a n a irfl ow meter, yo u ca n pull the tract off w ith th e engine run ning a nd spra y so me more cleaner in the bore to was h down the res idu e. Goose the throttle a coup le of tim es. Then tighten the clamp a nd let th e motor idle so tha t the engin e- ma nage ment system ca n re lea rn th e parameters necessa ry for increased throttle p late a ir bypass.

(Fig. 3) Spray carb cleaner around the throttle bore to find air leaks.

If yo ur engine does use an a irflow meter, it' ll probably sta ll w hen yo u pu ll the intake tract off the bore. Get it started aga in a nd just pull th e end of the rubber t ract bac k a bit w ith o ne o r two fin gers to spray some more cl ea ner down in the bore . T he engine wi ll stumbl e for a second , but tha t's okay. Whatever yo u do, don't spray the clea ner into the tract before the a irfl ow meter. Yo u co uld da mage t he meter. Sing le- a nd dual -p o int inj ectio n thro ttl e bo di es typ ica ll y don't sludge up much beca use th ey're up top o n

HOW IT WORKS

Engine Management An automotive computerized enginemanagement system works like any computer as it controls idle speed. The central processing unit relies on various inputs to calculate necessary outputs. On modern motors, however, the inputs to the processor, or powertrain control module (PCM) , are called sensors. The outputs are called actuators. And the PCM is programmed to control the actuators under any condition that the sensors deem necessary. Key sensory inputs of most enginemanagement systems include engine speed, coolant temperature, crankshaft position, intake airflow, manifold vacuum, throttle position and exhaust oxygen content. Many systems go further, factoring in such inputs as camshaft position, barometric pressure, intake air temperature, detonation detection, EGR valve position, misfire detection, engine-oil temperature, power-steering pressure, air-conditioning pressures, gear-lever position, vehicle speed, automatic-transmission-fluid

94

: ?

J

POWERTRAIN CONTROL MODULE

----c:::=-_~ IDLE SPEED CONTROLLER

/

AIR FILTER

EVAPORATIVE EMISSIONS CANISTER temperature, catalytic converter efficiency, system voltage and others. Key actuators on many systems include the fuel injectors, idle speed control motor, EGR valve, evaporative canister purge, ignition coil timing and dwell (saturation time), torque converter clutch, smog pump diverter valve, cooling fan, alternator output and fuel pump.

ENGINE

th e engin e and rcv vapors flow in be low them. H owever, if the plate(s) looks rea ll y d irty, it's okay to hi t it w ith so me c lea ne r. JU St be careful not to drown th e fuel inj ector sitting di rect ly above the p late. Assuming no o ne has ever p layed w ith th e ba se idl e settings (the screw may be sea led) and there's nothing wrong w ith th e powertra in contro l mod ul e's programm ing (th e malfunction indicator lamp has never illumi nated), th at covers the bas ic idle controls. Un less the ma nufacturer has issued a softwa re upd ate, today's engine-m anage ment systems are sma rt eno ugh to take it from he re and co ntinu e to pro vid e a smooth, ca refree idl e until the nex t tim e th at t h rottl e bore has jan ito r ial need s.

Loaded to the Hilt W hen yo u cons id er th e number of be lt-dr iven accesso ries hangi ng off th e typical engin e today, in add iti o n to a ll th e mecha ni ca l a nd e lectr ica l loads, it's a wond er th e pi sto ns ca n co ntinu e pumping a t a ll. That's w hy some ve hi cles today have 120-amp a lternators and 140-amp fuses. In rainy, co ld weather at night, yo ur a ltern ato r is worki ng overtime to mak e eno ugh amperage to power eve rythin g. Probl em is, it's a lso try in g to sto p th e eng in e from turnin g. H ere's wh ere yo ur idl e speed cont ro l rea ll y shin es. As soo n as a ltern ator o utp ut drops to a certa in leve l, the vo ltage

(Fig. 4) Pull the idle speed controller out of its bore to inspect the pintle tip, spring and air channel.

BOTTOM SIDE OF THROTTLE BODY

regulator does its thin g a nd th e engin e- ma nagement system sees the need for in creased idl e rpm to keep charging-system vo ltage between 13 Y'2 a nd 15 vo lts. If a signal gets lost throu gh a shorr or an open circu it or a n intermittent conn ection, however, yo u' re likely to ge t a lump y or just plain low idl e. H ere's w here yo u rea ll y need the specifi c service manua l a nd w iring d iagra ms for th e veh icle, beca use t here are too man y variati o ns in form and function to discuss these systems in general terms. Some simple things yo u can do, however, incl ud e visua ll y checkin g for corroded-and even burned-conn ections a t th e a ltern ator a nd battery terminals. Eyeba ll the co nditi o n of a ll the fusibl e link s arou nd the battery, a nd check for fo ul ed spark plugs (Fig. 5) . Make sure the accessory belt(s) is tigh t and unfra yed. Every time the alc co mpressor kick s in at idl e, engi ne speed wou ld drop a co upl e hundred rpm were it no t for th e idl e speed co ntro ls keeping t hin gs at a n eve n kee l. H e re aga in , intermittent conn ections a nd a faulty p ress ure sw itch or two cou ld ca use th e climate contro l to cyc le in a nd out. A low or co ntamin ated refr igera nt charge might do the sa me th i ng. Somet im es t he re's a p ress ure sw itc h monitoring your power stee ring syste m, es pec iall y o n 4-cylin de r eng in es. Dur in g a ti gh t pa r k in g- lo t ma neuve r, when power-steer i ng p ressure sk yrockets, the

engine contro ls ta ke the reins and bump open th e idl e speed control mo tor so yo ur eng in e doesn't sta ll or bog down to th e po int of misfirin g. A bad co nn ectio n o r leak a t th e sw itc h wo ul d affect this system a nd possib ly lead to a hunting id le. Periodic power-steeri ng-system fl ushes go a long way toward preventing clogged switc hes a nd ori fi ces. An eng in e w ith hi gh mil eage that's tired and worn o ut may not pu ll a healthy vac uum o f 18 to 20 in. H g at idle (c losed t hro ttl e pl a te) anymore. That means t he MAP se nsor w ill always read t he engi ne as under load (low vacu um=hi gh vo ltage ) and-just doin g its job-inform th e powertrain computer to add more fuel. Whe n the oxygen se nso r picks up the ri ch mi xture in th e ex ha ust strea m, it wi II ca II for a lea ner mi xture. Commo n strategy is to o pen t he id le a ir-bypass va lve to let some more a ir in. Bur an engin e that's just o n th e borderline of w heezing may intermittentl y "loosen up," leadi ng to a ro ll er coaster idl e. It ma y have troub le breathing w hen co ld , but once warm-with expa nded pi ston rin gs, gaskets a nd th e like- show a perfectl y hea lt hy intake vac uum. What it a ll bo il s do w n to is tha t there's a w ho le lot more than just a carburetor 's throttl e stop screw controllin g yo ur engin e's idl e speed th ese da ys . Si mpl y und ersta nding th e system , howeve r, is ha lf t he battle toward fi ndin g a nd fi x ing the offending troub lema ker. ~

(Fig. 5) Fouled spark plugs can lead to misfiring at idle. They can be cleaned and regapped or simply replaced.

SMOOTHING

OUT A LUMPY

IDLE

95

DIFFICULT

Replacing Your Water Pump chroni ca ll y low leve l, p erhaps?) ca n open up the working space and reduce flow, as ca n co rrosion from weak antifreeze in th e coo lant mix .

: :::::-:- ..... . :... ;;., .

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-,,-

......... ·;0·.·.-...

.... .... .

ombing down the interstate, yo u glance at the odometer and realize yo u've just reached an automotive mil estone: 100,000 miles with no major repa irs. Time was a car th at had passed its bell y over that much rea l estate was considered pretty much used up, but yo urs still run s grea t and loo ks practica ll y new. Amazing how tec hnol ogy has advanced. Then yo u notice th e temp erature ga uge . H o ly smo kes-pegged! You put it in neutra l, coast off onto the sho uld er and shut her dow n. T here's that ma ple-sy ru p-sp ilI ed-o n-th e-radia tor o dor aga in-yo u've sme ll ed it before, but fi led it under " things to think about later. " Sooner wo uld 've been better-no w yo u're wa lking.

B

Seal Deal The biggest change in water pump design occ urred decades ago when the spring-loa ded mechanica l sea l was adopted . Howevel; its rubber parts may di sintegrate if the engine overheats, and its po lished sea ling faces can L ear and wa rp if the engin e is run dry.

96

A~

(Fig. 1) Wet liquid seeping from the weep hole signifies the end of the service life of the seals in your pump.

Typ ica ll y, pumps wi ll sta rt leak ing ca tas trophica ll y shortl y after a boi l-over. Thi s kind of failure can be wo rse th a n it so und s. Besides the vastl y exp ensive internal engine damage that runni'ng without coolant ma y cause, a leak ing sea l can wash away th e shaft bearing's lubricant, perhaps res ultin g in a se ized shaft, and a fl yin g fa n o r belt pu ll ey ca n destroy the radiator o r even dent th e hood. So, leakage is th e o . 1 fa ilure. o ise is seco nd, and is always indicati ve of a termin a l condition. While service litera ture on water pumps often will show a pictu re of a badly eroded impell er th at contributes to over hea tin g, tec hnicians say that's not as co mm o n as it once was. Another poss ibl e prob lem with the sa me conseq uences is an impell er th at 's come loose from its shaft. Erosion of the inside surfaces of the pump chamber caused by cav itati on (a weak cap or a

Evidence Gathering If yo u start to smell the distinctive odor of engine coolant, or you notice that th e level in the overflow bottl e is droppin g rapidly, it's time for a careful exa m. (If yo u're lucky, it may be just a leaky hose conn ectio n, but loo k the radiator over, too. If the smell is strong in th e passenger compartment and th e w indshield tends to steam up , thin k abo ut the heater core. In cases w here no ne of the above is the culprit, better check o ut the water pump. ) First, use an inspection mirror a nd a good li ght to view the vent ho le th at's at th e bottom of the pump casting's nose (Fig. 1) . Or, support the fro nt of the car safel y on jackstand s and look up fro m underneath. All sea ls are supposed to wee p sl ightl y (a littl e coo la nt is needed to lu be the faces), but dri ps mea n yo u'd better go shopp in g for an estimate. Next, grasp the fan or wa ter pump pull ey a nd see if it rocks from side to side. If there's anything but slight movem ent, the bearing is on its way o ut. Also, yo u can remove the belt and see how the bearing feels as yo u rotate the pump shaft (Fig. 2) . Roughness isn't acceptable. A low- fl ow situation that results in hot running ca n be hard to diagnose . Drain the leve l down to the top of the radiator tubes, get the engine hot, and th en shut it off for 10 minutes and let it heat soak to make sure th e thermostat is wide open. Now, fire it up aga in and run it at 3000 rpm. On Ja panese cars usin g the radi ator fill neck on th e top tank, look down into it w ith a flashlight and yo u should see strong circ ul atio n (Fig. 3) . Another p ossibility is to sq ueeze the upper hose to fee l

ENGINE

:w.>.-- - CHECK FOR PLAY

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.

.....

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WEEP HOLE

(Fig. 2) Almost any radial play in the water pump shaft is grounds for immediate pump replacement before something fails.

for flow, bu t that's pretty su bjective. Unfortunately, there's no good way for the do-it- yo urselfer to differenti a te a weak pump from a clogged rad iator.

Major Undertaking? On some front-w heel drives the job is a horro r sto ry. Make sure YO ll res ist the temptati o n to get into thi s repa ir if

(Fig. 3) With the engine warm enough to open the thermostat, but not hot enough to pressurize the system, look for vigorous flow at 3000 rpm.

yo u' re not p repared to invest the time requ ired. Find o ut the flat-rate hours by ask ing a loca l garage owner or dea ler service manager. It's a job that could take severa l hours, depending on wha t yo u dri ve, particularly if the pump is recessed into the engine block. T he first steps in removing a ny water pump are to let t he engin e coo l

off com plete ly, a nd t hen dra in the coo ling sys tem by ei th er openin g th e rad iator petcock or d isco nn ectin g the botto m radiator hose a nd remov ing engi ne coo lan t dra in p lugs . Next, do whatever is necessary to remove t he accessory dri ve belts. If t he car has a lo ngitudin a ll y mo unted engin e as fo un d in every rwd a nd so me front-

HOW IT WORKS

Water Pump Shaft Seals Two perfectly flat rings, one stationary and the other rotating with the pump shaft, are pressed together by means of a coil spring. The rings may be made of carbon or may be ceramic, phenolic, porous bronze, cast iron, etc., in any combination. This allows only enough seepage to keep the elements lubricated. It has a weak link, however, in the form of its rubber parts-the bellows that seals the spring and the rubber seat cup between the rotating element and the shaft. If the engine is ever run dry, the temperature of the pump is apt to rise far beyond what the rubber can survive, and a leak occurs. Another possibility is warpage of the sealing elements, also from overheating. There's conflicting evidence on whether silicates and phosphates from antifreeze, or other hard particles such as casting core sand, can actually damage the seal faces. Engineers have told us the ' running clearance is way too small to admit solids of any appreciable diameter. Since cars are lasting longer than they used to, and since we've become such a litigious society, carmakers are working harder than ever to make water pumps last. After all, when a pump goes you've got to get out and walk, which exposes you to dangers that horrify auto company lawyers.

So, there has been a push for water pump seals that will rarely, if ever, fail. One design that looks promising is from Michael Ostrowski and John Crane International, the leading supplier of conventional water pump seals. Called the Advanced Metal Diaphragm seal , it uses a flexible stainless steel diaphragm that acts as both the spring and the bellows, and incorporates an improved method of mounting the seal faces.

J REPLACING YOUR WATER

PUMP

97

(Fig. 4) This is an easy one, because it's near the top. Your job would be a lot tougher if the pump were near the bottom .

th e sea m open or you ' ll make a nick ley. Can yo u guess the possible misthat the gasket may not sea l. take ? Think a bout direction : The serPumps sea l aga inst th e engin e o r pentin e belt might dr ive the impeller in backing p la te with a gas ket, an 0the opposite directi o n from that of the dri ve rs, rem ove th e a ir shro ud s (in ring o r RTV sili cone. Get th e ma ting V-belt, so you cou ld end up in stalling a so me cases, the ra di ator, too), a nd su rface cl ean w ith a sc raper. pump tha t runs backward, ca using a then the fan a nd its clutch, w hich bo lt If yo u mu st use silicone sea ler, seemingly incurable o verheating situato the front of th e water pump shaft. use o ne ra ted for a utom o ti ve use . tion. Make sure yo u get exactl y Novv you can start on the pump by It should a lso be the ri ght part, and compare the disconnecting the hoses. Those for the labe led low-vo la tilit y. impell ers. Also, heed that routing hea ter w ill proba bl y be stubbo rn, so O utgass in g fro m th e di agra m (Fig. 5) . yo u ma y need to split th ei r end s w ith curing sea la nt ca n po iAfter evel'ything is buttoned a utilit y knife (if th ey' re lo ng eno ug h, son oxygen se nso rs-so up , fi gure o ut ho w much you mi ght be ab le to trim th em off lea ve th e ba thtub ca ulk coo la nt your system ho lds. square and reuse them ). w ith yo ur plum bing too ls. Thi s should be in your Ex tract the pump-to-engine bolts We shou ld menti o n a owner's m a nual, or in the and keep them and any brackets th ey po tentia l pro bl em. Suppose shop manual. Using the retain in strict order or you 'll regret it yo u're in stalling a water a ppropriate manufacat assemb ly. Th ere m ay be hidden pump o n a ca r with a se rpenturer's coo la nt, add ha lf bo lts, so ta ke a loo k at a d iagra m. tine belt. Engin es on man y that a mo unt a nd t hen top Th e pump sho uld co me off with a . o lder models were equ ip ped off w ith water. This wi ll good tu g (Fig. 4) . If not, ma ke sure w ith a regul ar ribbed or Vgive yo u a 50-50 mix. (Fig. 5) Vehicles with you didn't miss any bolts, and then belt, but the water pump Be sure to follo w the serpentine belts have a tap on the inlet or outlet neck with a for the old model ma y fit procedure for service belt routing diagram mallet or a block of wood and a ha mphysica ll y o n the new o ne, bleeding the air bubbles under the hood somemer. Don't use a screwdri ver to pry if yo u cha nge over the pu lwhere. Read and obey. out of the system. tI

98

ENGINE

-

ODERATE

Curing a Clicking Starter

Y

O U tw ist tb e ignitio n key to sta rt yo ur engine, a nd in stead of the syncopated w hirling of a cran king sta rter and crankshaft, yo u hear a click or a series of c harreriike c li cks. Th e engin e t ha t sta rted eve ry d ay for so lo ng is not go in g to starr toda y. T im e to hitch a rid e to wo rk . If it's a weeke nd , yo u get the cha nce to find out why yo ur ve hicl e has died and fi x the prob lem before Monday mornll1 g. Th a t cli ckin g noi se is from e ither th e starte r so lenoid o r the re lay. Th e so leno id is part of the sta rter. Typ ica ll y it has a terminal for a thick power feed w ire fr o m th e ba rre ry (Fig. 1), and a thinn er terminal fo r the current supp ly w ire ro a sw itching m echan ism in the soleno id. The rela y is a remote ly mo unted sw itc hing

CURING

A CLICKING

STARTER

d ev ice between starter a nd ba tter y t hat contro ls either the thi ck power feed or the thinner electrical feed to the so leno id 's sw itch termin a l. Th e first step (a lthou gh a t thi s point it do es n't tell yo u th e roo t ca use) is to find o ut w he re th e c li ck is co min g fro m. If you have a helper turn the ig niti o n key to start, yo u' ll be a ble to trace th e underh ood click . If it comes fro m the starter, yo ur probl em is in t he so leno id. Ford a nd C hrys ler produ cts ma y have a relay in th e circu it. If th e so lenoid isn't t he so ucce of t he cl ick, tracing th e so und sho uld ta ke yo u to th e relay o n t hose mo dels. Even after yo u know what pa rt is click ing, begin yo ur real di agnosis a t the batter y. If the barrery top has a n "eye" indi cator (actuall y a battery

(Fig. 1) Loose or corroded starter cables can cause enough voltage drop to cause a clicking, intermittent connection. Clean with a wire brush and then rinse with warm water.

h ydromete r th at in d icates th e state of charge), recharge if th e in dicator is bl ack. If it's g reen, it's got a no rmal charge. If it's ye ll ow, ge t a new batter y beca use the electro lyte is too low. Th ere's no indica tor eye? Con nect a vo ltm eter ac r oss th e ba ttery te rmina ls (pos itive lead to posit ive termi na l, nega ti ve lead to nega tive termina l). If the meter rea d s und er 12.4 to 12.5 vo lts, it's borde rline or und erc ha rged (depending o n the des ign of th e battery). R echa rge it for th e da y. Batteries do run dow n as a res ult of a temporary series of operating condi-

99

(Fig. 2) Check for voltage drop between battery post and starter terminal while a helper cranks the engine. Up to 0.50 volt is acceptable. tions (lots of short trips, for exampl e), but if the pro blem recurs, yo u' ll ha ve to check ch arging system o utp ut and th e poss ibility of a sho rt circuit. If th e rea din g is 12.7 to 12.9 volts, th at's a good starting point. After a recharge, operate the head lamps fo r 15 seconds to remove what is call ed the " surface charge. " Th e m eter reading sho uld not drop more tb a n a bo ut 0.2 volt. The rea din g is o kay? H ave a helper turn th e igniti on key to start, and in 15 seconds, rea d the meter. If it's below 9.5 volts, th e battery may not be strong eno ugh. Profess ionals have battery loa d testers to make sure. Your alternative: If th e battery vo ltage wa s no rm a l wh en you started, but is low during th e attemp t to crank, tr y a jumpsta rt. If th e engin e cran ks nor-

mall y w ith a boost, the battery probabl y is bad.

Corroded, Distorted Terminals If th e engine still wo n't cran k, next in spect the cables and their connec-

ti ons at both ends. If yo u see corros ion o r a possibl y poor conn ecti on, ma ke a voltage d rop test (Fig. 2) . First, conn ect th e vo ltmeter negative lead to the battery ground terminal and the positi ve lead to the engine block, cl ose to the starter. With th e key held in th e start pos iti o n, th e vo ltmeter should rea d und er 0.5 vo lt. If it's 0.5 vo lt or higher, the drop is excessive. In fac t, if it's above 0.2 volt, tb at's rea lly too high and co uld be a contributor to the problem if the battery is marginal. Perform the sa me check with the power feed side of the circuit (in thi s case, connect th e voltmeter's positi ve lea d to the battery, and th e nega tive lea d to the starter 's battery ca bl e terminal) . Get a high rea ding? Repea t the test, taking care to make co ntact at the battery post o r side-terminal bolt, not th e cable end. If th e vo ltage drop now is within reason, the cable terminals are the problem. A simple clea ning may be all th at's needed, but if a ca ble's

HOW IT WORKS

Starter Solenoids A solenoid is an electromagnetic device that is capable of doing work, and in some starters, it does two jobs. 1) It moves a plunger that makes electrical contact between terminals for the battery and the starter motor, so the motor turns. If that's all it does, it's really just a switching device. 2) In some starters, the movement of the plunger also pushes a linkage that moves the starter's drive gear into mesh with the flywheel ring gear. The solenoid has two wire coils. One is large, draws a lot of current and produces a strong magnetic field. That's enough to move the plunger. Once the plunger is in pOSition (having completed the circuit and moved the starter drive), the large coil is disconnected and the circuit for a small coil is completed. The small coil draws a small amount of current and produces a weaker magnetic field-just enough to hold the coil in position. This saves battery energy for the big job of cranking the engine. If there isn't quite enough battery electrical pressure (voltage) to provide the current flow, however, the plunger won't lock into position so the small coil can take

100

FIELD COIL

IGNITION SWITCH

FUSIBLE LINK

T

!--

BATTERY

I

....L

I

~

~

.

;u •••••
NEUTRAL SAFETY SWITCH (AUTOMATIC TRANSMISSION ONLy)

over. If this happens, all you hear is a solenoid click, and the plunger springs back. Some solenoids have an extra small-gauge terminal. This bypasses the ballast resistor, ensuring a hot spark while cranking.

ENGINE

fr o m th e battery's nega ti ve post to engin e g round, o ne fr o m t he battery pos iti ve termin a l to t he sta rte r so leno id te rminal. Do a fo ll ow- up test Overtightening cast battery w ith th e booster to th e starter battery terminals can terminal , plus a jumper to the so leleave them loose. noid terminal. Th ese test proced ures ca n be physical ly diffi cult to perform DON'T OVERTIGHTEN I o n ma n y ve h icl es, pa rti c u la rly those w ith a sid e termin a l batte ry, but th ey usua ll y ca n be do ne. Ju st ta ke th e tim e to ma ke good co nn ec ti o ns w ith t he jumpe rs. If yo u ca n get the engin e to cra nk this way, th e prob lem obv io usly is in the cab le connectio n. If a Ford or C hr ys ler product'S relay is the so urce o f th e click, it ma y no t be o peratin g properly. If runnin g (Fig. 3) Be sure the ground wire to the body as well jumpe rs to th e so leno id o r starter as to the engine block is good. Replace corroded wires and tighten fasteners. (bypass in g th e relay) ge ts th e eng in e to cra nk, test the re lay. post termin a l is distorted, the jaws sta rter ), try direct wiring with jum per O n Fo rd products, connect a ma y be tight even though the inside ca bles, and if cra nki ng still is weak, booster ca ble across th e t hick-wire surface is not making good co ntact. th e starter a ppa rentl y is bad. terminals of th e relay, a nd if the If the cable end is distorted or corengin e now cra nk s, repl ace th e relay. roded, replace it (Fig. 3) . Get a qua lity Don't Have a O n C h rys ler ve hicl es, find th e powe r feed (it's th e w ire te rmin a l th at turn s Good Meter? ca ble end , w hi ch includes a section of ca ble w ith a protective shea th , no t just If yo u don 't have an acc ura te vo lto n a gro unded 12-vo lt test li ght). meter, yo u still ca n eyeba ll a nd make Co n nect a jumper wire fro m t ha t tera termina l. C ut the corroded cable back min a l to the one for th e power output ha nds-on inspectio ns for tig htn ess of to w here the copper wire is absolutely th e cable connections at both ends. w ire (usua lly red ) that goes to the free of any corrosion. Insta ll the new cable end and jo in it to the rema ining C lean and tighten the cables and see if sta rter so lenoid. Needl ess to say, be cable (some repair cab le sections have the engi ne w ill crank. sure th e ve hicl e is o ut of gear and th e heat-shrin k in sulation , and o th ers have w hee ls a re blocked befo re ma kin g a ny Stil l no success? Disco nn ect both a ttempt to turn th e engin e over. screw reta iners o r crimp on). battery cab les a nd ma ke direc t No sign of cor ros ion o n a ground conn ection s w ith booster cab les, o ne O n models w ith p lug- in relays, yo u ca ble? Rem ove the gro unding bolt at may have tro ubl e findin g th e co lo r the engine, cl ea n the cab le end a nd codes, but the w iring di ag ra m sho uld ,. indi ca te the power feed a nd output bolt, reinstal l a nd ti ghten . term in a ls and their numbers, w hich Checking the yo u' ll find o n th e relay itself. Turn o n Starter Terminals th e igniti o n. Yo u now can use a gro unded test lig ht to find th e power At the sta rter, in spect the termin a ls for both the battery (thi cke r w ire) a nd feed termina l, but yo u' ll have to eyesolen oid sw itc h for corros io n a nd ball the re lay'S termin a l numbers to physical damage . If the corrosion is figure ou t which is th e o utput wire termin a l (to the soleno id ) in the underminor, yo u may be able to re move th e hood center itse lf. Connect a jumper retainin g nut a nd battery cable a nd w ire-brus h co rros ion away. If th e co rfrom t he powe r feed to th e rosion is so severe t ha t clean ing it off utput, and if th e engi ne o SELF·TAPPING REPAIR STUD leaves th e threa ds dam aged, in sta ll a cra nks, rep lace t he relay. (Fig. 4) Use a self· repair stud , w hi ch c uts new threads Ma ke cl ea nin g a nd ti ghtentapping repair o nto the da maged studs (Fig. 4) . in g a ll th e conn ections a stud rather than Now try to crank the engine. No spring and fa ll ritu a l a nd yo ur replacing the improvem ent ? With good connection s whole starter if the terminal threads engin e wi ll make reli a ble cra nking a a t both end s (battery, gro und a nd are damaged or stripped. year-ro und habit. tI ~: ' .:. , . ~.

"."

~~ ~~

CURING A CLICKING STARTER

101

EASY

Repairing Cooling System Leaks kay, yo u replaced yo ur lower radi a tor hose las t wee k after it burst o n th e fr eeway, and th e syr up y, turki sh ba th odor of boiling glyco l coolant hitting a red -h o t exhau st manifold is so methin g yo u ca n li ve th e rest of your life witho ut ever smell in g aga in. Lying face-up in a spread in g poo l of coo ling coolant to change the hose is pretty low o n th e li st, too. So it's a ba d o men when that smell hits yo u a t a tollboot h a week later -a nd a worse o men when yo u open th e hood a nd rea li ze th e new hose is lea kin g from both end s. Wh a t g ives?

hose cla mps . You can ti ghten so me o f th ese, but no t a II. (See page 121.) These a re th e o nes yo u ca n ti ghten: SCREW-TOWER- Th e screw is pe rp end ic ul a r to th e ba nd , a nd turning it down ti g htens th e band. It's been aro und for ever, it's c heap and it fust-freezes in pla ce, so ti ghtening a n o ld o ne usua ll y is impossi bl e. To get it off, spray it ge nero us ly wit h penetrating so lve nt, loosen the to wer screw and s lip in a slim screwdr iver if necessa ry to pry it o pen. Or ju st cut it off.

O

(Fig. 1) Spring-band clamps can usually be removed or replaced with pliers or locking pliers.

DOUBLE-WIRE OR BAND WITH RETAINING SCREW AND NUT-A doubl e-w ind-

ing of wire o r a band is held together by a tangenti a l There are a bo ut twO do zen screw a t on e end that fits in to a nut at the other. coolant hose co nnec ti o ns underhood to d ay, a nd it's a When it's overti g htened, th e co nsta n t effort to find a nd w ire type di gs into th e hose fi x th e loose o nes that leak a nd may c ut throu gh. coo la nt. In ges tin g a ir is a WORM-DRIVE CLAMP-Thi s has been the longtime routin e iss ue. It used to be simple: Loo k for an antifa vorite, a nd even was considered a premium design. fr eeze sta in , th en just tighten the hose c la mp , r ight ? Sorry, Some worm-drives are, b ut but th a t's not a lways true most are n 't. One reason it's anymore. p op ul a r is that it can be First, th e powertra in ope ned up and take n o ff w ith o ut di sconn ectin g th e compartment is so ti ght tha t (Fig. 2) Shrink-fit hose clamps will continue to shrink as hose, a lth o ugh th at feature yo u can ha rdl y spot a lea k engine warms up, ensuring a tight seal. witho ut a d edicated inspecha s limi ted utility. Th e qua lity worm-drives tion. Yo u' re more likely to look c lose ly a t a hose connection ments a re so ti ght that the engi neers have such features as : rust-res ista nt have to use specia l hose designs to prowhen yo u have to disconnect a hose to plating; ro ll ed up edges so the ban d vide safe routing. Some of those hoses doesn 't d ig in to th e hose if overtig htreac h somethin g else. In eith er case, have plastic fittings, ca lled quick-conened; offset teet h that keep the ba nd when yo u d o look at t he coo la nt hose nects, to help a n assemb ly lin e worker fr o m twi stin g w hen tightened; and conn ecti o ns under yo ur hood, you make errorfree connectio ns. even " teeth " th a t a ren 't cut thro ugh may see ve ry few of th e type yo u Depending on t he age of yo ur car th e band, so the hose r ubber doesn' t loosen and ti g hten wit h a screwdriver. a nd whether or not cl a mps we re extrude into the slo ts. Today's engines have complex CONSTANT-TENSION WORM-DRIVE-Th e replaced , yo u co uld have a var iet y of coolant Row patterns a nd the com part-

Drip Patrol

102

ENGINE

best ones (by Oetik er, a lea din g E uropean maker w ith extensive U.S. ma rket ing) have a n internal ba nd th a t gli des throug h a slot in sid e th e main band, bridg in g th e jo int o f th e worm drive. Res ult: Th e cl a mp prov id es tru e 360 clamping. That clamp a lso ha s a coil spring to provid e constant tension even if t he hose undern eath takes a compress io n set. 0

HOW IT WORKS

How Coolant Hose Leaks Occur

Spring-Band Clamp Toda y m ost ca rmak ers a re usi ng a clamp that yo u ca n't tighten, so it a lso never ca n be retightened. I t's th e spring-ba nd (Fig. 1) , a n in ex pensive form of con sta nt-tensio n c la mp . It may not be eve ryw here und er th e hood, but it usua ll y is in a lo t of p laces. Because it ca n't be preti g htened to a ny spec, it's sized so even if the hose takes a set und ern ea th , it maintains so me tens io n, hopefull y a deq ua te to prevent a lea k, but o nl y if th e hose nec k is in perfect shape.

Shrink-Band Clamp Would yo u lik e a low-cost nona dju stab le c la m p th a t no t on ly maintains tension but sea ls we ll even if th e hose neck is far from perfec t? It's here, a nd it a lso ca n help w ith other problem clamping situ a ti o ns: th e pl astic sh rink-ba nd c la m p. You mu st bu y a shrin k ba nd th a t's sized for yo ur partic ul ar hose d ia meter. Th e band comes o n a t hi ck cardboard roll so it doesn't shrin k in storage. Just crus h the roll, remo ve th e band , lube t he hose neck wit h a ntifreeze, slip the band o nto the hose a nd t he hose o nto th e neck. Un li ke a conve nti o na l cl a mp, th e shrink band sho uld be pos iti oned so it extend s onto a bea d on a hose neck. App ly heat with a ha ir dr yer (Fig. 2) or hea t gu n (from wit hin a co uple of inches or so), a nd in a co upl e of minutes the band confo rm s completely to the neck a nd bea d, increasing leak res ista nce. And th e hea t from the coo la nt w ill ca use it to co ntinu e to shrink in se rvice to co mpensate for an y compress ion set in th e hose . H ow do yo u get it off? If yo u' re rep lacin g the hose, just c ut it w ith a

REPAIRING

COOLING

SYSTEM

LEAKS

Why does a coolant hose connection leak after you 've tightened a conventional clamp? After all, the I clamp itself doesn't loosen. What I happens is this: Both the hose neck and the hose expand when the coolant warms up. The clamp, however, is relatively unchanged , so it squeezes the rubber underneath even more, and this causes the rubber to become permanently compressed, which is called a set. When the engine cools, the neck contracts more than the hose. Many hose materials become virtually glued to the neck, so a seal is maintained . Others do not. In fact, silicone is almost immune to heat-sealing. That makes the silicone hose easy to replace, but it is the most prone to cold coolant leakage. Always install the clamp next to, but not overlapping, the raised bead on the fitting to keep from trapping a bubble of coolant in the void space inboard of the bead.

:-

sing le-edge razor blad e. If you're planning to re use th e hose, you have these choices : 1) C ut t he band itse lf w ith a so lder ing iro n , b ut be ca refu l; 2) Force a fee ler ga uge between band a nd hose, a nd run th e razor blade t h roug h th e ba nd ju t over the fee ler; 3) If yo u p lan to use these shrink ba nd s eve ryw here o n yo ur cars , get a band-slitte r, a too l

th at d oes basicall y t he sa m e thin g but is eas ier to use .

Those QuickConnects [n ma ny cases, today's cars and tru cks use qu ick-co nnects in stead of c la m ps for man y heater circu it hoses a nd a lso fo r so me ra diator hoses. The qu ickco nn ect is a fitting w ith a n O -rin g

I

J' 103

sea l, a nd if it eve r lea ks, yo u have so methin g else- o ne or two 0rings-to check a nd rep lace. Every q ui ck-connect co mes off a bit differentl y, but it's usuall y obvious. On GM pickups you unthread a retainer, th en turn a meta l tab that provides a seco ndar y ho ld and pull th e hose . T he hose end is a pla stic fittin g w ith O-ri ng sea ls. Ju st pee l t hem off a nd in sta ll new o nes . C lea n o ut any debri s from in sid e t he fema le m eta l fittin g o n the engin e. So if the lea k is fro m the quickconnect, get a replacement from the car dea ler, th en just pry open and remove th e o ld qui ck-connect's perm ane nt cl a mp and in sta ll th e new qui ck-co nn ect o n th e hose. 1£ yo u ca n't get a new quick-con-

104

nect, yo u may be able to cut through a meta l secti o n in a long underbody coo la nt lin e, in sta ll a short hose secti o n (sec ure it w ith some form of constant-tensio n cl a mps), and th a t shou ld give yo u th e extra hose length at the end tha t has the leaking quick-connect. Then yo u should be a bl e to remove th e qu ick-connect a nd m ake a hose-to-m eta l fitting cla mp jo int.

The Hoses Ma ny of today's hoses, p articu la rl y for th e heater circuit, have crimpedon sections, a nd crimps are known to leak. A brand -new hose is a si mple but expensive so luti on. An a lternative is to g rind o r saw into the crimp, just eno ug h to be ab le to break it ap a rt. Eve n without crimp sectio ns, the

coo la nt hoses themselves are a nythin g but sim p le, fl ex ibl e lines of rubber. O n ca rs with pressurized coo la nt reservoirs (wh ere the cap is o n th e reservoir, not the radiator or engi ne) , t he upper radiator hose typica lly has a tee fitting with a seconda ry hose to the reservoir (a nd th e lower hose may have o ne to the hea ter circuit). So unl ess a repair tee is ava il ab le, don 't be surpri sed if th e hose prices o ut a t $100. Other hoses (a lso not cheap) are permanently crimped to meta l lines, much like a n air conditio nin g line or power steering hose. And even where there is a simple-looking hose, it ma y be a molded design, so that it fits into a very tight area (perhaps so it ca n co nn ect to a meta l line) w ith o ut th e possibi lity of kinking. (;

ENGINE

MODERATE

Curing Slow Cranking

o u've just treated yo ur date and yourself to a postpra ndial doublecaf no-fat cappuccino, and the caffeine courses thro ugh your veins like lava . Yo u're p um ped fo r a night of dancing as yo u head fo r the nightclu b. The world seems to be in slow motion as the caffeine hits yo ur bra in-especially w hen yo u twist th e key and your car engine grinds over very slowly, far too slowly for the engine to start. The ugh-ugh-ugh of an engine

Y

CURING

SLOW CRANKING

that's cra nk ing too slow to sta rt is a so und that everyo ne ca n ide ntify. And the immediate- if tempo rary- cure is to ca ll for a ba ttery boost. T he longterm fi x, however, requires careful exa min ati o n to make a di agnos is.

Thinking Positively If the ba tte ry pos iti ve-cab le te rmin a l o n th e sta rter is easil y visible, beg in by inspecting it for w hite/green co rros io n and fee ling th e ca bl e end for a

(Fig. 1) Remove the wires from the starter motor or solenoid and clean off any corrosion with a wire brush and warm water. Rinse thoroughly and reassemble. Smear protective grease on the terminals to keep them clean.

loose co nn ectio n. A wire-br ushing to re move corros ion fro m th e stud , nut and ca bl e te rmina l, or just a tightenin g, may be th e simp le fix (Fig. 1) . Per haps the ca bl e termi na l h as beco me loose beca use at some tim e it

105

th e necessa ry a ir flow thro ugh t he co mpl ex flow HYDROMETER EYE pa th s to start to day 's Fo urs . And w it h th e powe r de m a nds of th e electro n ics a nd th e fuel sys tem, a ligh t-duty ba ttery ju st ca n 't hac k it. So if th e o ld ba ttery di ed a nd yo u in sta ll ed th e lowestpri ce rep lace ment yo u co uld get, th at co uld be the reason behind th e slow cra nking. In th e days o f carbureto rs, th e ba ttery-ra tin g r ule was o ne co ld-cra nk in g amp for eac h c ubi c in ch of engine di spl acement. Well , we ta lk a bo ut (Fig. 2) Check the battery's hydrometer eye for enough liters for di spl acem ent today, electrolyte or low charge. but even if yo u look fo r 61 co ld -cra nking a m ps per liter, th a t's just no t eno ugh. Having a Heat Wave? Whe n th e slo w c ra nkin g There 's ha rdl y a ny la teGROUND model engine- or any occ urs o nl y o n a ho t TO BODY resta rt in wa rm weather, engin e- t hat w ill start reliyo u have to co nsid er th e ab ly in a ll conditi o ns w ith a poss ibility of hig h interba ttery ra ted a t under 500 na I res ista nce in th e co ld -cra nking a m ps. sta rter, w hi c h is often A lso, yo u ca n 't ju st loo k a t th e battery to determine ca use d by underhood h ea t. Som e sta rter s are its co nditi o n , eve n a ba ttery fact o ry-equipped w ith w ith th e circ ul a r w ind ow h ea t shield s, p a rti c ul a rl y ("eye") in th e to p (Fig. 2) . th ose in rec rea ti o nal T ha t eye is over just o ne of ve hi c les, a nd th e shi eld th e s ix ce ll s. T ha t ce ll might m ay have been bent or be o kay- a nd yo u ' ll see a tak en off a nd n ever rein d a rk gree n, th e in dica ti o n stalled. Or it co uld just of hea lth-whil e th e re's (Fig. 3) Check the ground connection to the vehicle's body be that the sta rter wa sn 't w ea kn ess in a no ther cell. for good contact. designed to h a ndle the M ay be yo u 're rea d y to heat w ell-a p ro blem both w ith th e sta rter, or if it's buried and yo u bl a me th e ba ttery beca use yo u ca n 't so m e o rigina l-equipm ent sta rte rs wa nt to begin so mewh ere else, then see the " hea lthy" co lo r. T ry tapping a nd w ith re builts th a t m ay fit ph ys imove o n to th e ba tter y. But we're not o n t he eye before yo u sta rt shoppin g call y but a re n't des igned to ta ke t he rea ll y giving the starter a p assing fo r a new ba ttery. The co lo r may h ea t of a heavy -d ut y appli ca ti o n . gra de just ye t. cha nge. If the en gine sta rts eas il y after it Th e onl y reli ab le c hec k is a loa d cools off, the starter is o ne poss ibilBatteries Not Included test, w hi ch requires a spec ial tester. ity. An easy c heck is to spray th e Di scard the o ld a d vice that says a H owever, a t least yo u ca n check the starter with co ld wa te r if yo u get sma ll , cheap ba ttery is adeq ua te fo r ba tter y vo ltage w ith a meter conslow cra nkin g during a hot res ta rt. a 4-cy lind er, a nd o nl y a bi g V8 needs nected"across th e ba tte ry te rmin a ls. Now it cra nk s we ll ? If th ere's no a ba tte ry w ith a hi gh energy ra tin g . But do n't just loo k fo r so methin g miss ing hea t shi eld , check w ith a W hen yo u cra n k a n engine, th e el ecover 12 vo lts beca use it's a 12-vo lt dealer to find o ut if a heavy-dut y t ro ni cs a ll wa ke up a nd th e air sta rts sys tem . If it's unde r 12 .7 to 12.8 sta rter w ith better h ot-star ting a bilfl ow in g thro ugh th e th ro ttle bo d y vo lts, the ba ttery is und ercharged , ity is a vailable. into the cy lind ers. It takes much and a t 12 vo lts it's 75% di scharged. If there's no sign of a pro bl em at hi gher cra nking speeds to p ro duce Yes, d isc ha rged . had been re in sta ll ed o n da m aged sta rter-s tud threa ds, or the nu t had bee n c ross-threa ded w hen install ed. Poo r-qua lity rebuilts, used starters, goofs during ca bl e or sta rte r repl ace ment a re som e of th e usua I suspects. In fac t, th ese pro blem s are so co mm o n th a t yo u ca n buy a n inexpe nsive (less than $5) starterterminal rep air stud kit a t auto parts stores . This cuts its own threa ds as it is threaded o nto a stripped stud (exampl e: T hexto n Nos. 53 0 a nd 5 3 1). See page 89.

106

ENGINE

If the ba tter y is under to 200 amps, w ith 25 0 at th e hi gh end of no rm a l. charged , yo u have to find o ut w hy. With th e engin e Oil Is Thicker Than running at fas t idl e, yo u Water should check charging When a ll th e battery co nn ecvolta ge across the ba ttery ti ons are good , there are two terminals. If the voltage comm on ca uses of high isn 't well over 13, so medraw : engin eltransmi ss io n thing's wr ong . U nl ess fri ction and a bad sta rter. th er e's a loose o r glazed In co ld weather, th e fricbelt yo u ca n p la inl y see, ti o n may be ca used by engin e insp ect the battery-ca bl e o il th at's too thicle If yo u conn ection s to ma ke sure were using a few can s of o il they' re clean and ti ght. thickening additive during You can't see what the the summer to try to cure an contact surfaces of sid e o il -pressure pro bl em , p oor terminals look like withcompression a nd so on , and out taking them a p art. ha ven't changed th e oil sin ce, An almos t-invisibl e coatyo u sho uld do it befo re the ing of corros io n ca n con(Fig. 4) Check the ground connection to the vehicle's engine for contact as well. co ld wea th er hits. stitute a charging barri er, If the ve hicl e has a ma nso wire-brush them even ual tra nsmi ss io n but ca n if they appear good . norma ll y be cra n ked in Then, recheck the chargNe utra l w ith o ut hav in g th e ing voltage. clutch p eda l fl oo red , a thi ck If chargin g vo ltage gea r o il may be slow in g still is low, in spect th e down engin e cra nkin g . Th e other end of the gro und t hi ck gear o il may sil ence (nega ti ve) ca ble . If the gea r noi se durin g wa rm ground cabl e is a split wea ther, but by w inter yo u design, the ca ble to the may need so mething mu ch ve hicl e's bod y or chass is li ghter, bo th for eas ier startma y be th e eas ies t to see . in g and better shi ft qu a lity. But it has less to d o w it h So me ca rm a kers recomm end char ging and startin g, so a uto ma ti c transmi ss io n fluid more ca refull y ch eckin a ma nu a l transmi ss io n o il and tighten if necesfor cold wea ther. Thro w in sary-the cable to the the clutch p eda l a nd if th e engine, which may not be engin e no w cra nk s norm a ll y, quite as accessible. th at's th e tipoff. C heck th e Warning: Som e cars have own er's ma nu a l fo r acce ptjust a single ground ca bl e a bl e lubes. from the ba tter y to the bod y (Fig. 3) . But d o n't In hot wea th er, engin e fricti on has th e o ppos ite stop there. Som ewh ere ca use: engine o il th at's too else on the ca r ther e will thin . If yo u do n't change the be a second strap , from o il frequentl y eno ugh, the (Fig. 5) You can monitor the cranking current with an inexthe bod y to the engin e or pensive induction ammeter. additi ves in it w ill wear o ut tran smi ssi o n (Fig. 4) . It a nd the oil wo n't prov ide th e may eve n be buri ed thin -film lubri ca ti on th e cy linder und ern ea th th e ca r, so look a ro und. may not be a prec isio n in stru me nt, With a full y cha rged battery, but it's cl ose eno ugh to pinpo int wa ll s need . Synthetic o il s a re better at yo u're rea dy to find o ut if the sta rter excessive current draw. Compare the ma inta ining th eir lubricity, but they' re circuit is pulling n ormal current. A rea ding w ith factory specs, if they also slightl y more expensive . low-cost induction ammeter (Fig. 5), exist. If th ey don 't, here's a general In addition , if yo ur engine is run ning on th e hot side-n o t ove rh ea tw hich clips onto the battery ca bl e, guidelin e: Avera ge starter dra w is 150

CURING

SLOW CRANKING

107

th e cra nk ing so und s ing, just running a bit ho tter un even ly slo w a nd th e th a n it sho uld-th a t thin s eng in e see m s to be tr yi ng o ut th e o il a b it mo re. The to sta rt but w on 't, va lve extra engine hea t a lso may t im in g d efini te ly moves to hea t up t he sta rter, w hi ch th e top o f t he Iist o f poss ith en w ill dr a w more current biliti es . tha n normal. If the cool a nt Access to the be lt o n a temperature ga uge is readtra nsve rse eng in e m ay no t ing o n the hi gh side, ge t a be easy, a nd ch ec kin g th e p rec ise rea d ing, and if it's ca m timin g ra re ly is a Spu shing 24S·F o r even 2S0·F, th a t's just too hi gh . minute o pe ra ti o n. Eve n t he o ld C hr ys ler 2.212. SWh en ever ythin g else seems a ll r ight, m a ke the li ter 4 -cy lind er, wh ich was fo llowing checks: o ne of t he ea siest to ge t to (thank s to a n access w in• Is the ignition timing d o w in th e timing be lt's bein g upset by e lectro ma gnetic inte rference fr o m th e upper cove r ), ta kes a bit (Fig. 6) Pull the primary wiring to the ignition module or coil batte ry ca bl es durin g eng in e lo nge r th a n that. to check for misfires during engine cranking. c ra nking? Thi s is mos t O n mos t ca rs, it is like ly to ha ppen if the ba tfa ir ly easy to ta ke o ff o r a t ter y or ign itio n w iring has leas t substa nti a ll y loosen .___...__._______ u_____ _ been m oved , even sli ghtl y, th e upper-h a lf belt cove r, durin g ser vice. Perh aps a ge ntl y fl ex it a w ay a nd ca bl e was n't re in se rted in a in spect th e be lt. If yo u see cli p o r g uide. A sim ple d a maged be lt teeth, th a t 's chec k is to di sco nn ect th e a stro ng indi cat io n t ha t belt t imin g may be o ff, igniti o n prim a ry w iring, suc h as fro m a di stributor a nd it's wo rth the ex tra o r di stributorl ess ig niti o n effo rt of a timin g c hec k m o dule (Fig. 6) . If t he a nd a mo re careful be lt in spectio n . Few la teeng ine now cra nks fas ter, mo d el ove rh ea d- ca m loo k fo r a m isloca ted ca ble. If th e eng in e has a con ve neng in es a re " fr ee -w hee lin g" (ca pa bl e o f to lerat in g t io na l d istributor, a lso li ft t he ca p to see if it's c ra ck ed a snapped belt wit hout or has carbo n tra cks (Fig. 7) A camshaft drive belt can jump a tooth or two and maj o r eng in e dam age). lf affect cam timing and cause slow cranking. yo u fi nd t he belt is nea r between termina ls. E ither th e end of its li fe a nd h as cou ld disturb spark-p lu g fir in g eno ugh to affect cra nking. a lm o st-forever items. However, a jumped tim e, too, yo u not on ly cou ld belt ca n jum p a co upl e o f teeth , a nd c ure s lo w c ra nkin g, but save t he • If th e batte ry and igniti o n pass in sp ecti o n, a nd t he slo w-c ra nkin g mo re th a n ha lf of ove rh ea d -cam sha ft eng ine o r a t leas t a cy lind er hea d . A nd if th e be lt has n' t jumped b ut is engines have be lts, no t c ha in s. W hen pro bl e m ca me on sudd enl y, c hec k to see if th e ca m sha ft -timin g belt a belt jumps tim e to a d va nce va lve we ll -wo rn , replac ing it is grea t in s ura nce, so yo u rea ll y ha ven 't lost a n yjumped a too th o r tw o (Fig. 7) . timin g, thi s ca n kee p th e eng in e from Un less th ey snap, t imin g cha in s a re c ra nking and starting smoothly. If thin g w ith t he effo rt .

tJ

108

ENGINE

I

0

ASY

Finding Oil Leaks

(Fig. 2) Oil pan gaskets may be a simple cork cutout or a pricey engineered rubber molding with metal inserts.

CRANKSHAFT (Fig. 1) Check the dipsticks to see where your leak is starting.

Y

o ur ta bb y cat crawl s into yo ur lap, purring. N ice, but th ere's a hu ge patch of sme ll y, slim y, o ily goo cover in g most of its ba ck. Ick. Backtracking o il y littl e catprints leads you into th e garage, w here a pool of oleagin o us fluid ha s mysteri o usly stained th e concrete floor. What is it and exact ly what part of your car is ooz ing it ? Tim e to put th e ca t down and ge t und er the car. But th e re's leakage a ll ove r th e engin e co mpa rtm ent, a nd even a di stinct patte rn of w indblown drops freck lin g th e trunklid. Where's it coming from? Begin b y finding out w ha t kind of oil is lea kin g. You can usua ll y determine th e co lo r by puttin g a few drop s o n a shee t of w hite pa per. No rmally, engin e o il turns bl ac k. Automati c tra nsm iss io n and power steering fluid is red but ma y di sco lor to brown or even be so dark th a t yo u can 't tell it from engine o il. Was her fluid is blu e a nd antifreeze is, we ll, it

FINDING

OIL

LEAKS

co uld be gree n, go ld , orange, brown o r blu e, d ep endin g o n th e suppli er. Fee l th e fluid. If it's very oily, it's lubri ca nt. Antifreeze may have a li g ht o ilin ess. Yo ur initial a na lys is points to o il , but yo u' re not sure a bout the co lor or wh ere it 's coming fr0111 . Start pulling dipsticks . The power steer ing rese rvoir is a good p lace to start if th e o il see ms reddi sh (Fig. 1) . If the rese rvo ir is topped up , a nd th e lea k is at th e fr o nt, check the a uto matic transmi ss io n coo ler lines, p a rticularly if they have sections of rubber hose wit h clamps . If th e oil is d efinitely black a nd t he drop s are directl y unde r th e eng in e, it's engin e o il , which is th e most commo n lea k. But, o nce aga in , yo u're fac ed with that sa me qu estion: Wh ere is it coming from? A slow leak fo llo ws ribs on th e engine block, is blown a long the top of gasket jo ints, a nd o il gets everywh e re. Put a lot of

(Fig. 3) A leaky main seal will spray oil all over, and will need to be replaced.

Iight in th e engi ne compa rtmenr and take a look . You might get lu ck y a nd see the so urce. But unl ess you're sure, don 't repla ce a n ythin g ye t. A lot of gas kets are not on ly tough to repl ace, but they have sophisticated d es igns that are anyt hing but cheap (Fig. 2) . It would be a shame to waste a da y replacing a costl y gasket and still ha ve the leak. Oi l a lso may be seep in g past a worn cra nk shaft or camshaft sea l (Fig. 3) . Th e rubber lip that sea ls to the rotating shaft will eve ntu a ll y wear to the point at which the tension in the garter sp ring wo n 't keep o il from lea king. Thi s type of seal w ill onl y lea k w hen t he engin e is runn1l1 g- a nd when it do es o il w ill spray eve ryw here from th e spinnin g shaft. Because pinpointing an engin e o il leak can be difficult, you shou ld ge t a ll the help yo u can and , fortunately, a method preferred by the profess ionals is within easy reach: trace dyes

109

HOW IT WORKS

Gaskets When you look at a pair of also called a "compression . RIGID COVER ~3 ~ (GROOVED GASKET machined surfaces, or even set." Retightening gaskets ~=_ RETENTION) today's well-finished engine helps and may work for a surfaces, you may wonder ~~~ .~~ ~ i-PIECE OIL considerable time. But when ~",'~ FILL TUBE why a gasket, an O-ring or it doesn't, the gasket must other type of seal is needed be replaced. Today's oil-seal"' . . ,. \ AND DIPSTICK to prevent an oil leak. ing gaskets (like all automo,,~ FRONT COVER Except for seals around tive gaskets) are made of iA MOLDED ' (GROOVED ~ SILICONE _ GASKET rotating parts, wouldn 't high-temperature synthetic RETENTION) GASKETS " " clamping the parts together materials, in combination 8 tightly be enough to prevent with natural fibers, that are oil leakage? more resistant to a compres~~ '\ ~ The answer: close, but no. sion set. They have engiSorry, even mating joints neered shapes that, when bolted together look a lot compressed, provide a more more precise than they effective seal. There may be ~ really are, and fluids can metal grommets around bolt WIDER RAIL WITH STAND- - - - STATO SEAL seep past them. It takes a holes to prevent overtightenOFF BEAD flexible material in the joint ing. The gaskets often are to compensate for any made with raised rubber unevenness and looseness to prevent, or at least mini"beads," in some cases a single broad bead, in others, mize, leakage. That flexible material is a gasket. The two or more riblike layouts, which set up a series of barridesign of a gasket itself is a complex art. Simple materiers to oil leakage. Gaskets often are shaped to fit into als such as cork compress nicely and compensate for a grooves in the mating metal surfaces. Or a gasket may fair amount of unevenness, but under the compression look almost like a large rounded band or square-cut rail of a line of bolts, cork gaskets soon take a "heat set," and fit into a groove in each gasket surface.

~ J

.~~A~i [=In~: - ~ '~ ~ ""

'~l~~~·7 )"

with ultrav io let (UV) light (Fig. 4) . These ca n be used fo r a ll fluid s-oils, fuel, coo la nt, even a/c refrigerants. Th e trace dye is flu o rescent, so und er UV light (so-ca lled black li ght ), it produces a n unmista kab le yell ow/green glow. Aim the light, and a sma ll dye stain m ay show you the so urce of the leak. The newest trace dyes were formulated in response to complaints fro m mechanics a bo ut low visibility of th e dyes and the difficu lty of positioning the large UV lamps. Now yo u can find kits with compact, fle x ible lamps, improved trace dyes and coated ye ll ow glasses that enh ance th e appeara nce of the dye. The kits typically include two bottl es of dye, one for oil s and another for antifreeze/coo lant. (Fig. 4) Ultraviolet light will make trace dyes glow brightly.

110

The trace dyes for a/c refrigerants are ve ry specific formulations, and th ey require specia l inj ectors. They are not part of the genera l purpose kits, but are sold in spec ific a/c kits. We used the Tracer Products LeakFinder Kit, a product that won a Popular Mechanics Editor's Choice Award at the 2000 Automotive Aftermarket Industry Week trade show. It's under $60 and includes a compact UV lamp with a flexible head , so it ca n be a imed

into all sons of underhood nooks and crannies . It a lso comes w ith a 10-ft. cord that has alliga tor clips to connect to th e battery ter minals, yell ow glasses, and l-ounce bottles of trace dyes for both oils and antifreeze/ coo lant. You can buy indi vidual bottles of any trace dye yo u use up. Start by mix ing a dose of o il-leak trace dye (Y2 ou nce, which is ha lf the amo unt in the see-thro ugh bottle) w ith as mu ch engine o il as yo u have left in yo ur top-up bottle, then pour that into the engin e. You co uld just pour the 1!~- o unce dose in to the engine, but if there's a leak yo u're pro bably down on oil anyway. If yo u just po ur in the trace dye dose, it will coat the o il fill er nec k, and take a lot lo nger to be was hed away by engine oil and mixed thoroughly into the oil suppl y. And it w ill take longer for the leak to show up .

ENGINE

After driving the car lo ng eno ugh to a ll ow oil lea kage, park th e car over newspaper to catch the lea kin g o il. C heck th e drops o n the paper w ith th e UV la mp. If the drops glow, yo u're read y to loo k for the leak. Jack up th e ve hicle, sup port it on safety sta nds and connect the lamp clips to the battery. Th en, put o n the ye ll ow glasses, aim th e light up from undern eath a nd press th e switch. Beca use lea king oil may follow a twisty path, look for the highest point of any oi l trace, and that sho uld lead yo u to the source. In our case, the path started at the oil dipstick tube, w hi ch had a lea kin g O-ring seal. In most cases, yo u'll find a loose gasket joint, which yo u may be a bl e to ti ghten. However, in ma ny cases, the gasket w ill have tak en a severe "set" in th e joint, and retightening wo n't stop the leak . If yo u don 't wa nt to m ake th e inves tm ent in a trace dye kit, t here is

FINDING

OIL

LEAKS

a n a lternative m eth od for finding a lea k. Yo u ca n use a co upl e of prod ucts yo u may a lread y have at home- one in th e ga rage, one in th e med icine ca binet. Th e garage item is aerosol engine degrease rlcleaner. Use the aeroso l cl ea ner to loosen road film, then rem ove the film fro m th e engine, transm iss ion a nd ad jace nt und erbody w it h a wa ter hose . Dri ve the ve hicl e to dry it off- or whe n you jack it up a nd sup po rt it all safety stand s, w i pe th e a rea clean and dry with a clo th. Th a t's wh a t you may have to do a nyway to remo ve a lo t of the road film. Th e objecti ve is to clea n th e und erbod y we ll enough so road film a nd leak in g bl ac k o il are n 't confu sed. From th e medi cine ca binet, get aeroso l powder, suc h as that used to trea t ath lete's foot, a nd spray the und ers ide of the genera l a rea of the lea k, going as high up the block as

(Fig. 5) Clean the suspected area thoroughly and dry it. Coat liberally with powder to locate seepage.

possible (Fig. 5) . T he powd er w ill adhere to a nd coa t the m etal, producing a white haze . Then, d r ive the ve hicl e until th e oil lea ks-be ca reful to avo id wet, muddy roads in th e process. T he hope here is th a t th e lea k w ill tak e a single large, reaso na bly direc t dow nward path (eve n if there are some strea ks from airflow ). If it does, it w ill show up as a primary "stream" down the engin e. Yo u ma y have to perform a simil a r trea tment closer to the top of t he engin e to rea ll y pinpoint so me lea ks, particul arly those from intake manifo ld gas kets. However, if th e oi l strea m is blo wn through a compl ex p a th a lo ng the engine before a drop hits t he gro und , using a trace d ye a nd UV light is a surer way. (I

111

l!~uShing Your Cooling System _ term coo lant li fe- yo u'd still face the usua l 2-yea r dra in interva l.

Glug, glug First, let's do a prope r jo b of dra ining th e coolant. Start by checking the specs to see how much is in the system. Thi s is importa nt, beca use ca pacities vary a ll over the lo t. So me Toyota Fo urs a nd V6s, fo r exa mpl e, ho ld o nl y a bo ut 5 1 quarts. Other systems ho ld 14 to 18 quartS . T hi s w ay, yo u' ll kn ow w hat perce nta ge o f th e cool a nt drain s o ut. Start with a coo l engin e. If th e press ure cap is o n the engine or rad ia tor, loo k at th e overfl ow reservo ir (Fig. 1), a nd if it's easy to di sco nn ect a nd empt y, go a hea d . T hen, remove the rad ia tor ca p a nd o pen th e rad iator dra in cock. If t he dra in cock is in ti ght quarters, use a specia l socke t avai la bl e a t most a uto pa rts stores (Fig. 2) . Let th e coola nt dra in into a pa n. Unl ess yo ur town has a coo la nt co ll ecti o n setup , po ur the o ld a ntifree ze in to a ho use ho ld drain, c1othes-

n

RADIATOR

---w._

OU take off t he ca p a nd loo k a t the coola nt. It's a nice sha de of green, o r may be red, or may be even orange. It looks good. Sho uld yo u leave it in? Unl ess it's recommended by the ve hicl e or coolant ma ker for extend ed li fe, the answer is no, especia ll y if it's been two years o r mo re since th e last tim e yo u drain ed it. Today's engin es a re loa ded with a luminum co mpo nents: cy lin der hea ds, water pumps, ma nifo lds, even eng in e bloc ks . And th e twO p rim a ry heat exchangers-radiator a nd hea ter-are also aluminum. Aluminum needs grea t corrosio n protection to sur vive, a nd the co rrosio n protecti o n in conve nti o na l a ntifreeze is used up in about two years . If yo ur car ca me with co nventional , yo u ca n't sw itch to extended li fe w ith o ut a fa ir a mount of prepa ra ti o n . And if yo ur car is much m ore th an fo ur years o ld, a sw itc h is no t li ke ly to yield lo ng-

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112

(Fig. 1) Remove the overflow tank, and carefully pour the coolant in it into your drain pan.

(Fig. 2) Start by unscrewing the petcock on the radiator. You may need a special wrench.

\

/

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ENGINE

(Fig. 3) It may be necessary to remove the radiator hoses to completely drain the system. Remove the clamps and twist the hoses off. w as her p ip e or a to il et . T ha t 's an en viro nm enta ll y sa fe a pproa ch. D o n 't po u r it o n t he grou nd o r in to a sto rm sewer. If yo u r ca r has a co pper r adi ato r o r hea te r co re, the coo la nt m ay be conta mina ted w it h lea d so ld er. M a n y m uni c ipa li t ies h ave haza rd o us-w as te di sposa l fac ili t ies t ha t w ill ta ke it. Also, in m ost o f t he Un ited Sta tes it's ill ega l fo r pro fess io nalmec ha nics to dump used coo la nt, so yo u m ay be ab le to ta ke it to a sho p or t he muni cipa lit y fo r recyc li ng. Next, move t he d a shboa rd temp era t ure lever to HOT , so if yo u r ca r ha ppens to ha ve a hea ter coo la nt control va lve, it w ill o pen . If th e p ress ure cap is o n the p las ti c rese rvo ir, rem ove the cap , t hen o pen th e d ra in cock . N o ra diator dra in cock ? D isco nn ect t he low e r ra d iato r hose fr o m th e radi ato r (Fig. 3) . Move t he hose c la mp bac k fro m t he ra di ato r neck , sli p a th in sc rewdr iver betwee n th e hose end a nd rad iator neck to fr ee u p t he hose, then twist sli ghtl y to di scon nec t the hose . Dra in ing t he ra d iato r a lo ne norm a ll y sh o ul d rem ove 4 0 to 4 5 % of the coo la nt. A ft er th e first dra in , fi ll the system w it h w a ter, th en wa rm up the engine a nd let it coo l. Dra in th e ra d iato r aga in a nd fill it o nce m o re w ith wa ter. Repea t. O r rem ove eng in e co o la n t dra in p lugs if th ey 're no t corrod ed in p lace.

UPPER

RADIATOR HOSE

w it h coo la nt. T he fill ca p a nd neck a re supp osed to be a t th e hi g h p o int o f t he sys te m to he lp a ir b leed o ut, but often t hey a ren 't. A n d even if th ey a re, yo u need a ll t he n a tur a l help yo u can ge t. So jack up th e front o f t he ca r, whi c h ge ts t he coo la nt fill neck as h ig h as possib le. C hec k fo r air bl eed s o n th e eng in e . Som etim es yo u ' ll see an obv io us a ir b leed , suc h a s a bolt li ke item thread ed into a hose . If th e re's a n a ir b leed, o pen it. If th e re are sev e ra l, o pen t hem a ll. If yo u have access to facto ry o r a fter-m a rket service in fo rm a ti o n fo r your car, chec k it fo r a coo la nt fi ll procedure . Po u r in the requ ired a m o unt o f a ntifreeze slo w ly unt il yo u see coo la nt oozing o ut o f the open a ir b leed s. Th en cl ose t he bl eed s a nd top off t he system w it h th e rem a ining anti freeze a nd th en p la in w a ter.

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yo u w a nt to in sta ll 6 q ua rts o f un d iluted a nti freeze, o r exactl y ha lf o f the coo li ng system 's ca pac ity (Fig. 4). The coo ling sys tem h as lots of nooks and cra nn ies t ha t trap a ir, m a kin g it d iffic ul t to fill t he system

I

Let it bleed Now comes t he ha rd pa rr-fi lling th e system. If th e system ho ld s 12 qu a rts,

(Fig. 4) Refill the system t o half its capacit y with coolant. Then add wate r to fill , achieving a 50 percent concentration of coolant. Check the concentration wit h a hydrometer. L

FLUSHING YOUR

COOLING

S Y STEM

113

HOW IT WORKS

Cooling Your Engine A coolant pump, or water pump, circulates the antifreeze and water mixture between the engine and the radiator. After the coolant circulates through the engine, the pump pushes it out the upper radiator hose into the radiRADIATOR ator, a heat exchanger made of metal tubes (aluminum on today's cars) to which fins are attached. RADIATOR FAN , The fins draw away heat ~~E~~~PC and dissipate it to the air MOTOR that is drawn through the radiator by fans and the forward motion of the car. RADIATOR HOSES & CLAMPS The cooled coolant is drawn from the radiator RADIATOR DRAIN PETCOCK through the lower radiator hose and back into the engine by the pump, and the cycle starts all over again. When the engine is cold, coolant circulates only within the engine, so engine heat warms it up faster. At about 195 F, the coolant heats a temperature-sensitive valve (the thermostat) that opens to allow the coolant to flow through the radiator. The thermostat may be located at the engine outlet, in line with the upper radiator hose, or at the inlet to the water pump (the preferred location on today's cars). The coolant also flows through hoses into and out of 0

If the system has a hea ter coolant va lve, close it by mov in g the temperatu re contro l lever o r kn o b to COLD. With the engin e runnin g at fast id le a nd wa rmed up , have a helper move the lever o r kn o b to HOT w hil e yo u listen at th e coo la nt va lve . If after the fir st rush of coo lant yo u hear a con, tinuous gurglin g no ise, there's still air in the coolant, and yo u shou Id be' prepared to watc h the coo lant level in the reservo ir over the next few weeks.

Picking the right antifreeze Most antifreeze is made with a base chemical ca lled ethylene glycol. Green, ye llow, red, orange, pink, and blu e dye

114

THERMOSTAT

AlC & HEATING OUTLETS

/ the heater, which, like a miniature radiator, gives up its heat to the surrounding air. In this case, however, the heated air is blown into the passenger compartment. Raising the cooling system's pressure also raises the coolant's boiling point, so the radiator cap (which also could be on the engine or on the separate reservoir) has a pressure valve to raise the pressure in the cooling system by about 15 psi. This increases the boiling point of the coolant by about 40 F. So, the boiling point of a 50/50 mix of antifreeze and water in a properly functioning system is about 265 F or higher.

is used. The dye is not an indicator of the formula. Extended- life antifreezes, rated for fo ur yea rs/60,000 mi les, were on the market until th e mid 1990s. But the newest entries a re superlong- life a nrifreezes w ith tota ll y new rust/corrosion inhibi tors, in some cases developed origina ll y for di esels. The original, from Texaco (used as original equipment by GM), is ca lled Dex-Cool. Other Dex-Coo l antifreezes also are ava il a ble from Prestone and Zerex, perhaps oth ers . Dex-Coo l is recomended for fiv e yea rs o r 150,000 miles. Ford and Chrys ler Gro up use a different antifreeze ca ll ed a " hyb rid ," recommended for five years or 100,000 miles.

0

0

The ru st/corrosion inhibitOrs va ry, but if antifreeze is a maj o r bra nd th at is not extended li fe, but is in a ca r w ith a lo t of a luminum co mponents, cha nge it in two years or 30,000 miles- w hi chever comes first . You ca n push th at to a third year if the engine is a ll cas t-iron. "Toyota Red" is a spec ific formula, but if yo u drain it, you ca n rep lace it with any name- brand America n formul a . He re again, th e rep lacemen t interval is two yea rs o r 30,000 mil es. If you ha ve at least 50 00 mil es o n the antifreeze, the chemica l bond with the aluminum components is "so lid ." So if you wa nt to get extended life with a coo lant insta ll a -

ENGINE

ti o n , ju st do a thorou gh dra in-bydiluti o n, at least three times . T he coo la nt yo u drain o ut sho uld be virtu a ll y cl ea r, like th e co lor o f wa ter. If it's still co lored, yo u have to repea t th e process until it's a ll o ut. With the radia tor a nd rese rvo ir dra ined, po ur in the a mo unt of a nti freeze necessary-there should be p lenty of room-and then top up w ith wa ter. Fo ll ow the procedures we've

FLUSHING YOUR

COOLING

SYSTEM

di scussed to ensure a full system. Remember : Yo u sho ul d do thi s o nly as a maintenance procedu re, not as a fin a l step w hen replac ing a parr, such as th e wa ter pum p a nd radi ato r. W hat a bo ut "pet-fri endl y" o r "safer " a ntifreezes made with a base of p rop ylene glycol? The na me bra nds (S ierra and Preston e Lo-Tox) w ill do the same jo b as eth ylene glyco l. But they cost a little more a nd act ua ll y

require a grea ter qua ntity to provide the sa me freeze pro tecti o n, and in t ruth , t hey're o nl y a bit less haza rdo us. Th ey are n 't swee t, a nd co nsequ entl y a ren 't as lik ely to be co nsumed by todd lers o r pets. D o n't rely o n thi s, howeve r. Sto re all unu sed coolant, low-tox or not , sa fel y. Di spose of a ll dra ined coolant in a sani tary sewer o r in acco rd a nce w ith loca l reg ul a ti o ns. t6

115

ASY

Checking Your Ignition Timing

(Fig. 1) It's deep and dark in the engine compartment, and filthy to boot. On a cold engine, clean the timing tab and scale for better visibility. OU floor th e accelerator to pu ll a ro und a lin e of exit traffic, a nd yo u rea li ze t ha t yo ur car is barely respo nding. A tax ica b is camped ha lf a n inc h from yo ur rea r bumper, a nd th e ca bby is a ltern a tin g betwee n usin g one of hi s fingers to sema pho re hi s di sp leas ure with yo u r fo rwa rd prog ress a nd lea ning on the horn bu tton. Your car's accelerati o n, non eth eless, rema in s a frac ti on of its form er se lf. What could be w ron g? The engin e run s smooth ly, but simpl y lacks power. Th ere's no C hec k Engin e li ght o r tro ubl e codes. Pardon o ur asking, but w hen was the last time yo u checked the ignition timin g ? Ign ition timin g? H ey, yo u're dri vi ng a '97 mo del w ith a big, fast engine computer. All of t hose elecn'o ni c gizmos ha ndl e th a t stuff, ri ght ? Ac t ua ll y, yo u may need to di g o ut yo ur o ld timin g li ght a nd put it to use. C heckin g a nd , if necessa ry, a djustin g ignition timing may have becom e lost sk ill s, but a ma jo rity of ca rs and trucks o n th e road still have timing

Y

marks-a nd t hey weren't put th ere just for show. If th e spark s a rri ve a t th e plugs too early o r too la te, eng in e perfo rm a nce drops a nd the ve hicl e is lik ely to fa il a n emi ss io ns test. Sure, cha nges in ignition t imin g have been co n tro ll ed by the engin e co mputer o n cars a nd lig ht trucks fo r man y years. H oweve r, the bas ic timi ng still has to be ri ght. Th ere is a movem ent towa rd " coil o n plu g" igniti o n, elimina tin g spa rk plug w ires (a nd th e co n ve ni ent a ttac hment fo r t he t imin g lig ht) a nd th e rim ing ma rk s, too . If yo ur engin e has no ma rks, yo u' ll have to check timing w ith a sca n tester, w hich reads th e sensor d ata processed by th e COI11puter. H owever, if th ere a re ma rks, yo u ca n make th e mosr mean in gful c heck-the ac tu a l tim ing rat her th a n a computer-p rocessed signa l. If yo u have a car w ith a di stributor, th e timing probably is a dju sta ble. It may have ve ry li ttle range for ad justmem , but if yo u see a n y sign o f a slot in tb e d istribu to r's ho les for t he reta in -

ing bo lts o r nuts, t iming can be reset. Eve n if th ere is no di stribu tor, there is a base timin g specification, a nd if it's in co rrec t, th e eng ine wo n't run ri ght. The pro bl em co uld be ca used by a bad signa l fro m a sensor or even by a bad computer, but unl ess yo u check the timing, yo u wo n'r know. Mos t pre-'96 mo d els we re eq ui pped with an e mi ss io ns di agnosti c system ca ll ed OBD (O n-Board D iag nosti cs) . A la rge number o f th ese mod els, in cluding two best-se llin g ca rs, H o nda Accord a nd To yo ta Ca mr y, have a dju stabl e ig nition timing. In 1996, a far more sensi tive, comp lex system ca ll ed OBD II ca me in to use. With eith er system, th ere's no gua rantee th at a n igniti on timin g error wi ll prod uce a C heck Eng in e li ght or even a tr o ubl e code. C heck ing ignitio n timing is a stra ightforward procedure-if yo u have a good timin g light that's ri g ht fo r yo ur car. Th e t ype yo u need depends o n th e t ype o f timin g ma r ks on yo ur eng in e. Ge t the riming spec fr o m a shop manu a l o r a n afte r-ma rk et se rvice info rm a rion system.

(Fig. 2) The timing mark on the flywheel may be under a dust cover or plug.

ENGINE

116

Finding Timing Marks Loca tin g th e m a rk s may no t be easy if th ey' re o n t he engin e's fro nt a nd are cove red w ith dirt (Fig. 1) . Th e m a rk s m ay be fo und o n a n o pening In the tra nsmission bell housing . (A rub ber plug may be used to keep roa d film o ut o f th e bell ho usin g. R emove th e plug for the timin g check (Fig. 2) .) C lea n o ff th e ma rk s if necessa ry, a nd hi ghli ght the sp ec ified timin g w ith a pi ece o f cha lk o r w hite na il po lish (Fig.3) . Kee p the hig hlight thin since a wid e m a rk ca n span several d egre es . Yo u wa nt the ti m ing to be right o n. W hen a timing light is a imed a t the timin g ma rks w ith the eng in e runnin g, a fi xed mark sho uld a lign w ith th e illumin a ted m ar k o n th e spinning parr, be it th e cra n ks haft pull ey o r d a mper, or th e fl yw hee l. If t he ma rks do n't ali gn , ma ke th e n ecessary a dju stment of the distribu tor or go throu gh a sho p ma nu a l di agnosti c p rocedu re to fi nd

(Fig. 3) Chalk or light-colored touchup paint will make it easier to see the timing mark.

o ut if a senso r o r the co m p ute r is bad . If th ere's just a fixe d po int a nd a sing le line o n th e crank shaft da mper o r p ull ey, yo u pro ba bl y ca n't check timin g wi th a simpl e timin g lig ht. Wh en th ose two m a rk s are a lig ned, t he timin g is ze ro unl ess o th erw ise ma rke d. Zero mea ns th e spark wo ul d ar ri ve w hen th e p isto n is at th e very top of its stroke- " top dea d center." T he ac tual timing is typica ll y some number of degrees befo re (or even a ft er) to p dead center. If th ere's 110 ma rk fo r th a t spec ifi ca ti o n, a ll yo u' ll see w hen t he t iming li ght fl as hes is t hat the two ma r ks a re some space a part. Is it th e co r rect num ber of d egrees? Yo u need a n ad justa bl e tim ing ligh t. W ith it, yo u ca n change the timing of th e st ro be li ght so tha t th e li ght fl as hes ea rlier o r la ter. Yo u th en

rea d th e di a l or di gita l di spl ay to d etermin e how m a n y d egrees yo u bad to chan ge the fl as hin g of the timing li gh t befo re t he timin g ma r ks

HOW IT WORKS

Distributorless Ignition An electronic module with a double-ended ignition coil for each pair of companion cylinders is the most common type of distributorless ignition. The companions are cylinders with pistons that are in the same position in their respective cylinders at the same time-one on compression stroke ready for spark ignition, the other on exhaust. The coil module also contains electronic circuitry that communicates with the engine computer and executes its commands for ignition. There are three key inputs to the computer: the crankshaft and camshaft position sensors and a detonation (knock) sensor. The first two generally are electromagnetic devices that react to precisely located gaps in trigger wheels on the shafts. Changes in voltage caused by changes in electromagnetism provide signals from these sensors that tell the computer when each piston is rising on compression stroke. So, the computer can tell the coil module exactly when to discharge an ignition coil to provide a spark. The computer then can keep track of the sequence of cylinders for the electronic coil module to fire (so long as the engine is running). All the system continues to need are the crank sensor signals. If the weather, fuel quality or operating conditions produce engine knock, the detonation sensor sends a signal to the computer, which retards ignition timing. Each ignition coil discharges a spark from both ends, but only the one in the cylinder on com pres-

CHECKING YOUR

IGNITION

TIMING

COMPUTER-CONTROLLED COIL IGNITION

ELECTRONIC COIL MODULE

DETONATION SENSOR

rFi~~

ELECTRONIC CONTROL MODULE

SENSOR INPUTS CRANK SENSOR

This ignition uses a separate coil for every pair of cylinders, usually in a pack of three or four coils mounted together. sion has a f uel mixture to ignite. The other spark dissipates harmlessly in the exhaust gas of the companion cylinder. Ignition timing, along with fuel injection, is computer-adjusted primarily according to changes in throttle position, rpm , altitude and vehicle speed.

117

ADJUSTABLE TIMING LIGHT

12-VOLT POWER FOR TIMING LIGHT

(Fig. 4) Modern timing lights often have an adjustable delay/advance function that allows you to set ignition timing at a value that's not printed on the timing tab.

appeared to ali gn. If yo u cha nged it 16' in th e retard direction, the timing rea ll y is advanced 16' . If the factory spec is 10' advance, the timing is too far a head . If yo u cha nged it 6' but th e timin g spec ifica ti o n is 10' advance, the timin g is retarded . In ei ther case, an ad justment is needed . Okay, th a t's the way it should work. Let's go thro ugh a real timing check to demon st ra te. First, the timin g marks have to be clean a nd visibl e. Visibility often is to ugh, because of engine-co m pa rtment crowd in g. You may have to unbo lt a nd ha ng a fluid reservo ir out of the way to get a straight-on viewing angle. That's important, beca use if yo ur view ing a ngle is bad, yo u get what's called "para ll ax error," and it ca n mi slead

yo u by several degrees . Connect the timing light. The power and ground lead go to the battery, the lead with the plastic clip (ca lled the pickup) goes to the No. 1 spa rk p lug (Fig. 4) . The pickup must be squarely positioned on the plug w ire. On an inline four-cylinder or sixcylinder engine, the plug nearest the belt-and-pulleys end of the engine is virtuall y always No . l. If yo u have a V-type engine, yo u'll have to check the manual, since No .1 could be the first plug o n either side. After connecting the timing light, start the engine a nd warm it up, so it run s at idle speed. It's rare, but some manu fac turers specify checkin g timin g at a speed other than idle. If the timing isn 't correct, yo u've got to find out why. The usual reasons are a defective crankshaft sensor (the part that reads cra nkshaft position for tim-

ing ad justment by th e computer) o r throttle-position sensor. T here mayor ma y not be a trouble code to guide you, but w ith an ignition-timing check, yo u've made a good start. Scan-tool and Illultimeter tests of the sensors can take yo u the rest of the way.

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L..._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - -

ENGINE

118

MODERATE

Replacing Engine Mounts RIGHT FRONT STRUT TOWER

STRUT

RUBBER BUSHING INSERT

NOTE DETERIORATED BUSHING

RIGHT SIDE MOTOR MOUNT

(Fig. 1) Check for deteriorated rubber bushings in the dogbane (shown) and other engine mounts that may permit the drivetrain to move too far and shake at idle. Replacement is usually straightforward.

Y

OU pull up to a traffic light and once yo u've stopped, yo u can feel the engine shakin g. Okay, it's not so bad w hil e you're stopped, but as yo u acce lera te yo u can feel th e engine clunk a nd shudder. Hey, you just did a tun eup last month , and yo u know it sho uld last for a couple of years . You start to think, " I must have left a p lug wire loose or som ething like that. " Lift the hood and check every w iring conn ection in sight, every a irduct clamp, ever y vac uum hose. No thing looks out of place. But the engin e is shaking. If yo u h ave a rearw heel dri ve w ith an engin e-driven fan, yo u may see the hint of a fa n "sca llop " o n the rear of the radiator

REPLACING

ENGINE MOUNTS

core, a clear-cut sign that the engine is tipping forward o n acceleration. It's time to check the engine mounts and " dog bone" struts before th ere's a major failure and poss ibl e stick in g of th e gas peda I (Fig. 1) . Today 's engin e m ounts are anything but simpl e two-piece metal brackets with slabs of rubber bond ed between them. They ha ve engineered shapes, spec ific durometer measurements (hardness) a nd often have strange ly sha ped c uto ut areas ca ll ed "vo id s" - a ir gaps that tun e th e mounts' operatio n. In some cases th ey have hydraulic cham bers that are filled with silicone fluid , a nd a lso in limited use are ones w ith electronic contro ls.

Okay, your car isn 't bra nd-new a nd that's w hy the mounts are likely to be worn. The rubber may have been soa ked w ith road film and o il (fro m a lea king va lve-cover gasket). But it's mo re likely, particul ar ly at 50,000 to 60,000 mil es and up, that the mounts have cracks and distorted shape from the high temperatures common in toda y's engine compartments. If the wea therstripping along th e cowl is mi ss ing, for examp le, that breaks the sea l for the bac k of t he powertrain co mpartment, all ow in g air to flow over the top instead of circu lating t hrough the compartment to cool the mounts (a nd other components). The mount at th e drivebe lt (front ) end of the engine has the biggest job

119

(Fig. 2) It might be necessary to use a pry bar to look for extra play in engine mounts.

in today's tra nsve rseengin ed mode ls. It reacts to bo th ve rti ca l a nd fo reaft sha ke, so chec k it w ith a pry ba r (Fig. 2) and look at th e rubb er. If it crack s open at th e internal edges o f any vo id ed area, or if it exhibits virtua ll y no res ista nce, it is not p rovidin g mu ch CO ntrol. C heck fore-a ft mounts, a lso by prying. In t hese cases, however, yo u' ll probably ha ve to force t he bar aga inst th e metal edges of the mo unts to be ab le to pry ha rd enou gh.

What? Leaking Silicone? Mounts w ith hydraulic cha mbers are circular and have a meta l shell as part of their structure. It is possib le for them to leak internall y, but you ' re more likely to encounter a n extern a l lea k. Surface cracks in th e rubber ge nera ll y a re harm less, but run yo ur fi nge rs a ro und th em a nd if yo u pi ck up

leaking h ydra ulic mount ? Probably, particularl y if th e car is not destined for man y, ma ny years of addit io nal use .

Replacing Engine Mounts

some thick , black goo that's not road film, it's the silicone oi l leak ing o ut. As w ith an a ll-rubber design, th e only fi x is rep lacement. You often ca n obtain aftermarket rubberll1l etalm o unts to rep lace h yd raulics at a signifi ca nt savings. Are th ey lik ely to be as smooth ? Probabl y no t. Are t hey lik ely to sa ti sfy yo u aft er ex peri encing th e sha ke of a

Alth ough the powertrain end mounts on a transverse-e ng in ed car can be replaced individu a ll y if th e o ne at the oppos ite end is good , it's better to rep lace bo th. When a fore or aft mount is bad o n a tra nsve rse powertrain, a lways rep lace bo th . Ditto for th e mounts on the dri ve r and pa ssenger sides of a north -so uth powe rtrain. Support th e engin e w ith a hydraulic fl oor Jac k. If yo u ha ve to pl ace the jac k o n th e o il p a n, put a bl oc k of wood o n the jac k li ft in g p ad to protect

HOW IT WORKS

Electronic-Hydraulic Engine Mounts The Honda electronically conPOWERTRAIN trolled mount is typical of highCONTROL MODULE tech mounts used in a variety of cars to dampen the last little bit of shake produced by the powertrain. It's a hydraulic engine mount with two fluid chambers connected by a large orifice (kept closed by a rotary valve) and a small orifice (always open). The small orifice allows the mount to operate much like a simple, fairly stiff shock absorber. At idle, however, a vacuum diaphragm unit operates the rotary valve to open the large orifice, permitting more fluid flow between the chambers. It's like a shock that suddenly becomes softer, in this case absorbing the idle shake of the engine. The vacuum (from the engine) is fed through a solenoid valve that is controlled by the powertrain computer. This system operates when the engine is idling, perhaps triggered by turning on the alc (which produces a load that affects

120

engine idle). The computer opens the solenoid valve, and the engine vacuum flows to the vacuum diaphragm unit at the engine mount. When the solenoid valve closes above idle speed, the vacuum is vented and the engine mount goes back to single-orifice operation. If the vacuum reading fails to hold steady, there's a vacuum leak in the mount and it should be replaced. The next stage in electronic control of engine mounts already is in limited use (on some Lexus cars): A diaphragm pulsates in the hydraulic mount. The diaphragm creates a proportional countervibration to the frequency of the engine shake in the 600to-900-rpm range, canceling the shake so the engine idles smoothly. If one of these mounts ceases to work, you may need to troubleshoot the wiring and check the mount itself. ENGINE MOUNT CONTROL SOLENOID VALVE

ENGINE

WOOD BLOCK

(Fig.4) Pad the nose of a floor jack with a block of wood to support the engine while you replace the mounts.

t he pan (Fig. 3) . If th e mo unt's nuts or bo lts a re froze n, sp ray them w ith penetra tin g so lve n t so yo u ca n loosen th em w ith a w rench a nd not have to reso rt to a chi se l a nd ha mmer. ln most cases, re moving the fasteners a nd jacking th e engin e up slightl y is all th at's necessa ry to slide o ut a defective mo unt a nd in se rt th e rep lace ment. If yo u have to jack up a lot, th ere's a cha nce yo u co ul d stress a no th er mo unt unl ess you loosen it. C heck before yo u pum p the jack handl e. If t here's a st ud in th e mo un t yo u're rep lac in g, m ake sure yo u have it a ligned prec isely w ith its ho le befo re yo u lower t he eng in e. O n ma n y ve hicl es, yo u have to work bo th fr om unde rn eath a nd a bove to in sert a nd ti gh ten nuts a nd bo lts, a nd yo u occas io na ll y w ill need a helper to p ry o n th e engine w hile yo u get a bo lt st arted t hro ugh its m o unting ho le. If t he mo unting ho les are slo tted , run t he eng ine a nd let it id le fo r a minute or t wo so t he engin e settles in th e mo un t. T hen t ig hten th e Iiu ts a nd bo lts. Do the fin a l tig htening w ith a to rqu e w renc h.

Shock Absorber and "Dog Bone" Struts So me eng ines have a shock abso rber fo r vertica l shake co ntro l. W hen used , it typi ca ll y is bo lted to th e eng in e at t he top end , a nd a c hass is cross membel' a t t he botto m . Disconnect t he shock a t either end and o pera te it by ha nd , just as yo u wo uld to check a

REPLACING

ENGINE

MOUNTS

shock at a w hee l. If yo u fee l looseness o r ro ug hn ess w ith lost mo ti o n, t ha t's a su re ind icator of a worn-o ut shock. Is t here a dog bo ne stru t or two? The d og bone usuall y is at th e to p of the eng in e co m pa rtm ent, at t he fo re side of a tra nsverse powertra in . H oweve r, usua ll y does not mean a lways . It may be in sta ll ed a t t he top rea r side (t yp ica ll y a t the accesso ry- be lt end, w he re it ca n direc tl y ass ist t he engin e mo u nt), or even a t th e bottom ce nter o n th e aft side of a tra nsverse engin e. So if yo u d o n 't see o ne at fi rst glance, do n't ass um e it isn't th e re.

T he ends of th e dog bone ha ve rub ber sleeve b ush in gs (Fig. 4) , a nd if th e ru b ber is crac ked or di sto rted, repl ace t he enti re str ut (th e b ushin gs are not rep lacea ble) . It's a straightforward job . Ju st un bo lt it at each end , a nd install th e new o ne. T he engin e w ill shift sli g ht ly w hen the o ld d og bo ne is removed , in w hich case yo u' ll have to p ry it fo rwa rd into a li gnm ent w ith t he bo lt ho les. Yo u a lso may need a helpe r for thi s o pera ti o n. Some premium aftermarket dog bo ne struts include hydra uli c chambers, much like a shock a bsorber-so the da m ping is do ne hydra ulica ll y (Fig. 5) This inexpensive vacuum pump will in stead o f by sq ueezing ru bber make it easier to diagnose bad actuators on bushings . T here's no noticeable some hydraulic motor mounts. di fference in engine smoothn ess, but the hydraulic type reported ly has better long-term performance. The electro nic- hyd ra ulic engine mo unt (see p age 108) may VACUUM look com p lex, but it's easy even DIAPHRAGM ACTUATOR fo r a less experi enced Sa turday mecha nic to check. Turn on t he a ir cond itioning with the engin e id ling, and then d isconnect the w iring a t the soleno id va lve. If th e engin e shakes no ticea bl y more, the system is wo rking. If there's no d iffe rence, fi rst disconn ect the vacu um hose at th e eng in e mo unt to chec k fo r vac uum fl ow th ro ugh th e so leno id va lve. If there's vac uulll fl ow, turn off the HAND VACUUM engine a nd appl y vac uum to the PUMP d ia phragm unit neck w ith a ma nua l vacu um pump (Fig. 4) . (I

121

MODERATE

Cleaning Throttle Bodies INTAKE AIR DUCT

slip behind the wbee l for the mo rning co mmute. Th e engine starts easil y, runs fin e whil e fas t-idling down the driveway and down the street for a few mil es, but then stall s. Yo u kn ow instantl y when the sta ll occurs beca use the air horn in the trac tor-trail er rig immedi ately behind yo u curdl es the flui d in yo ur inn er ear's semicircul ar ca na ls when forwa rd mo ti on fa ils to p roceed at a n ord erl y pace. Yo u res tart, yo ur car acce lerates w ith a slight stumble, and w hen yo u coast to a stop at a traffic light, it stalls aga in. The stumble and poss ibl e stall pro blem does n't go away wh en the engine is wa rm , so th e co mm on cold-engine poo r-running poss ibilities are scra tched fro m yo ur pri o rity checkli st. This is more tha n ann oying and as soon as the weekend ar ri ves, the hood goes up.

Y

OU

Diagnosis: Deposits All sensor w ires are connected. Th ere's no C heck Engin e light and th ere are no tro uble codes . Wh at do yo u look for now? A di sconn ected or damaged vacuum hose? Sure, th at's a good bet, beca use man y vac uum hoses can be pinched and da maged w here it's rea ll y difficult to see. But

122

take the tim e to check them al I, making sure th ey're not o nl y on tight, but not cracked or burned thro ugh d ue to contac t w ith an exha ust pipe or exhaust gas recircul a ti o n tube. Don't be surpri sed if the last hose yo u check is the o ne that 's damaged. If a ll the hoses are intact and o n tight, th ere's another poss ibility th at's just as lik ely: dirt and gum accumul ati on in the throttl e body.

Get Dirty To check for this, yo u've got to re move the intake air duct between the a ir cleaner ho using and the throttle body (Fig. 1) . Firs t, di sconnect all hoses and unplug any sensor wiring connectors (Fig. 2) . If there's a chance yo u could confu se a hose connection or wiring connector, put a piece of masking tape on the hose or connector, another on the hose neck or sensor, and mark each with the same letter. Next, loosen any cl amps, work the duct off th e thro ttl e body and set it aside. Wi th the wiring and hoses disconnected , you sho uld not run th e engine. Even if it sta rts and r un s, it w ill log tro uble codes, possibly triggering the Check Engine light. T hen you 'll have to go thro ugh a code-

(Fig. 1) Remove the air duct and inspect it carefully for leaks or tears that might permit uncleaned air into the engine.

clear ing procedure- extra work yo u don't want. M oreover, th e computer may have to relearn some drivea bility tr im settings, which may leave you with a m arginally running engine for a while. O n some ve hicl es, it's p ossibl e to lea ve hoses and sensors connected and still move the in take a ir duct safely out of the way. In that case, it wo uld be possible to spray a solvent into the throttle body opening with the engine run n ing. H owever, there's no grea t adva ntage to thi s and , as yo u' ll see, th ere are reaso ns why it's not such a grea t id ea . Ta ke a good look in side th e th ro ttl e body using a fla shlight. Operate the throttle linkage to open the throttle plate so yo u can see pas t the outside surface of the thro ttl e body. If yo u see a coating of di rt and oily film 0 11 th e inside wa ll of the thro ttl e body or th e edge o f the thro ttl e plate, yo u've likely fo und th e pro bl em . T he coa ting both upsets and restricts the airflow when the throttl e is closed o r slightly open. Where do these deposits come fro m ? Some are in airborn e dirt that gets th ro ugh tb e air filter or past a crack in the in ta ke air duct. So be sure to check th e intake air duct for crac ks, particularl y in the "accordi on " area where they're not as obvious. Most deposits, however, are fro m oil gases transferred from the positive crankcase ve ntil ation system and p ushed forwa rd by norma l engine pul sation as the intake va lves close and open, and fr0111 exhaust gases that seep in. Some th ro ttl e body bores have a coa ting to redu ce the buildup , but, in time, bores with protective coats can be affected. There are several w ays to

ENGINE

(Fig. 2) Remove any hoses or wires on the air duct connecting the throttle body to the air cleaner housing. Mark which hose or wire goes where to avoid confusion later.

a rea of the thro ttl e pl ate, a nd a stro ng so lve nt or h ard bru shing might dama ge it. In a ddition , a se nso r O-r ing sea l may be da m aged by a stron g so lve nt. T hird, t he th rottle pl a te sha ft is sea led at th e mo untin g ho les in the t hro ttl e bod y to prevent en tr y of unmeas ured a ir (w hic h wo uld upset the f uel mix ture). A strong so lvent (a nd ha rd brus hin g) co uld da mage t he sea ls. clea n o ut th e area . The best is wit h a profess io nal too l ca ll ed th e Inta ke Sna ke, w hich co mes w ith a n effecti ve ye t safe so lvent, a nd the si mplest is w ith an o ld worn-out toothbrush w ith soft bristles a nd a mild so lvent. Tbere are tbree reason s w hy yo u have to be ca reful, both in cho ice o f so lve nt a nd in app li ca ti o n :

First, if th e th rott le body has a protec ti ve coa ting (as o n ma ny Ford products) to reduce th e buildu p, a strong so lve nt and hard brush ing will remove it, so you 'd have to d o th e job more oft en. If yo u see a wa rnin g labe l o n a Ford produ ct, th at's wb y. Seco nd , th ere may be a senso r tip proj ectin g into a sm a ll o penin g in th e

Stronger Than Dirt Most aeroso l ca rburetor a nd choke clea ners a re pretty st rong. Ditto for those aerosol clea ners that can be sprayed into the a ir intake with the tb ro ttl e open for combustion-chamber clea nin g. T hese aerosols have to be very stro ng to clea n surfaces w ith o ut the mecha nica l ad va ntage

HOW IT WORKS

How A Throttle Body Works An engine runs primarily IDLE on air (about 15 parts AIR by weight, to one of BYPASS fuel), and the throttle body in a modern fuelinjected engine is the device that controls the airflow through its round opening. When the intake valve for a particular cylinder is open, the air flows through the throttle body, which is mounted on the intake manifold. The airflow continues into the intake manifold, through a chamber, and then through the open intake valve into the cylinder. At the same time the fuel injector sprays in fuel, the inrushing air and fuel mix, the intake valve closes and a spark from the plug ignites the mixture. The intake airflow control is provided by the throttle plate, a pivoting plate on a spring-loaded shaft that goes through the cen-

CLEANING

THROTTLE

BODIES

ter of the throttle body's round opening. The throttle plate is a type of air valve, often called a "butterfly." When your foot is off the gas pedal, the throttle plate springs closed , and only a minimum amount of air, enough for engine idle, goes through a bypass around the throt· tie plate. One end of the throttle plate shaft also holds the movable conTHROTTLE tact arm of the throttle 1IIi-- - , - - - - POSITION SENSOR position sensor, a vari able resistor-type sensor that tells the engine computer whether the vehicle is idling, accelerating or holding a throttle position. On many new engines, the gas pedal is just a variable resis· tor, sending a signal to the engine computer. The computer controls the throttle plate to produce the desired opening. This is called "drive by wire." THROTTLE LINKAGE

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(Fig. 3) Spray·can carb cleaner may be a little too aggressive for safetydilute it with gasoline to prevent dam· age to seals and sensors. Always remove the negative connection from a battery first and reconnect it last to prevent shorting the wrench out on nearby metal objects.

of a rubbing brush. A strong solvent can ca use deterioration of not only sensor seals, but also throttle shaft seals. Further, you can't see which deposits have been re moved and which have not. The aerosol spray will not clean all areas, particu larly the back side of the throttle plate. A tune up/injector cleaner mixed with gasoline (1:4 or 1:5 ratio) should be safe (Fig. 3) . You won't be using m uch, and you can pour the rest into the gas tank after you're done. (Fig. 4) The Intake Snake is one way to safely clean t hrot· tie blades and throttle body castings of deposits.

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Start by cleaning the exterior of the throttle plate, and then hold it open using a wire tied to the throttle linkage so you can clea n the inside perimeter of the plate. All you're trying to do with brushi ng is to loosen all tbe deposits . Next, clea n the thro ttle body wa ll , being carefu l to work aro und any electronic sensors, and around the throttle p late shaft holes. When

you're done, remove the deposits with solvent and a clean rag. Beca use this service is something your vehicle may need every few years, the professional kit (www.intakesnake.com) is a worthwhi le investment at under $60. It incl udes a conta iner of two clea ni ng tips (containers of two tips are ava ilable separately for under $15). T he "snake" is made of a smooth plastic and won't scratch anything. It's 14 in. long and moderately flexible, so you can reach deep into the throttle body and fo ll ow any contours (Fig. 4) . T he rool holds the sponge like work tips that are coated with a hypoallergenic solvent that's also safe for sensors and throttle plate sea ls. Because the dirty film is held by the work tip, there's little or no wiping needed when you're done. Press a release tab and the dirty tip fa lls off the tool (into a garbage can).

G

ENGINE

EASY

Electric Cooling Fan Problems (Fig. 1) Check the high-amperage fan fuse in the underhood electrical box.

link-a short section of wire typically four ga uge numbers higher than the wire of which it's part. You may see it's singed. Even if it isn't, pull on the ends of the wrap, and if it stretches, the wire underneatb is broken.

Checking The Fan Motors Fuse okay? The most practical approach is to go next to the end of the circuit: the fans themselves. Most cars ha ve two fans. Unplug one fan's wiring connector and (referring to the FAN CIRCUIT FUSE wiring diagram color codes) hot-wire the fan motor's half of the connector. Run one jumper wire from the current t's a really, really warm day, but the of a powertrain computer, but the basic feed terminal of the con nector ha lf to circuit is pretty straightforward. the battery's positive terminal. Attac h temperature ga uge reads normal a second jumper wire to the other terand the alc is blowing out a lot of On almost all cars the fans shou ld minal of the connector and run it to cold air, so who cares? Tben the traffic go on if the alc is turned on, triggered suddenly slows to a crawl and doesn't an electrical ground (Fig. 2) . The fan by the powertrain computer or by an get any better. Gradually the temperashould run. If it doesn 't, the fan ale pressure switch. The fans may not ture gauge needle creeps toward the go on instantly, but certainly within a motor apparently is defective. couple of minutes. If tbey don't, proSome cars have a single fan that Hot end of the dial, and the air blowing out of the alc registers is anything ceed to a circuit diagnosis. runs at two speeds. In these cases, the but cold. In fact, to forestall overheatThe simplest first circuit check you connector may have: can make is the current feed, starting at ing, yo u shut it off. Even worse, you • Two terminals (one frol11 a du a l soon bave to turn on the heat to try to power feed-through a dropping the fuse, which on late models is in an prevent a boil-over, and open the winunderhood fuse box (Fig. 1). Just pull it resistor for low speed and a resistordows to try to get a breeze. out and look. Replace it if it's blown. bypass circuit for high speed-plus If yo u're luck y, the traffic tie-up On older models it's often a fusible the second one for the gro und). breaks, and yo u're cru isThere's a sp li ce or con(Fig. 2) Try jumping the battery direct to the fan to see if it spins. ing again. The gauge neenector for the dual power dle starts dropping, and feed ea rli er in the circui t. yo u turn off the heater. If yo u check by hotStill sweaty, yo u turn on wiring at the fa n motor the alc again, and even if itself, it will run at high the air isn't frigid, it's cold speed. enough to make you feel • Three terminals (one for better. low-speed feed, one for Later, yo u lift the hood high-speed a nd a common witb the engine running gro und). Check each near an overheat and tbe power feed terminal sepaale on-the radiator rately, using the commo n electric fans aren't running. ground in each case. But why? The fan may be • Four termina ls (high , under the complex control low and two grounds).

I

ELECTRIC COOLING

FAN

PROBLEMS

125

.I~..-.

Hot-wire each pair separately with your Jumper wIres.

Testing Coolant Switch Or Sensor If both fans run when they're hotwired, the problem is somewhere between the current feed at the fuse and the fan motors. On older systems where the trigger for the fans is a coolant temperature switch, unplug the switch connector. Be sure you ha ve the right one, as some vehicles have as many as three: one for a dashboard warning light, one for an overhead console and one for the powertrain computer. With the engine running and with the coolant switch unplugged, the fan should come on because the powertrain computer logs a troubl e code for a failed switch and turns on the fans in most systems. If it doesn't, and the switch is a typical domestic design, it has a normally open type that stays open until coolant temperatures are high, wh en it closes to turn on the fan . To double-check, just

·.111'

ground the unplugged connector's single wire terminal, using a jumper wire. The fan should spin. Many older Japanese cars have circuits with normally closed switches. They open with hi gh coolant temperatures to turn on the fan, so a simple unplugging (with the ignition on) always should get the fans to operate with this setup. Most late models have a coolant temperature sensor. It isn't a switch, but a temperature-sensitive resistor

.11{:..:r . . . . l.I~lllt

(thermistor) that sends a signal to the powertrain computer. The computer, which also has some control over alc operation, then decides when the fans should operate and at what speed. You may not be able to get a response by simply unplugging the sensor connector or even by grounding it. Instead, check its calibration by connecting an ohmmeter (Fig. 3) . The thermistor develops lower resistance as the temperature goes up, higher resistance as it

(Fig. 3) Connecting an ohmmeter is one reliable way to check the thermistor.

126

ENGINE

drops. If the sensor rea ds a thou sa nd o hm s or more (w hich signa ls lo w tempera ture) w hen the engine coo la nt is war med up, it's o ut of ca li bra tio n. Replace it. Even eas ier is to use a sca n tool w hich w ill give yo u a reading in degrees (c. o r F.) .

Relay Diagnosis H ead fo r the fan relay (or re lays- some systems have low- a nd high-speed fa n re lays) (Fig. 4) . Turn on the igniti o n, and locate the relay termina l for the wire from the switch. When yo u ground its terminal with a jumper wire, the relay shou ld click a nd the fan should run. If it does, the relay and its circuit to the fans a re good. Any problem is in t he w iring between the coo lant tempera tu re switch and the relay. If th e fan still won't spin, conti nue at th e relay, wh ich has two current feeds, one to the electromagnetic coi l, one to the electrical contacts. Probe the two cur ren t feed te rmin a ls of its wir ing connector with a g round ed test light. With the ignition o n, it sho uld go on in both cases. No lig ht in one? There's a break in the wiring from t he fuse to th a t relay terminal. On systems wi th computer contro l via a sensor signa l, make a simil ar test of the relay c urrent feed term in a ls wi th a g ro und ed (computer-safe) test li ght and th e igniti o n o n. If th e c urrent feeds are good, gro und th e relay'S switch term in a l (the one w ith the wire that goes to the coo la nt sw itch ). If there's a sensor a nd the switch te rminal wire goes to th e powerr rain computer, unplug the wire before g ro undin g the terminal. Th e relay sho uld c li ck and operate th e fans. If it doesn't, rep lace the relay. Yo u ma y have trouble doing this with relays that plug into an und erhood relay "cen ter. " Unplug the re lay, turn on the igniti on and with yo ur test li ght probe the two current feed (Fig. 4) You can jump across the fan relay to confirm the relay 's failure.

ELECTRIC COOLING

FAN

HOW IT WORKS

The Electric Fan The fan is powered by FAN RELAY an electric motor, B+.---------__-+--~ ~--+-------------, which is wired to a 12V FROM relay. The relay is a BATTERY magnetically controlled switch. It typically has four terFAN minals, two of which MOTOR TO IGNITION SWITCH are current feeds from a fused source of 12-volt electricity. NC SWITCH COOLANT TEMPERATURE At the relay, there is SWITCH one current feed into the coolant temperature sensor, also an electromagnetic coil, and one feed into a set of contacts for the wired to it, the powertrain computer switch, which is open. The other tercan choose to ground the coil terminal. This energizes the coil, creating minal for that open switch is cona magnetic field that pulls the arm on nected to the electric motor for the the power feed contact, so that it fan. The fourth terminal, also for the touches the terminal for the wire to coil, is wired to the powertrain comthe electric motor. That closes the puter, which may look at various signals to determine whether or not to switch of the relay. Current flows through the closed contacts of this provide an electrical ground for that coil. If, as in this circuit example, it switch to the electric motor, which gets a high-temperature signal from spins to operate the fan.

terminals in the rela y center. If th ey pass (turnin g o n th e test light), make up short jumper w ires to connect to th e unplugged relay and one lo ng jumper (th at yo u run to a n electrica l gro und ) for t he sw itch termin a l. If the re lay still doesn 't work (ignition on), replace the re lay. If the rela y does cli ck, probe th e output terminal to t he fa n motor w it h a gro unded test lig ht. Light goes on? Th e prob lem is in th e w irin g from re lay to fa n motor.

Your diagnosis may point to the powertrain com pu ter. It's ra re , but a computer failure ca n be res pon sibl ew ith o ut a C heck Engine lig ht or trouble code. Perhaps just a sin gle dri ver has blow n, so th e co mputer itse lf seems to be perfo rming norma ll y. In addi tio n, in a number of cars, particu larly some GM mode ls, the powert ra in co mputer turn s off the fans if th e ve hicle is cruis ing 40 to 45 mph o r hi gher. T hi s stra tegy reli es on the ve hi cle speed se nsor, w hi ch may be misbehaving. If your speedo meter is way off, or not working at a ll, it's somethin g to consider if the relay works w hen grounded. Want to work throug h o ne of th ese problems? Open yo ur factory se rvi ce manual , plug in a Saturd ay Mechanic-leve l FUSED -~~-r~~~~?)J ~~~~~~ scan too l and go through JUMPER the troubl e-tree diagnostics WIRE to find th e answer. ~

PROBLEMS

127

MODERATE

Finding Engine Knock

Y

Ou're waiting in the drive-up line at the bank, all the better to redeem some of your hardearned cas h from the vau lt. But as yo u inch yo ur way to the teller window, yo ur engine misses so badly that it either stall s or has to be held at high idle with your right foot. The teller sends yo u a note through th e pneumatic tube, " Sir, yo u forgot to en dorse

128

Fig. 1. Try to isolate engine noises with a mechanic's stethoscope. You can usually determine which cylinder is at fault. Try pulling one plug wire or injector harness at a time to see if the noise changes.

this check, and please get your car fixed- I can't hear a thing." It's off to the garage instead of the beach. Days later, you're at the end of yo ur rope . Above idle, the engine purrs like a kitten. But below 2000

rpm, there's a steady miss in the No.4 cylinder. You've checked everyth ing you can think of. Spark, compress ion and the fuel inj ector to that cylinder are working just fine. Yet the miss rema1l1s.

ENGINE

Complete Engine Testing Man y peopl e-even mecha nicsthink that th e beginnin g a nd end of interna l engine di ag nosis li e in using a compress ion tester. But th e truth is that many internal engine problems (s uch as a weak va lve spring, for instance ) are not revea led by compression testi ng a lo ne. "A weak va lve spring is easy to spot, if yo u use a vac u um ga uge," said Dave Hakim , an engi ne and fue l system specia li st with Federa l Mogul Corp. "Connecting the ga uge to the intake vacu um would reveal normal vacuum at idle. But when a valve spring is bad, the vac uum needle would flu ctu ate rap idl y betwee n 12 and 24 in . when yo u ra ise the rpm ." You can di agnose most internal engine problems using a vacu um ga uge, a compression gauge and a leakage tester. And you can usu ally get to the root of mys terio us interna l engine noises by bein g a good li stener.

Engine Noises The most common so urce of engine noise comes from the va lvetra in . The noise-usually a clicking or tapping at half the engine's rotating speed-is caused by excess ive clearance between components or a bad hydra ulic lifter. On camsh aft-in-block engin es, yo u can iso late valvetrain noises by bri efl y running the engine w ith th e va lve cover off and pressing on eac h va lve rocker w ith the end of a hammer handle. When the pressure from the handle remo ves the clearance, the no ise disappears and yo u've fo und th e problem. Diagnos ing va lvetra in no ises is more difficult on overhea d-ca m engines beca use yo u can't run th em with the valve cover off. Running the probe of a mech anic's stethoscope a long the length of the va lve cover w ith the engin e running sho uld a ll ow yo u to iso late the noi sy va lvetra in component (Fig. 1) . If yo u don't have a stethoscope, use a lo ng screwdri ver as a probe a nd listen by placing yo ur ear against the ha ndle. Other internal noises include mainand rod-bearing knocks, wr ist-pin

FINDING ENGINE KNOCK

.: . ,",

...........-,- ....... : .... , .,.:; .. ,- .. . ., .,.-.-.-.-',.;,;-.. ... ; .... : ......

~ -:-:-:-:;

.. .

Fig. 2. With low, rapidly pulsating vacuum, this engine probably has valve guides that are worn out.

noi se and piston sla p. A main -bearing knock has a deep metallic so und and is usually loudest w hen the engine is under load. If the knock is beca use of a failed bearing, low oil pressure ma y accompany the so und. Conn ectingrod noises have a li ghter rapp ing so und under light engine loa d . D isconnecting the spark plug to th e offending cy linder usua ll y resu lts in a marked decrease in the noise. Pi sto n slap, caused by excessive piston-tocylinder wall clearance, causes a du ll rattle. Disco nnecting th e spark p lug ma kes it go away. Wr ist-pin no ise usuall y gets lo uder w hen the spa rk p lu g is di sconnected. Keep in mind that there are many external engine noises that can mimic internal noises, such as a loose flywheel or broken flexplate. Drivebelt p ull eys can also cause noise, which can be iso lated by running the engin e briefl y wi th the drivebelts removed .

Vacuum Testing A good manifold vacuum ga uge costs o nly a bout $35, yet it can quick ly tell yo u a lot about what is going on in an engine. A vac uum ga uge ca n revea l

how we ll the va lves are work ing, w heth er the piston r ings are sea ling adequately or whether camshaft tim ing is retarded. To perform a manifold vacuum test, begin by connecting the vacuum ga uge to an adequate so urce of intake-manifold vac uum. On most engines it's eas iest to tee the ga uge hose into a vacuum hose such as the hose th at runs from the intake manifold to the vac uum bra ke booster. W ith the ga uge connected, start the engine a nd let it warm up to operating tempera ture. O n most properl y running engines, the ga uge w ill hold stead y between 15 a nd 20 in . If the needle fluctu ates at idl e, it indicates that one or more va lves are lea king. Doing a compress ion test or an engine leak-down test will revea l the lea king valve or va lves. A slightl y low vacu um -ga uge reading, along with a slight flutter of th e ga uge, ma y indi ca te that th e va lve guides are worn (Fig. 2) . On engin es w ithout overhead camshafts, yo u ca n verify guide and seal condi tions by removing the va lve cover(s) and squirting engine oil o n th e tops of th e

129

va lve g uides while th e engin e is running. If th e vacuum-gauge rea din g inc reases a nd blue smoke sta rts to appear from the tailpipe, it's a good indi cation that the valve guides are worn. If th e vac uum reading fluctuates between 5 a nd 7 in ., it indicates that va lve timing is excessively la te. A sk ipped tooth or excess ive ly worn timin g cha in or belt a re a ll lik ely ca uses. To check for weak or bro ken va lve sp rin gs, increase engine speed to 2000 rpm. If the gauge needl e fluctu ates between 12 and 24 in. and the fluctu atio ns increase as engine speed increases, th e va lve sp rin gs a re weak. If th e flu ctuation is irregul ar, it's likely that o ne va lve sprin g is weak or brok en. If intake vacuum appears normal in the above tests and the engine o il is in good cond ition, yo u can do a quick test to determin e piston-ring sea ling. To do thi s, bring th e engin e speed up to 2000 rpm , then let th e throttl e snap closed. If the vac uum rea din g jumps 5 in. o r more over the normal readin g, it indicates that the piston rings are in good condition.

Compression Testing A co m pression test can reveal a lo t a bo ut a n engine's intern a l conditi o n, but o nl y if it's perform ed properl y. Many peop le mistakenl y do compression tests with old diluted oil, the engine cold or with the thro ttle closed. Begin by warming th e engine to no rm a l operating tempera ture. Th en, use compressed a ir to bl ow a ll th e sp a rk plug we ll s cl ea n before removing th e spark plugs. Disab le th e igniti o n, th en connect th e compression gauge to the No.1 cylind er, according to th e instructions suppli ed with th e gauge. Ha ve an assistant ho ld the thro ttl e wide open whil e c rank in g th e engin e over until five co mpl ete compress io n stro kes ha ve been co mpl eted (as indicated by pu lses o n the ga uge). Record th e compression readings on the first and fifth strokes . Repea t th e process for eac h cy lind er.

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A cy linde r has good compression if it ac hi eves two-t hirds of its total compress io n o n the first stroke a nd reaches th e minimum fa ctor y co mpress ion sp ec ifi ca tion by th e fifth stroke. If the com pression reading is low on th e first stroke and builds with following strokes but doesn't reach minimum co mpress io n, th e piston rin gs a re pro ba bl y no t sea ling well . If th e ga uge rea din g rem a in s low o n a ll five stro kes, it usua ll y indica tes a lea king va lve . Low compress ion in two Fig. 3. A leakage tester can pinpoint which cylinder is bad and where the leakage is.

adj ace nt cy lind ers indi cates a blown hea d gas ket. If a ll engin e cy lind ers achieve prope r compression, th en yo u're d one. If any of th e cy lind ers ha d low compression, however, you' ll have to confirm th e cause by doing a "wet compress ion test. " Squirting oi l into co mbusti o n cha mbers with low rea din gs temporaril y improves seal in g of th e piston rin gs. I f compress io n goes up 10 % or more w hen yo u repea t the compression test, th en the rin gs are bad. If compression stays th e sa me, then the compression leakage is most likely from the va lves . Keep in mind that a wet test won 't wo rk o n horizo nta ll y opposed Vo lk swage n, Porsc he a nd Subaru engin es .

Leakage Testing

Fig. 4. To look for combustion leakage into the cooling system, hold a bag over the radiator filler. The emissions probe should show no CO 2 when the engine is running.

Lo ng favored by profess iona l racing mechanics as th e most accurate method for testing an engine's co mbustion-chamber sea lin g, a cy linder lea ka ge tester works by pressurizing th e co mbu sti o n chamber with co mpressed a ir a nd th en meas urin g total leakage as a percentage. A leakage tester, which costs about $75, will not onl y tell yo u the conditi o n of the rings a nd va lves, it ca n tell yo u if the lea k is comin g from a n intake or exhaust va lve (Fig. 3) . To do a leakage test, warm th e

•

• •••

0

'

.. . .. .. . .... . - ' " . . . ... .. . . ... . -

.-

ENGINE

eng ine and remove the spark plugs . Remove the a ir cleaner a nd block the thro ttle wide open. Rotate t he engine so th e No .1 cylinder is at the exact top dead center (TOC) o n the compressio n stroke. Insta ll the fitti ng from th e lea kage tester in the No .1 spark plu g ho le, then co nn ect a n a ir-co mpressor line to the tester. Pressurize th e cylinder and note the percentage of leakage o n th e ga uge . An engine in grea t sha pe wi ll have cy lind ers with 5% to 10 % lea ka ge . An eng in e with 20% lea kage is still in prett y good condition. If the eng in e has a cylinder w ith mo re th an 30% leakage, however, yo u sho uld iso la te th e cause. Yo u can do that by li stenin g for esca pin g air while th e combustio n

FINDING

ENGINE

KNOCK

c hamber is pressurized. If th e sou nd co m es from th e intake m a ni fo ld , th e pro bl e m is a lea kin g inta ke va lve . Fro m th e ex ha ust ma nifo ld , it's a lea kin g ex hau st va lve. 1£ yo u hea r a ir

escap in g from th e oil/fill e r ca p openin g, th e prob lem is w ith pi sto n sea lin g. You can eve n loo k fo r bubbl es in th e engin e coo lant a t the ra di ator cap to check for a bl own hea d gasket. And, li ke th e compressio n test, hi g h lea kage rea din gs betwee n cy lin ders eq ua ls a hea d gasket leak. [t's a Iso possi ble to find hea d gasket leaks at th e loca l emissions in spec tion station. Warm th e eng in e a nd ask th e mec ha ni c to place t he emi ss io n tester 's exha ust probe in a plastic bag . By p lac in g the plastic bag over th e radiator opening while th e engin e is running, the probe w ill be a bl e to pick up any exha ust gases th a t are lea kin g from th e co mbu sti o n chamber into th e coo lin g system (Fig. 4) .

9

131

EASY

Plugging Leaks Fixing Obvious Leaks If a lea k is obvio us, such as a leak-

T

he sweat pours down yo ur brow as yo u lift the hood while gasoline gurgles into your tank in the se lf-serve la ne. Through the shimmer of heat th at escapes from underhood yo u lea n over to check the level of bright gree n coo lant in the translucent overflow tank. Empty, aga in . You've topped it up a few timesbut the last few tankfuls it's been dry inside. In fact, coolant seems to be disappearing at an acce lera ting rate. The weather is gettin g hotter, and yo u're abo ut to take a vacation. It's time for some action. It sho uld be easy to prevent most major coolant lea ks since they usua lly occur when a hose fails. And yo u should be a bl e to spot the bad hose before it bursts by those telltale signs of hea t crack ing and other deterioratio n, right? Wrong. Whi le coolant hoses near th e end of th eir useful lives used to show the classic warning signs, they no longer necessarily do . Today's hoses are so much better yo u can't tell only by looking.

132

Fig. 1. Remove a stubborn hose by carefully slicing it. Don't nick the neck it fits over.

You sho uld also be a ble to eas il y spot a coo lant leak, even a sma ll one. After a ll , the antifreeze conta ins a gree n dye th at leaves a stain. We ll , the truth of the situation is that yo ur current model engine may have more than a dozen hose connections- and other jo ints sea led by gaskets and 0rings- a nd many of th em are buried. To top off the prob lem, there are ways that coo lant can escape from the system witho ut leaving so much as a trace. Even w hen yo u find the leak, it may take so me special steps to fix it. Res ult: Findin g, fixing and preventing future coolant leaks inv o lves a lo t more tha n it use d to. But if yo u take the t ime to do the job right, yo u' ll be able to avo id the repeated need to top up the system, and th e disaster that wo uld occur if yo u forget .

ing radiator, cracked hose or badly leak ing joint, that's great-a so lid starting point. If it's an O-ring type at a coolant pipe, clean the groove if necessary with ultrafine sandpaper or steel wool. Wipe clean, and then replace the O-ring, lubricating it with antifreeze . Leaky radiator? Check with a radiator shop, and you may get away with an inexpensive repair. It might be possible to resolder a split seam or a leaking joint at the neckltank junction on an old copperbrass radiator without even removing the ra diator from the car. Even leaky plastic-tank radiators can sometimes be repa ired by replacing the O-ring between the end tank and the aluminum core. This is definitely a task to leave to a professional, however. It's a hose? If the clamp is not tight, and the leak is from the hose end, perha ps the hose has taken a compression set under the clamp. Try a simple retighten ing-but don't overdo it, or yo u'll distort the hose and neck, and just end up with a worse leak than you had. Tightening the clamp doesn't help? Replace the hose. Uh-oh, it's stuck. Grab it with pliers and twist? Not unless you want to crush the hose neck an d make it impossible to seal properl y. Better to cut it off instead. With a razor blade, slit the leak ing end of the hose at several points aro und the circumference, gently pry up each slice, then peel the rest of the hose end. Don't nick the neck on the radiator or engine, or it'll never seal again. Clean the neck- on the radiator, engine, heater core, connector pipe-with a wire brush and wipe clean. Then install the replacement hose, using fres h antifreeze as a hose lubricant. Radiator necks are generally pretty sturdy, but heater-hose pipes are usuall y very fragile. Twisting and prying

ENGINE

POSITION CLAMP NEXT TO BEAD _____ ..

~__""""'''''''''''''''''''''''''''''''''''''-'''''''-':-'~.::;?i'~;' .'(t't}'/!:~'~:~···~·':ii~~':::t~;·;':~r · 'M' .'

/ . I

~~J~~i,~~;'~~l4~~;~i~;@~,~~~~" RAISED BEAD

Fig. 2. OEM screw-tower clamps don't seal nearly as well as spring clamps. A regular worm-drive clamp provides a tight seal, too.

to remove a hose-or repl ace it latercan easily brea k the seal between the pipe and the hea ter core's tank. And removing a hea ter core to repa ir o r replace it ca n in volve removing half of the underside of the da shboard-an operati on th at ca n con sume a dozen hours or more. Use caution . Unless there's lots of slack in the hose, don't try to trim the cut end and reuse it. What's left pro bably w ill kink and ultimatel y restrict coolant fl ow. Use a new cla mp and p os iti on it correctl y for a leak-free connecti on, being extra ca reful if there is a ny damage or di stotion to the hose neck . The two best types of cl amps are the constant-tension spring band a nd the 360 0 adjusta bl e do uble- band. A decent-qu a lity, worm-drive ta ngentia l-force cl amp, w ith a slo tted band that wo n't di g deep in to th e hose rubber or cut it w hen you tighten, a lso does a good job. The screw-tower cl a mp, widely used as o rigina l eq uipm ent, is to lera bl e for a bra nd-new system , bu t is a bo ut th e least effecti ve fo r resea llI1g. Insta ll the hose as far as possible on the neck, and if there's a stop, right up to it. Position the clamp carefull y so that it's about mid way Fig. 4. Pump your system up to a couple of pounds higher than the rating on the radiator cap to check for leaks. You can rent the tool for an afternoon.

PLUGGING

LEAKS

Fig. 3. Don't give coolant a place to collect between the clamp and the sealing bead, or you'll give corrosion a place to start on copper-brass radiators.

berween the end of the hose and the end of the neck, typicall y a bout one-half inch or more fr om the end of the hose . If there's a raised sea ling bead on the neck, position the clamp flu sh aga in st the back side of it. If it's any dista nce away, it won't sea l as well and it will force a crevice berween the hose and neck. Coolant will collect and stagnate in the crevice, accelerating corrosion (a nd erosion) of the neck on copperbrass radiato rs, eventually resulting in a significant leak. If a hose neck is badl y di storted or eroded, get it reshaped or repa ired by a radiator shop if yo u expect it to sea l.

Finding Hidden Leaks Sure, yo u ha ve to loo k hard to inspec t a ll th e hose co nn ecti o ns, 0rin gs a nd gasket jo ints, but yo u ca n ge t so me help if yo u first press uri ze

th e system w ith a coo ling-syste m press ure tester. Pump up th e sys tem to its ra ted press ure plu s a co upl e of psi . If the ga uge rea ding ho lds fo r 2 minu tes o r so, th e coo ling sys tem isn 't leak in g- at th e mo ment. H owever, yo u may still be los ing coo la nt. Does the gauge's rea ding sta rt droppi ng a lmost immediately? T h at tell s yo u th e system isn 't ho lding press u re, a nd if yo u sta rt loo kin g yo u sho uld see lea kage from th e offendin g jo int o r poss ibl y th e wa ter p ump 's weep ho le. All wa ter pumps seep a min or a mo unt of coo lant (there's no such thing as a p erfect sea l), but if yo u see stea dy dri pping o r more, the p ump sea l is bad. Repl ace th e pump. O kay, th e press ure ga uge rea din g ha rdl y bud ged , a nd yo u' re still los ing coo lant. Now th e d iagn osis ge ts a bit to ugher, beca use th ere a re th ese p oss ibiliti es - Alth ough co ld engin e leaks are more co mm o n, it's a lso p oss ibl e th e leakage o nl y occ urs w ith a hot system . Run th e engin e to warm up th e system and r etest. -Th ere is mino r seep age fro m many joints and it a ll adds up . If yo ur engine's coo ling system has a lot of connecti o ns, inspect them a ll fo r even the sli ghtest trace of coo lant sta ining. Simple re tightening of all the hose clamps may do the jo b. -The leakage is fro m the

133

overflow reservoir, which o n man y cars is at atmospheric pressure a nd isolated from the pressurized part of the coo ling system. Hairline cracks in reservoirs often result in leaks that trave l a long body seams and are detectabl e o nl y if yo u are really looking for them. -The engi ne periodically run s so hot th a t coo la nt fills the atmospheric overflow reservo ir a nd overflows it. Or the press ure cap valve is wea k, so th a t coo la nt flows from the system into the reser voir even under normal operating temperatures. Check the coolant level in th e reservoir immediately after getting stuck in heavy traffic . If coola nt is rea d y to pour o ut of the rese rvo ir ve nt, pressure-test the cap to see if it's ho lding th e specified press ure. On systems where th e reservo ir is press uri zed, inspect the radiator-cap va lve sea l for deterioration. A bad sea l can a ll ow coolant to be lost by evaporation. Ifthecapisgood, nextcheckthe antifreeze concentration w ith a hydro meter. If the percenta ge of a ntifreeze is low (below 50 %) , the coolant w ill boil at a lower-tha n-normal temperature and contribute to the problem. If the problem is the coolant

134

Fig. 5. Check your hoses for electrochemical degradation by pinching and rolling the hose between your fingers and thumb. Feel for cracks in the inner liner.

running too hot, a poor coo ling system condition may be responsible. This wou ld include low coo la nt level, an electric fan coming o n too late (o r a mecha ni ca l clutch fa n slipping), a defective water pump, a plugged radiator o r even so mething as simpl e as a bug-a nd-road film coating on the front of the condenser or ra di ato r. Such a coating bl ocks the cooling a irfl ow.

Preventing Future Leaks Toda y's hoses fail more often from th e in side, beca use of a probl em called electroch emical degrada tion, th e catc hy ECD for short. T he metals of the coo ling system and the hose material, comb in ed w ith th e coo lant, form a n electrical cell that produces a low D C vo ltage, parti c ularl y a t high coolant temperatures. Over a period of tim e, th e electrica l fl ow is eno ugh to cause fine cracks to develop inside th e hose, starting at both hose ends and working a long th e length of th e hose. Eventua ll y, th e hose d evelops

a pinh o le lea k o r ma y eve n burst. You ca n't see t hi s da mage, but you ca n feel it. Wrap your thumb a nd two or three fin gers (not yo ur whole hand) aro und the hose at the end and feel with yo ur fing ertips for soft " channels. " Run yo ur fing ers around the hose to develop a menta l picture o f what the ins id e circumference of the hose must look lik e. Work yo ur way from each hose end toward the center of the hose, a nd if the hose feels more solid as yo u a pproach the center, it's probabl y suffering from ECD. According to studies by Gates Rubber Co., most upper radiator hoses, for example, are rea dy to lea k (if th ey haven't a lrea dy) a fter a bo ut four yea rs of service. So if any of yo ur cooling system hoses fa ils this fingertips test, drai n the system, cut the hose and peel it off. And insta ll new premiLU11 hoses designed to resist ECD. You can get silicone hoses, but newer designs of another synthetic, EPDM, are less prone to tearing and are designed to resist ECD. Secure them with good-quality clamps and yo ur engine should keep its cool. If yo u're topping up yo ur system after a leak, all you rea ll y need to do is add a 50150 mix ture of coo lant and water to th e radiator. But if yo u've been topping up with wa ter, yo u have no rea l id ea of th e relative co ncentratio n of the two fluid s. Perhaps yo u' ve been usin g water from some roads ide ditch or ra in pudd le-a better propo sition than walking or melting an eng ine for sure, but one that requires yo u to dra in th e cooling system complete ly a nd flush it. If yo u've flu shed th e system for wh a tever reason, don 't just start pouring 50150 coo lant into th e rad iator. There still wi ll be a lot of water in th e sys tem th at won 't dra in from the radiator (see page 101 ) a nd they'll leave yo u w ith a low concentration of g lyco l. In stea d, look up th e capac ity o f yo ur cooling system in th e owner's manua l or th e shop manu a l. Add ha lf that a mo unt of undiluted coo la nt, a nd top it a ll off with pure wa ter. Yo u did collect the drain ed coolant for proper recycling or di sposal, didn't you? ~

ENGINE

Turning Up Your Heater t's co lder t han a witch's belt buckl e outs ide, so you gulp down so me hot coffee, d as h to th e ca 1', start the engi ne and run in side. Alt ho ug h you know engine id li ng isn't a grea t way to warm up an engll1e, comfort co unts most on a co ld mo rn ing . O nce emba rked on yo ur mo rnin g commute, yo u turn the heater contro l up to H o t a nd flip th e blower sw itch. T he effect of th e hot coffee has worn off, but yo u're not getti ng eno ugh hea t from the fl oo r registers to ma ke up fo r it. In fact, t he w in dows start to fros t over. Your heater system is under-perfor min g. Yo u plan to tear into it as soon as yo u can get the car into a hea ted ga rage. First step : Co nfirm th e pro bl em by dri ving lo ng enoug h to war m up the

I

engine. Turn th e hea ter control to Hot, se lect th e fl oor mode and set the blowe r to medium/high speed. Make Sll re there's strong ai rfl ow fro m the fl oor reg isters. C heck th e temperature wi th a thermometer in se rted into the d ri ver's and passenger's registers. Altho ugh ma ny ve hi cles deli ver a toasty 135° to 155°, 115° to 120° is acceptab le. If th e a ir temperature is okay but a irfl ow is weak, th e prob lem is the blowe r or a das h board ductwork prob lem. Heater registe r tempera tures not even close to 115° to 120°? Check factory service bulletins to see if there's a know n problem (a t th e ve hicle ma ker's techni ca l serv ice Web site o r a t www.a lld atad iy.co m ). If no thing a ppli es, do a n und erh ood in spectio n . • The coo lant leve l in the reservoir

(a nd rad iator if it has th e pressure cap) shou ld be at specs. The coola nt sho uld loo k clea n a nd have been regul ar ly c hanged w ithin the spec ifi ed interva l. If it's been neg lected , all bets are off. • Ca bin hea t comes from hot coolant, so dr ive lo ng enough to wa rm up the engin e. Th e coolant tempera ture sho uld hit a t least 160" prefera bl y 180° to 220°. • The a ir condi tio ne r compressor sho uld be disengaged w ith th e cl imate control selector out of the defrost posi ti o n. If it's engaged, there's an a/c circuit problem. • If coolant tempera ture is acceptab le, feel both hea ter hoses, w hich sho uld be ho t. T hey a re? C heck the tem pera rure-co ntro l fla p-door o perati on in the under-d as h heater-ale case.

Dangle the thermostat in hot water while you monitor the temperature. The 'stat will drop off as the water rises above the 'stat's actual (rather than rated) actuation temp. Too cold, and your engine never properly warms up.

TURNING

UP YOUR

HEATER

135

If you have automatic temperature contro l, there ma y be built-in d iagnostics you can access for trouble codes cover ing th e temperature control door. (Refer to a service manual, factory tech serv ice Web site or www.a lldatadiy.com.) On many cars yo u can watch the temperature-door motor and shaft operation by removing an under-dash panel and/or lowering the glovebox. (Here again, yo u' ll have to check a man ual or Web site for in structions.) If yo u don't see and/or feel the motor or fl ap-door shaft operate as you change the temperature read ing, yo u've pinpointed the prob lem. In man y cases, the flapdoor shaft breaks and the assemb ly mu st be rep laced, but the motor is good a nd can be re used. On econocars w ith manual a/c, the temperat ure flap may be controlled by

a cab le £rom the dashboard lever or knob. Operate it qu ickly in each direction and li sten for a soft slam against a stop. If yo u feel binding, the cable is kinked or the flap is jammed. Total fre e play? The cable is loose or Remove or open any air bleed plugs on disconnected, or rhe flap is broken. the block or heads while refilling the engine to purge any air in the system. Nothing'S obv ious ly wrong? T here may be air pockets in the coo lin g system-these commonly develop over time. If there's a pressure cap on the ra diator or engi ne and a low coolant level in the radiator, but the level in the reservoir is norma l, a defecti ve gasket in the cap is admitting air. Replace the cap. Top up the system and p urge a ir, fo llowing the vehicle maker's specific procedure. As a generic approach, Simply blocking the radiator can make your car start with the engine cold, all warm up faster in extremely cold weather. bleed va lves open, and the side of the vehicle with the coo lant neck jacked up as high as possible. This raises the fill neck to the high point, so air bubbles o ut. Slowly add a 50/50 antifreeze/ water mixture to the fill neck. You'll see some coo lant (a nd perhaps air bub bles) oozing out of the bleeders. Close the bleeders, refit the pressure cap, and run the engine at about 2500 rpm until it's warmed up (or as warm as it wi ll get). Allow the

136

Check for good vacuum supply to the heater's control valve. If it's good, check the valve itself for proper operation.

engine to cool down, then repea t the top-up procedure. You may have to repeat this every few days over a week to get most of the air out. Coolant temperature too low? On vehicles with a clutch-type fan on the engine, make sure the clutch is not locked up . Sp in it by hand (with the engine off but warmed up ). If there's virtually no slippage, the clutch is defective. If it sp in s two to three times, it's probab ly okay. Co uld someone have removed the thermostat, probably trying to remedy an overheating situation? That's a very bad idea, not to mention the fact that it is illegal to tamper with emissions controls. No fan opera ti on problem and coo lan t temperature is very low? If you've neglected yo ur system, the thermostat might be stuck open from debris. If it's really bu ried, pour in a cooling system cleaner and run the car per the instructions . T hen, do a triple drain-and-refill of the rad iator and engine block, and go thro ugh the airbleeding top-up process. If coola nt temperature rema ins low, bite the bullet and remove the thermosta t for a test. If the access to the 'stat isn't bad, hold off on the drain-and-refill, an d

ENGINE

Flush the heater core with running water if it seems blocked. Drain coolant into a bucket for disposal first-it's toxic.

pull the 'stat for a look and a test. Clean if necessary, but before putting it back refit the 'stat housing, then run a cleaner through the system. Then do the triple drain-and-refill , and test the thermostat before you decid e to reinstall. Testing: Wedge a 0.002-in. feeler between the cl osed 'stat valve and its seat, then submerge the 'stat in a pot of water on a stove. Rest a radiator thermometer in the water, heat the water to boi ling, and note the temperature at w hich the thermostat cracks open-it wi ll drop off the feeler a t its rated temperature . Some engines, particu larly transverse four-cyl inders, radiate so much hea t so fast that there's no interna l fix for extremely cold weather. It may not be an elegant solution, but put a piece of cardboard against the front of the radiator, blocking a bout half of the surface area. Trim it back if the engine starts running hot. Remember to remove the cardboard in the spri ng. Coolant temperature read ing is normal, but one or both hoses are not hot? Refer to a service manual or Web

TURNING

UP

YOUR

HEATER

site to identi fy the heater inl et versus outlet hose. Neither hose is warm ? Many cars have a heater coolant shutoff va lve sp liced into the heater inlet va lve for better ale performance in summer. If the shu toff va lve fails to open full y, the flow to the hea ter w ill be restricted . Vacu um operated? D isco nnect the hose. If yo u feel vacuum (with some va lves yo u' ll also see the linkage move), the va lve is being held open by a defecti ve vacuum control. Leave the hose disconnected (plug th e end with a golf tee) and see if tha t cures the problem. If it doesn't, the shutoff va lve is stuck. Replace it. If the valve is cable controlled, yo u shou ld see the valve shaft move continuously as the das hboard temperature lever is operated. If it doesn't or if it moves just slightly, the cable needs adju stment. Note: The VW Go lf and Jetta have a cab le-type va lve, but it opens proportionally to the flow of hot coolant as neededthere are no flaps in the dash. On some other Euro pea n cars and

o n the Lincoln LS, the va lve works sim il ar ly to the VW's, but it's electronica ll y contro ll ed. Quick test: Unp lu gg ing the electr ica ll y contro ll ed type sho uld force the sys tem to fu ll hea t. If the hea ter inlet hose is noticea bly warmer than the ou tl et, the hea ter core is restricted from debris in old coo lant or from excess ive use of sea ler. First, try to reverse-flush th e heater core. Do this by either disconnecting both hea ter hoses from the heater necks on the cowl and attaching spare hoses, or by disconnecting both heater hoses at the engine. (Cla mp off the heater hoses if you're us ing spare hoses; p lu g th e engine hose necks if yo u're disconnecting there. ) Force a garden hose into the heater outlet hose, a im the inlet hose away from the vehicle, and open the bibcock. If the debris fl ows out and yo u eventually see a hea lthy flow of coo lant, yo u may have caught a break. Otherwise, yo u've got to rep lace the heater core. If hea ter performance during hi ghway operation is a ll right but it really drops off in low-speed d riving, there's a cooling system fl ow problem. Some systems have a hose restrictor in the inlet hose, and if it gets plugged w ith debris, that lowers the fl ow. You sho uld find thi s by fee li ng a long the inlet hose with the engine idling. (Yo u' ll reach a section where the temperature significan tl y drops.) A few engines (on the Dodge Durango, Lincoln LS and a number of German cars) have a uxiliary water pumps to improve coo lant fl ow at low speed/idle. If th e pum p fai ls, hea ter o utput drops during th at opera ti on. Of course, if th e coo ling syste m was long neglected, it's possible the engine water pump ha s eroded internally, reducing coo lant fl ow. In most cases, poor hea ter operation can be cured by fo ll owing the factory top-up procedure w ith the a ir bleeds open. Do th is severa l ti mes over the course of a week. Is there a fas ter fix? A pro with a coolant changer that purges a ir as it fills the system can give yo u faster heat. tI

137

138

CHAPTER THREE

Drivetrain Curing a Harsh-Shifting Automatic / 140 Replacing Your Automatic Transmission Filter / 144 Replacing Your Front-drive Car's Clutch / 147 Changing Your Transmission Fluid / 152 Replacing U-Joints / 155

139

MODERATE

Curing a HarshShifting Automatic (Fig_ 1) Adjusting the throttle-valve (T-V) cable is generally straightforward. Some cables (typically GM's) use a pushbutton-style adjuster at the upper end of the cable. Others have a more conventional adjuster, requiring two open-end wrenches at the transmission end.

T-V CABLE

here's coffee all over your shi rt, the dog refuses to ride in the car and your teenagers have threatened you with a class-action wh iplash lawsuit. The fact is, when yo u were a ' teenager, yo u wou ld have paid plenty for a car that got rubber in Secondbut w hen it happens leaving every traffic light, it stops being cool. An automatic that clunks into gear and suffers from irritating vibrations

140

in the process is not something yo u have to live with. Nor is it a problem you have to drop a few weeks' pay to correct. Most of the ca uses are things you can fi x or prevent, and although you'll need a good service manual for adjustment procedures, specs and parts locations, yo u won't need a co llection of special tools or instruments. There are two basic types of automatics: the fully hydraulic and elec-

tronic hydra ulic. In a fully hydraulic automatic, found primarily on older vehicles, all the shifting is controlled by piston-type va lves that slide in a va lve body and direct the pressurized fluid to the appropriate bands and clutches. The road-speed signal comes fro m a centrifugal hydra ulic device called a governor and the engine load (acceleration) signal comes from a cable or linkage between the trans-

DRIVETRAIN

VACUUM SUPPLY HOSE

VACUUM MODULATOR

(Fig. 2) The vacuum line at the modulator should exhibit healthy suction when disconnected and the engine is at idle. Look for ATF inside the modulator.

mission and the throttl e body. Shift quality a nd engine loa d also ma y be signaled by a vac uum modul a tor, a di ap hragm unit conn ected by a hose to engine vacuum, and by a link to a piston-type va lve in the va lve bod y. The electronic hydraulic may have a hydraulic valve body with electronically controlled solenoids that provide signals for directing fluid flow. Or it m ay have a set of solenoids that directly control fluid flow. The road-speed signal comes from a vehicle-speed sensor and the load signal from the throttle body's throttle-position sensor.

Garage Shifts If th e Park or Ne utra l to Drive shiftca ll ed th e "garage shifr"-is rou gh , but other shifts are normal a nd the idle speed is hi gh, th en high idl e is very likely to be the reaso n. There are many possible causes of high idle speed on cars with computer-controlled idle, including vacuum lea ks, a maladjusted throttle-position sensor and

CURING

lea kin g O-rings around fu el inj ectors. Idl e speed normal? If yo u'd been pulling a trai ler, partic ul a rl y in hot weather, th e automatic transmi ssio n fluid may be ox idized. This is a commo n ca use of harsh shifts, partic ularl y w ith the garage shift. You won't always get a bad smell from oxidi zed fluid , but if you've done the kind of hi ghloa d opera tion that cou ld overheat it, a fluid and fi lter cha nge mi ght help .

All Shifts If all the shifts are harsh, the mileage is hig h, the fluid has never been cha nged a nd the serv ice has been severe (s uch as hot-wea ther tra il er towing), it's possible th a t a ll th e co ntro l hydrau lics are sludged or sticky. You cou ld drop the oil pan for an inspection and if that's w hat yo u find, a straightforward fix is to bolt in a replacement valve body. That's still just a moderate investment. H owevel; before yo u go thi s far, check o ut all the other p ossibilities that can be easil y fixe d. Fo r ex ampl e, wh en the hars h shifting is ill every gear, the hydra uli cpressure feed, or line pressure, is likely to be too high. Also, on some tra nsmi ss ions the design is such th a t harsh-

A HARSH·SHIFTING AUTOMATIC

ness cou ld resu lt fro m press ure that is too low, so do n't forget a fluid-l eve l check with the dipstick. Note: Some late model a utoma tics may suffer poor shift quality if they were drained and fi lled with other than a specified fluid. A fluid designed for Ford Type F applications will ca use problems in a Ford transmission for which Type H is specified, fo r exa mple (see page 132). Before yo u go further o n a car or truck with a n electronically controlled automatic, watch the speedometer. If the readings bounce around a Jot, p erhaps from zero to 2 or 3 mph when the car is stopped a nd idling, the ve hicl espeed sensor apparently is mi sbehav ing and a bad roa d-speed signal m ay be what's upsettin g th e shift quality. No te: The sensor cou ld be misbehaving without the speedometer effect. The best check is with a sca n tool. On ve hi cles w ith fully hydrauli c tra nsmi ss ions, the hydra ulic governo rs that supp ly the road -speed signa l may cause la te or mu shy shifts, but are not li kely to ca use harshness .

Road Load Signals The transmission 's hydraulic press ure is modula ted by a throttle va lve,

141

.:::

\

: ~':'. . .--i·~?':

\.

.~.'

PISTON SPRING

which responds to how hard you're acce lerating. The valve is in the transmi ss ion's va lve body, the assembly of hydrau li c valves tbat routes the pressuri zed oi l to make the shifts in most transm iss ion s. And with an a utomatic transmi ss ion that is controlled hydra ulically instead of electronically, the va lve is connected to external linkage and a cable that goes to the engine's throttl e body to provide that throttl e-pos ition signal. H owever, almost all 1980s and up to mid-1990s cars and trucks use a cable from the transmission to the throttl e-body linkage, and that cable has an adj uster at one end. On most Genera l Motors and Ford products, it's at or close to the throttle body. On late-model Chrysler products with the 3-speed (basica ll y hydraulic) transaxle and many imports, including Honda and Toyota, the adjuster is at the transmi ss ion end (Fig. 1) . The adjuster has some provision for varying the length of the cable assembly, and it has a spring that takes up backlas h. T he details of adjustment vary (which is why you need a service manual), but the principle-including inspection-is similar among most makes. In spect the spring to see if it's broken or weak (so it doesn't compensate for free play in the cable). Replace a bad spr ing. Check the cable-retaining

142

brackets to ensure they're not loose or bent, and that they hold the cable housing properly. Look for a bent link at either end of the cable. Next, operate th e throttle linkage and watch the cable, which shou ld function smoothly and progressively at both ends. If it doesn't, make the adjustment. On General Motors vehicles, a typical procedure wo uld be to press the re lease button on the adjuster and pull th e cab le slider through th e ad juster with the throttle linkage held closed, leaving just a hair of free pl ay so there's no binding. On a Honda Accord, the usual method begins with running the engine at idle, pulling on the cable housing toward the throttle body to remove all play and checking for some free pla y between the bracket and the locknut on the throttl e- body side (abo ut .040 in. , which yo u can meas ure with a feeler ga uge ) (Fig. 2). If there's not enough or too much free play, hold the locknut on the transmission side (the lower locknut) and turn the locknut on the throttle-body side (the upper one). Things vary somewhat for electronically controlled transmissions . Because the throttle-position sensor provides th e upshift/downshift signals, it's the primary item to check. If the throttle-position signal to that throttle-va lve assembly is wrong, the shift

(Fig. 3) Check for sludge or heavy varnish inside the accumulator, which could also indicate sludge in the valve body. Check the spring as well.

quality goes down. To see if the sensor is operating within factory specs, perform a scan tool test. Or probe the signal terminal of the sensor with a highimpedance (minimum 10 megohms) digital voltmeter, following the service manu al procedure. Both fully hydraulic and electronica lly controlled transmissions may use a vacuum modulator. And the modulator is a major factor in shift quality in either case. The modulator takes the engine vacuum signal and uses it to control the shift characteristics, so if vacuum is low (because the engine is out of tune or because there's a vacuum lea k), the transmission wi ll behave as if the car is being accelerated and "stiffens" the shifts. With the engine idling, disconnect the vacuum hose and feel the hose end for a strong vacuum (at least 13 in. if you want to check with a gauge). Also test for a leaking diaphragm by inserting a cotton swab into the neck. If there is any transmission oil on the swab, the diaphragm is leaking. Replace the diaphragm unit. High altitude and low vacuum can affect shift quality, so if you've moved up to the mountains, ask the local

DRIVETRAIN

(Fig. 4) Some transmissions use an external damper bobweight at the end of the tailcone to control vibration. If it's missing or loose, you could have poor shift quality.

dealer if there's a specia l modulator with an altitude compensator.

Only One Shift Does the harsh shifting occur only in one gear change, such as First to Second or Third to Fourth, for examp le? Th e accumulator is so mething to susp ect on full y hydraulic and partly electronic automatics. Most hydraulic clutch/band circuits have an accumulator, which is a spring- loaded piston assembly in a chamber, to prevent shift shock. If the chamber is filled with sludge or the piston spring is broken, it cou ld be responsible (Fig . 3) . If the accumulator is externa l, yo u can remove the cover and look inside. Of course, a sludge-filled or varnished accumulator chamber could indicate a varnished va lve body und er the oil pan. So one harsh shift now cou ld become a ll harsh shifts soon. H owever, just cl ea ning out the one external-access accumu lator now could be smooth-shift news for a long time. If the accumulators are on the valve body, the job is more difficult because you'll have to remove the oil pan. But

CURING

at least you get a look at the valve body too. Refer to a service manual to see what's involved in an inspection.

Shudder and/or Vibration The a utomatic transmission 10ckllP clutch, used on every mod ern automa tic to help the carmakers meet fue l-economy standards, is responsible for a ll sorts of shudders, particula rl y if it engages at th e w rong time. A simple way to determine if it's the reaso n for poor shift qu a lity is to unplug the wiring co nnecto r on the transmission. Do thi s only for a brief test, as man y transmi ss ions will overheat fluid if the y don 't get clutch engagement. And be sure to unplug the right connector, as many automatics have more th an one, particularl y if they have electronic contro ls. If th e transmission beco mes si lk y smooth w ith the clutch circuit disa bl ed , check w ith the dea ler to find out if there's a factory fi x . On newer cars there may be a reprogrammed comp uter or a new computer module to raise the shift speed. Or there ma y be a recalibrated press ure sw itch (to accomplish th e sa me thin g) in a hydra ulic pa ssage for th e transmission-speed governor. Another cause of shudder or a vibration is a loose, broken or missing vibra tion damper that may be

A HARSH·SHIFTING AUTOMATIC

attached to your tran smi ss ion (Fig. 4) . No t a lot of cars ha ve a damper, and the damper alone doesn't directly affect shift quality. But if it's not intac t and tightly mounted, th e overa ll response of the tra nsmi ss io n is affected, and that may worsen the feel of the shifts. \1(1hatever yo u do, don 't tr y to cure shift problems by pouring so me additive, particularly a limited-slip differential oil, into the transmi ssion. Limited-slip o il conta in s a large dose of special friction modifi ers th at cures hars h shifts and shudder. But it a lso causes so much slippage that the clutches and bands w ill burn out fast. What about harsh downshifts on acceleration? Well, th e typical downshift, made at full throttle or close to it, genera ll y is harsh. If it's the only ha rsh shift and it sudden ly becomes much hars hel; check the fluid level. If the fluid leve l is normal, and yo u have a fully hydraulic automatic, open th e manual and look for a downshift cab le adjustment. It often is simi lar to the throttleva lve cable adjustment, but made at wide-open throttle. Check the manua l. The odds are ve ry good th at yo u' ll fi nd the reason fo r yo ur car's harsh shifts somewhere among the basic items we 've covered here. Then, you can send those nasty little shifts back to charm school. tj

143

EASY

Replacing Your Automatic Transmission Filter

(Fig. 2) Use a scraper to remove th e remains of the old gasket, being careful not to scratch the aluminum transmission casting.

Ou've just spent the hottest 4 hours of your life creeping through a colossal traffic ja m. You pull into the driveway and collapse into yo ur favorite comfy chair in yo ur a ir-co nditioned den. Later, in the cool of th e eve ning-before yo u begin p ac kin g the family car for a getaway-you check the car's vital fluid s. The o il and coolant are okay, but th e autom atic transmission dipstick is still too hot to touch- the fluid on it is as black as squid ink and smells like the ' bottom of a barbecue grill after a picnic. Time to change th e transmission o il a nd fi lter. The o il in your auto matic tra nsmiss io n ca n get very hot- often approac hin g 300°F-when you're pulling a heavy load or moving slowly in hot wea ther. But it also can get eve ry bit as torrid when th e w heels

Y

144

(Fig. 1) Jack up the car and get a goodsize drain pan. Loosen and remove the bolts on the transmission pan from rear to front, then drain the oil.

are sp inning and slipping on icy roads in winter, so this is a year-ro und iss ue. And th e oil becomes contaminated with particles that have worn off the transmission's clutch es and band s, even meta l shavings from th e pump a nd other moving parts. Don't wait until the oil sa mp le on the a utomatic transm iss io n dipstick has a burn ed odor to change both the o il and the filter. Unlike engin e o il , the a utomatic transmi ss io n oi l not on ly ha s to lubricate, it a lso has to prov id e hydra ulic pressure to operate the clutch es and bands that produce the gear-ratio changes. Factory recommendati ons for trans-

mission o il and fi lter changes range widely. GM, for exa mple, says 100,000 mil es, but that's under idea l conditions. And th e recommendation comes down to as low as every 15,000 m iles give n one or more of the fo llowing: yo u drive in a lot of traffic and high temperatures, period ica ll y pu ll a tra il er or other heavy load , let the car sit id li ng for long p eriods or subject it to other operation similar to ta x i, police or deli ver y services. Mom 's tax i serv ice surely fa ll s in the latter category, so a tran sm iss ion oil and filter change every two yea rs or every 30,000 mil es is good prac tice.

Getting Greasy Jack up the front of the cal; support it on safety stands, put a large catch pan underneath the transmission and loosen the transmission-pan bolts (Fig. 1). Remove the bolts at the rear, then loosen th e oth ers, so th e o il dra in s o ut one side into yo ur catch pan. On th e typical car, several quarts will come out, which is less than ha lf of the oil inside- and there's no practica l wa y to get out any more oil. Consider that

DRIVET R A I N

the next time you want to p ostpone a tra nsmission service. Fin a ll y, remove all the bo lts and lower the pan . (And no, most transmi ss ions don't have a dra in p lug.) Scra pe th e gasket from the pan, taking care not to go uge the fl a nge surface (Fig. 2) . Wire-bru sh a ny gas ket res idue from the pan. If a ny pi ece of gasket sti cks to the und erside of the transmi ssio n, gentl y remove it w ith a scraper-n ot a screwd rive r, as the surface norm a ll y is soft a luminum and p rone to being go uged. A go uged surface may not sea l, even with a new gasket. If th e gas ket is rubber with a ra ised center secti o n, it's re usa bl e if it is still in perfect co nditi on. Just clean and dry the gasket surfaces on the pan and tra nsmi ss ion. If it's damaged ,

REPLACING

YOUR

AUTOMATIC

replace it with o ne of th e same type. Clean the p an thoroughly, as there w ill proba bl y be a fair amount of silt in the corners, fro m sludge, worn fricti on-clutch materia l and tin y bits of metal. Big fl akes o f meta l might indica te a prob lem, but expect a certa in am ount of shin y stuff. If the o il -pan bo lt holes are distorted by p rev io us overtightening, place th e edge o f th e p an on a heavy metal surface (yo ur wo rkbench, for exa mpl e) a nd with a ba ll-peen hammer, tap them down fl at to ensure a good sea l.

This Is a filter? It proba bl y looks more like a fine-mesh w indow scree n, but thi s is w hat passes fo r a filter. It's adequate to

TRANSMISSION

FILTER

screen out chunks, but very sma ll a bras ive p articles pass right thro ugh, another co mpelling reason to service th e tra nny regularly. Remove the old filter, w hich typica ll y is held by screws. Pull it dow n slow ly, as it may have a neck with a n O -ring, and yo u sho uld remember w here th at ring is (Fig. 3) . Som e 0rin gs sit o n the neck , but are pro ne to stickin g in side the case when yo u remove th e filter. If you don't remove th e o ld O -ring a nd add a new o ne w ith the new filter, it won 't seat p ro perl y. Mos t Genera l Motors ca rs ha ve a n O -rin g, but there's a c up sea l th a t goes in the case on some m odels since 1994 . The filter neck is inse rted in to it, and there's no O-ring at all. Co nsid er retrofitting this new filt er

145

Glug, Glug DIMPLED BOLT HOLES

..-: •

••

I.

(Fig. 4) Overtightened bolts can distort the pan's sealing surface. Flatten the dimples with a hammer against a hard surface.

and cup sea l to the earli er-type u'ann y. A pp ly a thin film of no n hard ening gasket sea ler to the oil pan, lay th e new gas ket o n it and in sta ll a bo lt th ro ugh eac h co rn er to ho ld th e gasket in p lace , H and-sta rt eac h bo lt. Do n't ti ghten any bo lts mo re th an two o r three threa ds until they're a ll in p lace

146

(Fig. 4) . Then run them d own with a

ra tchet until the gasket is in contact a ll the way aro und. Tighten the bo lts to fa ctory spec ificati o ns with a to rq ue w rench , usin g a spira l pa ttern sta rti ng fro m th e ce nter of th e pa n a nd work ing a lte rn ately to the ends. Go in steps, a few foo t- po un ds at a time, up to the torque spec .

Fin a ll y, a dd fres h o il. No t a ll cars use th e sa me type . Most la te mo dels take D exr on lIE o r D exro n III , a ltho ugh Ford reco mmend s an o il th at meets its M ercon stand ard (including some older cars for w hich a "Type H " fluid was prescribed ). Chec k yo ur owner 's manu a l. Ma jor brands of o il are fo rmul ated to meet a ll th ese carma ke r r equirements, a nd yo u should use o ne of them. A few Europ ea n cars a nd o ld er Ford s (so me through 1981) ma y requi re a Type F fluid , w hich is no thing like the Dexron and M ercon fo rmul as. If Type F (or the virtu a ll y id enti ca l Euro -spec Typ e G) is li sted in th e ow ner 's ma nu a l, that 's w hat yo u sho uld pour in. Ne w N issa n pro ducts ma y call for Typ e J or Typ e K fluid , which is no t a Dex tro n typ e. Oil is gen er a ll y add ed to th e tr a ns throu gh th e dip sti ck tube a nd yo u ' ll n eed a lon g skinn y funn el o r a funnel a nd a hose to ge t it in . So me GM a utom a ti cs have n o dipst ick a nd re mova l of a fill p lug is necessa ry. W hatever type o f oil yo u need , fo llow th e carmaker 's precise recommendations for checking fluid level. Typi ca ll y, yo u have to cycle th e shi ft leve r fr om P to L a nd back a few times a nd add the o il w ith the engin e running. Do it slowl y, recheck re pea tedl y, as less than a pint can be th e differe nce . O verfilling ca uses as man y p erform ance p rob lems as a low fluid leve l, so if there's any transm iss ion o il left in the qu art bo ttl e, don 't p o ur it in . Pur th e cap bac k on a nd save it. If so meday dow n th e road yo u fi nd t he dips tick rea ds low, w hat's left in th e bottl e sho uld be JUSt th e right a mo unt to to p it off. tI

DRIVETRAIN

DIFFICULT

Replacing Your Front-drive Car's Clutch he probl em was almost imperceptible at first : Going up a slight hill at high way speeds, yo u noti ced th at the engin e was revving higher even th ough yo ur car wasn't go ing any faster. Backing off the gas or dropping into a lower gear made the problem go awa y each time. But that was a month ago . Now yo u spend yo ur days looking for routes that have no hill s, beca use eve n a sli ght inclin e causes the engin e to re v w ildl y w hil e th e car slows d own. There's also the smell of burnt buttered popcorn in the air as yo u downshift in a feeble attempt (the sem i driver on your bumper is bl ast ing his a ir horn ) to reduce the eng in e loa d and ge t the car go ing aga in . Your biggest fear is th at yo u' ll end up bac king do wn the hill. The prob lem isn't in the engin e or transaxle. All that slipping is caused by a worn-out or misadjusted clu tch. Compared to other automotive dev ices, the clutch (Fig. 1) is dec idedl y low-tech (see H ow It Works, fo ll owing page). And w hil e rep lac in g a nd adjusting the clutch doesn't require exceptiona l sk ill or high-tech equipment, there are some things yo u should look out for.

T

THROWOUT BEARING

MECHANICAL CLUTCH

CABLE-OPERATED CLUTCH

Please Release Me It co ul dn 't be simp ler: Push th e clutch ped a l in a nd the clutch sho uld disengage. H owever, if th e clutch doesn't fully disengage, yo u'll hear a lot of grinding during shifts or when yo u tr y to put the car in gear. "A lot of people immediately think there's a prob lem w ith th e clutch disc or pressure p late w hen the clutch doesn't disengage," says Ga be Vajda, a technician w ith LuK, a maker of clutch pans. "Any p lay in the clutch-pedal parts soaks up travel, so the clutch won't fully release," Vajda cautions. He says that before yo u remove the transaxle

REPLACING

YOUR

FRONT·DRIVE

HYDRAULIC CLUTCH

(Fig. 1) Regardless of method, depressing the clutch pedal will push the throwout bearing against the pressure plate. There should be some adjustment mechanism as well.

CAR ' S

CLUTCH

147

a nd clutch, it's w ise to check th e peda l-arm bu shings a nd the ac tu a tin g ca bl e, o r, o n ca rs w ith hydra ulic system s, t he slave a nd mas ter cylinders. Also , a no nreleas ing clutch could even be caused by so mething as simpl e as carpeting under the peda l tha t's too thick , whi ch has been the case with some 1988-9 0 C hevy Beretta a nd Co rsica mode ls. T rimmin g a way in sula ti o n under the carpet will restore full peda l trave l. If a clutch isn 't releas ing, start by manua ll y prying the relea se a rm at the bellhou sin g w ith a screwdri ver. If th e a rm mo ves fr ee ly a nd the clutch re leases th ere, cha nces are good tha t th e p ro bl em li es o utside th e bell -

TRANSMISSION OUTER STUB AXLE

(Fig.2) Remove the outer stub axle from the hub, and then pull the entire axle free of the transaxle. You may need to plug the inner socket.

HOW IT WORKS

Clutch Play At the heart of the clutch assembly is the clutch disc. It has friction material, similar to brake-lining material, on each side and a splined hub that slides back and forth on the transaxle's splined input shaft. When the clutch pedal is not depressed, the clutch disc is tightly clamped between the flywheel and the pressure plate to firmly connect the engine to the transaxle. Depressing the clutch pedal allows the clutch disc to spin freely between the flywheel and pressure plate, allowing the engine, flywheel and pressure plate to spin on their own, while the splined input shaft and transaxle freewheel with the disc. The clamping force that engages the clutch comes from a large spring, or series of springs, located inside the pressure plate called a diaphragm. Depressing the clutch pedal presses on the diaphragm spring, causing the pressure plate to move away from the clutch disc, and the clamping force diminishes until the engine can spin independently of the transaxle. To get the clutch moving, the clutch pedal is connected to a sheathed cable or a hydraulic master cylinder and slave cylinder. The cable system works much like a heavy-duty version of the brake-caliper cable that can be found on a 10-speed bicycle-depressing the pedal pulls on the cable to release the clutch. With the hydraulic system , pressing on the clutch pedal moves a piston in the master cylinder, which displaces fluid, causing the piston in the slave cylinder to move. This, in turn, operates the clutch. Some older cars and trucks use a simple mechanical bellcrank linkage instead of a cable or slave cylinder, but the mechanical principle is the same: Depress the clutch pedal and the clutch is released. How? Whether the clutch-pedal system is operated hydrauli-

148

RIVET

CLUTCH DISC

FLY-

PRESSURE PLATE

WHEEL BELLHOUSING

cally or by cable, it moves a release fork that pivots on the bell housing. The pivoting action moves the end of the fork toward the pressure plate. A throwout bearing (also called a clutch-release bearing) at the end of the release fork applies even pressure to the diaphragm spring and the pressure plate moves back, releasing the clutch disc. Let the clutch out, and the pressure on the spring releases and the clamping force on the disc returns.

DRIVETRAIN

ho usin g. O n ca bl e-op era ted clutches, t here co uld be too much p lay in t he cab le, w hi ch ca n redu ce trave l. To reduce cab le p lay, fi nd the adju sting nut at th e top or bottom of th e cab le a nd adj ust the ca ble to th e prop er sp ecifica ti ons. O n hydra uli ca ll y o pera ted clu tc hes, air in the lines, or a wo rn maste r or slave cy li nder, ca n res ult in reduced travel. To bl eed th e a ir, to p off the master cy linder reservo ir w ith brake fluid. Pl ace a pi ece of h ose o n the slave cylinder's hyd ra ulic vent, th en place the other end of the hose into a p artially fill ed glass bo ttle. O pen the vent, then have a n ass ista nt re peatedl y depress the clutch peda l slow ly until a ny bu bbl es co min g fro m th e end of the vent lin e di sappear. After tightening th e ve nt, clutc h trave l sho uld return to nor mal. If it does n't, then the slave and master cylind ers sho uld be replaced.

Removal and Inspection Ba rrin g adju stm ent, th e o nl y way to fi x a sli p pin g clu tc h is to rep lace it. In sta llin g a new clutch is very st ra ightfo rwa rd . But yo u have to ma ke sure the w ork is do ne ri ght, since fix ing any mistakes usua ll y m ea ns remov ing the tra nsax le- so mething yo u do n't wa nt to do Ill ore th a n o nce . It's best to co nsul t a serv ice ma nu a l for inst ru ctio ns spec ific to yo ur ve hicl e. T he follow ing is a gen era l procedure fo r replac in g a clutch. Start by disconnecting th e ba ttery positive ca ble. Then, while wor king unde r th e hood , prep are th e tra nsaxle fo r re mova l by di sco nn ecting the clutch ca bl e or hydra ulic slave cy lin de r. Also, remove or di sco nn ect items th a t p revent t he transax le fro m be ing re m oved , such as backup-lig ht w ires, air-clea ner ducting, exh a ust pipes, the starter m o tor, sp eed om eter ca bl e a nd other items. If yo u are in do ubt as to exactl y w ha t needs to be re moved, co nsult a ma nu a l. Next, chock th e rea r w hee ls a nd jack up t he fro nt en d of th e car a nd support it w ith stands. Wor kin g fro m und er th e car, remove a ny additi o na l parts th a t yo u couldn't reach fr o m under th e hood, including the bo lts

REPLACING YOUR

FRONT-DRIVE

SUPPORT BAR

(Fig.3) A support bar or a stout piece of timber will be necessary to support t he engine while the tranny is out.

tha t ho ld th e ax le shafts to th e transaxle o n Ill OSt ve hicles (Fig. 2) . To rem ove the tran saxle, yo u no rm ally have to re move o ne or more engin e lll o untS. But before yo u ca n start remov ing t hem, yo u' ll have to support th e engin e. W ith m a n y cars, it's poss ibl e to sup po rt the engin e from undern ea th by pl ac in g a jack

(Fig.4) The clutch is readily accessible-but only after removing the transaxle from the engine. You 'll need to remove or unhook the axles as well.

CAR ' S

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CLU T CH

. •

un de r t he o il pa n (w ith a third p iece o f wood o n t he Iift pa d to p revent da mage to t he pa n). But o n oth er cars, a specia l engin e-s upport rod th at all ows the engine to ha ng w hil e the tran saxle is o ut mu st be installed under the hood. (Fig. 3) Again, consul t a m a nu a l for th e prop er method. To d isco nnect the t ra nsaxle fro m the engin e, suppo rt t he t ra nsaxle w it h a jack a nd remove the bo lts fro lll aro und the fl yw heel bell ho using. Nex t, slide the tra nsaxle away fro m the engine until the transaxle input shaft cl ears the press ure pl ate, then lower the transaxle to the gro und and roll it fro m un der th e car a nd o ut of the way. O nce yo u have reilloved th e tra ns-

PRESSURE PLATE

'. THROWOUT BEARING

149

axle, yo u will then be able to access the pressure plate and clutch disc (Fig. 4) . Remove the bolts from aro und the pressure plate, then remove the p late an d clutch disc. Inspect the friction surface of the fl yw heel. If it is scored, checked or shows signs of hot spots, it mu st be removed, mac hin ed at a mac hine shop and then reinstalled . Keep in mind that it's good practice to have the flywheel machined so the clutch disc has a proper surface to break in on. If yo u don 't have the fl ywhee l machined, sa nd it lightl y wi th medium-grit sa ndpaper wrapped aro und a small block of wood, then wipe clean w ith a damp cloth. When inspecting the fl yw heel, also in spect the pilot bearing or bushing at

150

the center of the fl yw hee l. T he needle bearings (if applicable) should be lubricated and show no signs of galling. If there's any doubt abo ut the quality of the bearing, remove it w ith the appropr iate too l and insta ll a new one. You should also inspect the back side of the fl yw heel for signs of oil leakage at th e engine's rear main seal. If oil reaches th e surface of the clutch, chattering and grab bing will result. Some cars have "stepped " flyw hee ls, which is when the clutch disc rides on one surface and the pressure plate bo lts to a surface that's stepped a bove the clutch surface. It's important that both surfaces be machined the same amount, or slipping or fa ilure to release could res ult.

(Fig.S) You'll need an old tranny input shaft, this special arbor, or a wooden dowel to center clutch disc on flywheel as the pressure plate is installed and torqued down.

If the fl ywheel is m achined too much, it moves the clutch and pressure plate away fro m the release bearing. This ca n keep the clutch fro m full y re leas ing. You might be tempted to use shims between the crankshaft and fl yw heel to move the clutch assembl y toward the release bearing. However, it's possible for a thin fl ywhee l to burst at high rpm. Th e on ly safe a lternative is to replace the worn fl yw heel with a new one. Inspect the transaxle's input shaft

DRIVETRAIN

sea l to be sure it isn't leaking. (There's no need to inspect the clutch di sc, pressure plate or release bearing, since you'll be replacing those.) If the sea l is leaking, replace it. Next, look for leakage at the engine's rear main seal. If there's more than a hint of seepage there, this ma y well be the reason for the early demise of the clutch disc. Mark the fl yw hee l so yo u can reinsta ll it back on the crankshaft in the correct index. Remove the fl yw hee l a nd remove the old seal. Carefully install the new seal without gasket sea ler by tapping it in with a seal installation tool, or at least a large socket or a piece of wood. Check the crankshaft's sea ling surface for a depression where the seal has eroded th e metal (this is particula rl y common in dusty areas). There may be a repair sleeve available for your engine, so check with yo ur machine shop if yo u think yo u have a problem.

Installation Before you install a new or fresh ly machin ed flywh ee l, make sure th e crankshaft flan ge is clea n. After placin g the fl ywheel on the flange, tighten the bolts in a star pattern to the proper torqu e specification. There are two tricks to installin g the clutch di sc and pressure plate. First,

REPLACING

YOUR

FRONT-DRIVE

the disc is des igned to go on in one direction. If yo u look at the center hub, yo u' ll notice a series of damper springs. On one side of the cl utch, this damper hub sticks out from the friction surface. That side always goes toward the trans axle. Put it in the other way, and yo u' ll soon be taking the transax le out to do it all over aga in . Second, yo u' ll need a " clutch pilot tool" to in stall the clutch disc so it a ligns with th e pilot bushing in th e crankshaft (Fig. 5) . To install the disc, slide it onto the pilot tool, then secure ly stick the center of the tool into th e pilot bea ring . Install the pressure plate over the clutch disc, torque all bolts to specifications using a star pattern, then remove the pil ot tool. Before installing the transaxle, insta ll the new release bearing onto the release fork, then make sure that the fork operates free ly. Jack the transax le into position and slide it fo rward so th at the input shaft slid es into the splined hole in the clutch disc. Yo u may have to turn either the input shaft or th e engine's crankshaft (a nd the fl ywheel and clutch along with it) to get the sp lines to align. Don't fo rce th e input shaft into its splined hole. When everything's proper ly a ligned , th e shaft w ill slide right

CAR ' S CLUTCH

in. If it doesn't sli de right in , don't force it. Back it out and tr y aga in . Never let the tran saxle hang unsupported from the engine, since this ca n lead to damage to the pilot bearing, input shaft and front input shaft bearing. After in stalling a nd torquing all the bellhousing bolts to spec, yo u can reinstall a ny motor mo unts th at yo u had removed, the drive axles, as well as any other co mpo nents und er th e car. Once th e underside work is done, remove the jack holding the transa x le and lower the car to the grou nd. Rein stall any ul1derhood components. You don 't rea lly ha ve to replace th e clutch cab le at this time, but beca use it costs less than $75, replacing it is good in sura nce agai nst trouble later on. In any case, ad just the cable to the proper amount of free-play. Most hydra ulic clutch actuators are self-adjusting and, therefore, have no fr ee-pla y. Sti ll, yo u' ll want to make sure th e se lf-adjusting action is working properly. To do th at, simply pu sh the slave cylinder piston back into its bore. If it moves, the system is working properl y. If it doesn't move, it mea ns the slave cylinder's press urereli ef orifice is clogged and the slave cylinder should be rep laced. ~

151

"

___-O-D-E-R-A-T-E

Changing Your Transmission Fluid

It's messy, but you should remove the transmission pan and replace the filter at every fluid change.

Take A Look-See

Y

drive th e sam e ro ute to work ever y da y-s a m e op en stretc he s, sa m e inte rsecti o n s, sa m e stop- a nd-go. But to d ay th e re's a s ubtl e di sco rd in th e us ua l ha rm o n y, a blip o n yo ur ve hi c ul a r ra d a r, a ba d vib e in yo ur m ec ha nica l ka rm a . Shi fts see m oddl y la te nd so ft. La ter, as you pull into th e dri ve , you sense somethin g p ec uliar. Letti ng yo ur ca r id Ie, yo u pull th e OU

U 152

dipstick o ut o f yo ur auto transmission. Fresh autom a tic tra nsmission fluid (ATF) is bri ght r ed a nd h as a di stinct pe trol e um sm ell. Yo ur dipsti c k sh o ws a lo w leve l, is th e co lo r of in stituti o n a l lin o le um a nd sm ell s lik e th e bo ttom of a ba rb ecu e pit after a bik e r we ddin g. Yo ur tra nsmi ssion fluid is badl y in ne ed o f changing, a nd th e tr a nn y m ay a lread y be damage d.

An o ve ra ll inspection is the logica l fir st step. A low fluid level ma y indica te a lea k somewhere in the system, possibl y a t a coo ler line that run s to the bo tto m of th e radi a tor. Find it a nd fix it, th en top up the level. Remember t hat, unlik e th e engin e cra nkcase, it o nly ta kes a bo ut a pint to make th e difference betwee n the" Add " and " Full " marks. Also, m a ke sure yo u use the correct ATF, which we ' ll discuss la ter. If yo u' re luck y, the lag or shifting pro blem may just disappear after yo u add ATE The fluid sho uld be bright red , clea r a nd "sweet " smelling. If it's a smoky dar k co lo r, or has a burned od or, a complete change is needed, but th e dam age may already have been do ne.

--------------------------------------------------------------~

DRIVETRAIN

o FULL HOT I

DIPSTICK

Lockup? All modern a uto matics (except for the continu o usly varia ble t ra nsm issio nsC YTs- fo und on a few la te-model Asian cars) ha ve locking torgue conve rters to e liminate slip at cruising speeds, thus saving fu el. These are contro ll ed by th e powenrain contro l modul e (the engin e and t ra nsmi ss io n manage ment computer) o n th e basis of speed, temperature, throttle position, etc. If th e engine is running a t a higher rpm on the highwa y th a n usual-300 to 500 more-to ma intain th e same speed, it's possibl e that locku p isn't occurring. Besides reducing fu e l econom y, this can have the much mo re disastrous effect of ca using the tra nsmi ss ion to ove rhea t. C heck that the transmission converter clutch wire that runs from the ha rness to the tra nsmission is co nnected and intact.

Fresh Fluid

Check the dipstick in Neutral while the engine is warm and idling.

troubl e is, it doesn 't go far eno ugh. At least ha lf of the o ld , burned-up ATF a nd its co nta min a nts rema in in th e torg ue conve rter (th e days of those convenient conve rter drain plugs are long go ne ), clutch drum s, va lve body a nd elsewh ere. If yo u wa nt to get th e fu II benefit from th is ma intena nce se rvice, yo u've go t to work a littl e ha rder. R egardless of how far yo u're willing to go here, yo u still must take th e t ra nsm ission pan off, and there are a co upl e of ways of ma kin g thi s jo b a

Pour ATF back into the dipstick tube with a funnel.

The single most important thing yo u can do to head off big-bucks transmissi o n repairs is to change the ATF o n a regu lar basis. Some ca rm a ke rs have bac ked down fro m the unrea li stic 100,000-mile trans fluid change interva l recommended in the pa st. Every 30,000 miles is much more reasonable. If yo u tow heavy loa ds in hot wea th er, yo u mig ht even think abo ut annual changes. Going through the messy operatio n of dropping the transmi ssion pan and replac ing the filter is fin e as far as it goes. Th e

CHANGING YOUR TRANSMISSION

FLUID

Remove trans cooler line at the radiator to flush out the last of the ATF.

littl e nea ter. Sta rt by puttin g th e ca r o n sturd y jacksta nd s or, bette r yet, ra mps. Block th e rear w heels. If yo u ha ve a grave l driveway, toss a 4 x 8 sheet of plywood down first to preve nt th e sta nd s from tunn elin g into the grou nd w hil e you' re und er the ve hicl e. If yo u ju st remove the pan (leave a few bolts a long one side partway in ), AT F will fl ow out in a wave a ll aro und th e sea m , probab ly spl as hing outside the rad iu s of yo ur catc h pan. 1£ you've go t a suita bl e pump, yo u ca n run the pickup hose down into th e dipstick tube until it bottoms out, th en pump until yo u stop getting fluid. Thi s will vas tl y red uce spill age . To extract as muc h of the old ATF as poss ibl e, leave th e pan on, remove a trans coo ler line a t the radiator, put a drain pan und er it, th en start the eng in e for a few seconds to

153

find out which way the fluid is flowing. lr does n 't maner whether yo u use the inlet or ou ri et line except that you have to an ac h a small hose eith er to the line co nnector or th e radiator o utlet in order to collect th e ATE Put the hose into the largest jug yo u can find, and let the engine idle until air starts spurting. Many professionals en hance this procedure by pouring a few quarts of fresh fluid in to the dipstick tube at rough ly the same rate that the o ld fluid is coming out, thus adding flushing action. Now yo u can remove the pan. This is not only necessary for changin g the filter, but also a ll ows deposits and sediment to be washed o ut of the pan. There's ano ther importa nt cons id era tion: This operation prov ides the opportun ity to find out if fa ilure is impending. Judging this is somewhat subjective, so we asked an ASE Master Automotive Technician his opll1lOn. "You sho uld see next to no swarf or debris, and then only on the first change," he says. "Subsequent cha nges sho uld be nearly dead clean. If a newer gearbox is making junk, it's in trouble. You might find just a trace of a luminum shavings, or other very minor debris, but the assemb ly process is so clean, and the newer gearboxes so unforg ivin g of dirt, that any real accu mulation genera ll y means a problem is in development." Now's the time to replace the filter and its sea l, w hich probably can be purchased in the same k it as the transmission pan gasket. When reinstalling the pan, start every pan bolt by ha nd for at least two threads before tightening any of them. If the last person to install yo ur p an got overly enthusiastic with the wrench, yo u ma y find the pan ra il has dimples aro und the bolts. Use a hammer and dolly to flatten them out. Otherwise, the pan gasket will leak. A cork gasket often ca n benefi t from a thin layer of

154

Clean the inside of the pan of sludge and swarf before reinstalling it.

gasket sea ler or adhesive, especia lly to keep it in place while yo u're tr ying to start those first few bolts. Don't use a thick bead of si licone sea lant, as it w ill sq ui sh out between the mating surfaces into littl e silico ne wor ms, which will eve ntu ally break off and clog the pump intake.

auto service facili ty and have a trans flush and refill done. Many shops tOda y have a machine for this purpose, but you've got to be sure of wha t yo u're getting. Some quick-lube places w ill just attac h the machine to a coo ler line, excha nge the fluid , and ca ll it done. We beg to differ. The pan shou ld be removed for cleaning.

Delegate Of course, you can go to your favori te

You can try cleaning the filter, but it's usually better to replace it.

The Right Stuff Most of the autOmatic transmissions on the road will work just fine on Dexron III/Mercon ATF, except for '92 a nd earlier domestic Fords, w hich need Type E But the Dexron is essentially a generic fluid, and some experts sa y they've cured shifting problems simply by replacing it with the exact O.E.-specified stuff. They have a lso confided in us that they've in advertently ca used trouble by using bulk ATF that was labeled, "Will also work in ... " So, especia lly with imports, yo u might want to read yo ur owner's manual carefully where fluid specifications are li sted. You want real peace of mind? Then think abo ut spending the extra money for synthetic ATF. The master technician mentioned earlier a lways uses straight $5 -per-quart synthetic for his own ve hicles. (I

DRIVETRAIN

ODERATE

Replacing U-Joints hat vibration you've ma naged to ignore for weeks has fin a ll y gotten to th e point at which it's hard to keep fro m spilling yo ur mOrtling coffee o n yo ur pant leg. You resolve to ma ke two stops o n the way hom e from work this afternoon- one at the dry cl ea ners to pick up cl ea n pants, and a seco nd at th e m echanic's to investigate th e vibration. As yo u acce lera te away from th e dry clea ners, there 's a big cha nge in th e vibra tion. It's fo llowed immedia tely by a lac k of power a nd big clanging no ises, the la tter du e to your dri veshaft fa lling to the pavement. You 've had a universa l-j oint failure.

T

SNAP RINGS

Lack Of Lube Most of th e time, loss of lubrication is the rea son U- jo ints fail. Origin a lequipment joints typica ll y h ave no grease fittin gs, a nd even replacem ent units often have zerks that you can't reach with your grease gun. The tin y needle bearings in side the c ups over the ends of th e trunnions ru st a nd eventu a ll y crumbl e, w hich res ults in cl eara nce where th ere sho uld be no ne a t all. Another des troyer of U-joints is an excessive angle of operati on. This ma y be du e to a n overloading co ndi tion, which ma kes the tail end sag, or a set of helper sprin gs o r a ir shocks th a t puts th e rea r of th e car up into th e stratosphere. In either case, leveling the ve hicle is the o nl y way to increase the uni ve rsa l jo ints' life span. The drives haft itself is a simpleenough compon ent. Unless it's bent from contact w ith , say, a railroa d t rack or is ou t of balance due to the loss of a weight, it' ll keep spinnin g just about fo rever.

Rules Of Thumb Vibration cau sed by a U-joint or driveshaft usua ll y occ urs at 25 to 35

REPLACING U - JOINTS

mph, about 60 mph , or while brak ing a t low speeds. Th a t" body boom " that hurts your ears probably is ca used by a bent or unbalanced driveshaft. A clunk when the t ra nsm issio n is put into gear, or when " floa ting" a t a bout 10 mp h, is eith er the result of damaged U-joints or a differential prob lem. To find out if a vibration is coming from the dri ve line o r the engin e, attac h a tach o meter if yo u don 't have o ne o n the das h, run up to th e speed a t wh ich the rou g hness is felt, a nd note th e rpm. Then, shift into a lowe r gea r, go back up to the sa me rpm a nd see if th e vibratio n has diminished. No ? Then yo u've found engine trouble. If, on the o ther ha nd, the vibes cha nge considerabl y a t th e original engine speed, th e U-jo ints or driveshaft are proba bl y a t fault. Next, raise th e ve hicl e a nd support it under the rea r ax le o r susp ensio n control arms so th a t the springs a re compressed w ith a norma l amo unt of weight and the drivesha ft is at the proper a ngle. Gra b the shaft near

A bench vise and a pair of sockets make it simple to remove a worn-out U-joint. Use a small socket to press the cup into a socket bigger than the cup's outside diameter.

either end a nd force it up a nd down, then twist it hard back a nd fort h. Any p lay yo u ca n see or fee l is reason fo r rep lace ment.

Brutal R&R Odds are, yo u' ll need to ra ise th e ve hi cle off th e g round (unl ess yo u' re dri vin g a giant-wheeled 4x4 ). Ra mps are great fo r thi s, but a fl oor jack a nd a pa ir of jac ksta nds w ill do the job fine . To repl ace a U-joint, unscrew th e nuts of th e U-bolts th a t cl a mp the universa l's cups to the rea r ax le's yoke . Mark the parts so th a t yo u can put th em back the way t hey were. Us ing a big sc rewd ri vel', pry the sha ft fo rwa rd until [he jo int is free of th e yo ke, t hen lowe r it a nd pull it o ut of the transmi ss io n ta iIshaft hous ing. Wh il e a hydrauli c press is idea l for driving the cups o ut of th e yoke ears, yo u mi ght be ab le to ma nage w ith a

155

Remove the nuts on the U-bolts at the rear axle to disassemble the driveshaft.

If yo u believe the driveshaft is out of balance, first make sure that the problem isn't due to a defunct U-joinr, a n excess ively worn sli p yoke or transmi ss ion tailshaft ho using, w hee l imbalance, or excessive runout of the shaft itself (generally, this shou ldn 't be more than a bout 0.040 in . as measured with a dia l indica tor). Next, give the shaft a thorough visu al insp ection. Ma ke sure it's clean- i n high gear, it rotates at the sa me speed as the engine, so a lump of undercoa ting wou ld be eno ugh to give a car th e shakes-then loo k for ev id ence of a thrown ba lance weight. Also, see if it's bent. H yo u still haven't found the trouble, disconn ect the shaft from the rear, rotate it 1 80°, bolt it back up, and road test . If the vibra tion is still present, yo u ca n resort to the old hose cla mp trick : 1. Raise a nd support the car as safe ly and solidl y as yo u can with th e rear wheels off the gro und .

REAR AXLE

/

hu sky bench vise. Or, you can drive will ta ke an extra pa ir of ha nd s. Wh en it comes to in sta llin g the th e cups o ut with a drift and a heavy new jo int, first make sure it was hammer. If th ese are the originals, packed with grease at th e factory. The th ey're probably retained by inj ected nylon, w hich will simply be destroyed cups should be filled to abo ut onein the process. Another option is to ha lf of th e needle length with the see if there are C-clips in groo ves in proper grease (usua lly SAE 140). While forcing the cups in to place, yo u the inn er or o uter sides of the ears. The inner type can be forced o ut easmu st be careful not to dislodge th e needle bearings or jam them at an il y with a screwdriver and ha mmer, a ngle. but you may need snap-ring pliers for the o uter variety. Whether yo u're using Shaft Shivers a vise or a drift and hamDry U-joints will have rust inside, not grease. Do not try to save one that's rusty. Replace it. mer, place a socket that's bigger th a n th e o utsid e di ameter of the cup against one ear to accept the cup . Then, with a vise, p ut a smaller socket on the oth er cup to push it through the hol e in th e ear. Now, turn th e vise screw as necessary to force the cups through the yoke. If yo u' re do in g th e pounding ro utin e, position th e la rge socket under one ear a nd use a big drift aga inst the opposite cup. This probably

156

2. Start it up, put it in gea r, a nd ha ve a helper step o n the gas a nd rev it up to 40 to 50 mph.

3. Tape a piece of cha lk or a crayon to a broomstick, hold it firml y with both hands and slide it under the car. Slowly move it so that it has the least possible contact with th e shaft just ahead of th e rear joint, then just behind the one at th e front . The heavy side wi ll be making a larger

DRIVETRAIN

A new U-joint should have a zerk fitting even if the original did not. Fill the joint with grease until it runs out of the seals.

circle than the light o ne, so th e mark sho uld appea r w here the excess we ight is.

4. Shut the engine down and insta ll two worm-gear hose cl a mps around the sh aft w ith their heads 180' from the m ar k you just made.

5. R ev it up to 65 to 70 mph a nd see if the vibra ti o n has di sappeared. If it has, g ive it a road test to be sure. If it has n 't, rotate th e cl amp hea ds a bout 45 ' away from eac h o th er and try

REPLACING

U·JOINTS

Hose clamps are an acceptable field fix for a missing balance weight. Move the heads apart to adjust the weight.

again . Getti ng better? Then keep mov in g the cla mp hea ds apart until yo u get it ri ght. As yo u probabl y kn ow, the bas ic functi on of a U-j o int is to a ll ow two shafts to opera te a t an a ngle to each other. But you may not rea lize that while the dri ving yo ke rotates at a constant speed, th e driven o ne speeds up a nd slows down twice during each revoluti o n. At a n angle of 4' , the variati o n in speed is a negligibl e 0.5 percent. At 10' , however, the change is 3 percent, a nd a t 30' w ith the yoke going 1000

rpm, its partner goes from 866 to 1155 rpm eac h qua rter of a revo luti on. You ca n imagine th e surging vibra tion such a n a rra ngement wo uld set up . Fortun a tely, thi s condition is e liminated by the use of two jo ints with the driving yokes rotated 90' from each other. As long as th e angl e of each jo int is abo ut the sa me, th e acce lera tion a nd dece lera ti o n of o ne is ca nceled o ut by th e deceleration a nd acce lera ti o n o f the o ther, a nd a smooth transmissio n of power is accomplish ed. ~

157

158

Fixing a Dead Horn / 160 Repairing Your Windshield Washers / 163 Curing Radio Noise / 166 Servicing Composite Headlamps / 169 Servicing Electronic Suspensions /172 Fixing Power Windows /176 Replacing Your Fuel Pump /179 Eliminating Battery Drain / 182 Replacing Headlights / 186 Replacing Your Car's Computer / 189 Curing AlC Odors / 192 Low-Tech Work on High-Tech Cars / 196 Scan Tool Diagnosis / 201 Wiring Your Trailer Hitch / 204 Fixing Faulty Cruise Control / 207 Changing A Fuse / 210

159

MODERATE

Fixing a Dead Horn

(Fig. 2) See the panel cover or manual to know which fuse protects the horn's circuits. If the S-strip is broken (fuse at right ), replace the fuse.

fl as h o f ye ll ow w hi ps th ro ugh periphera l fie ld of vision, as a taxicab screeches in to a downshift in fro nt o f yo u. T he drive r flips yo u a hand signa l roo ted in antiquity as he blithely makes a right turn fro m the t hird lane, forc ing yo u to slam on the bra kes. T here's o n ly one appropria te res po nse- yo u sla m yo ur pa lm aga in st t he ce nter of the steeri ng w heel to a udi bly sig na l yo ur di spl easure w ith the hack ie's dr ivi ng, persona l hygiene and rela tions hi p w it h his mother. But yo ur horn doesn't bl ow. A sound mo re aki n to the utterings of a dyspeptic goat ema na tes fro m yo ur grille for a few seconds-then silence. Your ho rn is broken. T he mo ment is gone. And yo ur mood sours even further.

A

YO ll[

This Has Got to Stop Ac tu a ll y, blow ing yo ur horn as a sign of sheer disp leas ure is to ta ll y inappro-

(Fig. 1) The horns are usually mounted behind the grille and in front of the radiator, although they may be to one side, higher or lower.

priate. T he cab dr iver w ill un do ub ted ly continue to dr ive dangerously desp ite any message you mig ht have deli ve red . Some muni cipa liti es prohibit blow ing a horn w ithin the city lim its unl ess t here's a traffic situ ation t hat genui nely requ ires it- if not, you may get a ticket. But horns do have m o re purpose th a n lettin g your teenage son signa l to his date that he's wa iting in the driveway. A br ief too tle ca n gain the attention of a pedestr ian a bo ut to step off a cur b w it hou t lookin g, a nd may be th e best way to get t he attention of t ha t soccer mo m dr iving a 7000-po und SUV w hi le ta lking o n her ce ll p ho ne and look ing in the rearview m irror at her w hini ng kids.

T he ho rn is required eq ui pment by law-yo u' ll need to get it fixed or yo u may not be ab le to pass inspection . A zea lous police officer may even find it ap propr iate to write yo u a cita ti o n if your horn isn 't funct ion ing prope rl y.

Less-Than-Adequate Honking In our scenario, th e horn blew for a few second s a t re duced vo lu me. T his mea ns t hat the circ ui try that fee ds t he horn w it h 12 vo lts is a li ve a nd we ll. Mos t ve hi c le ac tu a ll y have two horns, wired to so und at t he same tim e. T hey usua ll y w ill be of a d ifferent p itc h, so und ing a c hord instead of a single note. Som e lux ury cars use th ree ho rns for a m ore co mp lex, me lod ious soun d . T he horns generall y are mo un ted to t he rad ia tor core support or somew here be hi nd th e ve hicle's grill e (Fig. 1). A cursory root in g aro und in t he engin e C0 111 partmen t shou ld fi nd t hem . If one or more horns are inoperati ve, the sou nd w ill be slightl y reduced and less pleasant. If yo u sus-

---160

ELECTRICAL AND

---- - - - - - - '

ELECTRONIC

SYSTEMS

(Fig. 3) Using a simple voltmeter, backprobe the horn 's connector to see if 12 volts is present when the horn button is depressed and the key is on.

pect o ne of yo ur horns isn 't so und ing, ha ve a helper depress th e ho rn bu tto n briefl y (key on ) w hil e yo u to uc h the suspected horn w ith yo ur fin gers. (We recommend ea rp lugs, for o bvio us reaso ns.) Sou nd vibra ti o ns ? Re move the w iri ng conn ecto r, cl ea n up the spade lu gs an d then reinsta ll the conn ector. Still nothing ? If t he horn has on ly one wire runni ng to it, it relies o n its mo unting bo lt to comp lete the circu it to ground . Unbo lt the ho rn , clea n up a ny co rros io n a nd reinsta ll it. If t here's sti ll no so und , ma ke sure that a ba d horn is indeed t he pro blem by run n ing a ju mper wire directl y to the battery termina ls. If o ne ho rn is defunct, rep lace it. Genera ll y, t he ho rn w ill have a n imprint o r a sti cker identifying it as a Hig h o r Low to ne. To prese rve t he O EM horn cha rac ter, yo u'll need a n exact rep lace ment. This w ill ensure that th e ho rn 's frequency (pi tc h) w ill be th e sa me. If yo u' re not fussy, any uni versa l rep lacement wi ll work, a lth o ugh the

F IX ING A DEAD HORN

mo unting ma y no t be th e sa m e a nd yo u' ll have to adapt it.

Sound Off No t so m uc h as a squ ea k fr o m eith e r o r a ny of t he ho rn s ? Th e n the pro blem li es e lsew he re in t he w iring. Now 's th e tim e to chec k t he fuse, w hi c h probab ly is bur ied in the bo ttom of t he da shb oard, t he driver's kick pane l or und er th e hood-o r

a lmos t a n ywh e re o n t he front ha lf of the ve h icle if it's not in o ne o f those o bvio us p laces . C hec k th e owner's ma nu a l fo r th e loca ti o n o f th e fu se box a nd o f t he spec i fi c fu se (Fig. 2) . If it loo ks li ke th e meta l str ip inside t he fu se has fa il ed , rep lace it wi th o ne of t he same a mp erage ra ting . Once in a b lu e moo n, fu ses w ill see m to fa il fo r no apparent reaso n. If t he fuse is ba d , o d ds a re yo u' ve go t a prob lem th a t w ill m a ke it blow aga in, sooner or later.

The Fuse Passed Inspection

(Fig. 4) Check at the horn relay for 12 volts when the key is turned o n.

No w yo u' ll need a 12-vo lt test li g ht or a voltm eter. Yo u also sh o ul d fi nd a shop m a n ua l o r, a t the very least, a schematic di ag ra m of the ho rn c ircuit. Start by testing for 12 vo lts a t th e connecto r to the ho rn (Fig. 3). O ne side of the c ircuit is ca rr ied by the ca r's meta l fra me, so yo u' ll need to check betwee n a good ground p o int and t he wi ring connector fo r the horn. If there's no vo ltage at the connecto r, try ch ecking th e ho rn relay (Fig. 4) .

_J 161

T he horn relay switc hes a la rge current ro th e horns at a signa l from the low-current horn burron in the steerin g whee l (Fig. 5) . It's a sim ple, in expensive single-po le sin gle- throw (SPST) re lay, packaged in a small metal or pla stic box w it h five spadelu g connectors. If yo u're un lucky, yo ur ve hicl e uses a relay that's integra ted in ro a larger box of sparks th a t a lso contro ls severa l other functions on your car, such as the headlights or the turn signa ls. This part is considerab ly more expensive. Sorry. Consu lt the shop manu a l for the location of the relay, as it, lik e th e fuse box, may be hi dde n a lm ost a n yw here und erhood o r unde r t he das h-and no t necessar il y nea r the fuse box. A sim ple SPST re lay will have a constan t supply of 12 vo lts to it, a lead that runs thro ugh th e harness ro the horn, ano ther lead that runs to t he horn sw itch in t he w heel, and a grou nd . C heck that vo ltage is co ming into the re lay at two termin a ls a nd leav ing it at two oth er term in als w hen t he sw itch is pushed. [f it's no t, try ground ing the lea d that goes to the ho rn butron to make the re la y pu ll in. If th e horn sou nd s, the relay is good but the horn button or its w iring is bad. You may be ab le to simp ly replace rh e relay if it's the prob lem. Otherwise, yo u'll need to do so me serio us detecti ve work to c hase down the open circ uit.

Button, Button, Who's Got The Button? If yo u have a "pa nic " button o n your keyfob/remote, yo u can c heck to determi ne if the horn circu it wo rks. If it so unds the horn, but the horn doesn 't work w hen you press the button, th e prob lem is in th e horn button or its wiring to th e re lay. Every latemo de l car has an a irbag camped in th e middl e of th e steeri ng w hee l. Th is a irbag, if imprope rl y ha ndl ed, ca n ex pa nd w ith letha l force. Even the stati c fro m dragging yo ur c lothing across the sea t ca n set it off. And th e horn button (or buttons) is genera ll y attached to th e top of th e a irbag sh roud. T ha t mea ns yo u sho uld get a

162

BATTERY

HORN

HORN RELAY

SWITCHED CONTACTS

(Fig. 5) The horn relay steps up the low current from the horn button to the higher current needed by the horns.

tra in ed tec hni c ia n to remove th e a irbag for yo u and th en re in sta ll it after yo ur horn has been fi xed. He can test th e a irbag system to be sure it w ill go off when it's supposed to and not go off w hen it's not. The a irbag mu st be removed to access the slip rings o r c lock sprin g th a t ca rries vo ltage up th e rotatin g steerin g co lumn from the re lay to th e horn button (Fig. 6) . If yo u need to access this, we recommend yo u leave the job to a ser vice technic ia n who has tra ining a nd se rvi ce ma nu a ls deta iling the cor-

rect procedures. Inciden ta ll y, a horn that inter mittently blows on its ow n genera ll y is caused by a bad clock spr ing th at shorts out to ground rando ml y. O lder car " budget " a lternati ve: C li p th e ho rn button w ire nea r th e relay, sp li ce a n a ux ili ary wire to it (a nd wra p th e splice with e lectrical ta pe) . Run the a ux ili ary wire to a n a ftermarket universal horn butto n yo u ca n mount o n the das h or conso le. It's not eye-appea ling and yo u do have to " learn" the loca ti o n, but it costs just a few d o llars.

9

STEERING COLUMN

(Fig. 6) The clock spring allows the wheel to turn in circles while still making an electrical connection to the car's wiring system.

ELECTRICAL AND

ELECTRONIC

SYSTEMS

•

A_S_Y_ _

Repairing Your Windshield Washers (Fig. 1) Replacing a nonworking pump is simple once the reservoir is empty.

t's a lig ht dri zzle-barely enough to wet th e windshield. So yo u press th e was her button a nd turn on the w ipers. There's nothing- or ma ybe just a weak squirt-out of th e washer nozzles, and the wipers quickl y slow down and just streak the windshi eld to cover up whatever clear a reas th ere had been. Traffic becomes a blur, a nd yo u're fo rced to slow down, pick yo ur wa y through a sla lom of ca rs an d trucks to a side street, and just shake for a few moments until you have the presence of mind to get out and clea n the w ind ow by ha nd.

I

Where's the Liquid? You just fill ed th e rese rvoir last week and haven 't used the was he rs since. So th e reservo ir sho uld ha ve pl enty of fluid , right ? It was a washer antifreeze so luti on? Okay, is the reservoir still full? It's empty? There must be a lea k. Even if that soluti o n co nta in s a d ye, yo u still are likely to have a tough tim e findin g a cracked sea m in the rese rvoir, particul arly if th e rese rvo ir is under the battery or in a fender well , the late-mod el loca tion of choice for space-deprived powertra in compartment engin eers.

REPAIRING YOUR

WINDSHIELD

Fill the reservoir a nd run yo ur fingers a lo ng any sea m, and a lso aro und th e pump sea l, which ma y be a simpl e rubber grommet. [f yo u're los ing fluid at a noticea ble ra te, yo u sho uld be a ble to find a wet spot pretty fast. If it's a seam, empty the reservo ir, dry th e exterior and apply a bea d of w indshi eld sea ler o r epoxy. If it's th e pump gro mmet, pull th e pump o ut (just work it side-to-sid e or up-and-down with a n outward tugging motio n). Replacement grommets are not necessa rily easy to bu y, so if you ca n't get o ne, it's worth tryi ng to a ppl y beads of RTV silicon e sea ler aro und the pump o pening in th e reservoir and aro und the bar bs of the pump. All ow adequate time for the RTV silicone to "sk in " (pa rtl y cure) so it doesn 't extrude out of position wh en yo u re insta ll the grommet a nd pump. The reservoir is full? Next question: Is the pump workin g? Have a helper press th e washer button wh il e yo u li sten a t the pump. If yo u hea r it working, disconnect a hose th a t runs from the pump, a im it into a container a nd repeat the test. If there's a so lid stream, repeat the test at the hose connection to a spray nozzle. If a car has

WASHERS

two nozzles, it's unlik ely that both nozzles wo uld plug up simulta neous ly, but it is possib le tha t the hose from the reservo ir is kin ked, that a check va lve (installed in so me lines) has closed up or an inline filter is plugged. So if yo u get a so lid stream from th e pump, but nothing a t a hose connecti o n, wor k yo ur way back to th e pump. If a ll yo u can find is a check va lve o r a n inline filter, remove it and make a temporary splice with a plastic hose connector. You m ay find th e was her system operates well enough to ma ke that yo ur permanent repair. If the pump isn't work ing, either it has fail ed or there's a break in the circu it lea ding to it. Unplug the wiring connector and aga in have your helper press the washer button while yo u probe the terminals w ith a grounded 12-volt test light. It shou ld go on with the pro be in o ne of the two terminal s, a nd when yo u identify that one (th e current feed ), try to jump ac ross the two terminal s w ith the test light. Aga in it shou ld go on. If you can't get the light to go on in the first test, there's a break in the current-feed side of the circuit from the was her button, and yo u' ll have to trace it from there. If yo u can't get the test light to go o n when yo u jump across the two terminals of the connector, there's a bad ground. The co nnector passes both tests? Th e pump is the problem. On most late models, yo u ca n just pull it out (th e rubber gro mmet may com e out w ith it ). On ma ny o lde r ca rs, w here littl e more th a n the end o f the pump sticks o ut, look for a serrated retainer yo u can pry out wit h a thin-blade screwdri ve r. Then p ull th e pump itself with slip-jo int pliers on a n edge of the electrical terminal (Fig. 1).

163

(Fig. 2) Replacing a damaged hose or nozzle is simple: Squeeze the plastic tabs together with pliers and the nozzle should pop out of the hood.

deposits, then blow compressed a ir th ro ugh the nozz les, a nd that sho uld restore th e spray pattern.

Nozzle Aim If the spra y doesn 't go where yo u wa nt it to, it may be pos sible to m a ke an a dju s tm e nt. Typ ica ll y, if th e mountin g pa d is round, and t he nozz le hea d has t wo or three spray ho les, it ca n be adj usted sid e-to -side , up -or-down or both, by insertin g a thin pr o be tool in to a sp ray ho le (Fig. 4) . Some nozz les h ave a rec tang ul ar ho le between t wo sp ra y h o les, m ea nt sp ecifica ll y to accomm o d a te a pr o be for Ju st a weak squirt from th e nozhas a sin g le, centrally loca ted no za dju stm e nt (Fig. 5) . zles? If there's a so lid strea m fro m th e zle, it's prob ab ly a "fluidi c nozz le. " O n o lder ca rs, th e nozzle may be a simpl e piece of meta l tubing (with a hose connections, the nozzles appa rIt see ms to a ppl y a sup er-w id e-a ngle entl y are plu gged. Th e eas iest spray to th e wind shi eld , but ac tu a lly ca lib ra ted orifice in sid e), held by a it produces an osci lla tin g strea m retainin g sc rew. With a p a ir of needleapproach is to just replace them, if nose pliers, ma ke a very you can get new ones. Most FLUIDIC NOZZLE no zz les are held by retaintiny bend, a t a joint if there SPRAY PATTERN is one, near the base if there ing screws or built-in isn 't. squ eeze clips. Some nozz les You ca n't reshape plas tic, have JU St a si ngle-side clip a nd most no zzles are recta n(press toward the nozzle gula r and fit into a positio n a nd push th e no zzle out) . tha t defies change . If it's Others have clips on both held by a screw, yo u may be sid es of the nozz le (squeeze (Fig. 3) Fluidic nozzles cover a large area from a single point. a ble to slip a thin piece of together and pu sh our the plas tic o r aluminum under the fore or that is so fast it deceives yo ur eye nozzle). If th e opening is large aft end of the nozzle to lower or ra ise (Fig. 3) . There are no moving parts eno ugh, yo u may reach in w ith fingers the spray tip, so the spray hits the wi thin the fluidi c nozz le, but it does to squ eeze th e clip (s) . Otherwise, use windshield higher o r lower. However, co ntain a co mpl ex set of passages needl e-nose pli ers (Fig. 2) . if it's retained by pl astic clips, yo u can't th a t produces th e osci ll at io n th a t Ca n 't get new no zzles? On some do this, or the clips won't seat. If a swings th e spray from one sid e to o ld cars yo u co uld wo rk in a nee dl e nozzle sta rts to spra y off the usual patth e o ther. to cl ear out th e p assage, but today, tern, that's usually the result of frontSoak th e cl ogged no zz les in vinefew no zz les h ave passages stra ight end bod yw o rk that included hood gar, at leas t overnight, to di sso lve enough to do that. And if the car

-- \- - - - -

164

ELECTRICAL

AND

ELECTRONIC

SYSTEMS

adju stm ent, a nd it may take some read justm ent to correct.

HOW IT WORKS

Nozzles in Wiper Blades Wh en th e was her nozz les a re in th e w iper bl a des, a da m aged bose can a ll ow leakage th a t weake ns th e spray. Or th e hose may have beco me kin ked from care less clea ning of t he w ind shi eld. Th e nozz les a re neve r a dju stabl e, so if yo u ca n't clea n th em, you ' ll have to p op in repl ace ments.

Rear Systems Som e ve hicl es, particu larly wagons, mini va ns and spo rt utiliti es, are equipped w ith rea r wash ers, which o ft e n mea ns a seco nd pump and du a l-c ha mber reservo ir, p lu s a lo ng hose to th e rea r to chec k o ut. If th ere are dual secti o ns, most a re des igned so th e rea r dra in s into th e front when th e front is nea rl y empt y. So th e fact that yo u haven't used th e rear, a nd it now d oes n't work, co uld mea n a p ro bl em with t he fr o nt syste m , particularl y a lea k fr o m th e fr o nt cha mbe r or a front ci rcuit hose . There's a lso a second was her pump, so be sure to ch ec k th e right o ne. Wa she r system serv ice isn' t co mpl ex, but it may require work in g in ti g ht, dar k quarters. So use a bright droplight a nd spend the extra minutes to do it ri ght.

A Washer System When you operate the FRONT NOZZLES washer button, you complete a circuit to the system's electric pump, typically mounted in the bottom of the reservoir. The pump draws fluid from the reservoir and pushes it through a hose to one or two nozzles in front of the windshield, typically in the hood or the cowl area just to the rear of the hood. On vehicles with a rear window washer, there's a second pump with its own hose, and generally a single nozzle at the rear. Some rear washers have their own reservoirs as well.

NOZZLE

n

Th e single flui d ic nozz le see ms to apply a w id e-a ngle fa n spray across the wi ndsh ield , but ac tually it's an oscill a ting strea m. Fluidics is th e name of th e operatin g p rinciple. Th e interna l passages of th e nozzle a re shaped so th e in coming fluid goes through a main passage, so rt of " lea nin g " agai nst one wa ll (a defl ecto r in the main passage " bi ases" th e nozz le to start the fl ow to o ne side). As it fl ows, some of the fluid is di ve rted through an opening on tha t wa ll into a feed -

REPAIRING YOUR

WINDSHIELD

f " R EAR NOZZLE

~~

~ESERVOIR ~

'.

(Fig. 4) Some nozzles can be aimed with a straight pin inserted in the hole.

PIN 'i~

Inside a Fluidic Nozzle

~

NOZ~ ZL~ r_

WASHERS

~:P

SQUARE HOLE FOR AIMING TOOL

back passage that produces a second fluid flow against the incoming fl ow at its entr y po int. Th e press ure of the seco nd flow defl ects th e inco ming fl ow to th e opposite side wa ll of the ma in passage. Th ere's a lso a fee dbac k passage o n thi s si de, and aga in the second flui d fl ow defl ects the ma in flo w back to the oppos ite wa ll. This goes o n so fas t that it appears to be a spray. But beca use it's a n osc ill a tin g stream , th e fl ow from o ne centra ll y located nozzle covers the enti re wi ndshield. Fluidi cs wor ks o n a irflows as we ll , and the same pr in c ipl e was used in t he defroste r nozz les o f th e 1990-96 Ge neral Motors mini va ns, w he re two sta nd a rd-size defroster nozz les w ith nor ma l a irfl ow could cover the la rge w ind shi eld . G

I

(Fig. 5) Other styles of nozzles provid,e a receptacle for a special aiming t ~

165

EASY

Curing Radio Noise (Fig. 1) A cheap AM radio makes a good Geiger counter-style device for hunting down RFI. Here, we 're looking for an alternator with a bad diode. Mind your fingers.

H ere's o ne sure way to tell. Turn the key to the Run pos iti on w ithout starting the car. The pump should r un for 2 or 3 seco nds. T h en, when t he computer senses th at th e engine isn 't running, it w ill shut off the pump to prevent sp ill ing fuel a nd dra in ing the battery. Other a lmost-constants are hea ter fans, w ipers and electric radiator-coo ling fa ns.

Engine-Speed Noises Can did ates here includ e the alternator/voltage regul ato r, a fau lty fue l inj ector and th e igniti o n system .

Geiger-Counter Test ou're looking forward to the chance to listen to the ballgame, having just dropped yo ur purple-h a ired teenage daughter off at her first semester a t co ll ege . A lot of ba ll ga mes, actua ll y, now that yo u do n't have to li sten to her head banger music, with its shriek ing voca ls and droning guitars. But in stead of the first inning, yo u hear w hat sounds like some awful guitar note-and it cha nges pitch as you speed up and slow down, turn ing to a man iaca l rhyt hmic click ing as yo u wa it for a tra ffic light to change. There's no tape in th e player. W hat you have here is rad io frequ ency interference (RFI ).

Y

Finding the Source T here are three classes of RF no iseco nsta nt, inter mittent a nd enginespeed fo ll owing. Our hap less father 's problem was in the las t categoryhi s noise varied up and dow n in pitch and vo lume as hi s engine sped up a nd slowed down. T his type of

166

noise is ca used by something that varies its speed with the engine. Like ly culprits includ e the ignition, the alterna tor or even a fuel inj ector. Constant-speed no ises are usual ly ca used by an electr ic motor-m ost like ly th e electric fuel pump fo und in the tank of most modern ve hicles which runs at a constant speed anytime th e engine is r unning. An electric fan motor w ill a lso run at a con stant spee d-until yo u chan ge the fa n settin g o r turn it off. Interm ittent no ises are eas ier to assoc iate wit h a source, suc h as an electric seat ad juster or a power-window motor. In other words, eve n though the noise comes from a radio speaker, it ma y be caused by any manner of device a nywh ere on yo ur ve hicl e.

Constants The one motor that's guaranteed to be on whenever the car is running is the fue l pump's, and unfort unately it's usuall y buried in side the fuel tank .

H ere's o u r favorite low-tech too l for hunting down and ki lling wild no ises- a cheap AM rad io (Fig. 1). Tune it to a n empty cha n nel aro und 1400 kH z, crank up the vo lume in yo ur hea dse t, and use the radio to sn iff o ut th e no ise. These chea p o radios use a ferrite-bar ante nn a tha t has good recep ti on a long its side, but poor receptio n a long its length. Once

TO DISTRIBUTOR

CORROSION AND ARCING

(Fig. 2) Carbon tracking in the ignition system is a noise source.

ELECTRICAL AND

ELECTRONIC SYSTEMS

(Fig. 4) Check grounding points by loosening, cleaning and tightening.

(Fig. 3) Be sure both ends of the antenna are properly grounded and corrosion-free.

0 ~

ANTENNA MAST

ANTENNA CONNECTION TO RADIO

CLEAN THIS AREA

yo u find th e no ise w ithin a few fee t, turn the radi o 90' to minimi ze the no ise. The to p of the ra di o w ill p o int a t the source like a g unsig ht.

Making Sure Find some w ay of di sconnecting the so urce of th e RFI a nd check to see if the no ise ceases. Thi s w ill be difficult in the case of th e fu el pump o r igniti o n, but yo u ca n pull the belt off the a lterna tor. (D o n 't d isconnect the a lterna tor electr ica ll y-th e back EMF [vo ltage] may smo ke the di odes.) If yo u think it's a fuel inj ecto r, tr y di sconn ecting it fro m th e ha rness.

Plugged Up Virtu a ll y all cars today use res istort ype plug ca bl es if they use spark pi ug w ires a t all. If your ve hicle is more th a n a few yea rs old , degra ded ca bl es may be th e so urce of th e pro blem. Remove a nd repl ace t he ca bl es o ne a t a time, cl ea n them of grease a nd dirt with mild detergent, a nd check the connectio ns to th e ends. No w get o ut yo ur o hmmeter and meas ure th e ca bl es' res ista nce alo ng their length-th ey sho uld meas ure a pproxim ately 10 ,000 o hms per foo t. Res ista nce in th e mego hm s o r single digits ma y we ll be the so urce of not o nl y yo ur RFI, but a naggin g mi sfir e. R eplace a ny suspect wires with factory or high-qu a lity aft erm arket w ires . Chec k the p lugs , co il a nd a ny

CURING

RADIO

NOISE

di stributo r fo r evidence of car bo n track in g or a rcing as we ll (Fig. 2) .

Intermittents Th ese noises a re easy to associa te w ith the so urce. Any RFI tha t so un ds onl y w hen o ne windo w is go in g up or do wn will be easy to bl a me o n th e wi ndow m oto r.

Which Way Home? Now that yo u've pinpo inted th e no ise, w ha t ca n be do ne a bo ut it ? It depend s o n wh ether yo ur RFI so urce is broa dcas tin g o r ca blin g th e no ise to yo ur radi o. T hi s ma tters beca use th e cure is di ffe r ent. Try pullin g yo ur radi o's a ntenn a lea d o ut. If th e no ise goes awa y or is su bsta ntially q uieter, it's coming in throu gh the antenna . If th e noise stays the sam e o r gets lo ud er, it's co ming in a lo ng t he 12vo lt power ca bl es . Try rem oving th e a ntenn a fro m the fender and cl ea ning th e fe nder sheetmeta l a nd the a ntenna mo unt. Clea n down to the shiny meta l, using sa ndpaper to rem ove any corrosion (Fig. 3) . Smea r the area lightl y w ith Vase line a nd rea ttac h. This w ill provide a proper gro und at the a ntenna. Be sure the ra dio chassis is p ro perl y gro unded to the ca r bod y (Fig. 4) . Afterma rke t in sta ll a tions are m o re likely to have a radi o that's gro unded o nl y by t he shield in the a ntenna co-ax. A simple w ire added betwee n tb e compo nent's

meta l case a nd the car's sheetmetal will often eliminate any RFI. There are two wa ys to reduce no ise: by usin g a n inducta nce in a powe r ca bl e to keep t he bi ghfre qu ency no ise fr o m trave lin g, o r by using a ca p acitor to shunt it o ff to gro und harml ess ly. So metimes both ploys a re necessa ry. In fac t, most of th e electri ca l moto rs in yo ur ve hi cle use so me so rt of capacito r fo r no ise supp res sio n . Any good car stereo shop o r Radi o Shack w ill have t he p arts yo u need. Th e no ise filter we sho w belo w is o ne exa mpl e (Fig. 5) . It ha s a la rge indu cta nce in seri es wi th the 12-volt p o w er ca bl e to a bu zzing afterm a rk et stereo, as well as a co upl e of sma ll ca pac itors in para ll el. T he indu cta nce preve nts no ise fro m enter ing th e amplifi er thro ugh the p o wer lea ds, a nd the ca pac itors bypass a ny leftover nOise. Electric m otors, as w e menti o ned, o fte n have a capac itor in pa ra ll el w ith the a rm a ture fo r th e purp ose of redu cing R FI. If the mo to r's bru shes a re wo rn a nd spa rkin g, th e no ise may overpower th e ca pacitor's filte r in g. Most a utom o ti ve electri c moto rs a re no t se rvi cea ble, a nd they ' ll have to be (Fig. 5) This RFI filter goes in line with both power and ground connections. IN-LINE NOISE FILTER

167

replaced if a simp le filter doesn 't qui et them. As we sa id earl ier, fuel pumps a re difficu lt to get to-in most modern cars th ey a re mounted in side the fu el tank. To a ccess th e pump , o r even th e wiring tha t connects to the pump, it's necessary to drop the tank o ut from und er t he car, w hi ch is a length y, messy a nd potenti a ll y da nge ro us job. Be ca re ful if you a ttempt to a dd a filter to th e extern a l ta nk wirin g, as th e filter itse lf is la rge and bulk y. Yo u' ll need to securely mo unt it to the top o f the ta nk to keep it from brea kin g loose ove r pothol es and bumps.

Soldering On e of th e m ost common so urces of RFI is poo r co nn ecti o ns. If yo u find a poor, co rroded co nn ection or a loose electr ical joint, don't just crimp the connector tighter o nto the w ire.

168

Remove th e conn ector and clea n th e w ire . It may be necessary to trim the w ire bac k a few in ches to get pas t a n y co r ros io n in sid e t he in sul a ti o n . Th ere's o nl y o ne acce pta bl e techniqu e fo r splicing wires if you ' re hav ing RFI iss ues- a nd the commo n a uto mo ti vestyl e crimp conn ector isn't it. Yo u' ll need a good, cl ea n, hig h- wa ttage so lde rin g penc il o r g un , ros in-co re 60-40 solder a nd PVC shrink tube. Sta rt by usin g pro per, stra nd ed a utoill o ti ve -grade w ire. Unstra nded ho use ho ld wire w ill fracture a nd eventu a ll y brea k. Start w ith w ire of a t leas t th e sam e di a meter as th e w ire yo u' re ad ding to. If yo u're a ddin g a p o w er ca bl e, a g ro und co nn ectio n o r a filter, use 12-ga . w ire fo r ultra low res ista nce . Strip a nd pre-tin both w ires to a llow yo u to tw ist th em toge ther fo r a so und m ec ha ni ca l co nnecti o n. Slip a length of PVC shrink

tube over o ne wire, twi st toge ther, a nd so lde r. Use eno ug h hea t a nd a spar ing a mo unt of so lder to ma ke a shin y, we t-look in g so ld er jo int. A ll ow the jo int to coo l w ith o ut di sturbin g it. Thi s w ill prevent the liquid sold er fro m crys ta lli zing as it coo ls. Cove r the joint with the PVC tubing a nd shrin k the tubing w it h a hea t g un , o r ca refull y w ith yo ur li ghter if you mu st. If the so ld er joint yo u' re mak ing w ill be ex posed to th e elements, use shrin k tube th a t has wa terproo fin g adhes ive inside it to keep corros io n fr om creeping into your fres h jo int. Silicone sea l o r liquid elect rica l tape is a good a ltern a ti ve. Dress an y new wires carefull y to prevent chafin g o n co rn ers. Suppo rt any compo nents yo u've added. Remember tha t even a fo o t o r two of heavy-ga uge wire ca n fl ex itself to the break ing point if it's unsupported. ~

ELECTRICAL AND

ELECTRONIC

SYSTEMS

EASY

Servicing Composite Headlamps (Fig. 1) The first step to replacing a lamp is to disconnect the wiring harness from the lamp holder. Never touch the glass on the replacement bulb with your fingers.

/

HEADLAMP ASSEMBLY

LAMP HOLDER

t'S yo ur first cha nce in mo nths to get o ut of Dodge. It' ll be grea t to pack up some co ld ones, a co upl e of fi shing rods a nd some o ld clo thes a nd esca pe to the co untry for a da y or two . But as yo u leave the merc uryvapor-illuminated metrop lex, yo u rea li ze w hat yo u forgot -ca rrots, lots and lots of carrots, because yo u can barely see the roa d in front of yo u in th e starlig ht of the countryside. Relax, it's not yo ur fai ling eyesight. It's a burn ed-o ut hea d lamp .

I

Older Ways For generations, America n ca rs, a nd any car sold in the United States, had th e sa me kind of hea dlight- a sea ledbea m, either in a single or a qu ad arra ngement. T hi s fragil e blown-glass enve lo pe was fill ed with a n inert gas and worked pretty well until it burned out. It had only modest perform a nce, but the Department of Tra nsporta ti o n ma ndated its use. Most modern cars use w ha t's ca ll ed a composi te headl a mp-a plastic reflec-

tor bonded to a plastic or glass lens a nd fitted with a bulb. The bulb is of a quartz-hal ogen design. The "glass" bulb is actu all y made of silica quartz, w hich is highl y resista nt to heat. T he filament is engineered to run at a much higher temperature, prod ucing more light and heat. The silica envelope is filled w ith a mixtu re of halogen gases (iodine or bromine) to scavenge evaporated tungsten filament from the inside o f the quartz, keeping each bulb's brightness constant until it fails. Simply replacing a bulb is easy. A socket holds the bulb in p lace at the back of the reflector assembl y. Unscrew

it a nd pluck the bulb out. New quartz bulbs are always packaged in a bag or sleeve. This is to prevent the oils o n your fingers fro m contacting the qu artz. Temperatures at the surface of the bu lb a re high eno ugh-severa l hu ndred degrees-that the oil s will carboni ze o nto the surface, creating a loca lized hot spot. This hot spot w ill overstress the silica, resulting in a crack that lets air into the bulb, blowing the filament o ut within minutes. Never allow yo ur fingers, or a nything that isn't squeaky clea n a nd dry, to to uch the bu lb (Fig. 1). If yo u do, clea n the bulb with alco hol and a clean cloth. The easiest way to avoid problems is to leave the protective sleeve on until the bulb is in the socket and ready to reinstall. W hen reinstalling the lamp holdel; a small smear of silicone grease over the O-rings w ill help it slide back in a nd keep mo isture away. For more detail on this work, read "Replacing Head lights" o n page 166.

Foggy, Foggy Nights Both of your hea dlights are lighting up but you still ca n't see? Are the sur-

BUBBLE LEVEL

(Fig. 2) Many modern head lamp assemblies have a bubble level to assist in aiming the light beam. You'll still need a marked wall to see the beam pattern.

SERVICING COMPOSITE

HEADLAMPS

ADJUSTMENT THUMBWHEEL

169

faces of yo ur head la mps fogged? Pla sti c lenses a re covered w it h a spec ia l UV-resistanr coa ti ng. After years of expos ure to poll uti o n a nd UV-contai n ing su nlight, it ca n fog. Us ing ru bbing co mpo und ro re move the haze is a sho rr-term solution. W ith the coa ting po lished off, th e lens w ill ye ll ow a nd haze. Yo ur o nl y so lu tio n is ro rep lace t he enri re asse m bly. If moist ure has crept inro th e asse mb ly a nd fogge d th e interior, yo u may have a pro bl em w ith the housing's venr system . Look for co ll apsed venr hoses, or hoses p lugged wi t h mud , insects or ru stproofing. If the ve hicle has been immersed in m udd y wa te r, yo u' ll need to remove th e enrire ho usin g a nd fl ush it o ut. Dry th o ro ug hl y ins id e a nd o ur before reasse mb ly. Corroded plat ing on t he in side of t he reflecror is gro unds for re pl acement.

Aim High Be sure ro se t the a im correctl y. O ld-style sea led-bea ms were no t fussy a bo ut ai min g, bu t t he mo dern q uartz

"ft\a~~::.:=~~

~ 25FT.

(Fig. 3) It's critical to keep both headlight beams' cutoff below the line at the bulbs' height from the pavement. Check this on level pavement.

~

la mp in co mpos ite head lamps has a very sharp horizonta l curoff ro keep light our of the face of oncom ing traffic. Conseq uently, the aiming of the beam s is critica l. Sea led-bea m lamps used a rela tive ly crude a iming mecha ni sm t ha t requi red a Phillips-h ea d screwd river ro tu rn adjus ti ng screws, w hich

inva riab ly go t more d iffic ult ro t urn as t he socket aged a nd corroded. Sooner or la ter, the hea ds of t he screws str ipped, a nd yo u ai med yo ur hea dligh ts poo rl y or no t a t a ll. Some hea d la mp assemb lies a re a d justab le by mea ns of a large Philli ps- head screw accessibl e fro m t he from of the ve hicle t h ro ug h ho les

HOW IT WORKS

High IntenSity Discharge Lighting Some high-end vehicles are available with an extremely bright, tightly focused type of lighting known as High Intensity Discharge (HID). Unlike conventional lighting, there is no filament to burn out, as the light is generated by incandescent gases in a quartz tube. How hot is it? Hot enough to create a plasma of the molecules by stripping the electrons away from their nuclei. This requires, at least initially, nearly 20,000 volts to discharge across electrodes in the bulb. The plasma envelope's shape is easier to focus than a springy tungsten wire , so less stray light goes into oncoming traffic's windshields and more, far more , goes onto the verge of the roadway. There's nothing to burn out, so the lamp should outlast the vehicle. Aftermarket retrofit kits are available to upgrade your vehicle. We've installed a Xenarc low-beam kit from Sylvania on one of our vehicles , and it has given us a new appreciation for the number of deer browsing near the side of the road at night. Just remember that correctly aiming these types of lights is far more critical than conventional lamps, because their intense light can potentially blind

170

COMPOSITE REFLECTOR HID ARC CHAMBER HID IGNITER HID HV BALLAST CABLE

- - - - - VEHICLE 12V INPUT

oncoming traffic if they 're aimed too high. Warning: Before you replace a bulb with this system, be sure the switch is off, battery is disconnected, and ballast connectors are unplugged. High voltage is hazardous.

ELECTRICAL

AND

ELECTRONIC

SYSTEMS

in th e g rill e. Others ma y have thumbwheels that yo u simpl y cra nk up a nd down a nd left a nd right without a n y too ls (Fig. 2) . Vehicles va r y, so yo u ' ll need to check yo ur owner's m a nu a l or the shop ma nu a l for specifics-but here are th e ge neric instruction s. Park yo ur car in front of a li ghtco lored wall in a dark spot ind oors, or o utd oo rs a t ni ght. Pos iti o n th e car so that th e hea dlights a re 25 ft. fr o m the wall, a nd be sure th e ca r is pa rk ed a t ri ght angles to th e wa ll . Measure the hei ght of the center of th e headlights from th e ground. Make a lin e on th e wa II with a marker or ma sking tape at thi s same height (Fig. 3) . Now mark a pa ir o f ve rtical lines directl y in front of each hea dli g ht. With th e a dju stm ent thumbwheel, yo u ca n now

transferred to the new housing.

slu e th e bea m up o r d own a nd left or right. If yo u have tro ubl e visua li zi ng o ne bea m because th e o th er o bsc ures its li ght, tr y pu llin g that lamp's conn ector, or just cove rin g it w ith your jacket. Th e specific numbers vary with eac h ve hicl e manufac turer, but at th e very least, th e left and ri ght beams sho uld be the sa m e w ith respect to th eir indi vidu a l centerlin es . T he cutoff lin e shou ld be just be low th e lin e at th e hea dlamps' center. T he kickup to the ri g ht of the bea m sho uld start just to th e right of th e centerl in e. Do a ll th e adjustin g with a trunkful of luggage, a tankful of gas a nd a warm bo d y in t he dri ve r's sea t. Many late-m o d el ca rs in co rp o rate a sm a ll bubbl e leve l directly in to th e

hea dlamp h o usi ng (Fig. 2) . Observing th e level w i II he lp yo u to ma ke ad i ustm ents w hen yo u a re a iming th e li ght beam. R emember th a t thi s is o nl y a n initi a l a dju stm ent. You'll still need to visua li ze th e bea m on a wall to trim out the correct a li gnment. Thi s is beca use m a nufacturing tolera nces d o n 't a lways place th e fil a m ent in th e la mp in exactl y th e sa m e pos it io n re la ti ve to the la mp 's metal ba se-whi ch ca n ma ke th e bea m 's alignme n t quite different when th e lamp is repl aced. Th e leve l w ill let yo u make hea d lamp a dju stments when yo u ha ve to driv e a heavil y loaded veh icl e. Check th e settings on th e bubble levels, load up th e trunk, reset the bubbl e leve ls and go . Don't forget to raise th e beam afte r yo u unl oad.

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II I I I

SERVICING COMPOSITE

HEADLAMPS

171

EASY

Servicing Electronic Suspensions and yo ur Corvette have been terrorizing the same back roa d on the way hom e for month s. A warning lamp that says SERV ICE RIDE CONTROL wink s at yo u from the dash. No prob lem, yo u say-I'll take it to the dea ler for service next week. That sensuous, sweeping switchback turn is dis appearing- rap idly, very rap idl y-u nder yo ur front tires. You've been thro ugh this turn a hundred times before, but this tim e something is different. A sma ll po thole sudden ly makes yo ur o utside front tire start to skitter across the aspha lt as yo u mow down a so lid hundred feet of weeds betwee n the verge and the ditch before regainin g control. Suddenly the need to see the dea ler has become much more urgent. Then the dea ler says it may cost as much as (gulp! ) two grand to fix. Time for the Saturda y mechanic to get busy.

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SHUTTER

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INNER SHOCK TUBE

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VALVE

Finding the Problem Consider the fact that the warni ng light mysterio usly came on after the car was jostl ed aro und on some broken pavement. That means there 's a good chance you're dealing with just a bad electrical conn ection . Or ma ybe one of the Bilstein shock absorbers was severely worn and just needed that last pounding to jam the adjustment mechanism. In re trospect, the right front corner has fe lt a bit mushy lately, hasn 't it? Luckily the Selective Ride Control (SRC) system in the Corvette is one of th e simpl est setups, if not th e simpl est, of its kind. OE replacement parts aren't cheap (the shocks cost about $300 ap iece), but at least yo u don't have to pay la bor w hen doin g the job yo urself. Pity the guy who has problems w ith an air-strut setup , such as those

172

,

·: ::' :

.,

:

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i.! Fig. 1. Lincoln Continental's air-strut damper shutter varies oil flow through ports. Other systems are similar.

found in Lex us LS 400s, some M itsubishis and the Lincoln Continenta l (Fig. 1). Except for the Infiniti 's Q45 active suspens ion, these are the most complicated systems on the roa d. The Lexuses and Mits us adjust dampin g rate, ride height and sprin g rate a uto matica lly thro ugh a computer. The Co ntinental changes just damping and ride height. Unlike the Corvette and some other ride-control systems, the Continental 's air struts

can't be converted to a conventional suspension. Tough luck.

Check the Basics First Roughly half of all the mainstream carmakers offer some type of electronic suspension system on some models. In genera l, they all make computer-co ntrolled adjustments on response to one or more of the following inputs: road conditions, vehicle speed and weight/load, brake

ELECTRICAL AND

ELECTRONIC

SYSTEMS

Fig. 2. With no trouble codes stored in a ride-control system's computer, begin the diagnosis by visual inspection of the parts and wiring.

app lica ti o n, steerin g-w hee l a ngle, p ower- steering press ure, thro ttle pos ition, lateral/l ongitudin al accelera ti o n and the positi o n of a das h- o r conso le-m o unted dri ver-se lectab le sw itc h . But do n't let t hi s li st ove rw helm yo u. Th e key to a ny modern a uto lll oti ve system is to keep it simp le a nd check the bas ics firs t, then m ove o n . O ne prerequisite fo r work ing o n almost a ny m odern car is adequa te documentati o n . Beg, borrow or steal the m a nua l for yo ur ca r, w hi ch may involve o rd ering it fro m the dea ler. With o ut so me sort of ma nu a l, yo u' ll be guess in g, a nd proba bl y no t o nl y wo n 't be a ble to ma ke the re pa ir bu t yo u might inad ver tentl y dam age so me pretty expensi ve par ts. In the ca se of your Corvette, th ere should be at least one tro ubl e code stored in the comp uter. 50 yo u wo uld jump r ight to "Corvette di ag nosti cs" o n t he p age ISS, beca use it wo uld pro ba bl y lea d yo u to the pro bl em a lot faster. If the computer hadn't turned on t he warning message but yo u fe lt something wrong w ith the suspension (or yo u don't have the self-diagnostic info rmatio n for the system yo u're dea ling w ith), yo u wo uld start by ta kin g a close look at the adjusta ble shocks fo r some signs of oil lea kage as if dea ling w ith plain 01' shocks. If you see a ny stains or drips, the first piece of business is to replace the bad unit and hope the system is

SERVICING

ELECTRONIC

open relay, a cl ogged air bleed-o ff va lve, a bl own fu se or even th e co mpressor itself. Fo rd iss ued a tec hni ca l se rvice bulletin o n thi s exact subj ect bac k in the mid-90s . It seem s tha t o n 1990 -93 Cro w n Victo ri a/Gra nd M arqui s a nd Town Car models, th e rea r a ir suspensio n may no t p um p up w hen loa ded beca use th e a ir-s uppl y lin e a t th e Y connecto r nea r th e No .4 c ross member tend s to rub o n th e und erside o f t he car bod y. Th e consta nt rubbin g eventu a lly wea rs thro ugh th e lin e a nd crea tes a lea k. An improved a ir line w ith a pro tecti ve shi eld w as issued to remed y th e pro bl em. Th e OE p a rt numbers a re F2AZ-5A89 7-B (C ro wn Vi c/G ra nd Ma rq ui s) a nd F2VY5A897-A (To wn Ca r).

Corvette Nitty-Gritty

Fig. 3. Air suspension must be off before jacking up Lincoln Town Cars or Mark VIINIlis.

fix ed. The sam e logic applies to all electronic suspensions, be they air, hydra ulic or both . N o m atter how comp lex the system is, the damping portio n of the shock/strut is still fill ed w ith hydra ulic oil a nd needs to be sea led. Next, do a visual in specti o n fo r a ny airlfl uid lines th at have burst a nd fo r da maged or mi sadjusted height senso rs o n th ose setups that use th em. Loo k aro und for any o bvious harness conn ector tro uble a nd check the shock/str ut actu a tors and their connecto rs (Fig. 2) . If yo u hea r th e air co mpressor runnin g co nsta ntl y, it usuall y mea ns a height sensor is o ut of w hack, there's a sm all air leak or a relay is stuck in the ON positio n . If the compressor never turns on, you ca n suspect a bum height sensor, a stuck-

SUSPENSIONS

Understa nding how th e 5RC system wor ks w ill help to di agnose a nd fi x it a nd w ill ma ke oth er setups eas ier to co mprehend . 5R C co nsists of fo ur ad justa bl e gas-c ha rged shocks, a n ac tu ato r moto r o n top o f each shoc k a nd a co mputer to dri ve th e actu ato rs. 5RC can adju st the da mping ra te o nl y-the ride height neve r cha nges. Inp uts to the computer includ e a 3pos iti o n dri ver-se lecta bl e sw itch, the ve hi cle sp eed se nso r a nd signa ls fr o m eac h ac tu a tor's H a ll -effect p os iti o n se nsor. Based o n th e ca r's sp eed a nd w here the dri ve r has the switch, the computer p owers th e ac tu a tor m o tors so that they rotate a certa in number of degrees . Every time th e key is turn ed o n, th e compute r ro ta tes th e actu a tors back to th e 0° stop. In side th e co nve nti o na l-l ook in g shoc k sha ft is a thin rod , ca ll ed th e damping rod. It extend s fro m th e top of t he shaft down to th e piston. On top of the da mping rod is a gea r. W hen the actu a tor is mo unted , its gea r fits ove r t he gea r o n th e rod , w hi ch ena bl es th e actu ato r to rota te t he rod up to 160 0 in sid e the large r shaft . Beca use th e bo tto m of th e ro d is beve led, as it turn s cl oc kw ise it gradu ally closes off the byp ass orifice m ac hined in the side of the la rger shaft. T he sma ll er th e o rifice

173

ACTUATOR

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(D-

gets, the stiffer the shock gets. Mechanically it's simple. As long as the electronics don't screw up, only norma l wear sho uld affect the system. Other electronic dampers work in basically the same way but they vary in design. For instance, the Continental's air struts use a shutter-type mechanism with different size orifices to vary the oil flow.

174

Replacing the Shocks If you find a leaker or one shock that's clearly worn out, replacing it is about as straightforward as any conventional shock. Start by loosening the lug nuts of the wheel that has to come off and jack up the appropriate end. Remove the wheel. (On some air systems, such as the Lincoln Town Car and Mark series cars, yo u must flip

Fig. 4. The Corvette SRC actuator must mesh cleanly with its shock's damping rod gear or the computer will set a trouble code. The locking clip should slide easilty into place.

off the air suspension switch in the trunk before jacking up the vehicledon't say we didn't warn yo u (Fig. 3) . Next, pull the actuator's locking clip

ELECTRICAL AND

ELECTRONIC

SYSTEMS

and pull the actuator straight up off the shock to expose the damping rod 's littl e gear. Lay the actuator gently on a frame rail if possible. Don't let it hang on the harness. If there's no place to set the actuator down, either tie it out of the way or pull its connector from the main wiring harness and remove the actuator and its harness comp lete ly. Now, you just need to remove the upper and lower mounting bolts and pull the shock. You ma y need to pump up like Arnold Schwarzenegger for a few seconds to compress the stiff gas shock enough to slip it out between the contro l arms. The same goes for slipping the new unit through the arms into place. Be carefu l not to damage the new damping rod gear. The ac tuator must remesh smoothly with the new gear. Anything that prevents the actuator from doing its job w ill set a trouble code in the computer (Fig. 4).

Actuator Precautions Don't hit the Corvette's actuator with anything during insta llation-press it on gently by hand. Never whale on the upper retaining nut with an impact gun or you ' ll jam the damping rod. The nut must be torqued to 33 ft.-lb. Hold things steady with a wrench on the flats of the retainer insulator while tightening the nut. Make sure there's a good mesh between the damping rod gear and the actuator gear, and a good fit for the locking clip (Fig. 5) . Once mounted, make sure the actuator harness pigtail points directly rearward for a front shock and directly

forward for a rear shock. This prevents the harnesses from rubbing against the fender splash shields and frame rails. The actuators on other electronic shocks/struts are usuall y held in place by two screws, so they can be installed in only one position. This means the com puter doesn 't need to take a zero reading with each key cycle. T here 's no way to install an SRC shock backward because the actuator position sensor keeps tabs on the damping rod angle . However, this doesn 't necessaril y apply to all electronic suspens ions. Be sure to check the manual for the latest information.

Fig. 5. Actuator must align with top of damping rod to maintain proper soft/hard positions.

Corvette Diagnostics Remember that SERVICE RIDE COp-.1TROL warning? When it's on, it means the system is in a fail-safe mode and the computer has locked a ll the actuators in the 60° position until the problem is fixed. With the car stopped and the ignition on, jump terminals A and B (1989 only) or A and C (later models) of the ALDL (assembly line diagnostic link ) located under the knee bolster with a paper clip or a piece of jumper wire to make the SERVICE RID E CONTROL warning message flash out 2-digit codes. There are 13 possible codes that can be spit out, but you'll need a service manual to decipher them and to do the proper tests. Four things can prevent the warning light from flashing codes or from coming on with the key for a bulb check: a burned-out bulb, a blown fuse, a bad harness connection

at the computer or a bad computer. The electronic brain for this system is found in the bin behind the driver's seat in the Corvette. In other cars, it's usually mounted behind the rear seat in the trunk area. Only two problems won 't set codes in the SRC system: a leaking or worn shock and system voltage out of the 10- to 16-volt range. To clear codes after the repair has been completed, jump ALDL terminals A and B (1989) or A and C (later models) three times 2 seconds each. The Real Time Damping system on late-model Corvettes (mid late 1990s) a lso permits on-board trouble code diagnostics without a scan tool, through the Central Control Module. Codes are displayed on the Driver Information Center. Refer to the factory service manual (or the service information websitewww.acdelco .com) . ~

L - - -_ _ _ _ _ _ _ _

SERVICING ELECTRONIC SUSPENSIONS

J

175

DIFFICULT

Fixing Power Windows (Fig. 1) Carefully backprobe the window switches to isolate any electrical faults in the switches, connectors or wiring.

nother toll-booth, another mile-or at least it seems as if the tollbooths come every mile on this road, with a half mile of traffic idling its leisurely way up to the token monster. Within an ar m's length of the bin, you toggle the power window switch with one hand while the other hand fingers a token, preparing to whip it into the basket just as you floor the throttle. All goes as planned-except th e window doesn't move, the token bounces back into your face, and yo u ha ve to jam on the brakes, crack the door and pitch a second token backhanded to keep from getting a ticket as a toll evader, all to the tune of horns blaring from the cars behind yo u.

A

176

Fortunately, power windows are usually one of the more reliable systems on a late-mode l car. And di agnos is and repair are usually pretty straig htforward.

What's Up? The most coml11on power w indow mechanism is pretty basic. There's a simple regulator mechanism, usually similar to the mechanism used on garden -variety hand-cranked windows. It comes in severa l varieties-rack, sector and cab le drive. Troubleshooting is pretty straightforwa rd , o nce you get the door panels off-but your problem may be terribly simple and may not require removing any trim at all. First: Are all of the windows on the

fritz? Or just one? If you can't move any of the windows, the first place to look is at the fuse. Window regulators are high-current dev ices, and the fuse is sized to just barely be able to open all four windows together. Age and a few sticky window channels can pop a fuse. Turn the key to the Run position, but don 't start the car. If th e fuse is blown, pushing a window button will do nothing at all: The motor won't groan and the glass won't quiver. If the fuse is good and yo u can hear the motor, or the glass acts like it wants to move, then yo u've got some sort of mechanical problem. If not, check the fuse. If the fuse box isn't labeled, check the owner's manual to see which fuse is the culprit. Don't go ya nking fuses willy-nilly looking for a bad one-you might interrupt th e power to the engine management computer, causing poor driveability for 30 minutes or so-or you might reset all the buttons on your car radio to that undersea -alien rock-gospel station. Fuse okay, but the window still won't budge? Aga in, are a ll th e wind ows dormant? Or just o ne? If it's ju st one, yo u still may get an opportunity to go spelunking inside the door. If it's all four, maybe it's something simpler you can troubleshoot under the dash.

ELECTRICAL AND

ELECTRONIC SYSTEMS

At this point, if you've narrowed the fault down to some electrical problem that's not as simple as a blown fuse you need to round up a schematic of your car's electrical system and a voltmeter or 12v test light. All that's necessary now is to start at the fuse panel and follow the wiring to the switch, and from there move on to the motor, testing along the way for 12 volts. Somewhere, you'll find a loose or corroded connector interrupting the voltage to the motor. Or, the switch itself might be bad. If the driver's door switch won't open the right rear door, but the switch in the door will, look for either a bad switch in the driver's door or a fau lt in the intervening wiring.

Open Sesame At this point, you probably need to be able to access the inside of the switch panel. On some vehicles, like the one in o ur lead illu stra tion, yo u can simply pry the panel up with your fin gers and backprobe the connectors (Fig. 1). Other vehicles may require that you remove the panel. Door panels are held on with a bewildering variety of fasteners. Start

to put your fingers into places where fingers norma lly don't go . As our mechanic pal Lefty points out, " A power window motor ha s enough torque to put a serious hurtin' on ya if it's actuated while errant digits are in the gears."

Proof Positive

(Fig. 2) It may be possible to replace a bad motor, or you may need the entire mechanism.

by p ulling off all of the door pulls and handles. The perimeter of the panel is customarily held on fragile plastic studs intended for one-time use . Pry them up carefully, and you should be able to re use them. Once you've got the door panel off, carefully remove the weather sheeting. You'll need to replace this later, and you may need fresh contact cement to do so. Warning: You now have the ability

HOW IT WORKS

Automatic Windows Some late-model high-end cars have frameless windows that automatically crank themselves open a quarter-inch or so as the doors are opened. It happens so fast that you may not notice it. The window opens rapidly, clearing the seal before the door latch clears. It then closes automatically about a second after the door latch latches. There are two advantages to this. First, the slightly open window vents interior air, which can actually make doors on tightly sealed cars hard to open by springing the door back open against air pressure. It also lets the manufacturer use a vastly different style of seal on the top of the window. The

FIXING

POWER WINDOWS

seal can more closely resemble a sedan door seal, with a small lip protruding over the top of the glass. This type of seal won't work on frameless windows because the glass has to clear the seal as it opens and closes. This type of seal allows less water and noise intrusion. A similar automatic system is used on those high-end convertibles with fully automatic tops, to provide clearance for the moving parts of the top. The downside with any automatic window system is with the logic control module needed to achieve this. Repairs will probably need a factory shop manual and, potentially, some expensive parts.

As an absolute proof that the problem is electrical, try running a jumper wire direct from the battery positive terminal to the positive side of the motor to see if it comes alive. Be aware that a few window regulator systems supply 12v constantly, and switch the ground side of the circuit. Check the schematic. Also, most vehicles have the ability to lock- and deactivate-the rear windows. Check this switch if only the rears are balky. Occasionally, the true problem is a bad motor (Fig. 2) . You'll have to replace it. Otherwise, you can simply trace the wires until yo u find the problem.

Sticky All windows have gaskets and sea ls to keep wind noise and rain out. If the window has a slow spot or won't open or close properly, check the gaskets. A gasket that's misplaced or torn can prevent proper opera tion. If the gasket is loose, or even torn, you may be able to repa ir it. If the gasket is simply loose, get some 3M Super Weatherstrip Adhesive at the auto parts store. Clean off the old adhesive with lacquer thinner and reglue the gasket into place. Allow this to dry overnight with the window closed, and be certain you' re not gluing the window to the gasket. If the gasket is torn, you might be able to use a super glue to simply repair the tear. You may be able to judiciously trim a loose corner of gasket away with a single-edge razor blade. Be particularly careful about doing this on the part of the gasket that sits o utside of the glass, because it may admit rain and salt spray to the inside of the door in quantities too large for the door's internal drainage system to cope with.

177

can use either a rub ber wedge doorstop or a co uple of feet o f d uct tape to anc hor the glass up w hile yo u wo rk . Sometim es t he prob lem is nothing more th a n a loose bo lt a ll ow ing the door 's lI1ner stru cture to m ove a ro und , mi sa ligning t he w ind ow tracle Ma n y doors have slotted ho les fo r th e a ttac hm ent po ints for intern a l pa rts, so careful conside rati o n of th e mi sa lignment will so metimes let yo u simply slid e o ne a dju stment a q uarterinc h o r so a nd stra ighten it a ll o ut. All bets are off if th e doo r has been damaged in a cras h. It ma y take a long time to get everything working right.

WEATHERSTRIP

OJ

8

h

SECTOR GEAR

(Fig. 3) Check the weatherstripping and window channel for torn , loose or folded rubber parts, or foreign objects in the way.

Rep lacing a gas ket o r sea l w it h a new part is genera lly stra ig htfo rwa rd . If it's not o bvio us th at t he gasket is as tra y, insp ect th e entire gasket and channel carefull y. Look fo r da mage, bur a lso loo k fo r such things as p in e sap, foss ili zed Froor Loops o r other fore ign o bjects tha t mig ht make t he w in dow stick o r bin d. Clea n th e surface of th e gasket and w indow w ith lacquer thinner to remove ox idi zed rubber and scum (Fig. 3) . The re's a fa ir am o unt of frictio n betwee n the gasket and t he w in dow g lass . Almost a n y mi sa li gnm ent ca n d ra mat ica ll y in crease t he fr icti o n to th e po int w here th e m o tor no lo nge r has eno ug h torqu e to m ove th e glass p ro p erl y. Lubrica te the entire chan nel wi th silicon e spray or protec tant, beca use th e red uced fr icti o n just mi ght get yo ur w in dow workin g aga in .

178

(Fig. 5) Severe misalignment caused by loose fasteners can jam gear-type regulators.

(Fig. 4) Reel and cable window regulators are simple mechanisms, but can be fussy about cable routing and may snag if jammed.

It's a lso possible tha t th e ptob lem is deeper inside t he door. If so, yo u'll need to p ull the door pa nel a nd go pok ing ato und. Re member to pull the fuse to prevent a mp utating yo ur fi ngers . Yo u

Last ly, the mec ha ni sm tha t runs t he window up a nd dow n may be fau lty. W heth er it's a gea r-a nd -secto r, scissors li ft o r cab le-operated m echani sm (Fig. 4) , yo u' ll need to wa tch it moving up a nd down a few times . Aga in , kee p yo ur fin gers o ut of the works . Sometim es the pro blem w ill be a loose faste ner or rive t, sometimes a btoken or mi ssing bu shing (Fig. 5). Cab les ca n bin d o n th e drum or beco me sti cky. Lube a ll th e fr icti o n po ints w ith w hite grease. Don 't forge t th ere a re gas kets in the w indow trac k down below the to p of the door, and yo u may need to reglu e, repa ir o r lu brica te t hem. S

ELECTRICAL AND

ELECTRONIC SYSTEMS

OOfl::::i!FFICULT_ Replacing Your Fuel Pump

ELECTRICAL CONNECTIONS

LOCKING RING

(Fig. 1) A plugged fuel filter won't only stop the engine, it'll also kill the pump. It wouldn't hurt to remove any junk from the tank while the pump is out. But don't use your shop vacuum. Use something nonelectrical, like a rag, so you won't burn down your garage.

T

en minut.es la te. G ulp ha lf yo ur co ffee, sprint o ut to th e ca r. Twist th e key and she cra nks. And cra nk s. And cra n ks . No fire, a nd yo ur ulce r potentia l increases a lo ng w ith yo ur bl ood pressure. It a lways see ms to happen when you're behind sc hedul e, as if th e gods of intern a l co mbu stio n are eternall y aga in st yo u. Yo u sho uld 've paid a ttenti o n to t hat occas ional buck ing on th e hig hway. If th ere's a n ything over 60,000 mil es o n the o d ometer, but more commo nl y 100,000 plu s, there's a good chance that the ca use of this distressin g no -start condition is an elect ric fuel pump tha t's no lo nger capable of

REPLACING YOUR

FUEL

PUMP

forcing fue l forward w ith suffic ient press ure. Eve n if the conditio n has n't reached th e point of gro undin g yo u, pump in a dequ ac ies ca n ca use numerous driveab ility prob lems, such as m o mentary cutting o ut, hes ita ti o n, low power a nd sta lling a t inopporrun e moments (typica ll y, it' ll start aga in after it's coo led o ff ). For years, th e ca r co m pa ni es have been look ing fo r a pump life of 10,000 hours (say, 400K mi les) as a bogey. Now, the y' re ask in g their O .E. suppliers fo r " Iife-of-car" (th at man y mil es isn't a car's li fe span a n ymore?) . To reac h this goa l, pum p make rs ha ve lowered a mperage d raw a nd ba la nced

armatures more precise ly. That's a ll ve ry a dmirab le, but as k a ny service technic ian and he' ll tell yo u th at t hey simpl y d o n't las t a n yw here nea r that long in most cases . What's hap penin g? In a word, crud. Many (most? ) o f the fue l filters repl aced are so jammed up yo u can't blow through them (Fig. 1). If yo u had checked the pump's a mperage draw before removing the o ld filter, yo u might ha ve seen up to twice the expected number-perhaps eight to 10 instead o f four to six. It shouldn 't take much of an intellectual leap to realize that a p lugged fuel filter at the o utlet site will ma ke a pump work harder, and a ll that extra current will wipe out the

179

brushes and groove the commutator, killing the pump prematurely. Also, the pump's already digested whatever's causing the restriction. While on the subject of pump fatalities, another reason pumps burn out is becau se immersion in gasoline is necessary for cooling, yet peop le run aro und on "E." So, try to keep your tank at least half ful l.

."" ....

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',":'--,.

Two-Legged Tripod? For a century, mechanics have been taught that spark , compression and fuel are th e legs of the tripod that support an engine 's ability to run , and th at's sti ll true. So, before you jump to any unfortunate conclusions about your fuel pump, do a spark check (a story for another day) and make sure the camshaft is still connected to the cranks haft (remove the oil filler cap and watch the cam or rockers while yo u have a helper crank the engine). If these two essentials are okay, you can start thinking gasoline. Turn the ke y on and listen carefully. In most cars, you ' ll hear the pump run for a few seconds. No? Then check the fuse. If it's blown, and the car starts after you replace it, yo u should still find out how man y amps it's bein g forced to carry. If pump electrical draw is too high, a fix now will head off a future breakdown. You'll need either a low-reading analog ammeter (Fig. 2) or a DMM

\ (Digital Multi-Meter) with sufficient current-carrying capacity. Amperage testing is done either by hooking up the meter in series with the load, or with an inductive pickup that you clamp around the wire. The latter works best with big current flow, such as yo u'd find in the starter circuit, so we prefer the former for diagnosing fue l pumps. That means yo u've got to break into the circuit. Connect one of the ammeter's leads to the positive battery post and the other to the pump's hot wire. Look this up in a service manual. Ditto for the specs, but we wi ll say that if yo u see anything over 5 amps with a low- to mid-pressure system (13 to 45 psi), or 7 amps with a high-pressure version (60 psi) yo u've got a problem. Will on-board diagnostics help you here? ot very often, although a problem in the pump relay circuit wi ll set trouble code No. 42 on a typical Chrys ler product, or code No . 87 on a gardenvariety Ford.

Excluder and PSI H ave you replaced the fuel filter at the recommended interva ls? How about ever? If you've been lax in th is regard, it's certainly one of the first things to check. Even if it's not the reason the engine won't fire up, it's

~

(Fig. 2) Find out how many amps the pump is drawing with a current draw test. Just bypass the wiring and run jumpers from the battery.

critical maintenance that you should be doing anyway, so yo u're not wasting your time. Important: Filter remova l will be a lot less dangerous and messy if yo u relieve system pressure first. Wrap a rag around the Schrader-type valve on the fuel rail and press down on the va lve's pin (Fig. 3). Or, remove the fuel pump fuse, and crank for 20 seconds. Checking fuel pressure is one of the basics of troub leshooting, and reasonably priced ga uges are available. Most screw onto the Schrader-type valve, but with some imports you' ll need a special banjo connector or a special fitting. Turn the ignition on and read the gauge . No or low pressure may mean the pump's electrica l circuit is faulty. This could be beca use of a defective control relay, but check for bad connections before yo u think about a new relay. Examine all the connectors for evidence of corrosion or looseness. Test for the presence of battery vo ltage at the pump's pos itive term inal or wire, and check for a bad ground as well. By the way, an inertia-type safety switch in the pump's circuit, as found on many Fords, can be tripped by a minor impact, such as bumping into a snowbank. Voltage-drop testing is the best way to locate high resistance. With the circui t powered up, use an accurate voltmeter to see if you get a reading across connections and lengths of wire. Anything more than about 0.2 vo lt is too much . Other possible causes of too few psi to start the car are the already-mentioned clogged filter, a pick-up sock in the tank that's blocked, a crimped line or, of co urse, a weak pump. If key-on/engine-off pressure was within specs, use a test light at the

(Fig. 3) Before you open any connections, relieve system pressure.

180

ELECTRICAL AND

ELECTRONIC

SYSTEMS

HOW IT WORKS

Fuel Pumps Unlike mechanical fuel pumps, which are necessarily attached to the engine, the electric variety is mounted back in or by the tank. There are three types: turbine, TURBINE GEROTOR gerotor and roller cell. The first uses rollers in a notched rotor to catch gasoline and force it into a smallvolume area of the housing. It has lots of moving parts and can be noisy. Gerotors are similar to some oil pumps-they squeeze liquid by means of the eccentric action between a star-shaped rotor and a matching element that surrounds it. Today, however, the O.E. trend is toward the turbine type. With throttle-body fuel injection (also called "wet throttle plate"), electric pumps typically put out 15 to

appro pri ate inj ecto r wire (or, pull a n inj ecto r conn ecto r a nd plug o ne of th ose in ex pensive " noid " li g hts in to the ha rn ess) . No Aas hing? Th en th e inj ecto rs are n't firing, whi c h mea ns t roub les hootin g w ill have to gradua te to a w ho le other level of com plexity as you loo k into th e electro ni c engine ma nage ment a nd EF! syste ms.

It Starts, But ... In cases w here th e engin e run s, but has a drivea bi li ty prob lem, co ncentra te on your ga uge rea din gs . You sho uld see vio lent needle swings between deadhead a nd run nin g press ures (Fig. 4) . A slow rise mea ns troub le. Pu ll the pressure reg ul ator'S vac uum hose a nd yo u sho uld see a n in crease . Too ma n y psi may be due to a defecti ve regul ato r or a restricted return line. Just beca use yo u' ve got specified pressure doesn't mea n t here's sufficient Aow. Tota l system vo lume a t th e Schra dertype va lve of 1 pint in 20 seco nds w ill run a n y ca r. (Whi le a (Fig. 4) A fuel pressure gauge can tell you plenty. Take readings dead-head (key on, engine off) and running.

REPLACING

YOUR

FUEL

PUMP

20 psi, whereas port injection requires 45 to 60 psi. If you're still wondering why mechanical pumps aren't used with fuel-injected engines, ROLLER CELL think pressure and volume. The former has to be higher than the 3 to 5 psi a typical mechanical unit supplies. Otherwise, you won't get that nicely vaporized plume that burns so well. Plenty of fuel has to be flowing all the time, too. Only a small percentage of what's available is actually used even at full throttle. The rest serves to keep those injectors and rails cool as it recirculates to the tank. That, plus the location of the pump way back in or by the tank, pretty much eliminates vapor lock problems.

typica l pump may Aow 30 ga l. per ho ur, less th a n a tenth of th a t is needed to run the eng in e. T he rest is return ed to the tank, w hich helps keep everything cool. )

Kaput Pump replacement may be easy or diffic ult, dependi ng o n the d es ign. O n ve hicl es w ith in-ta nk pu mps, access is so metimes just a ma rter of removing a sea t, o r fo lding back the trunk ma t a nd remov ing a pa nel. Oth ers require that yo u drop th e tank, wh ich can be quite a po nderous undertaking, es pec ia ll y if yo u've just fi ll ed up (gasoline weighs 6 po und s per ga ll o n ). We use th e term " drop" in a mecha ni c's sense here-we

do n't rea ll y mea n to dro p it. You ca n siphon it down-dump w hat yo u ge t in to yo ur o ther ca r, o r give it to a neighbor. If yo u have a good fl oo r jack, put a big sq ua re of plywood between it and the tank . R emember tha t th ere's stil l a certa in a mount of fuel in th e tank after yo u' ve drain ed it. No smo king, a nd dry up a n y spill ed fuel ri g ht away. It'd be a rea ll y good idea to work o utd oors, too. Remember tha t gaso line vapo r is heav ier th a n a ir, a nd will spill down the basem ent sta irs until it finds the pil o t lig ht for th e water hea ter. Poof! Spea king of fl a mmab le, don't even think a bout work in g o n an electric fue l pump until yo u' ve di sconn ec ted th e nega ti ve bartery cabl e. O n so me ca rs, the ta nk is a bove a rea r-suspensio n subfram e, so access requires unbolting it. Once yo u've go t access, th e actua l remova l a nd install a ti o n is pretty st ra ig htforwa rd. Special spa nn ers a re ofte n recomm end ed for unscrew in g the pump asse mbl y locking ring, but we' ll bet you 'll fi gure so mething o ut. Ju st make sure yo u ge t th at sock o r strain er o n th ere right. G

181

ASY

I

Eliminating Battery Drain t's a fa miliar feeling, tw isting na l res ista nce is very high, and th e ke y a nd be ing rewa rd ed ma ny sma ller chargers wo n't supw it h little more th a n a g roa n pl y eno ugh vo ltage to get ove r th e fr o m th e sta rter. Yo ur mec hanic hump (Fig. 1) . There a re p rofesdi ag no es it as no thing m o re tha n sio na l c ha rgers th a t sta rr o ut with a tired ba ttery, a nd a sim p le tra nswe ll over 12 vo lts (typica ll y 18 to pla nt cures the p ro blem . It's deja24 volts ) to break through, a nd vu, as yo u've hea rd the sa me thing yo ur trickl e cha rger (or even a every w inter-yo ur ca r's ba ttery reasona bl y decent homeownerneeds rep lacem ent o n a n a nnu a l model c harge r) just w o n't ki ck bas is. It's tim e to get to th e bo to ut th a t muc h. Yo u'll have to ta ke to m of the prob lem. the ba ttery to a se rvice sta ti o n G iven no rm a I circ um sta nces th a t has a premium ch a rge r. If yo u insist on trying to use your own a nd use, a car ba tter y sho uld last fo ur to fi ve yea rs or mo re. Sure, sm a ll cha rger, it may ta ke several days. Remember that the das hthere's a warra nty, but it's typiboard ga uge rea ll y doesn't tell yo u cally pro ra ta, w hi ch mea ns tha t (Fig. 1) Inexpensive low-current trickle chargers may not revive a completely discharged battery. much. Check the voltage ac ross unl ess the ba ttery di es a n a lm ost th e ba ttery termin a ls wh en yo u' re in sta nt dea t h, a ll yo u w ill get is a do ne (cha rge r off a nd headlig hts o n nect a trick le c harge r overni ght, a nd p arti a l credit towa rd the pri ce o f a fo r 15 second s to re move a "s urface t hen conclu de t he nex t da y th at t he new o ne. cha rge" ). It sho uld be at least 12.7 battery ca n't take the charge . But Th ere a re a lot of rea so ns w hy a vo lts, prefe ra bly a bo ut 12. 8 vo lts. there's a fl aw in this approa ch : If a car ea ts ba tteri es . If yo u' ve had hard Eve n if your battery isn 't so runmodern low-ma intenance ba ttery luck w ith the on es yo u've been bu ydown th a t it needs brea kthrou gh voltgoes sto ne dea d for some reaso n, it ing, th e p ro bl em a lm os t surely is no t age to sta rt tak ing a charge, it does ma y need a rea l jolt to accept a th e fa ult o f th e ba ttery m a nufac tu rneed good co nn ecti o ns fro m th e cha rge. The di scharged ba ttery's interers. O h, th ere's a n occas io na l dud , c harger. Un fortun a tely, but mos t o f th e tim e th e th e side-termina l ba tter y reaso n is in th e car itse lf. has a small contact area Dee p-di sc harging a fe w for th e cable's alligator times w iII damage a ba tclip . Unless you have a tery, a nd so w ill co nsta nt sp eci a ll y shaped clip, you over- o r und erc ha rging. really need a charging adapter, made o f copper, All Charged Up th at cl a mps all the way First, mel ke sure th e ba ta ro und the side-terminal tery reall y is da maged contact a rea (Fig. 2) . before yo u spring for a If the battery ta kes a new o ne. The simpl est test charge but runs down in is to full y charge it a nd see use, there's a pro bl em that if it takes t ha t charge. If it has to be t raced . Othertakes a cha rge, it's still wise, th e car will seem to good-b ut if it doesn't, it ea t the next ba ttery, too, mu st be bad. eve n if it's a hi gherH ere's w here we get to ca pacity model. the procedure th a t co nNow tha t the battery is vinces ma ny Sa turd ay charged , you ca n check mech a nics tha t th ey need (Fig. 2) It may be necessary to use a battery-charging adapter to the charging voltage . With let the jumper cables get a good bite on side-terminal batteries. a new ba ttery. They con-

I

182

ELECTRICAL AND

ELECTRONIC

SYSTEMS

PARASITIC-DRAW ADAPTER

th e en gin e runnin g a nd wa rm and a ll the power-consuming accesso ries switched off, the voltage across the battery should read at least 13. 8 volts. Next, turn on the hea d lights and rear-wind o w defroster, and set the heater/air-conditioning fa n o n hi gh. Th e voltage sho uld still be above 13 .5 vo lts. An ythin g less means you may have a malfunctioning alternator.

When demand exceeds supply Let's see if yo u 're pulling mo re juice than th e charging sys tem ca n repl ace during your normal driving cycl e. If you ha ve a high-perform ance sound system and a cellular ph one, and run other accessories, thi s kind of usage really sucks a mps. But you

ELIMINATING

BATTERY DRAIN

still sho uld be okay-if yo u drive th e ca r fa r eno ugh. A half-mil e in the morning with the alc on a nd a halfmile back ho me at night with th e alc a nd li ghts on, perha ps w ith yo ur fav o rite CD bla sting thro ugh the spea kers, is a grea t recipe fo r battery rund own. Dri ve yo ur car lo ng eno ugh to pa y ba ck th e battery for w hat you 've borro wed , plu s interest, at least once a wee k. In additi on, tod ay's cars p ull a fair a mount o f current even wh en eve rything see ms to be off, just to keep a li ve the memo ri es for all th e electro nics: th e engine computer, key lessentr y receiver, th e radio presets a nd the a larm system, to name the most common. To keep the dra w from depl eting the battery, the electronics a re sup-

(Fig. 3) An inexpensive parasitic-draw adapter can simplify the diagnosis of key-off current-drain problems. Connect it in series with the battery's ground lead.

posed to go into a dee p slee p, during w hi ch th ey require o nl y a few milliamps. If th ey do n 't ta ke thi s snooze , th ey can add to th e current loss. To check, di sconnect th e battery gro und ca ble. In stall a p a ras iti c-dra w ada pter (Fig. 3) in se ri es with th e battery and ca bl e termin a ls, th en co nnect an a mm eter to the termin a ls. O pen th e ad a pter to see if th e draw is less th a n 50 milliamp s. Norm a lly, yo u ha ve to wa it until th e electronics go into sno oze mod e, which can take 60 to 70 minutes on some cars. Until then, th e curre nt draw may be sev-

183

j,' L ."' -.' " 'j";"~'

ca use a battery to go dead ~:"~-;i ~~~=----......, in ho urs. More like ly, , ) th ere's a sma II -to- med ium draw t hat's bleed ing the e ,,-'_'~ .~" ~''{:'; ::G system, or a charging system that's not performi ng BATTERY HOLD DOWN up to speed. Sometimes, you ca n spot t he problem if yo u look h a rd. Many cars have interio r li ghting de lays, but occas iona ll y a key part of t he delay system doesn't shu t down . It might not be t he in-plain(Fig. 5) Check and t ighten the holddown view do me light, but pert o keep the battery from vibrating. haps the das h board lights or so me floor lig hting. If the door open ing a nd connect an t hey're still o n 15 m inu tes o hmm eter (Fig. 4) fro m t he sw itc h after the dome li ght is off, ter mi na l to its meta l bracket, w hi ch yo u've fo und a circu it provides th e grou nd. T he oh m meter (Fig. 4) Check the dome-light switch for intermittent glitch . For insta nce, 1990 sho uld rea d cl ose to zero (a co up le of or abnormal resistance with an ohmmeter. to '91 C hevy Lum inas had ohms is okay) . Repea tedly press the a p ro blem ca used by a n sw itc h plunger part of the way and era l hund red milli am ps, o r even as electrica l feedback fro m the radio. see if t he o hm meter rea ding goes to m uc h as severa l a mps . Eve n t ho ug h t he electronic timer sai d infi ni ty (fu ll y off pos itio n ). If it takes H oweve r, even if the d raw is near "Lig hts out!" a nd o th er bul bs were a lot of plunge r trave l, or if t he 50 milli a mps or so when yo u act ua ll y exti ng ui shed, th e instr um ents contin plu nger respo nse is in cons istent, the take your rea di ng, it m ig ht be far too ued to glow. swi tch is proba bly bad. high befo re the snooze, or perhaps t he T he lights for the glove box, lugA lso check fo r a sticky rad iator/ electro nics are awa ke for fa r too long . gage compartment and hood are o ut con denser fa n relay t ha t k eeps the fa n So, next, wake up the electro nics a nd of sight unl ess t hose areas are open, in going w it h the ignition off for a see w ha t the rea dings are. longer period of time t ha n any co mw hich case t he li ghts are supposed to To do tha t, disco nn ect t he a mmebe o n. Peek in sid e as yo u just li ft t he pu ter strategy dictates, until it fi na ll y ter fro m the parasitic-d raw adap ter. cover, deck lid or hood sligh tl y to see pops open . In fac t, th e re lay co uld if t he light already is on or just comkeep t he fan on unti l t he battery is Connect a ba ttery booster cab le from dead. Look a nd liste n fo r t hi s o ne. th e battery termin al to t he ca bl e tering on. If it's co nsta ntl y o n , t hen minal, bypass ing the adapter. Turn t he yo u've fou nd yo ur cul pri t. A bad doorj amb switch ignition key to the run (not to start) positio n . Wait a few seconds, then can cause a lot of problem s. If it's turn the key back to lock and take it making intermittent cono ut. Reco nnect the a mm eter, d iscontact, it's repeatedl y waking nect th e booster ca ble a nd ta ke t he up t he elect ronics and curre nt-draw read ing, w hi ch sho ul d tu rn ing o n the interi o r be the awa ke n um ber. If the awa ke n umber is accep ta ble, lights. The simplest overa ll make sure the electro nics go to sleep check is to rem ove the w ithin a reasona ble am o unt of time. fuse or fuses for the courIf the electro nics still are awa ke and tesy lamps to see if the pulling hund reds of milli am ps- or battery stops running even an amp or more-h o urs later, som ething is very wro ng. Yo u can iso- down . If th a t see ms to be a p ossibl e cure, check ou t late a hi gh curre nt draw to a spec ific .. ....... each doorja mb switch . circ uit by pullin g o ne fuse at a time D isconnect the ba ttery and rechecking. Just m ake sure the gro und st ra p , then (Fig. 6) Make sure the ground strap is connected ignition is off. and in good shape. It 's often hidden and neglected. re move th e switch from A hi gh-cunent-draw ing sho rt w ill ".• '

184

ELECTRICAL AND

--; • • rJ"

ELECTRONIC

SYSTEMS

Rocking the Boat If the current draw is acceptab le and the issue seems to be that the battery just suffered from short life, make sure that th e battery case is in good condition and the ba ttery holddown is tight (Fig. 5) . Even a slightly loose battery can vibrate enough to suffer a short life. Ju st because a top holddown looks tight doesn 't mean the battery ac tu a ll y is secure. See if it rocks, even a littl e. Many holddowns are against a bottom lip on the battery, almost out of sight, so if the battery mounting isn't rock solid , check a down-low holddown. Are the cables in good shape and securely tightened? T he a lternator ma y be pumping, but if the cable connections are bad, the juice won't actu ally get to the battery. The battery gro und usually is the big offender. In some cases, there's a split gro und cable, and you can see one of the cable ends, in plain view and clearly tight. But th e oth er part of the ca ble (usua ll y the one to the engin e) is buried deep, and what's o ut of sight shou ldn 't be o ut of mind. Find

ELIMINATING BATTERY DRAIN

BATTERY

(Fig. 7) Check all three ground points on this type of ground strap for corro· sion or looseness.

it, and put a wrenc h on it to see if it 's snu g (Fig. 6) . Many cars have a separa te ground strap between body and engine, and it's usually nowhere near the battery (Fig. 7). In fact, if it's underhood, it's often dis-

connected for service and never reco nnected. So the car's electrica l system "forces" the juice through less effici ent routes, and the battery is one of those that suffers . We've even seen engine-tobody ground straps that actually ran from the transmission to some part of the underbody. These gro und straps fray, come apart and are fa r from any place you normally wou ld look. So if yo u don't see a cl ea r-cut route from the battery nega ti ve (ground) termina l to both the engine and the body, look again- everywhere. Some old er Ford products have a single grou nd cabl e to the engine, but w ith th e in sul ation stripped at midpoint, a nd the bod y gro und made by a clip from the stripped section to the fe nder-well sheetmeta I. Okay, the ba ttery takes a charge and the cabl e connecti ons are good. Well, perhaps the accessories yo u use are simply pu lling more juice than the car can provide in yo ur short-trip operation. A regu la r d iet of trick le charging every night shou ld pro vide the vitamins yo ur battery needs for a normal life span. t6

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[ G EASY

Replacing Headlights Ou're cruising down a 2-lane road la te at night. Oncoming cars flash th eir li ghts a nd toot th eir ho rn s a t yo u. Or they co me stra ight a t yo u a nd suddenl y vee r away. No, th ey're not partied o ut. Unless yo u're blinding them with yo ur high beams, o ne of yo ur hea dla mps probabl y is out. R eplacin g burn ed-out hea d la mps is a stra ightforwa rd procedure, if th e probl e m is just th e head la m p. Alth o ugh most are abo ut $1.5, some head lamps are specia l numbers, avai la ble o nl y from a dea ler and can cost up to $45 apiece, even for a n eco no box. And there are even highertec h (a nd hi g her-pri ced ) syste ms, such as Hi g h Intensity Discha rge (HID ) hea dl a mps, in so me lu xur y models. Th ey ma y loo k li ke ordin a ry head la mps-just as h alogen sea led beams resemble the conventional sea led bea ms used years ago-but th e manufactur ing processes, th e coa tings, the materials a nd th e gases used in sid e th e bulbs are totally different a nd produce to ta ll y different lig htin g. Don't leave in a head lamp with a cracked lens just beca use the light hasn't gone o ut. Even if only a sma ll part of the lens is missing, dirt gets in and coats the bulb inside, wh ich reduces light o utput. And if there's a chun k missing fro m the lens, the light bea m isn't diffused as it sho uld be and can blind oncoming d rivers. With normal vehicle vibra tio n, the lamp also may not hold its aim and yo u won't get the best view of the road. Also read " Servicing Composite H eadla mps on page 149.

Y

Circuit Check If it seems th at a hea dla mp is burned o ut, make a simple circuit check. With just one of two or four on th e blink, the odds are that the sealed beam is the problem. It's unlikely tha t two hea dlamps wi ll go out simultaneous ly.

186

(Fig. 1) If the trim bezel screws are hard to turn, use penetrant to loosen the threads.

held by eith er Phillips or Torx external screws. A few may be on stu ds that project through to the back of the lamp asse mbl y-th ese are access ible fro m und er the hood. Next, look for a nd remove th e four screws holding the head lamp rim o r beze l. Be carefu l not to confu se th em wi th t he screws that control head lamp aim-the o nes w ith coi l springs under the screwheads. Are the screws rustfrozen in place? Don't try too hard to turn them, or yo u ma y strip o ut the

(Fig. 2) Use a simple 12v test light to confirm operating power and ground circuits before replacing an expensive bulb or sealed beam.

Of course, if the low a nd the high beams are in a sin gle bu lb, it is possible, but it's much less lik ely w hen they're separate li ghts. Check ing or changing a burnedout head lamp begins w ith ga ining access. If it's a sealed beam, there's probably a trim pla te in front, which co mes off first. Most trim plates are

screwhea ds. Spray them with penetra tin g so lve nt a nd all ow it to soa k in (Fig. 1) . The attachm ent screws usua ll y have a Phillips hea d, but-like the tri m screws- t hey may be To rx. Once the rim is o ut, pull th e sea led beam forward and unplug the wiring connector from the back. Yo u' ll see twO or th ree terminals o n the la mp

ELECTRICAL AND

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a nd connector. A 2- head la mp system a lways has th ree term in a ls. A 4-eye la mp ma y have two o r t hree, depend in g on how the entire circ uit is w ired . A simpl e check of th e c irc uit is to see if there's power at the connector and a complete electrical gro und. Take a n ordin ary 12v test light (Fig. 2) , connect th e a ll igator clip end to a gro und a nd check eac h connector termin a l with th e probe. T he hea dl a mps sho uld be turned o n. T he test li ght sho ul d go on in at least o ne termin a l. If the sea led bea m is a 2-eye with three terminals, flick on the high beam sw itch a nd the test li ght sho uld go o n w ith the p ro be in a second o ne o f th e three term in a ls.

Nex t, un ground th e test light a nd gentl y press th e a lliga to r clip end (w ith a na il in serted, if necessary) to make contact w it h the other (grou nd w ire ) terminal-gro und is usuall y a bl ack w ire. The test light should go o n aga in. If the test lig ht goes on during th ese two checks, install the new sea led bea Ill. If it d oesn 't, forget th e in sta ll atio n until th e circ uit prob lem is rep a ired. If th e tes t lig ht went o n w hen the a lligator clip was connected to gro und, but not when yo u probed t he o ther connector terminal for a complete gro und , the probl em is a defecti ve gro und connecti o n-a comIllon prob lem . C heck a facto ry Illa nu a l o r after-

ma rket in fo rm ation system , such as www.a lld a ta.co m . for the loca tion of yo ur car 's gro und. [f the conn ecti o n is corroded, w ire-b rush it cl ea n . [f it's loose, retighten it. No power to th e hea dlamp connector? Th a t can be more difficult to trace, and yo u' ll need a w irin g diag ram a nd parts locato r aga in . A new circuit co mplicatio n is o n th e scene: day tim e runnin g li g hts, or DRLs. These may be th e low- bea m or hi gh-beam hea dl a mp s, or o ther extern a llights such as tLirn signals. H ead la mps are wired in w hat is ca ll ed a para llel circ uit-each lam p receives full battery vo ltage . However, if yo ur ca r is a newer-th a n-' 96 mo del

HOW IT WORKS

Quartz-Halogen Sealed Beam The conventional sealed beam of years ago had a tungsten filament inside a lens assembly with a reflector. Today's quartzhalogen beam is a separate bulb inside that lens assembly. It produces a brighter, whiter light-at least 25% more downthe-road visibility, with less power draw. The bulb envelope is a high-temperature glassthe "quartz." The filament material is the familiar tungsten, but the bulb is filled with a special gas from a "family" called halogens, such as iodine or bromine gas (that family also includes alc refrigerants, by the way). In a conventional sealed beam, the high temperature of the tungsten filament causes particles of the metal to vaporize from it. The particles deposit on the wall of the conventional sealed beam (darkening it), and eventually the filament burns out. The quartz lens allows the bulb to operate at a much higher temperature to help produce that brighter, whiter light. The halogen gas inside the quartz envelope causes the "evaporating" tungsten particles to continuously redeposit on the filament, so it enjoys long life and consistent brightness virtually until it fails. Headlamp technology is fast-moving. The High Intensity

REPLACING

HEADLIGHTS

Discharge lamp (see page 150) is just one of the new approaches, but It's already installed as a low beam in some BMWs and Mercedes-Benzes and the Lincoln Mark VIII. This type has no filament, but instead it has two electrodes in an "atmosphere" of xenon gas. The current jumps the gap between the electrodes, producing a comparatively brighter light. You may have already seen these lights coming at you out on the highway. They're so white that they appear a little blue. But because there's no filament to burn out, the hour life of the xenon bulb is expected to go into six figures. There are several other new headlamp designs on the market, including one on the '97 Lexus ES 300 that uses multiple reflectors. All the new lamps-including the high-performance halogens-are capable of producing a lot of brightness with reasonable power consumption. And introduced in some 2003 models are "smart" headlight systems that use signals from sensors to pivot the headlamps side to side for the road conditions and the way you're driving the car. These combination bright/smart lights are in part a technological fix for the declining night vision of a graying population.

187

(Fig. 3) Newer cars use bulbs that can be replaced without using tools. Unscrew the socket from the reflector and change the bad bulb, then replace the socket.

with da ytime running lights and the head lamp high bea ms are used, there's a seco nd circuit controlling them throu gh an electronic modul e. The hi gh beams could be wired to th e modul e so that they ca n be fed current for DRLs in a series circuit-the current fl ows th ro ugh both, so that one acts as a res istor for the other. The res ult is less brightness, but also less current flo w for red uced p ower consumption . If you have a probl em w ith th e high bea ms, a defective DRL modul e is o ne of th e new possibiliti es of w hich yo u sho uld be awa re, both for sea led beams and rep laceab le bulb designs. Som e cars ha ve DRLs that are also designed to shut off when the parking bra ke is a ppli ed. Read those circ uit descriptions ca refull y!

Replaceable Bulbs Many late- model cars have a rep laceable bulb plugged into th e back of the lens asse mbl y

188

(Fig. 3) instead of th e sealed bea m.

(European cars ha ve always used this type.) Typica lly, the bulb has a wiring conn ector held by a pl astic lockta b, and a plastic lockring to ho ld the bu lb. Pry up the tab (w ith a thin screwdri ver, if necessary) and ho ld it up as you p ull the harness conn ector off the terminals on the bulb . You ca n probe th e harness connector the same way as on the sea led-beam design to make

sure the bulb is at fau lt. An a lternative: If the bulb is easy to remove, take it o ut for in spection. Turn th e plasti c loc kring, w hi ch may come o ut or stay loosely in pla ce. Then gra sp the bulb by its connector and gently rock it out (it sea ls w ith an O-ri ng to keep out dirt and mo isture). If the bu lb fil ament is burned o ut, that te ll s yo u it's most likely th e problem. Warn ing: R eplacea ble bulbs are usua lly qu artzhalogen-and touching the bu lb w ith yo ur fin gers will lea ve fin gerprints that w ill crack the quartz glass with in a few ho urs. The new bulb will be wrapped in cardboard or fo am, so don 't remo ve the wrapp ing until last and avoid touching th e bulb. Too late? Clean th e bulb with a lcoho l and a clea n cloth. When yo u insta ll the new bulb , work it in very carefull y, th en push smoot hl y to sea t it in th e lens ho using. Thi s ensures th at the O-ring sea ls proper ly instea d of bein g twisted or dis lodged. A bulb or sea led-bea m harn ess connector may have a ribbed-rubber moistu re sea l if the locati o n poses a problem with road splash . When yo u see thi s setup, make sure it enters the bulb connector uni form ly and seats evenly. Replace it with the same type of bulb or sealed beam as the one that came out. You may see high-performance versions of the type yo u removed on the auto parts store she lf. If yo u wa nt to insta ll one of these instead, replace the one on th e other side too , for even lighting. (I

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~

ASY______________

Replacing Your Car's Computer plug, w hi ch is under the das h or un der the hood. C heck yo ur serv ice ma nu a l. O n la ter models meetin g O BD II o nboa rd di ag nostic II regul atio ns, yo u need a sca n too l. Mo re o n O BD II la ter in thi s sectio n. Ju st a single code? Check th a t pa rti cul ar item, w hether COMPUTER-SAFE it's a senso r, sw itch, moto r o r TEST LIGHT so leno id. Th e ma nu a l w ill give yo u a " di agnostic tree," a seri es of step s to fo ll o w, typi(Fig. 1) Check the feed with a high-impedance ca lly using a jumper wire a nd voltmeter or a computer-safe test light. a computer-safe (high-impeda nce) m ul timete r to iso late th e pro blem (Fig. 1), w hich co uld be in th e pa rt itself o r so mewh ere in its wi r ing circuit. Or yo u ca n use a se nsor tes ter (Fig. 2) , w hich comes w it h ada pters a nd/or specia l ti ps so yo u ca n probe wiring connecto rs. Correcting a pro blem in a ny circuit tied to the computer is a n essenti a l first step in every case, as it ca n be respo nsibl e for a comDiagnosis puter fa ilure. Before you do act ua l bra in In ma ny instances, the d iagnosti c "., surgery o n your ca r, you have tree will concl ude w ith RE PL ACE C01'" I '. ~ '. to find o ut if th e engine is perPUTER. Yo u a lso co uld be led to th e . ,, :. ,I ', fo rming poorly becau se the co mp uter if there's a fli ckering CH ECK bra in is bad or if it's jus t ENG I:--.IE light, o r no light a t all (but the (Fig. 2) Check sensors with tester or voltmeter respo nding to a " bad case of to rule out noncomputer problems. bul b is good ). nerves" (bad signa ls fro m elecStill a noth er poss ibility: a tro n ic senso rs). la undry li st of tro ubl e codes. It coul d sim p ly be a blow n engin eIn ma ny cases, th e pro bl em is co mp uter circ uit fuse, but if no t, it's in w ha t's ca ll ed a d river, a type time for diag nos is. For thi s, refer to of electro nic sw itching dev ice yo ur vehicle's service m a nu a l-either tha t is in the computer box. a fa ctory ma nu al o r an afterm a rket H ow ever, it isn't replacea bl e, m a nua l w it h a co mpl ete engineso if it's bad , the o nl y cure is a co mp uter d iagnosti c secti on. new co mputer. C heck for di agnostic tro uble codes. Alth o ug h t he proced ure va ries Minor Surgery fro m car to ca r, o n m ost p re-1996 Co mputers t ypi ca ll y have ve hicl es there's a w a y t ha t doesn 't been loca ted under the das hinvolve specia l equipment. Typically, board, accessible after yo u make a simple jumper-wire conre m oving a trim p a d o r th e (Fig. 3) Some early Chrysler computers were necti o n a t the computer's d iagnosti c housed in an air duct under the hood for cooling. g love box o n th e passe nger's xperiencing bad engine performa nce? Yo ur ve hicle may need bra in surge ry, a nd beli eve it or no t, it's so meth ing a n expe ri enced Sa turday mecha nic can do . Yes, we're ta lking abou t the powe rt ra in comp uter-the " bra in " behind the o perati o n of yo ur engine, tra nsmission , even the a ir conditio nin g. Today, yo u can order a co mp uter fro m yo ur neig h bo rh ood parts store, w hi c h ca n c hoose o ne from a long li st of reli ab le a fter m arke t sup pli ers . T he co mputers are reconditi o ned, a nd in ma ny cases yo u change over a program m odul e, w hich ho ld s t he sp ecific ca libratio n instru cti o ns for t he powertra in , such as igniti o n timin g. If yo u're ca reful , yo u ca n do th e jo b. In fac t, in ma ny cases yo u' ll fi nd yo u do n 't have to repl ace t he computer, but ca n perfo rm a lower-cost o r even a no-cost " mino r opera ti o n ."

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REPLACING YOUR

CAR'S

COMPUTER

189

side. O ld er Chrysler compute rs usua ll y are under the hoo d, integra ted into a n engine a ir-inta ke duct, but th ey were a n exception for the 1980s (Fig. 3) . Today, an d as th e electro ni cs have become mor e hea tresi stant, ma ny comp uters a re located under the hood. Wherever the computer is located, the first steps are to turn off the ignition and di sconnect the battery gro und ca bl e. Next, unplug the co mputer's wirin g co nnector. It often has plastic latches or locking tabs, so you sho uld look carefully before yo u try to pry anything off and press tabs or latches wherever necessary (Fig. 4) .

190

Eyeba ll the terminal s in the computer and the wiring connector, looking for both co rrosion and signs of bending. You ca n try to straighten a bent pin-but no rough stuff. And don't try to sa nd or scrape off corrosion, or yo u' ll ruin the terminal. Brace the termina l w ith your fin gers and clean it w ith a pink pencil eraser. If everything looks good, start putting the connector back on by working it back and forth a few times, then push ing it a ll the way home. Thi s may clean off a small amount of virtually invisibl e corrosion (enough to create ha voc with electro nics and produce multiple trou ble codes) and get the computer sys-

(Fig. 4) Once you've determined that the computer is really fried, replacing it is simple. It's often situated under the dash or behind the passenger's-side kick panel. There may be a locking tab holding the computer's umbilical connector in place.

tern working aga in. If the problem comes back, well , at least you tried. Back to di sco nnecting the computer. W ith th e w iring connector off the computer, probe the connector's termina l for the gro und wire w ith a compu ter-safe test light or multimeter (set to volts), connected to a 12-volt so urce (either at the battery or at the fu se box). The test light should go on to fu ll brightness, or the meter sho uld

ELECTRICAL AND

ELECTRONIC

SYSTEMS

rea d batte ry vo ltage . Also check the 12-vo lt powe r fee d (or feeds) in the connector with a gro unded test light o r vo ltmeter. T he res ults sho uld be th e sa me. If yo u get a low-voltage rea ding o r a wea k light, there's a bad connecti on. W hatever the res ult, a lways do ubl e-check a ll electro nic ground s.

Brain Transplant Is it a clear-cut case of a bad co mp uter ? O rder the replacement and ma ke the module changeover, if necessary (Fig. 5). General Motors ve hicles and most European cars have computers w ith a plug-in progra m modul e, which doesn't come w ith the rep lacement co mputers. In fac t, so me have two modul es, and yo u have to change ove r both. Remove the mo dule cover, then ta ke o ut the mo dule. Some of them are held by re tainers- push them bac k a nd simultaneou sly lift the modul e stra ight up and o ut . W ith mos t o th ers, yo u have to pry it o ut, a nd th e sa fes t way is with thumb a nd fo refinger at t he end s, app lyin g a n ever-so -sli ght roc king up ward mo ti on . The typ ica l m odule is in a plas ti c carrier (don 't try to sepa ra te th e p ieces). If space is to o ti ght fo r yo u r fingers, use two sma ll screwd rivers- one at each end-to rock th e mo dul e asse mbl y up as eve nl y as p oss ibl e. Do not p ry one sid e up o r yo u may bend the terminals. Note the way the module comes o ut, as it has to go into the new computer the sa me way. It's poss ible to in sta ll it backward on some cars, whi ch co uld destroy the new co mputer. Pos iti on the module o n the mo untin g area of the repl acement co mputer, push slowly (so yo u k now that the terminals are lined up fo r engagement ), applying press ure o nl y

REPLACING YOUR

CAR ' S COMPUTER

co mpensating adjustments (primar il y to fuel-system ca librati o ns). So be prepared fo r perhaps 100 miles or 4 to 5 ho urs of so-so performance as the new computer (even w ith an old program modul e) learns how to do its job. Thi s is something to keep in mind if yo u are doing a test run to see if o ne of the mino r opera tions (clea nin g corrosion, tightening a gro und and so on ) fixed a (Fig. 5) You may need to remove your old calibrapro blem. D isconnecting the tion module and install it in the new computer. battery ca ble erases the tro uble codes. H owever, if th e fa ults re ma in , most tro uble codes on th e end s of the mod ul e, un ti l it show up aga in withi n a ha lf-hour of sea ts. Lock the ta bs. ve hicl e operati on, even though it Reco nn ect t he w ir in g harness t o takes much longer for overall engin e the computer. If yo u' re wo rkin g performance to re turn to normal after under the da sh, yo u may build up a lo t of static electri city w hil e slid ing a successful fix. All models since '96 have computers into wo rki ng p os it io n. As yo u ma ke that confor m to O n-Board Diagnostics the harness co nn ecti o n, yo u co uld II (O BD II ), an enhanced computer sysza p th e co mputer w ith eno ug h vo ltage fro m the stati c electri city to fry tem with some sta ndardization of trouble codes and diagnostic ro utines. O ne it. Simpl y gro und pa rt of yo ur bo d y scan tester (computer-system data anato a n und erd as h grou nd , suc h as by keep ing a bare elbow aga in st a lyzer) will fit the underdash diagnostic meta l brace. plug on all OBD II cars, and there are Make sure yo u not o nl y sea t the models for Sa turday mechanics for w ir ing connector, but th at yo u cl ose under $200 (see page 181). any latches that ho ld it in posi ti on. Th e OBD II co mputers o n ma n y Rein sta ll the co mputer, engagi ng a ll ve hi cles a re repr ogra mmable clips and tightening all bo lts, screws thro ugh th e di ag nos ti c plu g. With and nuts so the computer is held prev io us sys tem s, ca rmakers offere d securely in position. fa ctory fixes by havi ng the d ea ler Reconnect the ca r battery. The repl ace th e co mp uter or the progra m install ation instructi ons w ith the m o dul e. W ith th e speci fic OBD II rep lacement comp uter will provide a system , th ey now ha ve the d ea ler basic test of th e system (s imil ar to simpl y rep rogra m th e computer. A checking for tro u ble codes), and once few cars have had rep rogr a mma bl e th at's done, yo u sho uld be rea dy to co mputers in pas t (pre-OBD II ) dr ive . But all modern engine co mye ars, but w ith OBD II, it 's bas ica ll y puters must go thro ugh a per iod of across th e boa rd o n U .S. namepl ates " learning " how yo u dri ve and making and mos t im po rts. ~ COMPUTER

191

EASY

Curing AlC Odors

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(Fig 1) The simplest cure for odor is to run the air conditioning in fresh-air mode to lower humidity in the evaporator plenum.

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t's a swelteri ng day. You get behind the wh eel, start the engin e a nd hit th e ma x alc button. But instead of refreshingly coo l air hittin g yo u, there's a blast that smell s li ke a basketball team's locker room after a hard game. Your car's a ir conditioning is suffering from what could be ca ll ed "jock socks odo r." And yo u're no t a lone-it's o ne of th e most commo n co mplaints that Popular Mechanics rece ives from rea ders . If yo u ta ke the car in to a dea ler, he' ll tell yo u it's a fun g us growth in the under-da sh alc case that ho ld s the evaporator. Tha t's the hea t exc hanger tha t pulls the BTUs o ut of the passenger compartment. His so lution is a n expe nsive clea nout of th e alc with disinfecta nt. And after yo u've spent a lo t of mo ney, th e smell is gone- for a wh il e. It ma y be back befo re th e air conditioning season is over. Is there a less costly and mo re dura ble w ay to fi x it yourself? Ca n yo u preven t th e prob lem fro m occ urrin g in th e first pl ace? The a nswe r to both questions is yes.

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The price of p reve nti o n is free, and th e most impo rta nt ste p doesn't even req uire a too l. .lust do n't use ma x a/c. lf yo u have a ca r w ith a n a ir-recircul ation sw itc h o r lever, JUSt move it to the outside-air pos iti o n (Fig. 1). The evaporator case is a humid environ-

ment beca use it's w here the air is dehumidified (as well as cooled ), a nd w hen yo u shut off th e engin e, hea t build s up insid e th e evaporator housing. A ho t, humid environm ent w ith sta gna nt a ir is th e perfect setting for fung us growth. The recircu la ti o n switch cl oses o ff o utside a ir, and causes th e alc to mere ly recirculate the ai r in th e p assenger compartment. With little or no entr y of hot o utside a ir, th e interi o r gets coo ler faster a nd remains mu c h co lde r. It's okay to use rec irc ula ti o n to help w ith th e initia l coo ldow n o n a swe lter in g day, but after a few minutes, yo u shou ld shift o ut of recirculation to bring in fres h a ir.

(Fig 2) An evaporator-tray drain that's plugged with dirt and debris might keep moisture from draining onto the ground.

192

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(Fig. 3) There are effective and ineffective cures for alc odor. This aftermarket disinfectant works when sprayed directly onto the evaporator core. Before spraying, tape over the blower resistor opening (illustrated), making a small opening for the straw.

Many manual a nd automatic temperature-contro l systems are in recircu lation when in ma x alc or a t the lowest temperature on the a utom a ti c sys tem's dial. In this insta nce, you should also shift to a sli g htl y war mer se tting.

Garbage Collection The nex t step is to lift the hood a nd inspect the a ir intake at th e cow l. If it's packed w ith leaves a nd other

d ebris, yo u ma y ha ve a miniature compost pile forming. The odors from it are drawn into th e passenger compartment by the blo wer fan. These od o rs a re equ a ll y unpl easa nt, a nd yo u wil l need to dig o ut the debris or clean it up w ith a shop vacuum and was h o ut the area to get rid of th em . After you've cleaned it, remove the a ir-intake grill e, in sert a fin e window-screen mesh underneath, sea l the perimeter with p lumber'S putty, then refit the screen. Periodica ll y c hec k the sc ree ned a rea a nd remove d e bri s to ens ure a fresh a ir s uppl y. Most late-models have a n intake a ir filter tha t removes smoke and pollen from the o utsid e air. These fil ters a lso keep o ut d eb ri s

and ma y ha ve a rep lacement interva l of typically one yea r or 15,00020,000 miles. When yo u 're do ing an o il c hange or o th e r regular maintenance und er th e hoo d , in spec t th e eva po ratortray drains (Fig. 2) , which a re o ne o r two hoses on most ve hicl es. [f the hose end s are plugged or badl y d a m aged, the moisture that the evapora tor wrings from t he interior a ir wi ll no t drain properly, leav ing a stagnant pool for fung i. Dig out any road film with a thin screwd ri ver. Many hose end s have built-in c heck va lves, w hich shou ld be carefu ll y in spec ted for d amage . T h e e nd s are specia ll y shaped , so d o n 't trim them flat with a razor blade. Open the chec k valves ge ntl y, and if th e e nd s

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A I C ODORS

193

are n Ot dam age d or plu gge d, leave th e m a lo ne. If th e end s are dama ge d , how eve r, th e bes t route is to rep lace th e hose . Th e next step is at th e eva porator case . But before you do a ny work, check w ith the car dea le r to determin e if th ere's a spec i fi c facto r y so luti o n th at goes beyo nd di sinfecting a nd o th er steps we ' ll be coverin g. Fo r exa mp le, ma ny 1985-94 Cadi ll acs have evaporators with such ti ght spacin g betwee n the fins th at th e eva porator h o ld s too much moisture, increasing fung i growth . General Motors h as rep lace m ent

194

evapo rators that may decrease coo lin g a few deg rees, but drain mo isture m ore readily. Late-mode l C hrysler products since 1992, pa rticularly mini va ns, have been known to suffer fr o m a irconditioning odor. It doesn't smell like dirty socks, but it is o ffens ive, a nd the ca use is an overl y thick coa tin g of a corrosion trea tment. H ere aga in, the o nl y fi x is a new evapo rato r. See yo ur car dea ler. For th e overw helming majority of cars, the trea tm ent is to disinfect th e evaporator case. Som e shops use expensive profess iona l equipm e nt

th a t ta kes seve ra l hours to use correctly. It 's t he best trea tm ent , but it's fa irly cos tl y. You can save so me m o ney a nd ge t very good resu lts with a quality handhe ld di sinfectant spray if yo u work careful ly (Fig. 3) . A ho use hold disinfectant suc h as Lysol ca n be used, bur it isn 't m a de for this prob lem, a nd any resu lts will be too s hort- li ve d to ju stify th e effort. Listerin e w o n 't work either, desp ite th e fac t that it 's ofte n rec o mm end ed by people who do n 't k now a n y berter. Th ere a re severa l products you' ll f ind in auto accesso ry stores, a nd

ELECTRICAL AND

ELECTRONIC

SYSTEMS

those with w hi c h we're work in g outdoors is a fam ili ar see m to work to goo d id ea, too . some degree. T he o nl y o ne we know th a t has a sucThe Afterblower cessfu l trac k reco rd is a n Solution expe n sive ae ros o l (a bout No w let's talk about a $25-$35) ca ll ed ATP lo ng- ter m fix : the C lea n 'N Coat. This is afte rb low e lectronic modso ld under ot her labe ls, ul e. Its stra tegy is to run a nd nationwide by GM as th e blower a t hi g h speed AC-Delco air-co nd iti on in g for a bo ut 5 minutes a n deodorizer (Part No. 15hour after t he ignition is 102) . The aeroso l includ es turn ed off- if th e alc has a sp ec ia l st raw w ith been o n for at least 4 min stra teg ica ll y pl ace d pinutes. Genera l Motors hol es th a t pro duce a fo gdeve loped it as a factor y g ing spray, wh ich th o rso luti o n for Ca dill ac and fo und that it worked so o ug hl y sat ur ates th e evapo ra tor h o us in g a nd a ll of well a t drying o ut th e eva pt he fi ns. orator case tha t the el ecT he bas ic a pproach to tronic feature was incorpo(Fig. 4) Start installation of the afterblow module by finding the power connector for the air conditioner's blower motor. using the disinfectant rated into the alc computer begins by disconnecting th e so ft ware o n some Ca dill acs (yo u may have to check a se rvice a ir-co nditi o ner compresso r. Ju st in 1994. The kit was redesigned a nd remove th e w irin g co nn ector (typireleased for o th er GM mod e ls. If yo u ma nu a l to see the layo ut of th e HVAC case) . Dr ill a V8- in. ho le in a ca ll y two wires) betwee n th e c lutc h find a GM kit for your GM ca r or safe pl ace between them. Be careful tru ck, it co mes with connectors a nd a nd th e co mpresso r bod y. Nex t, run the sys te m o n hi g h not to drill in th e w ro ng p lace or too a w irin g sc hema tic custom ized for bl ower speed , in max imum hea t a nd deep , or yo u risk th e d a nger of yo ur spec ifi c mo del ve hicle. in rec irc ul at io n (o utside a ir shut drillin g into th e evaporator or eve n Th en, someone got off) . If yo u have a n a utom at ic temthe bri g ht idea to use the modul e in a the hea ter core. perature-co ntrol system th at see ms generi c kit for a n y make. So Air Sept, Attac h th e straw to th e can , to refuse to do this, overr id e t he AC Delco a nd others are se lling it in sert t he s t raw a n d ho ld the ca n relativ ely upright. Res ta rt th e a uto m atic fu nctio ns and p ick a w ith a n a ll -makes a pproac h to t he m a nu a l mode . Let the b lower run e ngin e, sw itc hin g the alc to o utw irin g a nd a ba tch of sc rew-l ock co no n hi g h spee d fo r a t leas t 20 mins id e -a ir m o de , m ax imum hea t a nd necto rs. You ca n in sta ll it in almost ute s. This sho uld dr y o ut th e evapoth e hi g hes t b lowe r sp ee d. Spray in a n y post-1997 car. rator case. o n e di rec ti o n, th e n th e other. Ju st Find a spot to in se rt th e di s infecWiring k eep turnin g th e no zz le and straw back a nd fo rth , spray in g in eac h Ju st loca te th e blower motor's wiring ta nt spray can 's straw betwee n th e blower fa n a nd t he evaporator. direction until the ca n is e mpt y. connector (Fig. 4) a nd , with a Don ' t tr y to spray into the cow l air Th e n stop th e e ng in e, let th e dising rou nd ed test li g ht, isolate th e curinta ke a nd re ly on the b lower to fectan t soa k in for 30 minutes, th en rent-feed te rminal if there are two blow th e di s infectant to th e evapow ires. Th e mod ul e's w irin g is ve ry restart a nd ru n th e bl ower for rator. If yo u do , virtu a ll y a ll th e a n o th er 20 minutes, fa n on high, stra ig htforwa rd, and w hen it's in sta ll ed , the mo dul e turn s on th e di s infecta nt wi ll sti c k to th e bl ower temp era ture o n m ax imum h ea t, w h ee l. sys te m in recircu la tion. Finish up bl ower a t th e appropriate tim e in hig h On m ost cars, yo u ca n rem ove th e by s huttin g off the e ng in e and a mbi ent tempera tures when ale o perreco nn ect in g th e wiring to th e co m- atio n no rm a ll y would occur. It rea ll y blower res isto r. If yo u look in side, yo u sho uld see the eva porator, p resso r c lutc h , then re in stal lin g th e is eas ier than it sou nd s. The most difw hi c h vaguely rese mbl es a ra di ator. fi c ult part wi ll pro bably be findin g a b lower resistor or sea lin g t he V8Tape over the resistor ope ning a nd in. ho le with plumber 's putt y. This good place to sin sta ll the modul e, m ake a sma ll ho le for th e straw. If disinfectant is to x ic, so d on't leave w hi ch is he ld by a Velcro strip. yo u can 't get to the blower res istor, th e ca t, the kid s or delicate h o useAnd w hen you're done, yo u' ll no t find a suita bl e locatio n between the plants in th e car w hil e yo u 're d o ing o nl y enj oy cool fresh air, but the b lower m oto r a nd the evaporator thi s. Opening th e ga r age d oor or sweet smell of success, too.

S

CURING

A I C ODORS

195

MODERATE

Low-Tech Work on High-Tech Cars th at yo u ca n't a vo id it, even if yo u stick to the basics . Ga ining respect for the sensiti ve items and learning how to avoid mi stakes th at prod uce pro blems is a learn ing experience (a lth ough less involved than the high-tech work itself). H ere are the important beginning steps.

Strapping In

_~ "'i

;

,/

/

00 INJECTION THERMOSTAT HOUSING

-'

. . . ------- .- -'- - -.--. -- .-. ::-~. --""'~ ~'

o u've fin a ll y gotten t he new ca r thro ugh t he wa rra nt y pe ri o d , a nd th e dea ler's mini stra ti o ns a ren't necessar y- or affo rda bl e- a ny lo nger. Time to start performin g som e of that mainten ance yo urse lf, a d a unting prop os iti o n o n m os t computer-co ntro ll ed techn orid es. W ith o ut ret ur n in g to co ll ege fo r deg rees in engin eering a nd co mputer science, how's a Sat urd ay mec ha ni c supposed to stay a head of the ma intena nce curve? No t to menti o n hav in g to bu y a sh op full of too ls a nd test equipment .

Y

196

\

(Fig. 1) Many late-model cars with low hoodlines require bleeding the cooling system, not simple topping up.

Fortunately, most of the work necessary on yo ur ca r is "low tech. " It's ro utine ma intenance such as replacement of lubri ca nts and p arts, basic electrica l di ag nos is, brakes, shocks and struts, spa rk plugs, cooling systems a nd belts, a nd gaskets. It's a ll the kind of work yo u ca n do with out a major inves tment in equipment and shop man ua I " boo k learning." H owever, there's so mu ch in today's cars

Draining the coo ling system and refill ing it wi th a fres h mi xture of antifreeze and wa ter is the No. 1 do-it-yo urself job, and it's wo rth doi ng right. That means opening the engine block drain (if there is one) as well as the one on tb e radiato r and getting o ut all the o ld coolant. Yo u then face th e problem of compl etely fillin g th e cooling system. Beca use th e radi ato r or surge tank neck on many ca rs isn't the high po int o f the system, air is trapped elsewhere. Even if it is the high p oint, there are nooks and cra nni es in modern systems, many of w hich were deve loped with sophi stica ted co mputer programs fo r a n effi cient fl ow pa ttern . Sta rt by jac king up the fro nt of the ca r, to help expel a ir. Then fill the system as we ll as yo u ca n and start the engine. Yo u have to either crack open the little bleed va lves (Fig. 1)- and some systems have several-or you may have to re move a plug. Even with th ese preca uti ons, yo u sho uld check th e coo lant level rep ea tedl y over the next few weeks and keep topping up as necessa ry. If yo u do n't, the engin e will feel the diffe rence in summer and yo u' ll feel it in winter, when the hea ter o utput is low. If there's a reall y big bub b le trap ped in tb e system , the engine co uld ove rh ea t. C heck yo ur serv ice man ua I for specific bleeding instructio ns fo r yo ur ca r. Need to repl ace a drive belt? The new multi -V ribbed typ e is almost uni versal. If yo u get the right belt (not just o ne that's cl ose), foll ow the

ELECTRICAL AND

ELECTRONIC

SYSTEMS

TO RADIATOR

(Fig. 2) Bypass·style thermostats force all the cold water back into the block during warmup and all of the hot water into the radiator at running temperatures. If you use one that doesn't have the needed bypass valve (as at left), coolant flow will not go to the radiator for proper cooling.

underhood deca l's routing diagram and m a ke sure the belt is prop erl y aligned in a ll of its gro oves, a nd it w ill tra nsfer p ower smoothl y. If yo u have to cha nge a th erm ostat, d o n 't just get o ne th a t fits. Ma ny la te models have a sta t w ith a bypass va lve, intended to m ake all the ho t w a ter-not just m ost of it-flow through the ra di ato r (Fig. 2) . If yo u replace the th ermosta t w ith o ne th a t doesn 't have a bypass va lve, th e engin e w ill wa rm up slow ly, a nd it may run hotter in summer a nd heat po orl y in winter. A th erm osta t a lso m ay have a ji ggle va lve, a pinli ke device that balances p ress ures in th e system and helps bleed a ir. Even if yo u get th e ri ght therm osta t, you have to insta II it correct! y so it o pera tes no rm a ll y. On m a ny J apa nese ca rs w it h th ermostat ji ggle va lves, fo r exa mpl e, th ere's a spec ifi ed pos ition for th e va lve, suc h as being align ed w ith a tab a t 12 o 'clock . The gaskets that seal the thermostat hou sing a nd wa ter pump a lso a re ver y differe nt fr o m th e fib er/pa per t ype yo u may be fa mili a r w it h o n o ld er engines . In fac t, new gas ket desi gns are a ll over th e po w ert ra in.

Gaskets The simple precut gasket is still a round, a nd it may even be a good

LOW·TECH

WORK

ON

HIGH·TECH

w hen c la mped dow n a precise a mo unt. Still o th ers, w hi c h rese mbl e co nventi o na l gas kets, have to rqu elimit butto ns, w hich are meta l o r hard pl as tic rin gs fo r th e bo lt holes, to res ist over-tightening. Others use a ha rd-pl as tic carrier to ca rry an enginee red-s ha pe rubber sea ling rin g, as show n in th e illu stra ti o n o n the follow in g page . Inta ke ma nifo ld gas kets are tra diti o na ll y difficult to sea l o n vshaped engin es, especially when th ere's a combin ation of a luminum cylinder hea ds a nd a cast-iron block. Yo u co uld use a conve ntional gasket in pl a ce of th ese hi g h-tech wonde rs, a nd it will cost less-but it ha d better be m a de by a r eputa bl e gas ket co mpa n y spec ifi ca ll y li sted for yo ur ca r's exac t yea r a nd a ppli ca ti o n . Usua ll y th e torqu e required to seal a gasket p ro perl y is a lot less than yo u would think feels ri ght, a nd if yo u ove rti ghten, yo u di stort th e 0rin g and it w ill lea k. Yo u have to use a to rqu e w rench to be sure.

Exhaust System To day's hi g h-temp erature sta inl ess-s tee l ex ha ust systems are a n ythin g but cheap , a nd th ey' re e ither weld ed toge th e r o r held by superduty cla mps (Fig. 3). If you ha ve to cut a we ld to rep lace a pipe o r muffl e r, ge t a hi g h-qu a lity c la mp to en sure it ho ld s th e jo int o n to d ay's heav ie r pi pes. Yo u m ay have to (Fig. 3) Stainless-steel exhaust systems necessitate heavy-duty clamps to properly seal pipes. sho p a r o und , o r eve n pl a ce a sp ec ia l order, beca use m a n y p a rts stores stock cho ice on o lder ca rs fo r repl ac in g o nl y th e in exp ensive cl a mp s w ith fo rmed -in-pl ace sili cone, w hic h ca n be n t m eta l sa ddl es . Th e pre mium smea r durin g insta llati o n a nd th erec la mp s have we ld ed o r d o ubl efo re sea l p oo rl y. c rimped sa ddl es a nd a re pro babl y H owever, mo re of th e gas kets used today are hi g h-tec h des igns tha t t wo o r three ti mes th e price of th e m o re comm o n va ri et y, but th ey a re resemble gia nt O-rin gs . So me of th em th e o nl y kind tha t ca n take the 60 have a ro und cross secti o n, o the rs a re ft. -Ib , o r m o re o f torque needed to ova l o r eve n an ind escriba bl e engic la mp th e thick er pipes . neered sha pe that is des igned to sea l

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197

Brakes If yo ur car has antil ock brakes, be carefu l not to damage the w heel sensor when yo u pu ll a ca li per for bra ke lining work . In fact, it's a good time to inspect the sensor conn ecto r for ph ysical damage and the trigger whee l for badl y chipped teeth. Yo u ma y find a reaso n for mi sbehav ior of yo ur high-tech brake system that's

repairable w ith some pretty common do-it- yo urself parts replacements. Bl eeding brakes at the wheels after yo u rep lace a ca li per shou ld not be a problem with antilock brakes-just stuff a tapered plastic plug into the bra ke hose end w hen yo u di sconn ect the ca li per, to help keep o ut air. H owever, replacing the ma ster cy linder might be a special problem. If

it's p hysica ll y sep a rate fr o m the a ntil ock hydra ulic components, yo u can bl eed a mas ter cy lind er very we ll on the bench (or in so me cases on the car, just before you reco nnect the brake lin es)-th ere are specia l kits avai lab le in auto parts stores for this. And when yo u insta ll th e master cy linder on the car or recon nect the brake li nes, th e peda l sho uld be firm .

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ELECTRICAL AND

ELECTRONIC

SYSTEMS

tiona I shocks . T here a re some cases w here doing thi s confuses the car's electron ics. This problem afflicts late-mode l Thunderbirds and Cougars wit h Programmed Ride Contro l, ea rl y Mazda 626s with Auto Ad just Suspension (but not the later models), Nissan 300ZX Turbos a nd more exceptions to come. We suspect, however, tha t th ere wil l be computer bypass kits avai la ble eventuall y.

(Fig. 4) Replacing ride-control shocks doesn't necessarily mean replacing the actuator.

Just p lug any hydraulic lin es you disconnect to keep out as much air as possible w hen yo u start the job. If the master cy linder and antilock system are a sin gle assembly, you may have to fo ll ow a specific shop man ua l procedure to bl eed it. Sometimes this is d-i-y doab le, and sometimes it isn't. For examp le: The master cylinderlanti lock assembly on many Fords requires a special procedure. But, the late-model TauruslSable also ca lls for a special electronic switching device and a breakout box (a specia l adapter for testing circu its) to bleed the single assembly which (for now) makes it a job for a dealer.

Shocks and Struts Those computer-controlled shocks may have seemed like a neat feature when th e car was new, but they may cost hundreds of dollars a pair at replacement time. If you want to maintain the electron ic control, on many cars yo u can transfer the electric motors that operate the originals to a pair of new shocks and save some money (Fig. 4) . Even w ith switching over the motors, yo u ca n be in for major expense with electronica ll y controlled shocks, and it may not seem worth it on an older car. Fortunately, on most cars yo u can unplug the computer at a connector in the trunk and then in sta ll conven-

LOW-TECH

WORK

ON

HIGH-TECH

Tuneup and General Electrical

require spec ia l too ls. The pick-type tools for Genera l Motors and ma ny Ford cars are ava il ab le from auto parts stores, but yo u co uld have diffi culty wit h other makes. In ' 93, Chrysler switched to a new line of connectors that require a half-dozen spec ial tools that we still haven't seen in auto parts stores . • If you ha ve to disco nnect a battery cab le, consider the use of a computer memory saver. It not on ly wil l kee p the time on the electric clock and ho ld the preset radio stations, it will maintain the long-term ca librations of the powertrain comp uter. If you lose these, the car's driveability may be poor until th e computer "re lea rn s," w hich could ta ke 100 or more mil es of driving. There are two basic types of memory savers. The 9-vo lt battery wit h one type is okay, but just a small vo ltage drop could kill the memory. So you must keep a II electrica I accessories and li ghts off (that mea ns door domeli ght switches, too, so either keep the doors closed or install ho ld-closed clips on the sw itches). An a lternative is a saver th at hooks up to a 12-volt battery. If yo ur battery is okay, just carefu lly make the co nn ection s as yo u dis-

Tuneup and genera l electrica l are areas w here yo u have to be careful, but if yo u are, yo u shou ld not let fear of smok ing some expensive component keep yo u from doing work. Here are a few guidelines to fo ll ow: • W hen you have to disconnect a fuel lin e on most Ford and C hrys ler products, yo u' ll genera lly find it doesn't have a threaded fitting, but a q ui ckconnect type. It takes a spec ia l but inexpensive tool, available from auto parts stores (Fig. 5) . Don 't try to pry the fuel fitting apart, or yo u ' ll damage it. These fittings often have 0ring sea ls, which should be replaced. Be sure to get these in a packet for the exact app li ca ti on. Ford , for example, uses spring-lock couplings on both fuel and alc lin es. The O-rings are not FUEL LINE on ly a slightly different size, SPRING-LOCK but a tota ll y different rubCOUPLING ber. Fuel-lin e O-rings won 't li ve in alc and vice versa. • If you have to di sconnect a wiring terminal from a SPECIAL TOOL plastic connector, such as for an electrica l test, yo u can't just shove in a small screwdriver blad e to disengage it, or yo u cou ld damage the terminal and create a problem where none existed . Virtua ll y a ll late-model cars ha ve spec ia l terminals and plas tic connectors for positive (Fig. 5) Spring-lock fuel and alc connectors need a special inexpensive tool to open them. re tention, and these usuall y

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199

connect the cab le. Or use the battery from another car or a lantern battery. • Use a comp uter-safe test li ght. A standard 12-volt li ght may allow enough current draw through a circuit with electronics to measurably shorten the life (or even fry) some solid-state components. Computersafe test li ghts sta rt at under $15 , and even th e best-which plug into a cigarette lighter socket a nd id entify both power feed and gro und-are under $60, including one that has a built-in flashlight (for probing under the dash ) and a buzzer if you're probing a power feed in a blind spot . • The test meter should be a "highimpedance " type (10 megohm s or greater), for the same aspects of safety for electronic circuits as the test light. Name-brand multim eters may go o ver $500, but there are suitable volt-ohmmeters that start a t under $50. If you have to probe a circuit and

200

wa nt to do it safely, o ne way is to bu y a " bed of na il s" test lea d that ma kes mini ho les in a wire, and w hen yo u di sco nnect th e lead, they self-hea l. You ca n pi erce the insulation with a dressmaker's hemming pin , but it may not mak e good enough contact w ith th e copper w iring inside. • Don 't repositi on wires underhood. Thi s app li es not on ly to spark -plug w ires, but to a ny harn ess, including a ba ttery cab le (particularly if yo u get a repl ace ment that's a different length from th e original , or is outside a harness a nd is not easy to route the same way). Th e reason is the high-voltage electricity from spark-p lug wires may produce electrical interference in adjacent low-vo ltage circu its, particul a rl y if th ey conta in electronic components. Because man y electronic components operate on 5-8 vo lts, even th e sudden flow of 12-vo lt high-ampera ge electric ity through a battery cabl e

dur ing cranking can cause big troubl e. • Never di sconnect or connect a circuit, or a n electronic module, with th e ignition ke y in the O N position. In fact, to avo id static electricity damage, unplug an electronic module with one hand held to a body ground. Static electricity that discharges from yo ur ha nd ma y not totall y trash an electro nic modul e, but it can shorten its life from years down to weeks or even days . Professionals who face this problem all the time ma y wear a ground ing strap on one of their wrists. As yo u get familiar with yo ur car and read the manuals, yo u will be able to move into higher-technology service . You' ll discover that it ta kes careful attention to the diagnostic procedures in the manuals, but it isn 't rocket science, and it doesn't take a degree in computer science, either. The high tech yo u've already learned in doing the lowtech service will get yo u started.

ELECTRICAL AND

fI

ELECTRONIC

SYSTEMS

.

EASY

Scan Tool Diagnosis

t's state inspection time and yo u' re rea dy to leave bright and early for the inspection station w ith the famil y's '98 miniva n. You 're starting the day in a less than jovial mood because your daughter said "the light came on" last night on the way home. She said she threw a few dollars of gas into the tank to make it home. Turns out yo ur ann oya nce is mi sp laced. Sure enough, the light's on a ll right, but it's not the fue l warning, it's the CHECK ENG INE warning. You stop for gas anyway, and then you pull into the inspection lane. Well, full tank or not, the minivan does not pass muster.

I

SCAN

TOOL DIAGNOSIS

Failure Is Not an Option Thi s is a late-mode l ve hicle w ith what's known as OBO II, the seco nd genera tion on-board diagnostic system th at replaced OBO I starting in 1994. It's industry-wide and federa lly mandated. One of the problems with OBO II for the do-it-yourselfer is that yo u can't get trouble codes by counting the blin ks on the CH ECK ENG INE li ght like yo u can on ea rlier computercontro lled ve hicles. You could take yo ur minivan into a high-tech shop, where the minimum charge for di agnosis and inspection could run yo u somewhere into three figures. Or yo u can lea rn abo ut OBO II yourse lf, but

(Fig. 1) OBO II scan tools hook to the car's engine-management computer via a connector under the steering wheel.

yo u will need a pi ece of diagnostic equipment that you probably don't have-an OBO II scan tool (Fig. 1). If the Check Engine light came on, it should be no surprise that the ve hicle failed an em issions test. With OBO II, that li ght comes on on ly if there's a failure that significa ntl y affects emissions. That makes the scan tool even more important sin ce it will reveal a lot of the problems that do not cause the warning light to come on. With many problems, the light

201

the tester. Then we rechecked: The code ca me back quickl y. We clea red it aga in and looked at the reading that was coming from the tra nsmission temperatu re sensor to the powertrain comp uter. It was 131 F, nothing abnormal. The p ro blem apparentl y was in the sensor or the circuit, possibly a bad connecti on. T he wiring was good and when we started p oking around , we found ph ysica l damage that clearl y indicated the p ro blem was a defective sensor. 0

So Many Choices

stays on after th e repa ir is made and the code rema ins in the computer memo ry for a certain number of ignition ortloff cycles. Your daughter didn 't tighten the gas cap correctl y, ca using a code for the evaporative emi ss ions system to set. Eventually the light will go out and the code will self-erase, perha ps a fter the next time yo u start and sto p th e ca r. Yo u also ca n use th e sca n too l to erase it immedi ately. W ith many oth er pro bl ems, however, the only wa y to turn off the light and erase the cod e is with the scan tool. Just a warning: If yo u erase troubl e codes with a scan tool or di sconnect th e batter y fo r any reaso n, you al so era se th e comp uter's co ntinu o us monitoring system. So if yo u ta ke yo ur car in fo r a stare inspecti o n befo re enough normal dri ving, the computer might not have comp leted all its tests, and your car w ill fa il in spection for that reaso n. The OBD II scan tes ter not onl y will ena ble you to find an swers to the simpler probl ems, but will tell yo u into what areas the seemingly mo re complica ted ones fall. Then yo u w ill have a better understanding of w hat the technician is (or should be) looking for.

Cracking the Code With an OBD II sca n tool yo u a lso ca n rea d a certain amo unt of engine opera ting data: typically rpm, igniti on timing, fuel-injection calibrations, rea dings from a variety of sensors (such as the oxygen, throttle position, barometric and mass airflo w sensors), a "calcu-

202

(Fig. 2) Datastream scan tools will let you investi gate the functioning of most sensors, like the throttle position sensor being checked here_

(Fig. 3) Units with more features will let you snapshot and store data while the car is being driven.

lated loa d " va lue and so metimes switch positi on signals (Fig. 2). OBD II a lso includes a "capture" mode, in w hich yo u ca n use th e sca n tool to take a "snapshot " of what the sensors were rea ding at th e exact instant a dri vea bility hiccup occurred (Fig. 3).

Sensor Scan With enhanced scan too l ca pability, yo u ca n discover pro blems that do not trigger the engine-warning light. For exa mpl e, we recentl y turned up a generic P0 713 code on a late-model car. This is listed in the shop manual as " tra nsmission fluid temperature sensor circuithigh input." If the transmission fluid is running very hot, the transmission could completely fail , and quickly. A sca n tool could save a lot of worry and effort if it has enhanced diagnostics. You ca n do much of the troubleshooting from the driver's seat the way we did. First we cleared the code w ith a simple p ush of a button on

If yo u have a late-model vehicle, yo u have OBD II. H owever, just beca use it's generic, and the w iring connector fro m any OBD Il sca n tool will plug into yo ur ve hicle, doesn 't mea n any O BD II scan too l will work on yo ur car. The Europea ns are the problem , as th e ones after 1998 req ui re a softwa re upgrade. Korea n cars are also pro bl ematic, and how we ll they work with any given scan tool needs to be investigated on a caseby-case basis. Further, new cars are being converted (on a phase-in basis sta rting with Saturn and Saa b in 2003) to "CAN" (Contro ller Area Network). Thi s is a new di agnostic "protocol" and most sca n tools will need an adapter module, or complete replacement. The OTC M ind Reader for OBD I can be upgraded with an additional chip to rea d generic OBD II in domestic, Japanese and earlier Europea n models (but not the later Europea ns). T he Actron Sca nToo l for O BD I ca n be upd ated to the sa me level of OBD II as th e O T C Mind Rea der with a plug- in cartridge (or yo u ca n bu y an O BD II-only model ). AutoX ray p roduces a programm able sca n too l. Although it doesn't have the OBD I Chrysler comm and tests o f the M ind Rea der, it is the one home mec hanic's scan tool we've tested to date th at cove rs all generic OBD II models (including the Europeans) with more on the way and cove rs the new CAN di agnostic w ith just a softwa re

ELECTRICAL AND

ELECTRONIC SYSTEMS

(Fig. 4) Simple code readers/ resetters like this one do not give you sensor data. ers is th e Actron CP9 08 7, a si mple code rea der w ith read-codes and code-erase button s. You get no sensor rea dings or other data item s (Fig. 4) . It's a low-co st device (under $200 ) that comes w ith a good assortm ent of w ire lea ds for makin g test conn ections-incl uding a back probe adapter th at has a thin, curved metal term in al. T hi s term inal lets th e probe slip thro ugh a wa t ersea led connector to reac h a w ir ing termin al for a tes t connection. update. Th e so ftware is so ld over th e Internet. You' ll be ab le to store it o n your p er so nal com p uter and then dow nl oa d it t o your sca n tool via a cable ava il able from th e m an ufacturer. Any A utoXray scan tool is designed to be upgraded electronicall y, from onemake OBD I coverage through th e latest models. A lth ough th e professionals

OBD II has bee n in use on all ve hicl es sin ce 199 8, so th e ea rli est ve hi cles th at have t hi s syste m are we ll

have had thi s software (and a lot more) in th eir sca n tools, you have to wa it for it in t he consumer market. O ther sca n tools may be upgraded to enhanced st atus and beyond wi th new cartridges, CD-ROMs or via th e Internet. Ask

off warra nty. OBD II is co mpl ex and we ' ve given yo u ju st a bas ic introduction. Th e OBD II powertrain computer is getting a lot better at fin din g

about upgr ades before you buy. A lthough Actron has a line of OBD II scan tools, its top tester for ca r own-

problem s and l oggin g co des. But, th e computer won 't te ll yo u a thin g unl ess yo u hook up a sca n to o l. (I

HOW IT WORKS

How OBD II Transmits Data Today's powertrain computers are at the heart of a vehicle's communications network, circulating information from switches and sensors to the other computers that control anti lock brakes, air conditioning, transmission, suspension and safety systems. The powertrain computer is also in charge of systems that affect engine emissions, so the information it processes has to be available for evaluation by a technician. That information travels along a wire to a standard 16-terminal diagnostic connector (although, generally, fewer than a half-dozen terminals are live in any given vehicle). Because manufacturers do not all use the same data transmission protocols, the scan tool must be programmed to recognize which one is being used. Fortunately, there has been some standardization, but we're not down to one trans-

SCAN

TOOL DIAGNOSIS

mission protocol for all, hence the problem with late-model European cars (including the Cadillac Catera). There are four different so-called standard data pins in the standard connector, and at least four different types of data transmissions that could be used, plus enhanced versions of the standard stuff (other pins are available for additional manufacturer-specific data, such as vehicle diagnostic systems for alc and ABS). As anyone with a household PC knows, "plug and play" doesn't always work, and OBO II scan tools can encounter compatibility problems. Some European and Korean cars don't always work when they're suppossed to. How can you tell? Checking a scan tool manufac- . turer's Web site for updates is the way to keep your tool current.

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MODERATE

Wiring Your Trailer Hitch

T

he r enta l ya rd is bu sy. Th e utility t ra il er yo u wa nt is in expensive, a nd the yard help ass ists yo u in hoo king up th e tra il e r hitch a nd safet y ch a in s . Now to dr ive ho m e a nd loa d th e t ra il er w ith th e enti re t y o f a tee nager's life, then ship her off to coll ege several sta tes awa y. But not until yo u hook up the lights on the tra iler. T he tra iler dea lership wo n 't let yo u lea ve unti l the lights wor k. And the tra iler plug o n th e back of yo ur truck doesn't re motely m atch the one o n the tra iler. The fr iendly tra iler-h itch co unterman p o ints to the display of electrica l connectors and suggests that if yo u ca n 't get them working on yo ur own , he

,/

can have a mechanic do it fo r yo u, fir st thing Mo nd ay mornin g.

Desperate Times, Desperate Measures Trailer w iring may be easy. Ma ny ve hicles, particularl y pickups and SUVs, come prewired fo r trailers . If there's a preinsta lled hitc h, the con nector might a lrea d y be in p lace behind a conve nient spring-loa ded cap. Or, if yo u've bo ught a new ve hi cle, yo u may find the ha rness needed to install the connector inside the glove box. Si mply unp lug the connector to the rea r lights on yo ur truck, plug in the trailer ha rn ess between the male and fe ma le ends, and yo u're rea dy.

Bu t w iring a tra iler may not be easy. If yo u're tow ing just fo r the day a nd do n't ever p lan to tow aga in , yo u ca n pick up some adapters tha t repl ace the taillight bu lbs in yo ur vehicle a nd have pigta il ed wires ha nging fro m them. H ow yo u route the wires o ut of the li ght sockets and down to the hitch can be problematic. And w hat if yo u have a trai ler w ith simp le I- la mp lights a nd a car w ith mu ltip le ta illi ghts, lik e most Europ ea n ca rs? At the very least, odds are th e trai ler and ve hicl e use di ffere nt connectors, as the tra ilering indu str y uses at least fo ur differe nt styles.

Red To Green To White Let's start with the bas ics. M ost tra ilers

....-

This pickup came an adapter harness the trailer hitch in the glovebox. Simply disconnect the loom to the truck lights and plug in t he adapter. You'll still need to wire the trailer.

204

ELEC TR IC AL A ND

E L EC TR O NI C S Y STEMS

7-PIN CONNECTOR TO 4-PIN ADAPTER

7-PIN CONNECTOR

This st andard RV-style connector has high-amperageca pacity f lat pins and room f or six circuit s.

A simple adapter can make 5-, 6- and 7-pin connectors work with other styles of connectors.

have three circu its-for runnin g lights, o r accesso ri es powered by th e ve hicl e Splice It a nd left a nd r ight brake lights. T he ba ttery, so t hat means a not her circ uit. Wo rst case- yo u have a ca r or truck brake lights wi ll flas h for th e tu rn -sigDo no t freak. As lo ng as yo u conw it h no prov isio n fo r tra il er li ghts, na l fu nction-it's up to the flas her cern yourse lf w it h o nl y o ne circuit a t a nd a t ra il er w ith a ha rn ess th at ends relay in t he ca r to know w hen t he w it h chopped-off w ires . Yo u' ll need a ti me, t hi s job w ill no t req uire yo u to bra ke lights are on and to flas h the read th ose sch em a tic di ag ra ms th at no thin g m ore complica ted tha n a 12appropriate fil a ment. So technica ll y, ha ve tin y littl e w ires la beled w it h type volt test lig ht or volt-meter, a nd some yo u need o nl y th ree w ires to th e t ra il er sp li cin g ca pa bility. Start by turning on too sma ll for even a lawyer to read . plu s a gro un d wire. th e ve hicl e's running lamps . Now Always r un a gro un d w ire from t he Over-The-Counter probe t he ve hicle w irin g to fin d o ut Go t a 7-p in co nnector o n t he tr uck w hi ch w ire lea ding to th e ta illights is frame of t he ve hi c le (not from t he hitch o r bumpe r) to the ho t. Splice into thi s tra iler. T he meta I-tow ire a nd bring it to the vehicle side of th e m eta l contact in the hitch is not re li able trailer conn ecto r. Which pin ? Th e conenough for a consistent necto r sho uld co me co nnec ti on. T hi s mea ns yo u' ll w ith a li st spec ify ing need a conn ecto r w ith w hich pin ha ndl es eeCE which circuit. Fo ll o w at least fo ur contac ts. No t surpri singly, th e it-but do n 't for a minute trust th at somesta ndard fl at-style conone else w ho w ired nector for tra il ers uses yo ur ve hicl e befo re yo u four p in s, w it h o ne fo llo wed a n ything un shro uded ma le p in except hi s ow n whim. o n t he ve hicl e end fo r Tag eac h wire with its the gro und. O th er functi o n as yo u identify comm on styles of conit. Now yo u ca n t urn nectors use fi ve, six or POSI- LOCK CONNECTOR off the runnin g lamps seven p ins, a nd t hese and acti va te th e left are the sty les yo u'll see Posi-Lock or crimp connectors can be used without turn signa l. Id en tify installed by th e m a nusoldering, but aren't weathertight for long-term use. whic h c ircuit is th e fac turers on new ve hiblinker, a nd rep ea t fo r cl es. W hy mo re t ha n th e ri g ht turn signa l. Wire a ll to the a nd a n inline 4 -p in conn ecto r o n the fo ur? Large r tra il ers sometim es use a co nnecto r. t ra il er? We fo und a n a dapter at t he separ ate circ ui t for r unning li g hts on a uto parts sto re that m akes thi s p lugthe sides a nd fro nt of the t ra iler. So me a nd -p lay. Other permuta ti o ns of conSeparate But Not Equal trailers use e lectrica lly actu ated A few ve hicles use separate lamps for nectors may be a daptable w ith offbra kes. It's not uncommo n for th e bra ke a nd the turn-s igna l functions enclosed tra il er s to have interi o r li g hts the-s helf parts.

-

W IRING Y OUR TRAILER HITCH

205

mend ed. This will prevent discharging th e ve hicle battery from the trailer, and preve nt surges of current fro m overcooking the wiring o r blowing a fuse.

RV-STYLE 7-WAY CAR END BLACK

GREEN

Whoa, Nellie

RED

BLUE ELECTRIC BRAKES

WHITE GROUND

This wiring color code is supposed to be the standard, but vehicle manufacturers don't always follow it. Check with a test light or you risk blowing fuses.

of th e rea r lights . That's fine-unti l yo u rea li ze th e tra iler uses a single 2 fil ament bulb for a ll three function s. Adding another taillamp housing to the trailer is one option, but a simpler solution exists. Your trailer-rental place, and most a uto parts stores, sell simpl e electro ni c adapters that w ill combine the brakelamp and turn -s ignal func tions. It installs in the harness just before the trailer connector.

Other Circuits Som e large r tra ilers ha ve a separa te circu it for cl eara nce or ma rker li ghts, which are sep ara te from the running li ghts in the taillamp asse mbli es. You ma y need to add another circuit This to handl e th em. If you try to wire th em in para llel with th e custo mary p a ir of running lam ps, yo u may overl oa d the ve hicl e's hea dl a m p switch-so yo u'll need to add a relay to handl e the extra current. There a lso may be a 12-volt circuit

206

This lea d s to th e concep t of electric tra il er brak es . Th ese are ac tuated by a contro ll er in the vehicle that increases th e voltage to th e brakes proportional to th e ve hicle's decelerati on . This requires a wire from the co ntro ll er to the trail er bra ke. (This is why some connectors ha ve as man y as seven pins, to m ake provisions for the multipl e circuits .) Use 12-ga. wire for thi s circuit. If yo u have elec tri c tra il er bra kes, there mu st be an a uxiliary ba ttery and a breakaway switch in th e circuit to slow the trailer if it comes loose from th e hitch.

Keeping It All Together

H ow to make the connections? We've see n p lent y of trail ers lumberfor ru nning lights in sid e the trailer or ing d ow n the road with blinking or for chargin g the trailer battery in th e case of a travel trailer. This circuit dim li ghts. Odds are, if you looked at th e wiring on one of these rigs, probably will be hot whenever the yo u ' d see wires twisted together and engine is running, but it may be contro lled by a switch on the da sh. Be in sulated with electrica l ta pe. Alm ost as bad are th e a utomotivesure th e w ires are of a ga uge la rge style crimp co nn ectors, which can't ha ndl e th e vibration and moisture. Any crimp connector exposed to th e elements will ha ve a sho rt life span. Don 't even think of using househo ld -sty le wire nuts-they' ll unscrew th emselves w ithin a few hundred mil es . We use the scr ew-in Pos i-Lock connectors ill ustra ted here for quick jobs. Our own trailer h as every co nn ection made controller allows the use of electric trailer brakes. with so ld er a nd PVC Many vehicles are prewired to accept it. shrink tube. As yo u button up, smea r enough to handle the loa d (a full y dis- a fi lm of dielectr ic grease on the hitch charged deep-cycle trail er storage batconnectors to prevent mo isture from tery may draw 20 or mo re a mps w hen corroding the pins. tI yo u start the engine). Th e use of a battery isolator is strongly recom-

ELECTRICAL AND

ELECTRONIC

SYSTEMS

DIFFICULT

Fixing Faulty Cruise Control

erratic cruise control? Vacuum leaks caused by deteriorated hoses.

larm ingly, the speedo meter needle stea dily wind s down from 75 mph toward 50 . Just as yo u uncurl your feet and try to accelera te back to traffic speeds, th e vehicle downs hifts with a lurch and abruptly climbs bac k to over 80 mph. So yo u tap the brakes and dise ngage the crui se contro l to avoid a conve rsa tion with one of the many law enfo rcement officers lurking behind every oth er billboard. Toggling the Resume sw itch settl es things down, holding to a legal speed on both the uphill and downhill sections of the interstate . The kids in the back sea t

A

FIXING

FAULTY CRUISE CONTROL

have stopped threatening to throw up, too. Th en yo u look in yo ur mirror 20 mil es later and see th e li ghts. Red an d blue fl as hing ligh ts. You're do in g over 85 mph and , odds are, Smokey isn't going to believe you have th e cruise set to 70. Time to find out why yo ur cruise control ha s a mind of its own.

It's not a bug, it's a feature Does your crui se contro l fa ll out of engagement partwa y up stee p hill s? Actu ally, it w ill norma ll y drop o ut if the engine has to work tQO hard, mainly because after a w hil e th ere

isn 't eno ugh vac uum left to pull in th e servo after sustain ed near-wid e-openthrottl e. Yo u' ll just have to put yo ur foot into it. Do wnshifting helps. Does yo ur Japanese car not remember the set speed after tollbooths? Unlike most American and European cars, some Toyotas and Hondas are des igned not to remember th eir set speed if th e ve hicl e speed fa ll s below 25 mp h, a nd yo u're supposed to acce lerate th e ve hicl e to yo ur set sp eed and hit the Set button aga in. An noy ing, but that's the way they were designed. Do you have to ride th e brakes on

207

WHOA, NELLIE!: If your brake light switch is incorrectly adjusted, your cruise control may not lock in. A burned-out brake light can do the same.

longer downhills to keep from bui lding up excess speed? T ha t's norma l too. Th e crui se contro l on ly has a uthor ity to reduce engin e speed to idle. It doesn 't activate th e brakes. Modern cars, in an attempt to improve mil eage, have very tall gear ratios, low-friction engine des igns, low-roll ing- res ista nce tires and optimi zed aerody na mics. That long dow ngrade outs ide of town may have accelerated yo ur '6 0s-era Pontiac to o nl y a co upl e of miles per hour above lega l. But, it may well propel yo ur new eco nomy ca r to bl a ta ntl y ill ega l ve lociti es unl ess yo u interven e by braking o r downshi ft ing.

Smooth and steady Crui se control on yo ur ve hic le is a terrific device . It substantia ll y reduces th e driver's work load on longe r trips, a nd can save substa nti a l amou nts of fuel a nd expense ove r th e li fe of th e ve hi cle-until it stops work in g. We' ll get to th e sce nario of not ho ld in g a stea d y speed la ter, but here are a cou ple of things to chec k imm edi a tely if the cruise control is o n strike. Does th e Cr ui se icon o n the dash lig ht up when yo u turn the switch o n ? Duh. C heck the fus e. You ma y need to look in t he owner's man ua l to see which o ne if it's not tagged o n th e fu se box cover. An afterm arket crui se m ay ha ve an inline fuse ho lder in the wirin g to the controll er. If there is power to the system, th e next check is the brake lig hts. Brake li ghts? Yup, cru ise contro ls have a switch to toggle th em off when yo u touch the brake peda l, and ma ny use th e sa me swi tch as the brake li ghts. If o ne of t he brake lig hts has fa il ed, the cru ise contro l thin ks the brakes a re

208

o n a II th e ti me a nd won't co me o n. Same res ult if th e switc h is in correctl y a djusted or broken or jam med. Wa it, t here's m o re-if yo ur ve hi c le has a manua l transmissio n, th ere's a similar sw itch o n the clutch peda l. You ma y need to break o ut a test light or multimeter to verify the function of this array of switches . T hese sw itches usu a ll y a re no rm a ll y closed sw itches, a nd WHAT'S THIS THING?: The cruise control servo motor could be anywhere in the engine compartment.

close t heir co ntac ts when the peda l is depressed. We've seen seve ra l cases of intermittent cr ui se co ntro l dropout ca used by a brake li ght switc h that was a dju sted very tight. Any sma ll bump wou ld jiggle the brake pedal d own far eno ugh to togg le t he brake lig hts o n for a brief in stant-l ong enough to shut down the c rui se. Adju stin g the sw itch to specs (usua ll y so the brake lig hts come o n after the pedal trave ls 11 in.) fi xed it. Once yo u ve rify all of t hese things, it's time to look for mo re subtl e causes . C heck und erhood . In spect the link age between the cruise contro l ac tuator a nd the throttle. It may be as simple as a toilettank bead chain or a separate throttle cable w ith its own actuator cam to the throttl e body. Look fo r di sconnected o r damaged wirin g to the contro ll er or ac tu ator, particular ly if it's a n after marke t system, w hi c h may have been insta ll ed by som eo ne with poor mecha nica l skills. Anot her obvious fai lure point is the vacuum line to th e actuator. If it has fallen off, there's no vacuum to the act uato r and no force can be ap pli ed to t he throttle. We' ll get a hea d of o urse lves here and menti o n that a vacu um line th a t looks fine m ay

ELECTRICAL AND

ELECTRONIC

SYSTEMS

WHERE'S THIS THING?: Speed sensor may be buried under the dash near speedo head.

SPEEDOMETER HEAD

have a subtl e lea k ca used by aging, br ittl e rubber o r connecti ons that don't sea l we ll. A lot o f the crui se contro ls we've seen w ith iss ues in regulating their speed co rrectly are fi xed by simply repl ac in g a ll the vacuum lines between the servo, vacuum reservoir (if there is one) and the intake manifo ld vacuum supply.

Control issue with your servo There are two ma in components of the cruise co ntro l system: the co ntroller and the servo. The controller integrates all the inputs a nd tell s th e servo how far to actuate the th ro ttl e pl ates. N orm a lly, there is no way yo u ca n se rvice thi s item, so if yo u trace a pro bl em to the co ntro ll er, yo u' ll have to buy a new one. A bad contro ll er pro bably will require a se rvice manua l fo r specific diagnostics. Yo u'll also need a scan tool to access any co mputer tro uble codes to boot. Th e servo does th e work of mov ing th e th ro ttl e bl ades to speed up the vehicle. Conve nti o na l systems are actuated by m anifo ld vac uum. Check the lin kage fr om the servo to the throttle to ensure it's p roperly hooked up and not bindin g or stic ky. Insid e the servo is a di ap h ragm that moves to p ull o n the lin kage. So me older systems, used on cars o r trucks that do n't have throttle-pos iti o n sensor s, ma y have a rod th at moves in and out of a magnetic co il to tell the controller the throttle position. There are also two electricall y opera ted solenoid val ves. O ne va lve admits vac uum to the di a ph rag m chamber to add more th ro ttl e. T he o th er bleeds a ir bac k into th e cha mber to reduce thro ttl e. N orma ll y, th ey w ill never be open at the same time, so if o ne is sticky or leaking, crui se co ntrol operation w ill be erratic at best. C heck fo r leakage

with a ha ndheld vacuum pum p. A leaky va lve m ay benefit from a quick shot of silicone spray. Diese ls and some late models may use a servo that is completely electr ical. These usually are mo unted o n the fe nd erwell or firewall, and are co nnected to the throttle by a seco nd throttl e ca ble. Other th an keep ing th e ca bl e lubricated and properl y adju sted, there's not much to fiddl e with . As a lways, check the shop manua l for spec ifics on yo ur ve hicl e.

•

SUCK IT UP: The vacuum reservoir provides an added source of vacuum for those long uphill grades.

Ma ny late-model cars have throttle plates co nnected di rectl y to a n act uator controlled by the engin e manageme nt computer. There is no phys ica l co nnection between yo ur right foo t and the throttle blades (Sca ry, eh?), and there mayor m ay not be a separate cruise control se rvo or cont ro ll er.

How fast was I going, officer? If yo u still have no engage ment, there may be an iss ue with th e crui se co ntro l's speed input. M odern cars use info rmation from the ABS 's vehicl e speed sensor (VSS ) beca use the engine-

management computer needs to know road speed. If yo ur Check Engine light is on, the cruise may not work, especially if the VSS is malfunctioning. Older vehicles may use speed informati on from th e speedometer. Afterm arket systems ma y reso rt to a ring of magnets cl amped to a dri ves haft o r axle shaft, w ith a magnetic coil positioned nea rby. If the magnets ha ve fallen off or the coil ha s been smashed by a rock or roa d debris, there's no speed data for the controller.

Urban Legend Th e legend has been related to us by a ll mann er of peo pl e, including a co uple of sta te po li ce o ffic ers. Using the cruise co ntro l in ra in y or slick conditions w ill m ake your car speed up unco ntro ll a bl y, until you lose contro l and cras h. It's a myth. Engaging the crui se will no t ma ke the car speed up. The crui se will attempt to ma inta in a stea dy speed . If th e wh ee ls lose tra cti o n and the car starts to slow dow n, the crui se will speed up th e engine to attemp t to accelerate back to the set speed. T hi s w ill make the dri vewhee ls spin more briskl y. The vehicle speed will go slower, rega rd less of how furi o usly th e wheels spin. If yo u have a rea r-w hee l-dri ve car, th e effect is to desta bili ze the ve hicle, and you pro ba bl y w ill spin o ut unless the vehicle rega ins trac tion in a rea sona ble length of time. A front- whee ldr ive car w ith spinning tires w ill attemp t to continu e in a more o r less stra ight lin e- w hi ch will make stee ring contro l dodgy at best. H eavy ra in or snow makes use of the crui se control ina dvisable , but such conditi o ns ce rta inly won 't m a ke yo ur ca r acce lerate to ludicrou s speed s whil e yo u hang o n fo r dea r life. If th e cr ui se is engage d a nd yo u perce ive a loss of tr ac ti o n, th e bes t bet is to tap the bra ke to di se ngage the sys tem , a nd then add just enough thro ttl e to m a intain stee rin g until the ve hicle slows down to a more appro pr iate speed . t6

L-______________________________________________________________________________________

FIXING

FAULTY

CRUISE

CONTROL

~

209

ASY

Changing A Fuse t's a d a rk a nd stormy night. Made eve n darker because t he head li g hts o n yo ur car ha ve suddenly quit. The car runs finebut yo u have to ha ve it towed to a garage . Tow: $85. Labor to rep lace headlight fuse: $25 . One lO -amp bl ade-s t yle fuse: 65 cents. The rea lization t he next morning that th ere was a spare fuse a lrea dy in the fuse box that yo u cou ld have swapped in you rse lf for free in a few seconds: Priceless.

I

210

Better To Light A Single Candle Modern cars a nd trucks are heav il y dependent on their electrica l systems. The one in your car probably generates more power than was available in yo ur great-grandfather's entire hou se. You might find three different fuse boxes on your ve hicl e, and dozens of fuses. Unlike domestic (house) electrica l pan els, w hi ch rely 0 11 reusab le, resettab le circuit brea kers, most automotive circuits use disposable, one-

tim e-onl y fuses. Th e o nl y a utomotive app lica tions th a t we're aware of tha t use circu it brea kers use self-resetting brea kers, w hich w ill cycle automatically every few seconds.

Fuse basics Let's start wi th the basics. Any electrica l component uses a certa in amo unt of power to accomp li sh its task. Take, for examp le, a 2l-wa tt bra ke-light bulb. Two of these add up to 42 wa tts, w hich at yo ur car's nominal

ELECTRICAL AND

ELECTRONIC

SYSTEMS

operating volta ge of 14 vo lts is about 3 amps of current. Suppose the wires to the lamp soc ket were chafed a nd the bare wire touched so me ex posed metal , shortin g the circuit to ground. Th e current draw could in sta ntl y ri se to do zens of a mps- a nd in a few seco nds the wiring harn ess would becom e a sm ok ing, charred r uin-if it weren't for the fuse. The fuse is des igned to car ry a precise a m o unt of c urrent and no m o re. Ask it to do more, a nd a sma ll w ire o r strip of metal in sid e it melts ra pidl y, sparing the rest of the w iring. And then yo u can find the short, repa ir it and replace the fuse for a few cents . Fu ses so metimes fai l for w ha t seems to be no good reason. Go figure. One co mm o n scenario is w hen a ma rk er lamp or head la mp burn s o ut. Th e meltin g filam ent in t he bulb ca n mo mentaril y sho rt th e con tacts in side the bulb just as it vaporizes, suck ing eno ugh current to pop the fuse. You'll need to rep lace t he bulb a nd th e fuse .

CHANGING A

FUSE

You'll need pliers or some sort of tool to pull the fuse out of its spot.

Gone Fishing Not sure which fuse is popped because yo u do n 't have a cha rt? You cou ld a lways pull all o f them, o ne a t a time, a nd in spect th em. A faster way is to use a vo ltmeter o r test li ght. T he co ndu ctors inside bl ade-type fus es are exposed a t th e upper surface. Start by turn ing o n th e ignition and the circu it yo u're trying to tro ubl es hoot. Co nnect the gro und w ire of yo ur meterltest Iigh t to a good chass is gro und point-o ne with bare meta l. To uch the probe to the fus e's exposed conducto r. A good fuse wi ll show vo ltage o n both sides. A blown o ne wi ll be electrica ll y dead on o ne sid e.

What Amps? Fuses a re ca refull y manufactured to permit o nly a ca libra ted a mount of current to fl ow. Replace a blown fu se w ith o ne with a higher ampe rage ra ting at your own risk . Yo u could cause a meltd own in the w iring ha rn ess, w hi ch wi ll in turn cause more S h ~

211

This glass fuse fuse-box housing melted after a loose clamp overheated.

circuits, some o f w hich may no t be protected by othe r fuses. You may need to replace th e entire wiring ha rness, or yo u may start a n electrical fire that destro ys your entire car or truck. Now tha t I've go t yo ur attenti on, I'll backpeda l a nd say that in a n emergency I o nce had to rep lace a blown I S-a mp w ith a 20-a mp beca use th a t wa s the o nl y spa re in the fuse box. Bu t first t hing the nex t m ornin g I rep laced the fuse w ith th e cor rect o ne-whi ch pro mptl y blew. The fuel pump was drawin g tOo much current because th e fue l fi lter was dirt y, but that's a d iffere nt Satu rd ay Mec han ic. Th ere are t hree sizes of bla de-style fu ses-mini , normal a nd max i. And they are a ll co lor-coded: normal-size lO-a mp fuses are red a nd IS-amp fu ses are blue, and so o n . Ju st to confuse th e issue, th e co lor-coding is d iffere nt fo r th e max i sizes . Don't make a mi stak e a nd ass um e a red fus e is a lways 10 a mps. Add iti o na l warn ing: Don't ass ume th e last person to replace a fu se did so w ith one of the co rrect ra ting, even if he was a professio nal. As a lways, you can look in the ow ner 's manua l-and probably on the fu se chart o n the fus e box cover-for th e co rrect ra ting.

No Spares? So me ve hicl e m a nufacturers do not provide spare fuses o r eve n a place in th e fu se p a nel to stO re them. Even if th e re are spa res in yo ur fus e box, th ere a re probabl y on ly a co upl e, a nd no t o ne of eve ry va lu e. Go to th e a utO parts department o r a utO parts stO re a nd buy a fuse kit. For less than 10 bucks yo u ca n get a box co ntaining a n assortment of fu ses w ith a fuse puller insid e. Leave thi s in yo ur glovebox to keep it dry a nd cl ean . t;

-------------' 212

ELECTRICAL AND

ELECTRONIC

S Y STE M S

214

CHAPTER FIVE

hassis Curing Premature Brake Wear / 216 Replacing a Parking Brake Cable / 219 Dealing With a Low Brake Pedal / 222 Servicing Front Brake Calipers / 225 Flushing Your Brake System / 228 Servicing Drum Brakes / 231 Solving Steering-Pull Problems / 234 Diagnosing and Repairing Wheel Vibration / 238 Replacing a Steering Rack / 242 Servicing Brake Discs / 245 Fixing Suspension Clunks and Rattles / 248 Curing Steering Wander / 251

215

IFFICULT

Curing Premature Brake Wear Ou' re ta king a p leasa nt ride in th e country, enj oy in g yo ur ca r's pe rfo rman ce . A stop sig n. Yo u step unhurri edl y o n th e bra ke ped a l wh a t th e hec k? Yo u let o ff a nd tr y again . Th ere's no mi sta ke. Yo u hear a hi gh-pitched squea l th at yo u recogni ze a s a pa d w ear indi ca tor so undin g off. Those front linings a re go ing, gO lllg, go ne. Th a t wo uldn 't be so tro u b ling except that yo u di stin ctl y remember d o ing a bra ke jo b less th a n a yea r ago. H ey, what's go in g o n ?

Y

Low-Life Linings Thirty yea rs ago w hen di sc bra kes were beco min g co mm o n, we we re impressed by ho w lo ng linings las ted. No t a nymo re. Ma n y late mo del ca rs a nd tru cks ea t th eir pa d s qui ckl y. Th e tend ency is to bla me new fri cti o n ma teri a l fo rmula s fo r accelera ted p a d wear, but the real reason is usua ll y som eth i ng else al toge th er. No w, yo u've got overdri ve, a lowfricti o n V6 a nd a n aerod yna mic design th a t not o nl y lets the ca r coast fa rther, but also cuts airfl o w to th e bra kes. Ano th er factor in th e sho rt-li ved pa d scenari o is th e SUV ph eno meno n . A typical Bla zer or Ex pl o rer might weig h 4 800 pound s, but the b rakes a re no t eno ug h better th a n those desi gned fo r th e 3 000 -po und pickups most o f th ese vehi cles evo lved fr o m . ft d oes n't ta ke much o f a n inte ll ectu a l lea p to see that even no rm a l d r iving amounts to heavy-duty service.

Take a Proactive Role What ca n yo u d o to extend th e life of th ose bra kes ? First o ff, b u y th e hi g hest-qu a lity bra nd -na me linin gs you can find. Th ese may be " full ceramic, " have ce rami cs add ed to th e semimetallic mix, o r have a sacrificial titanium coa tin g tha t speed s break-in a nd improves initi a l fee l.

216

Innards and Fresh Juice Even the most dilige nt perso n in thi s regard is still go ing to ha ve problems if the self adjusters o f th e rear di scs a ren't o pera ting. Typi call y, corrosion and conta mina ti o n ja m th e pi ston a nd immo bili ze th e sc rew mechanism. So me pro fess io na Is ha ve switc hed from (Fig. 1) Coat those star·wheel adjuster threads with ove rhauling rear grease or antiseize compound. ca lipers to in sta lling qu a lity rema nufa cTh a t's not, however, a ll th ere is to tured uni ts, say in g th a t it was n 't wo rth th e la bo r a nd hea d ac he to th e jo b by a lo ng sho t. Yo u've go t to p ull th e m a p a rt a nd put in a kit-it's loo k a t th e brake system as a w ho le. ha rd to ge t th e a dju sting mec ha ni sm Ma ny moto ri sts just d o n't use the pa rkin g bra ke. Some may think it's to wo rk pro p erl y. G reat, except ca lipe rs ca n be exp ensi ve in som e a n emerge ncy stopping system o nly. But w ith man y commo n rear-di sc cases . Tha t's th e price you pay for des igns a nd so me rea r drums, liningdri vin g a m o de rn car and neg lectin g ma intenan ce . to-rotor/drum ad justment sim ply does n't occur unless t he parkW ha t ma intena nce is tha t ? Bra ke ing brake is applied (a symp to m is a flui d cha nges, of co urse . W ith th a t lo w peda l). So, a do pt th e sensibl e ha bit pa rkin g bra ke/se lf-adjustm ent mecha of engaging thi s device eve ry time yo u ni sm present a nd immer sed, intern a l co rros io n is to be strenu o us ly pa rk instea d o f just depending o n Pa rk avo ided. Ergo, peri o dic fluid changes to keep the ca r from ro lling away. a re even mo re impo rta nt th a n with di sc/drum systems. Thi s has bee n ad vised b y ma ny import ma nufa cturers fo r d eca des, a nd is no w sta rtin g to show up in the se rvice reco mm enda ti o ns fo und in the o wner 's manual s o f do mesti cs. Thi s car-care item can save you seri o us mo ney in th e long run . Bes ides di sc bra ke intern a ls, con sid er ABS. Co rr os io n a nd d ebri s in the contro l unit ca n result in a di sastro usly ex pensive repa ir-$ 1500 isn't unu sua l! Use a turkey bas ter to get most of the o ld stuff o ut of the ma ster cy linder reser vo ir, refill it with fr esh, (Fig. 2) Drum brake self-adjuster hardth en use a c lea r bottl e and hose setup ware is frequently faulty.

CHASSIS

left ove r fr o m th e days w hen linin gs were suppli ed "gree n. " Pani c stop s wo ul d in deed ge t th at fricti on

(Fig. 3) A partially clogged brake line can let pressure build up in the caliper. at each o f th e bl eeders and pump unti l you see a nice, cl ea n liquid appea r. D o

m ate rial h o t en o ugh to cure

it. But yo u do n 't get

thi s eve r y oth er yea r.

uncoo ked pad s and shoes fr o m manufac turer s an ym o r e, so thi s w h o le idea belo ngs to a b ygo ne era, a tim e of igniti o n po ints and

Beaten Drums Rear drum brakes o ften shirk t heir duty, to o, resulting in burn ed- up fro nt pads. Se ize d star-wh eel sc rews (Fig. 1) and o th er w ise in o perati ve se lf adju st er s (Fig. 2) are practi ca ll y an epidemic, so you 're asking f o r accelerated f r ont lining wear if yo u don 't inspect and lubricate th e h ardw ar e involved, and replace an y item s yo u 'r e dubio us abo ut (frayed o r fati gued ca bl es, f o r in st ance). W e fi xed a car recentl y th at had fried pads and a badl y grooved ro t or on one side. It rurn s o ut th e hose was p lugged-it allowed pressure t o gradua ll y build up in the caliper, and th en th e pi ston co uldn 't retrac t (Fig. 3) . Anoth er poss ibl e ca use of drag is ove r-

b ias p ly tires. Th er e's n o wa y to ove remphas ize the im po r-

fillin g th e ma st er reserv o i r, w hi ch ca n appl y th e brak es as th e fluid expa nds.

Broken In or Just Broken? We know peopl e who still believe that th e ri ght w ay t o sea t new linin gs is to rea ll y st and o n th e brak es a few tim es. Th at 's an anachro ni stic idea

t ance o f prope r lining brea kin (so me authoriti es say o ve rl ookin g thi s procedure is th e No . 1 ca use o f n o ise and hard ped al co m pl aints) . Th e id ea l way to st art new linin gs off is t o m ak e 30 slow stops (s paced 2 minutes ap art ) from abo ut 30 mph using li ght to m oderat e pr essure. You m ay not be wi lling to tak e th at much tim e, but yo u' d be foo li sh n o t to m ak e at leas t 10 m odera te stops at 30 -seco nd interv als (you

HOW IT WORKS

Pad Wear Indicators Mechanical pad wear indicators, which have been around since the early '70s, are so simple and can head off so much damage that it's surprising they didn't show up even before then. All that's required to warn the driver that he's almost down to the rivets is the addition of a light steel tab that contacts the I , rotor when the linings are getting too thin for comfort. This It produces a high-pitched WORN NEW squeal that appears suddenly and is unmistakable. The tab By the time you hear and feel either, is too flimsy to cause any damage to considerable rotor damage has the disc, unlike the rivets, which will already begun. grind away at that nice stopping surUnfortunately, many of the cars face, leaving wide, deep grooves. out there still aren't so equipped, With bonded linings, the steel pad and often replacement pads for cars plates will do the same, and have that had wear indicators as O.E. been called "full-mets" by brake don't include this helpful device. guys with a twisted sense of humor.

LJ,

o o n

CURING

PREMATURE

BRAKE

WEAR

u,

A slightly higher-tech variation on this theme is the electrical pad wear warning system, which first appeared a couple of decades ago on such cars as Toyotas and Mercedes. Here, the pad is drilled for an electrical contact that stands slightly proud of the lining rivets. When wear reaches the point that this touches the rotor, the ground circuit to a Brakes warning light on the dash is completed, and the lamp winks on. Again, unfortunately, some companies that manufacture replacements for these applications don't bother to include the contact, with the result being that the wire ends up tied off in the suspension somewhere.

tJ

tj

h

217

shou ld be a bl e to feel th e ac tion smooth o ut ), t hen avo id heavy braking for th e first 200 mil es . Wh a t if o ne pad is worn-out, but the other still has lots of fri ction m ateria l left ? Think a bo ut t he way a single-pi sto n caliper o pera tes. The piston pushes one side direc tl y against th e di sc, a nd thi s act io n p ull s the other side into co ntact. If a nythin g interferes w ith th e sliding or fl oating movement tha t tran sfers a nd di vid es the force, o nl y the pad th at the p iston actua ll y bears on w ill wear. So, every time yo u put in a new lining, clean a nd lubr ica te th e machin ed groo ves of sliding ca lipers, using specia l brake grease (Fig. 4) . Ditto for th e bus hings a nd pins o r bolts o f th e fl oati ng variety, a nd make sure a ny rubber pans are in good shape .

Voice of Experience When lubrication is ca lled for o n a n (Fig. 4) If the caliper won't slide on its grooves or pins, brakes will wear fast. Clean, and then lube sparingly.

l___ 218

----=

(Fig. 5) Discs need to be refinished to a finer finish for today's pad material.

internal mechanism, use silicone grease . Anythin g else wi ll attack th e rubber pans . Do n't force ca li per pistons back for pad replacement w ithout opening the bleeder. T he lin e comes in near the bottom of the cyl in de r w here th e sed iment is, a nd th is forces debris up into the ABS unit-often resulting in a glowing a ntil ock warning light. In fact, many brake experts say just opening the bleeder isn't good enough. They wa nt yo u to clamp that hose (use a specia l too l or pad the jaws of locking pliers w ith heater hose). Don't believe yo u ca n get away

w ith the ro ugh directiona l disc fin ish tha t worked fin e with asbestos. Smoothness is th e ru le today. If yo u're fam ili ar with roughness sca les, w here 80-100 RMS or 73-91 RA was o nce co nsid ered correct, now 40- 60 RMS or 36-55 RA is recomme nded (yo u ca n ch eck thi s w ith a surface compar itor ga uge) . In oth er words, finis h th a t rotor up w ith 120- to 150 gr it paper in stead of th e trad itiona l 80-grit (Fig. 5) . Regard less of wheth er th e rotors have been refi ni shed, yo u abso lu te ly mu st take the tim e to cl ea n th em. Otherwise, hard particles w ill become embed ded in th e new linings and yo u' ll get noise and scoring. But brake cleaner isn't th e a nswer beca use it wo n't fl oa t those iron fi li ngs away. Use detergent a nd wa ter, a nd then d ry w it h a paper towel. ~

-~ CHASSIS

MODERATE

Replacing a Parking Brake Cable Ou' ve just parallel-parked your manual-transmission car on a steep side street, ca refull y setting the parking brake by pulling it up fa rther th an yo u've ever pull ed before. So fa r that it ac tu ally pops a little as it edges up that last cli ck. Exiting the ve hicle , yo u turn to lock th e door-j ust as yo ur car slides forward 3 ft. and nudges the lux ury car in fro nt of yo u in th e bumper. Setting off the a larm. Hurri edl y, you restart yo ur ca r and bac k up to yo ur or igin al position, determined to pull the brake up far enough to anchor the Titanic this time. Unfort unately, this time the hand brake offers no resista nce whatsoever until the mechanism tops o ut-a nd yo u ha ve no parking brake at a ll , forc ing yo u to find a fl at parking space three streets away and walk thro ugh the ra in to your job interview. Not to mention having to rep lace th e parted handbrake ca ble.

Y

Why It Failed Parking brakes are opera ted by a lo ng, stee l cab le th at runs between the ha ndle in the cockpit and the rear wheels . It has crimped-on ends that can potentially slip off (unusual but not unknown) . More comm onl y, the r ubber-covered outer cable that runs between the car and the rear brakes tears or sp li ts, a llow ing moisture an d road sa lt to corrode through the inner steel cable. Sooner or later, the corroded cable fails under tension. Live in the desert w here it's flat, and never use your park ing brake? Or maybe you have an automatic transmiss ion and just put yo ur car in Park. Then yo u face another iss ue-the ca bl e needs to be exerc ised regularly or it will se ize up. So yo u should use the parking brake regularly. Ever have trouble getting yo ur tra nsmission out of Park when parking on a grade

REPLACING

A

PARKING

BRAKE

(Fig. 1) Unlike the two separate cables shown on page 190, this vehicle uses an equalizer bar to distribute the pull to both rear wheels equally. This means three potential adjustments.

CENTER CABLE

f_-:::-:- \ ~.....-__ ---

beca use the parking pawl in the tranny is jamm ed against its gear? Settin g the parking brake before purring the trans in Park and letting th e ca r ro ll forward will prevent thi s.

Getting Dirty First, you need to determine which ca ble has parted. Remove the boot over the mechanism between the sea ts and see which ca bl e is slack. If there's onl y a single ca ble to the handle, you' ll often need to pull up the rear sea r and look for the equalizer bar (Fig. 1). O ne cable to the bar will be easy to pull straight out. Warning! Parking brake ca bles are generally lubricated with thick black grease that will get eve rywhere, and genera lly destroy yo ur car interior and your clothes. Be ready with rags to contain the mess. Now, you need to check the outer cab le that leads to the rear whee l. If it's damaged, yo u'll need to replace that as well. You ma y have no option if the inner and outer ca ble are sold as

CABLE

an assembly, which they often are . To actuall y look at the o uter cable, yo u'll need to get under the car. This mea ns either backing onto ramps or jac king up the car and resting it on jacksta nds. If yo u're using jackstands, loosen the lug nuts fi rs t. (Never get under a car that's lifted on a jack, even a floor jack.) Be sure to block the wheels. Check the outer cable, w hich lea ds from th e bac king plate of the brakes over to th e car body. Don't confuse it with the brake hydraulic lin e, which is a stee l tube connected to the bod y at some po int with a short rubber hose. The brake cable will be much thicker and rubber-covered along its whole length . Look fo r cracks, a brasions and deteriorated rubber, and do n't forget both sid es-if the other side is dam aged yo u may as well replace both ca bles now.

Inside the Brake Drum Once you've determined which cable(s) to replace, get the car up in

219

(Fig. 2) The final adjustment of the new cable is usually done at the handle inside the car. You may need to hold the new cable with locking pliers to keep it from turning as you use a socket on the adjuster nut.

th e air and the wheel or wheels off. N ow you need to remove the bra ke drum. Generally, the drum is simply sa nd w iched between the axle fl ange and th e whee l, reta in ed by a small sheetmetal clip o r Phillips setscrew to keep it fro m landing on yo ur foot w hen yo u remove the wheel. O ccasionally, they will become intimately attached to th e hub and need persuading. Judicio us applicati o n of penetrating oil, light hammer taps nea r th e hub, profanity and moderate hea t w ill see them loosen. Yo u may need to back off the adju ster mec hanism to get the shoes o ut of th e way if the drum ha s developed a wear ridge o n the inner lip . Now yo u can see the brake shoes and mecha ni sm. (This might be a

220

good time to replace the shoes if they' re worn down to anyw here near the ri vets). If yo u' re replac ing onl y the inn er ca ble, simpl y disassemble th e mec hanism fa r eno ugh to p ull o ut th e o ld ca bl e and threa d th e new one into pl ace. If yo u need to replace the o uter ca ble as well, it's proba bl y pretty well rusted onto the backing plate. Spray it with penetrating oil, and twi st with pli ers until it lets loose. So me ca bles are reta ined by snap rings or a sma ll co ll et-style clip-check the new ca bl e fo r its attachment style.

SELF-ADJUSTER MECHANISM

Clean It Up

(Fig. 3) Be sure the rear brakes are properly adjusted before trying to set the parking brake adjustment.

N ow's yo ur chance to w ire brush rust and dirt from all the hardware and mating surfaces on the brake mech anism, and sparingly lubri ca te all the moving parts w ith anti seize compound or high-temp grease. Replace any suspicio us hardware like springs and clips. Be sure to clean the mating surface of the axle flange and brake dr um , to prevent foreign matter from

keeping the drum from seating properl y o n the flange . Lightly lube the mating surfaces with antise ize so yo u won't have to cuss the next time yo u need to take it apart. Reinstall the brakes and drum, hooking up the new ca ble to the actuating arm. Adjust the brake shoes properly if you needed to back off the adjuster.

CHASSIS

.

:'.

(Fig. 4) Some cars with rear discs use a small set of brake shoes dedicat ed t o the parking brake.

Back Inside No w it's t ime to hoo k up th e inner ca b le's fo rw ard end (Fig. 2) . If it d idn 't com e w ith a new n ut , yo u' ll ha ve to resc ue th e o ld o ne. It m ay be a locknut, o r there may simp ly be two nuts ja mmed toge th er. T h rea d the th rea ded end of th e cab le in to th e equ a li ze r bar or t he ha n d le, a nd lightl y run t he nut d own. Pu ll th e ha nd le up (or dep ress t he peda l) t hree clicks, and then tighten the a d justin g n ut unt il th e w hee l li g htl y sc ra pes as yo u ro ta te it. T hi s ass um es yo u ha d the bra ke shoes ad justed co rrectl y a nd th ey d o n 't scra pe with the ha ndl e do wn . If yo u do n 't ha ve the bra ke shoes

correctl y a d justed , a nd t hen yo u ad just th e ha ndbra ke, bad t hi ngs can happen. As t he bra ke shoes' a uto matic a dju ster m ech a ni sm (Fig. 3) k icks in ove r t he next few d ays, t he s lac k in t he ha nd b ra ke ca b le w il l gra du a ll y di sa ppea l; a nd yo u r bra kes w i II sta rt to drag. Be ca reful fo r the first few d ays t ha t t he ha nd bra ke reta ins two or t hr ee c li cks o f fr ee p lay. Is t he eq ua li zer bar stra igh t ? N ot cocked over a t so me w ac ky an gle, but reasona b ly cl ose to pe rpend ic u la r to th e ca b les? If n o t, a dju st t he nuts a pp ro pri ate ly. If yo ur b ra kes use two se p a ra te cab les w ith no equ a li zer ba r, a dju st th e indi vidu a l ca b les so both rea r w heels have equ a l tensio n w hen th e brakes a re ac tu ated.

Four-wheel Discs If yo ur ca r has fo ur-w heel d isc bra kes, yo ur jo b is sim pler, beca use the attac hment o f the ha ndbra ke ca ble to the caliper is genera ll y much simpler to get

CABLE

:..---- PARKING BRAKE PEDAL

a t than with drum bra kes, req uiring less di sassemb ly a nd rea djustment. Some rea r disc bra kes actu a ll y have a sma ll drum bra ke system just for the pa rkin g brakes (Fig. 4) , but the cable a rrangem ents are pretty easy to dea l with. Yo u genera ll y can rep lace the ca ble witho ut removing the d isc o r ca li per. O ne las t wo rd of adv ice: R ega rd less o f t he sta te o f hea lth o f yo ur bra kes, a lw ays turn yo ur fr o nt w hee ls in to t he cur b w hen park ing o n a h ill.

tI

HOW IT WORKS

Self-adjusting Brakes Self·adjusting brakes are Granny, the mechanism may not be doing its job. Try a few universal now, except for LEADING SHOE some elderly Volkswagens smart applications of the brakes while backing up still on the road. The service (needless to say, this needs brakes are act uated by a to happen where you won 't hydraulic cylinder that forces PARKING hit anything). You don 't need the t wo shoes apart, jamBRAKE LEVER to go fast-just walking ming them int o the inner speed. Hit the brake pedal diameter of the brake drum. good enough to stop rapidly, But as the lining material but not fast enough to chirp wears, a mechanical escape· the tires. You may be surment mechanism is necesprised-your wimpy handTRAILING l~ sary to keep t he shoes close brake may regain some to the drum. Otherwise, the SHOE & authority, and your braking pedal would gradually get SELF ADJUSTER ' ,,may improve. Repeat as neccloser and closer to the essary. If you 've been rocking about floorboards as the friction material brakes are applied in reverse. Norwith the manual adjuster, you may mal driving will keep the clearances wore down. This self·adjust mechaneed to do this a number of times. nism is actuat ed by the slight vertiappropriate. If you have a circular You 'll need to do it if you 've disasdriveway, never back out of parking cal movement of the t railing brake sembled the rear brakes as well. shoe that occurs whenever the spots or generally back up like

?-"- I

REPLACING

A PARKING

BRAKE CABLE

221

DIFFICULT

Dealing With a Low Brake Pedal

(Fig. 2) Brake drums will be marked clearly as to how far they can be machined safely to remove out of round.

BACKING PLATE

DEPRESS

TAB WITH TOOL

ROTATE STAR WHEEL WITH

TOOL

"

oney, can I borrow yo ur car?" No problem. She tosses you the keys. But at the first stop sign you draw a startled breath-the pedal's going, going, a lmost gone ! There's even a little dent in the carpet under the pedal. Didn't she notice? Well, no she didn't. Typica ll y, low-pedal trouble develops so gradua lly that people don't realize it. Hydraulic brakes have been aro und since Duesenberg introduce d them in 1921, but apparentl y a lo ng hi stor y is no defense aga inst trou bl es. And professionals and doit- yo urselfers alike are often guilty of mi sd iagnosis-th ey bl ame the master cy linder, though it is seld om the cu lprit. There are on ly two plausible reasons for a low pedal: air in the system; and excess ive movement between linings a nd rotors or drums (d ue to lack of ad justme nt, an o utof-ro und drum, or a wobb ly disc

222

H

(Fig. 1) Depress the tab while you rotate the star wheel to close up the clearance. When the wheel scrapes lightly, go back one click. BLEED SCREW SEAT OPEN

that's knocking the pistons back so that there's extra space to take up before brak in g action begins).

Isolation You can find ou t a ll you need to know a bo ut the master cy linder by removing the lin es, screwing brass or plastic plugs into the o utlets, and then applying the brakes. If the pedal's high and hard now, the master has been properly bled and its sea ls are okay. The pedal wou ld sink gra du a ll y if it were bypass ing-that is, if fluid were finding its way aro und the slid in g sea ls. You've a lso confirmed that the booster is okay. Reattach the lines. Continue the process of elimination by clamping hoses to isolate each

(Fig. 3) Bubbles collecting in high spots in the brake system need to be removed by opening the bleeder valves to flush them out.

wheel. Use a su itab le ro unded-jaw tool, either the locki ng-pliers type or one of those inexpensive J-hooks with a knurled screw. Releasing one at a time should locate the problem.

Use That Parking Brake If you never engage the parking brake, se lf-adjustment of the pads and rotor simply wo n't occur, and that means a low pedal. Another impediment to adjustment is corrosion and contamination of the piston, cylind er and self-a djustment hard-

CHASSIS

round (Fig. 2) , leav in g excess shoe-todrum clearance and , of co urse, causing pu lsation.

ware. So, change your ha bits and start using the parking brake every time yo u leave th e car, and rep lace th ose calipers if the y're not just ri ght . H th e parking brake isn't used reg ularly, o ne of these days a parking lot attendant w ill apply it and yo ur car wi ll be imm ob il ized until those corroded ca bles an d other se ized parts are replaced.

Beat the Drums

Bubble Trouble

OUTLET PORTS

Rear drum brakes can ca use a low ped al, too. Seized star-wheel screws and otherwise inoperative selfadju sters are a ll too common, and yo u' re risking trouble if yo u don't rep lace the hardware when replacing shoes (Fig. 1). At the very least, clean the star-whee l threads and treat them to a coating of antiseize compou nd . T here 's ano ther fac tor that's usually not recognized: d rivers who never stop aggressively eno ugh in Reverse

MASTER CYLINDER

(Fig. 4) Bench bleed a master cylinder to get air out before installing it into the vehicle.

to ratchet the self-adju sters. It's a good idea to stomp on the brake peda l every week or so w hil e backing up- preferably in a deserted lot or other safe place. What abo ut the drums themse lves? They're frequently o ut of

For a ll practica l purposes, brake fluid is incompressible. Air, o n the other hand, can be squeezed down into a sma ll er-than-na tural volume, and its presence w ill di srupt the operation of any hydrau lic system. It promotes internal corros ion, too. Ergo, it must be expe ll ed (Fig. 3). One poss ible ca use of pedal p roblems is failure to bench bleed a new ma ster cylinder (Fig. 4) . Screw the suppli ed fittin gs into the o utlets a nd pla ce the tips of the tubes in the fluid in the reservo ir. Clamp one of th e master's mounting ears in a visedon 't grip aro und the cylinder- so the unit is as level as possible . Use a rod or drift to stroke the piston slowly. Wait at least 15 seconds

HOW IT WORKS

The Dual Master Cylinder Whether you call it the dual, split or tandem master cylinder, it has been used on every car sold in this country since 1967, although Cadillac had it in '62. Even so, most people don't understand its construction and operation. A typical modern specimen is of the composite varietyaluminum with a plastic reservoirbut iron 1-piece units are still around on older vehicles. Two pistons ride in the bore, and here's where we encounter some potentially confusing terminology. The rear piston is the primary, the one in the front is the secondary. This apparent misnaming resulted because the rear piston is the first to receive the signal from the brake pedal, so it does make a certain amount of sense. Kind of. Each piston has a primary cup seal at its front and a secondary at its rear. In normal braking, the pushrod from the booster forces the primary piston forward. No pressure is created until the primary seal covers the compensating or vent

DEALING WITH

A LOW BRAKE PEDAL

port from the reservoir, but once it does fluid is trapped in the chamber between the pistons and it becomes a solid column. Pressure is routed from this chamber to two wheels. A combination of the trapped fluid and the primary piston coil spring bears on the secondary piston, to which the line to the other two wheels is attached. The replenishing ports allow fluid to move freely between the chambers behind both pistons' primary cups and the reservoir, determined by demand and expansion and contraction from temperature changes. If a hose lets go or a saboteur has sawed through one of the brake lines, the other half will still provide a means of decelerating the vehicle, albeit with a lower pedal and reduced stopping power. This protective function is, of course, the dual master's reason for being.

223

between strok es to all ow th e lowpressu re cha mber to release a ll its bubbl es a nd fi ll comp letely. Keep stroking until th ere's no more ev idence of a ir a t th e ports and tube tips. If th e car has a replacement cylinder that som e bod y didn't bench bleed, you mi ght be a bl e to do it w ith the m as ter in pl ace, prov id ed yo u ca n jack th e rear of th e ve hicl e high eno ugh to get th e cy linder to be leve l. Aga in , pump slow ly a nd a ll ow time between strokes. An important precaution to observe during a ny bleeding procedure that in vo lves pumping the pedal is to limit pedal travel. You do n't wa nt the de licate lips of th e master cy linder's piston sea ls to r ide so deep in the bore th a t they encounter rou gh corrosio n o r dep osits, w hich can scratch them. Just throw a chunk of 2 x 4 on th e fl oor under the pedal. When it comes to the bleeders at

224

the w hee ls, most peop le just ope n them a nd let the fluid sq uirt. Not on ly wi ll thi s result in sli ppery pudd les o n the fl oor, the fluid ca n shoot farther than yo u might expect-think a bo ut the 2S00-p lu s psi of line press ure o n so me ABS-equipped cars. Brake fluid is a pretty effective p aint remover, a nd it really burn s when yo u get it in yo ur eye . Wea r eye protection. One conve ni ent setup is a tube a nd tran spa rent bottl e kept half fu ll of fresh fluid (Fig. 5). There are a lso inexpensive I-man bleeder hoses that contain a I-way va lve to eliminate the possibility o f air bein g dra w n back in w hen yo u release th e pedal. The bl eeder cups and hoses that a re often included in manu a l vac uum pump kits, such as those from M ighty Yac, wo rk well. O nce aga in, yo u ca n see w hat yo u' re getting, and yo u don't have to keep climbing into the seat to pump the pedal.

(Fig. 5) The old-fashioned, low-tech way to bleed brakes is to use a jelly jar half full of brake fluid, a short piece of hose, and a patient helper to depress the brake pedal.

You shou ld a lso be aware of sp ecial proced ures . For example, on Teves Mark II ABS systems, you ca n't get fluid to the rear brakes unless yo u turn the key on a nd th en apply the peda l slightl y. Be sure to check th e shop man ua l if your ve hicle has a n antilock brak ing system. Finally, there's the bleeding seq uence . Since yo u're supposed to do the lo ngest lin e in the circu it fi rst, the traditiona l order is ri ght rea r, left rear, right front a nd left fro nt. But w ith the diagonal ly sp li t system s yo u' ll find mostl y on fwd cars, the o rder is right rear, left front, left rear th en right front. ABS-equipped cars may ha ve spec ial procedures to fo ll ow. (I

CHASSIS

EASY

Servicing Front Brake Calipers

(Fig. 1) Before you go too far, be sure the bleeder isn't frozen. It may need to be retapped.

B

rake lights in fr ont of yo u fl as h suddenl y, and fo r no di scernibl e reason. Yo u mas h th e brake p edal to avoid rear-ending a driver who must have suddenl y remembered leaving the stove on. Your car stops, but yo u've swerved well into the adj acent lane, where, fortunately, an a lert dri ver slowed and pulled over to give yo u so me cl ea rance . Too close. Your p ani c bra king attempt should have had two different results: Your car should h ave slowed more ra pidly, and sho uld have tracked in a straight line as it slowed. There's obviously something wrong.

Check It Out Your car pulled to the left, but the problem is more likely to be at the right front wheel. It didn't brake as well as the left, so the car pulled in the opposite directi on . Remove the w heel and take a look. Don 't be surp rised if yo u see th at both shoes have a reaso na ble amo unt of brake lining left . The pro blem is mo re likely to be a bad caliper, th at big hydraulic clamp that forces the brake shoes against the disc-brake rotor.

SERVICING

FRONT BRAKE CALIPERS

Turn the forcing screw and the ca liper sho uld move smoothl y as th e pi ston is pu shed back. If the caliper passes this test, make one more (if yo u haven't already ): Check the bleeder valve to be sure it loosens (Fig. 1). If it doesn't, you can drill it out and install a repl acement. But this ca n be a difficult operation , and installing a remanufactured ca liper is a sa fer bet. If the caliper binds or moves onl y (Fig. 2) Some types of sliding calipers can be with unusual effort, there are pushed back without removing them from the two possibilities: The ca liper caliper mounts. Be sure it's not seized sliding surpiston is frozen in pl ace (the faces that are binding, though. most common), or the caliper Most cars have sliding ca lipers with is nor a ble to slide beca use of corroded a single hydraulic piston. Wh en yo u bolts (a long which most ca lipers slide), step on the brake pedal and that p iscocked or damaged bushings thro ugh ton is pu shed out, it forces the inner which the bo lts go, or rusted sliding brake shoe against the inner side of " ways" (guides) in the anchor that holds the rotor. T he caliper simultaneously the caliper. You'll have to remove the caliper to see. slides inward, pulling the bra ke shoe in the o uter side o f th e ca liper aga inst the o uter surface of the ro to r. Some Sliding Caliper Ta king off a sliding ca liper is a cars have fixed ca lipers with one or straightforward ope rati on (Fig. 2). two pistons in each side of the caliper Usually there are two bo lts that hold (two or four pistons total ). When you it to its anchor fra me. Or, there's a step on the pedal, all of the pistons fo rce the brake shoes against the rotor. singl e bolt at the bottom and a locatin g stud at the top , a des ign call ed a C heck the brake fluid level in th e flip up. C la mp off the brake hose reservo ir and if it's been topped up to cl ose to th e ca liper with a C-c1amp or maximum level, sipho n o ut a small padded loc kin g p li ers to minimi ze loss a mo unt (oth erw ise it ma y overfl ow of brake fluid and to reduce the necesduring the test ). Set up the clamp so sity of after-the-jo b bl eeding. Next, th e top edge of the C is against the loosen the bo lt th at holds the hose to midp o int of the inboard side of the the ca liper. Remove the bo lt or bolts ca liper (behind the piston ) w ith the ti p o f the forcing screw directl y op po- ho lding the ca li per. If the ca li pe r is the type th at is held site. Depending on the shap e of the in mac hined guides, th ere are two ca liper, th e forcing screw co uld also co mm on setups. T here is a lower bea r aga inst the bac k side of the o utguide that can be unbo lted a nd dri ve n board brake sh oe or even against the off the a nchor. Do thi s, and then li ft roto r surface. If the ve hicle has antithe ca liper up from the bottom of the lock bra kes, loosen the brake bleeder ancho r and o ff the upper guide. Or, screw (see p age 188 ).

225

there are bolt-on retainers at the top and bottom to hold the ca liper aga inst the guides. Remove both, then pull the caliper away fro m the anchor.

Replacement With the caliper off the bracket, unthread the brake-hose banjo bolt and catch any drops of fluid with a rag. Install a replacement ca liper, using new sea ling washers for th e brake hose (Fig. 3) . Many ca liper bolts are not recommended for reuse, so if the ve hicle manufacturer says thi s is the case, get new ones (Fig. 4) .

grease. H eavy rust m ay require a li ght touchup with a file. However, if the bolts are sticking in the bushings, replace them, and lubricate with the same type of grease. If the O-rings are deteriorated , replace them, or they could allow the bushings to cock. In a ny case, clean th e caliper ears, then relubricate the O-rings.

The Details Making It Slide If the caliper piston returns smoothl y, yo u' ll likely find that the ca liper isn't sliding properly because the movement of the caliper bo lts is hindered by corrosion or sticking in the caliper ear bushings . Or, the m achined guides are rusted. You can use a wire br ush to remove rust from the guides (and th e caliper edges), th en lubricate bo th with suitabl e water-repellent

(Fig. 3) Always replace any copper sealing washers on brake line connections with new ones.

Don 't lea ve out any dust or mo isture boots from the caliper ears . And if the o ld ones are deteriorated, replace them (they cou ld be the ca use for corros ion seizure of the sliding caliper bolts in the bushings). If a sliding rear ca liper is reusable and it incorporates the parki ng brake mechanism behind the piston, be sure to threa d back the piston (turn back the intern a l sc rew mec ha ni sm ).

Fixed Caliper With a fixed ca liper, yo u won't know if the pistons are st ick ing until you take it off. So d on't loosen the brake hose (a lthough yo u should determine if the bleeder va lve is frozen). Remove the mounting bolts-usually just two but possibly four. Hang the caliper with wi re to re i ieve any tension o n the

HOW IT WORKS

Rear Disc Caliper with Parking Brake If the parking brake uses the rear disc-brake shoes instead of a separate set of drum-brake shoes, there is a mechanism in the caliper piston cylinder to push the piston and apply the rear brakes when the driver operates the linkage. That mechanism, which is connected to the parking brake linkage, has a screw setup to compensate for the fact that in normal foot-brake operation, the piston automatically moves out to adjust for brake-shoe lining wear. The type shown here is a common design. There is a cone behind the piston and it moves with the piston when the foot brake is applied. When the parking brake is operated, the brake lever turns the screw on which it is mounted (it also is an adjusting screw threaded through an adjusting nut).

226

Rear calipers with parking brakes require special techniques to retract the pistons at pad replacement time. The nut can't turn because it's splined into the cone. With the inboard brake shoe in place, the piston (and shoe) can't turn either. So the lever operation causes the piston to be pushed out to apply the disc-brake shoes. When the lining wears, some clearance develops between the piston/cone and the nut. When the foot brake is released, hydraulic pressure in the caliper cylinder also is released. The adjusting spring then causes the nut to thread out on the adjusting screw to take up the clearance.

CHASSIS

bra ke hose (Fig. 5) . Now use th e Ccl a mp to c hec k t he pi sto n s. Pl ace a brake shoe aga in st a pi sto n (o r pa ir o f p isto n s) to di st r ibute th e force eve nl y, a nd put the C-c1 a m p forc in g sc rew aga in st th e shoe . Th en , turn the fo rc in g screw to dete rmin e if th e pi sto n m oves sm oo thl y. If it's sti ckin g, repl ace th e ca lip er. A fi xed ca liper w ill be mo re expensive than a sli de r, and yo u may be tempted to sa lvage one by d rilling o ut a fro zen bleeder. D on't ta ke the risk. Let a machine shop do it for yo u. Also no te if the fi xed ca liper bo lts are reusable.

Restricted Brake Hose

(Fig. 4) Some makers say that the mounting bolts cannot be reused. Check before removing.

It's rare, but yo u may find th at there's no leak a nd th e probl em isn 't a t th e caliper. It's poss ibl e th a t the brake isn 't a ppl yin g no rm a ll y becau se there's ina dequ a te h ydraulic pressure

to th e ca li pe r, th e res ul t of a res t ricted hose. H ave a helper a ppl y th e b ra ke a nd see if yo u ca n turn the w hee l w ith a w rench o n a lu g nut-ma ke a rea l effo rt a nd use a wre nch w ith a long sha nk. If the w heel can be turn ed a t a ll , no m atter how mu ch effo rt yo u' re a ppl yin g, the ca liper is n't gett in g full h ydra ulic press ure. To chec k, o pen th e bl eeder va lve full y (w ith a hose over it a nd th e other end in a glass ja r) a nd have a helper appl y the brakes. Look to see if there's a so lid co lumn of fluid com ing o ut of the ho se. Th ere isn 't ? Eith er a bra ke lin e is k inked o r th e hose is defecti ve . (I (Fig. 5) Check for a frozen caliper by attempting to push the piston back. Don't hang the caliper by the hoseuse a piece of wire.

BRAKE DISC

SERVICING

FRONT BRAKE CALIPERS

227

MODERATE

Flushing Your Brake System

I

t's a dar k a nd stormy night, w ith steady rain and scattered li ghtning. But traffic moves a long smartly-until it doesn't. Yo u wind up hammer ing the brake pedal to keep from eating the license plate in front of yo u. N atura ll y, you expect- yo u COunt o n-the a nti lock brak ing o n yo ur new car to ensure a safe, co ntrol'. :$' lable, steady stop. In stea d, the .... BRAKE ' . car begins to fishtail and it tak es ",/ CLEANER / a monumenta l struggle to keep the car in a single lane as it (Fig. 1) Clean the master cylinder (Fig. 2) Remove almost all of the old brake fluid comes to a stop. The extra disreservoir to prevent dirt from falling in. with a turkey baster before adding fresh fluid. tance yo u had from the ca r in front of yo u saves a co lli sion, but yo u pushed back, where some of it gets to reac h them on so me ve hicl es wi th know something is wrong with the into the ABS actuator. The prospects the wheels on the ground. antilock braking sys tem, a .k. a. ABS. for an ABS failure go up , up, up. • Piece of clear hose to fit on the The shop gives yo u the bad news: Even if yo u don 't have ABS, contableeder valve. The actuator is defective, and yo u can minated brake fluid can affect caliper • Tight-fitting wrench for the bl eeder figure on $1400 for a replacement (or a nd wheel cylinder bores. The old er (like a tubing wrench ). Don 't use an even worse, it's part of an integrated systems with the reservoir built into ordinary open-end wrench. unit with the brake ma ster cy linder th e master cylinder are even more • Spray can of automotive cleaning soland the price is even higher) . No, it prone to contam in ation, beca use the vent and a spray can of penetrating oil. didn 't log an ABS trouble code, but reservoir cover gasket ma y ha ve take n • Turkey bas ter to draw fluid o ut of that does n't mea n a nyt hing. It's not a a set and be lea kin g. Or a lot of dirt the reservoir. A baster costs und er $1, bad connecti on and it's no t a factory ma y ha ve gotten into th e system when so don't try to clea n a nd reuse one defect. What caused it ? Maybe even the cover was removed as part of a fr om the kitchen. the technician will shrug his sho ulbrake jo b. Even simple moisture in • A pint container of brake fluid for ders, but there's a good chance it's the fluid is a real problem, beca use the an econobox, a quart for a larger car. contaminated brake fluid . hea t of braking wi ll cause it to boil, The brake fluid may be labeled DOT The brake fluid reservoir is ve nted , 3 (minimum boiling point of 400°F), causing brake fad e. DOT 4 (minimum bo il of 450°) or so that's an en try poi nt for dirt and Flushing the system is no t a difficult job. There is equipment for a oneeven DOT 5.0 or 5.1 (500°F). Your mo isture. And the rubber brake hoses system conta ins DOT 3 or DOT 4. man bleeding job, but the good stuff is are permeabl e-th ey a ll ow even more moisture to get into the fluid. Dirt and expensive and we have reservations These twO a re fully compatible, so yo u can mix them without worry, and a bout trying to use the low-cost altermoisture move through the lines. one of these is what yo u should use. natives (hose with a one-way va lve, Most goes to the ca lipers and wheel Brake fluid is hygroscopic, which and manua l vacuum pump are exa mcylinders, and some may get to the means it's like a sponge. But it's ples ). A simpler, effective approach is ABS actuator, w here it ca n cause the to have a helper step on the brake supposed to be, so if any moisture can delicate so lenoids o r motors in sid e to get in , th e fluid embraces it. However, pedal. If yo u can line up someone, the behave erratica ll y. moisture causes the norma l boiling onl y equipment yo u need is: And if yo u or the shop does a disc point of the fluid to drop. Just 2 % • Ramps or jack and stands to raise ca liper brake job, and someone pushes moisture in a fluid is consid ered the vehicle a few inches in front and back the caliper pistons, the possibiliThere are moisture testers, excessive. back, so yo u have access to the ties are ominous. A lot of the dirty, but we d on't know a repair shop bleeder va lves . H owever, it's possible moisture-laden fluid in the calipers is

228

CHASSIS

th at has one. And there's no guarantee t hat th e moi sture leve l in th e reservo ir is th e sa me as at th e ca liperit ma y be high er at th e ca liper. Warning: T here ar e silicone brak e fluid s (label ed DOT 5 ) that are i mmune to moisture (5. 1 is n ons ili cone, but DOT 3 and 4 are what you sho uld use). Don't even think abo ut usi ng DOT 5 si licon e fluid in an autom o tive brak in g sys tem , because it ma y ca use faster wear of th e sea ls, and if eno ugh water gets in to a sys tem it co uld ca use loss of pedal. DOT 5 and 5.1 h ave app licati on in some racin g vehicl es.

Flush Twice Now for the flushing job itse l f: R aise th e vehicl e a few in ches on ramps or w ith a jack and stands. Begin by cleaning t he master cy li nder's brake fluid reservoir (or top and sides of th e mast er cylinder with th e integral reservoir) , using aeroso l clea nin g so lvent and p ape r towels o r a clean ra g (Fig. 1). Don 't rem ove t he reservoir cover unri I th e area is

squeaky cl ea n. If it's an o ld er st y le- the ma ster cy lind er with th e integra l reservoir-you'll fin d a rubb er gasket. Inspec t th e p erimeter for det er ioration and r eplace the gas ket if n ecessary. Otherwise, ju st cl ea n it

CALIPER

(Fig. 3) Spray the bleeder bolt with penetrating oil and tap lightly with a hammer to loosen it.

w ith so m e fresh brake f luid. Siphon most of th e flui d ou t of th e reservoir (Fig. 2) , th en add fresh f luid up to th e l eve l mark. On front-drive vehicles, where th e h ydraulic sys t em i s split left frontlright rear and rig ht front/l eft rear, st art at th e left rear w hee l. Next, go to t he rig ht front, th en ri ght rear an d las t, th e left front whee l. On rea rdrives w ith a di ago nal sp li t, do the same. If th e rear-dri ve sp lit is front/rear, however, st art at the right rear, then left r ear, right fro nt and Jeft fron t. The object i s to begin at th e w heel brake farth es t away from th e m as ter cy lind er and gra du all y work toward th e clo sest. If th e bl eeder valve can be loos-

ened w ith the wrenc h, yo u 'r e go lden . If not, spra y it first w ith penetrating oil (Fig. 3) , let t hat work in, and try aga in w it h th e wrench . Won't loosen? C lea n th e penetrating o il and hea t th e bl eeder w ith a propa ne torc h. Tr y aga in . If yo ur w rench handle isn 't that long, or if th e fit isn 't very ti ght, yo u

HOW IT WORKS

Testing Brake Fluid with Dip Strips If the brake fluid in the reservoir is obviously dirty, flush the system. If it isn't, flush if it contains excess moisture, which you now can determine with "reagent dip strips." Reagents are substances used in a chemical reaction to detect other substances, and Wet Check strips for brake fluid now are marketed by Wagner Brake. Insert the strip into the fluid, remove it in a second, wait 30 seconds and compare the change in color of the two pads with a chart. One pad merely identifies the type of fluid-DOT 3 or DOT 4. They're compatible, so this is not critical (and a SO/SO mixture of the two merely produced an 10 color close to that of DOT 4, in our tests). The pad closest to the end, however, turns tan if moisture content is excessive. We tested the strips in separate containers of DOT 3 and DOT 4, with different percentages of water. With pure brake fluid, the color was in the definitely okay range: dark green. At 1.64% water content, there was a very

FLUSHING

YOUR

BRAKE

slight indication (some lightening of the green) that the fluids were less than pure. At 3.2S% water, there would be at least a 2S% drop in brake fluid boiling point with DOT 3. It could be as much as SO% with DOT 4. The color change to tan was unquestionable in three of four tests. In the fourth, there was some indication of less-than-perfect fluid-fuzziness in the light green-but not tan. At S% water the pad turned tan as soon as it was taken out of the fluid-we didn't even have to wait the 30 seconds. Read the strip almost exactly 30 seconds after removal from the fluid. If you read it too early, you might get an okay indication with 3% water. If you put the strip down for a few minutes, it can absorb enough moisture from a humid room to indicate contaminated fluid when none is act ually present.

SYSTEM

229

(Fig. 5) A hose ca n tr y loc king pliers This w ill cause the level over the bleeder (Fig. 4) . So me ta ppin g in the master cylinder bolt will keep fluid o n th e wrench or p li ers reservoir to rise slightl y. off of your arm and end w ith a hammer It ma y take 25 to 35 out of your eyes. m ay help. pedal applications to do Wh en the bleeder this, but w hen the level just brea ks loose, stop stops rising after a coua nd pu sh the end of the pl e of dozen, that sho uld clear hose o nto the be it. If yo u don 't do bl eeder nippl e. Aim the thi s, the reservoir might o th er end o f th e hose overflo w under some in to a cl ea r glass or conditio ns. bo ttle (Fig. 5) . W hen you ' re do ne, a Put a block of wood hard bra ke applica tion under th e pedal to presho uld ex tinguish the ve nt the pi ston from bra ke wa rning light. (Fig. 4) You may bo tto ming o ur in the And remember when need to use a mas ter cy lind er. Then special wrench. yo u next do a disc bra ke tell yo ur helper to step jo b, do n't just push bac k o n th e peda l and press down gentl y sta ll and close the va lve. Add fresh fluid the pi sto n with a C-clamp. First, cla mp but firml y. Open the bleeder va lve a nd to the m aster cylinder reservoir again the bra ke hose with locking pliers, w atch the fluid as it fl ows thro ug h th e a nd repea t the procedure . When the wrapping the hose with a protective cl ea r hose into the clear glass o r bottle fluid col or cha nges from grungy black sheath of thick rubber, perhaps fr om (Fig. 6) . If yo u do n 't get a ny fluid to something closer to wha t the new an o ld radi ator hose . Open the bleeder move ment a t the rear brakes o n a ca r fluid looks like, yo u ca n stop. Close the (a nd w ith a ntiseize o n the th reads, it w ith ABS, cl ose th e bl eeder va lve . bleeder va lve a nd go to the next wheel sho uld cooperate quite nicel y actu all y), H ave yo ur helper turn o n th e igniti o n a ttach a hose to the nipple, then push bra ke. Be ve ry sure to add fresh bra ke a nd a pply the brakes o nce, th en turn fluid up to the level in the reservoir the pi sto n bac k, coll ect the fluid in a off th e ignitio n a nd just lig htl y rest every single time. contain er a nd discard . hi s/her foot on the pedal. Open the Before yo u do the fina l top-off, Thi s job is a bout more than sa ving however, ha ve yo ur helper apply the m o ney o n a n ABS actua tor. N o matter bl eed valve sl owly. If a stream of fluid how new o r old your car, it's abo ut fl ows fro m th e val ve, a ll ow it to co me bra kes over a nd over, to exhau st the for abo ut 10 seconds, th en close th e high-pressure reservoir of the ABS. sav ing yo ur sk in . ~ va lve a nd add fluid to the m aster cy lin de r. Depe nding o n the system, th e press uri zed reservo ir m ay pu sh o ur eno ugh fluid. O r the fl ow may continue o nly if the helper presses BLEEDER BOLT down on the pedal. On most ca rs, the fl ow w ill start and continue with o ut th e preliminari es-o nl y the helper's CALIPER foo t pressin g o n th e peda l. W hen the pedal hits the wood block, tell yo ur helper to hold it there. If yo u had a lot of trouble loosening the bleeder, remove it completel y. Apply a thin film of anti-seize compo und to the th rea ds of the bleeder valve, then rein-

(Fig. 6) Use a box wrench or tubing wrench to loosen the bleeder bolt while a helper depresses the brake pedal. Tighten the bolt after brake fluid stops flowing, but before your helper releases. Repeat until clear fluid comes out.

230

CHASSIS

EASY

Servicing Drum Brakes

y:

ou're halfway down the hill when yo u realize how much speed yo u've picked up. So yo u hit the brakes. Hard. Too hard, apparently, beca use the front tires repeatedly lock and aren't able to kill off much velocity. At the first turnoff, you check yo ur front brakes-hot as a cup of McDonald's coffee. But your rear brakes are cool. Obvious ly, the front disc-brake job yo u had done over the weekend wasn't eno ugh. It's time to look at those rear drum brakes .

forma nce and, in som e systems, setting off an ABS trou bl e code.

Drums Off

Pulling off stuck brake drums may require a penetrating solve nt. You might even have to apply- gently-heat from a propane torch to th e stud holes and the drum/hub joint. If a drum is still stuck, yo u may need to use a screw-type drum puller. Once the drum is off, check its shoe-contact surface for any grooves in which yo u can catch a fingerna il (Fig. 1). Discs work (Fig. 1) The surface of the brake drum should be totally free of any grooves, cracks and shiny well enough with deep scores Diagnosis spots. (a lthou gh they may get noi sy), Block the front wheels. With th e but drums don 't. And even if a ve hicle's rear off the ground a nd drum is super-smooth, get it meas ured If you can't turn the ad juster, take off on safety stands-a nd w ith the parkat a machine shop to see if it's o ut-ofing brake off-turn each wheel. If yo u the drum to free it. round, worn past specs or misshapen hear a uniform light scraping noise, Look As You listen in some way. Norma ll y (but not that's okay. Otherwise: To gain a better look at the brake always), a fa ulty drum will create an • If the wheel is binding a ll the way aro und the rota.tion, th e brakes aren't drum , remove the tires and w heels. une ve n lining wear pattern or cause releasing properly. If that's the case, Now, as you turn the brake drum, short lining life. remove the drum and check for either eye ba ll its relationship to the backFind a drum that needs cutting? one of two possibilities: 1. The brake ing plate at var ious points. If the Take both drums to the machine shoes are not retracting fully beca use drum see ms to move in and out or shop, and ha ve an eq ua l amount the return springs are weak, perhaps rock up a nd down-even slightlyremoved from each. There may not be combined with the shoes hanging up the wheel bearing is bad, or the enough metal remaining, which on the backing plate; or 2. The autowheel spindle or axle shaft is bent. If means new drums. After a drum is matic adjuster for the shoes is overthe drum appears to turn evenly but mac hined, clea n it out with a dedoing it. its relationship with the backin g tergent and water so lurion, th en wipe • If yo u get an intermittent scrap ing plate is uneven, perhaps th e plate is it w ith a lintfree rag and a brake so lo r binding, maybe the drums are ourbent-also no t a n unu sua l problem. ve nt. Wipe until th e rag comes clean, of-round, the shoes aren't retracting (If you're not sure, compare o ne rear and let the drum dry. properly, a back ing plate is warped or drum brake with the other to see if Next, inspect the linings. Even if an axle problem exists. the appearance is different while the y're thick enough to be left in (y, • If there's no hint of a scrapeturning it.) Either wa y, yo u'll have to in. or more ), the y ma y have a glazed despite the fact that yo ur rear brakes pull the drums to confirm the ca use. surface and need replacing. Don't tr y have been nois y or haven't been conInspect the drum where th e wheel to sand off the gla ze. The linings tributing to the car's brak ing-they mounts against it. If a w heel is ha ve undergo ne a chemica l change may need to be ad justed . If th ere's an deformed, the drum ma y be from over hea ting, possibly combin ed access opening in the back ing plate or deformed as well. Also, compare the with the effects of ag in g as well as drum, turn the adjuster until the shoes tire sizes side to side and front to clima te. make light contact with the drum. rear. Odd-size tires can trigger a vehiThe linings may also be glazed Then rotate the wheel to see if the lincle's antilock brakes at the wrong because the brake shoes were draging drag is relatively even all around. time, affecting the rear-braking perging. Perhaps the automatic adjust-

SERVICING

DRUM

BRAKES

231

(Fig. 2) After you've removed the brake drum, use a dial indicator to check for both axial play and radial runout of the rear-axle hub. For good braking performance, total runout should be only a few thousandths of an inch. Excess runout probably indicates a bent spindle.

ment mec hanism is bad-or so meone keeps forgetting to release the parking brake before starting to drive.

Running Out-Literally Did you encounter that intermittent scrape when yo u turned the drum in a pre-disassembly check? But despite the noise, did the drum and shoe hardware seem to be good? Thi s is the time to check for a bent spindle or axle shaft, and/or a bad bearing. Use a dial indicator (Fig. 2) . (If you don 't own an

232

indicator, you can rent one from an auto parts store or rental center.) To check the radial runout, mount the dial indicator on the suspension, body or chassis so that the plunger is against the edge of the spindle or shaft hub. Then turn the axle shaft or sp indle. Ca ution: Turn the axle slow ly, so you won't be foo led by a burr or nick on the hub-particularly one on the edge-as you're checking radial runout. To get an accurate reading, yo u may need to cl ea n up some corrosion on the hub with sandpaper or a wire brush. To check for lateral runout on ax le shafts with a hub, relocate the dial indicator so the plunger is touching the outer face of a hub . Then turn the shaft again. Runout, in any case, should be

within manufacturer's specs-typically just a few thousandths of an inch. If your brakes have objectionable shudder, yo u'll probabl y find that the runout is .010 in. or greater.

Putting It All Together Ready to insta ll new shoes, springs and other hardware that come in th e typical drum-brake repair kit? Don 't use a screwdriver or your neighbor's 1S-year-old set of brake-spring pliers - a spring cou ld fly off and smack you right in the mouth. Instea d, get a pair of spring pli ers (Fig. 3) designed for late-model cars-it has jaws that engage the spring hooks and th e shape to actually expand the spring enough to remove it. Ditto for latemodel brake holddowns, which come in more than one size and call for a

CHASSIS

(Fig. 3) Brake-spring pliers make t he process of reinstalling springs both safe and easy.

new too l with the two popul ar-s ize ti ps . Clean off the shoe side of the backing plate and make sure that the wheel cylinder isn't leaking. H ow shoul d yo u insta ll sem imetallic shoes if yo u live in an area w ith co ld , wet win ters? If th ey freeze to the drums after an overn igh t cold sna p, the fi rs t bra ke applica ti on may be uneven. Cha mfer the ends of the shoes (up to the firs t rivets) and they'll break loose m ore easily and retract

(Fig. 4) Chamfering the leading edges of the lining material can improve your car's braking performance in certain weather conditions.

SERVICING

DRUM

BRAKES

when yo u take off (Fig. 4) . If the prob lem occurs even at temperatures just above freez ing, yo u might want to check with the car dea ler-he ma y have a substitute lining (with a lower meta l content ) that's less affected by the co ld weather. If pre-disassembly checks in d ica te a warped back ing p late, do n't try to bend it back into pos iti on-i nsta ll a new one. O n many rear-d rive Genera l Motors cars built from t he late 1970s thro ugh the ea rl y 1990s, there may be ano ther pro blem: wear in the cuto ut for the clip-held whee l cylinder. The res ul t is a loose cyli nder. If yo u ca n force it to ro tate even slightl y-say, by moderate prying on eac h end of the cy li nder w ith a large screwdriver-that's reaso n eno ugh to insta ll a new backing plate. The " by-the-book " method of replacing a brake backing plate on a rear-drive car is to remove the axle shaft . T his is a to ugh job, so if yo u need a new p late, it's a lot easier to insta ll an aftermarket 2-p iece p late (ava il ab le for many GM cars) (Fig. 5) . J us t loosen and cut the o ld o ne with a hacksaw and yo u can bolt o n the new one wi thout breaking a sweat. If the platforms on which the shoes slid e are burred or ru sty, they're probab ly a co ntr ibutor (along w ith weak springs) to the shoes fa il ing to re tract q uickly- no t to mention overheat ing or premature wear. Smooth off th e platfo rms using fi ne sand paper, w ipe clean an d apply a coa t of silicone dielectric grease. Also, yo u sho uld sand smooth the edges of the new brake shoes w here they r ide on the platforms. If yo u saw a lot of road fil m on the ins ide of the backing plate, or evi dence of water/snow entry in wi nter, seal up the back of the plate. If any inspection! adjustment covers are missing, buy and install replacements. And if yo u ca n see any light coming thro ugh the wheel cyli nder cutout in the backi ng plate, sea l it. Fina ll y, bo lt on the wheels and tighten them to specifica tion with a torqu e wrench, using a crisscross pattern . T hi s is not onl y important for

(Fig. 5) Aftermarket 2-piece backing plates can help you avoid the very difficult job of removing the axle.

fro nt-d isc rotors, but it w ill a lso keep rear drums from warp ing. T he botto m line? If yo u to uch a ll the bases thi s time arou nd, yo u' ll get 100 % brak ing acti o n the next t ime yo u hi t that pedal.

tJ

233

EASY

Solving Steering·Pull Problems our perso na l trainer menti o ns that th e diameter of yo ur left forea rm is tw ice th a t of your ri ght, unu sua l for a rig ht handed indi vid ua l. Popeye would be proud. And your spo use na gs yo u con stantl y to keep to the right lane of the freeway, becaus e you're a lways bru shin g the edge of th e sh o uld er in the fast lane a t 5 under. G uess it 's tim e to find o ut w hy your car pull s so hard to the left. The tire press ures are co rrect. You have n't bounced the fro nt end into a concrete embankment or over a rocky roa d lately, so there's proba bl y nothing bent in the suspension/steering under body. Is it just something yo u' ll have to li ve with? Probabl y not. T he so urces of most p ull s are pretty easy to pinpoint if yo u define the bas ic prob lem and systematica ll y check th e poss ibl e causes. First question: What k in d of pull is it ? T hat ca ll s for a road test, made under prec ise conditions: correct tire press ures w hen the tires are co ld, no w ind and a smooth, leve l road (no crown ). Drive at a steady speed (somew here between 30 a nd 45 mph) , then shift into Ne utra l. Next, w hen there's no traffic around, remove yo ur hands fr o m th e stee ri ng wheel. No te whether the pu ll occ urs in gear and a lso in Ne utra l, and if yo ur hand s on th e steerin g w heel make any difference. If the pull is most noticeab le und er acceleration and goes away when yo u shift into Ne utral , it's called torqu e steer. And , yes, torqu e steer a lso ca n occ ur at steady speeds. If it occurs w ith the transmiss ion in Ne ut ra l, it's a typ ica l pull. Still no pull or torq ue steer? Make a turn a nd a ll ow the ca r to return to faci ng straight a head . Then, repeat the test to see if the ca r pulls in the same direction as the turn that was made. This is ca ll ed memory

Y

(Fig. 1) Rock the tie-rod ends to check for binding or wear. Some light resistance is fine, but there should be no slop.

steer, and yo u' ll see th at it's most obvious when yo u take yo ur hands off the steering w heel.

CONTROL ARM BUSHING

Torque Steer Torque steer results fro m more possibl e causes than any other source of pull, so it's toug her to iso late. If yo u have a powerful engin e and yo u mash the throttle, some torq ue steer-particularly on acce leration- is normal. Transverse-engine front- drive cars with high-performance engines are particularl y prone to torque steer, although proper suspension design helps minimize it. When significant torque steer is evident, something is wrong and you should be able to trace it. Checking for brake drag is a good first step. Even slight differences in

(Fig. 2) Worn bushings can often be detected visually-look for shiny metal where the bushing has been moving.

CHASSIS

234

(Fig. 3) Pry the control arm lightly to find worn bushings. The arm should return to its original position when you release the pry bar.

d rag o r betwee n the fr o nt tires ca n co mpo und a ny tend ency to wa rd torq ue steer. A seco nd chec k sho ul d be for a d iffere nce in looseness of th e front suspensio n o r tie-rod ends fr o m o ne side to th e o ther. Yo u ca n feel

=

SOLVING

ma jor looseness by gra sping a nd pu lling/pu shing o n t he tie rods (Fig. 1). O r yo u ca n have a hel per ho ld t he steeri ng w hee l stea d y w hi le yo u roc k the roa d w hee l side to side a nd up a nd down to look fo r play in t he tie-ro d ends. In a dd iti o n, eye ba ll a n y r ubber bushi ngs, pa rti c ula rl y a t t he co nt ro l a rm s (Fig. 2) . W hen t hese b ushings a re ba d, t hey loo k it- c rac ked , di storted . Also, pry t he co nt ro l a rm s to fee l fo r a n y looseness (Fig. 3) . ext, m eas ure the fr o nt suspensio n ride height (Fig. 4) . Factory ser-

vice ma nu a ls deta il th e ma n y poss ible meas urement po ints, but t he o bject is to co m pa re rea d ings betwee n a pa ir o f fi xed p o ints- o ne o n the suspensio n and the o ther o n the chass is. Yo u' ll need a n abso lu tely dea d-fl at pi ece of pavem ent for this, a nd bou nce th e car u p and dow n o n the suspensio n a co uple o f times a ft er yo u park. On e wa y to c heck fo r sY I11J11 et ryo r th e lac k t he reo f-in th e suspensio n is to tie a stri ng betwee n th e botto ms of the lower contro l ar ms (such as from t he ball-j o int grease fi tti ngs) . The str ing sho uld be ver y tig ht (a nd "straig ht as a string") . M easure fro m (Fig. 4) Wit h the car on a dead-level surface, check for correct symmetry in the suspension ride height. Stretch a string between a pair of convenient points on the shocks or ball joints, and measure to the frame rails. It should be level to within less than a half-inch.

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STEERING - PULL PROB L EMS

235

(Fig. 5) You may need to pull the strut apart to properly check the strut bearing for binding.

the string to the und ers ide of the fram e rail to w hich th e contro l ar m mo unts , a nd th e di stance should be the sa me fr om side to sid e, within less than a ha lf- in ch. If it's grea ter, there's front sp ring sag, a common major contributor to torque steer. Repl ace th e springs to fi x thi s prob lem . Bad ly sagged rea r springs ca n ca use a ve hicle to pull as well , but yo u' ll be a bl e to see the height difference vis ua ll y before the pull gets bad eno ugh to notice while driving. Just look carefully at yo ur car or truck from the rea r when it's park ed on th at leve l patc h of pavement. Good springs? Check the engin e mo unts for deteri ora tion, as weak mo unts a ll ow the powertrain to shi ft unevenly on acceleration, and that can mo ve the car in one direction or the other. If the rear (transaxle) mo unt is an a ir-ga p typ e and it's bad, the engin e will rock bac kward, mas hing th e metal of th e mount against the rubber center section. To check for thi s, have a helper hit the gas pedal while in Neutral. Also check to see if the tra nsaxle is level, which yo u ca n do w ith a carpenter's leve l. It doesn 't ha ve to be a bso lutely, perfectl y leve l, but with in a quarterin ch or so. If it's not, try loosening the transaxle mount, running the engine at idle (have the park ing and service brakes app lied, once more) and, if yo u have an automatic transmission, shifting the transmi ssion back and forth between Reverse and Drive severa l times . With a manual

Still look ing for answers? It's certai nl y possible that prob lems w ith th e front tires, such as mi sa ligned belts-under the trea d a nd out o f sight -are a factor. No rmall y, tire problem s are going to cause p ull even when yo u're not accelera ting, but it is possible th at yo u are more sensitive to it o nl y during acce lerati on. So let's look at the ti res, and ta lk a bout a straightforward pu ll.

Tire-Related Pull

box, yo u ca n try pry ing the powe rtra in fore and aft a few times. This sho uld resettle the powertra in. R etighten the bolts a nd recheck the level. If it's still on a tilt, yo u can tr y shimmin g up th e low end of th e powertrain, using suspensio n shims.

••

I

Hopefu ll y, yo u had yo ur a li gnm ent checked at a shop that uses fir st-rate electronic eq uipmen t, one that eve n checks caster and camber on " net-build ' (nonad justab le) front suspensions. A good a lignm ent shop knows what is accepta bl e as a suspe nsio n ages and sp rings sag sli ghtl y. And it can sla nt the ca mber readings ever so slightl y to minimi ze pull in o ne direc ti on. Tires are the first do-it- yo urself items to check, even if the pressures a re th e sa me and right at specifications. Are they exactl y the sa me size and type, and worn a bo ut the same? If not, th ey're probabl y at least contribu tors to any pull. Even if they look exactly the sa me, th e tread belts of one or more may have been damaged. Get the fro nt end of the ca r up in the air on proper jacks tand s for the remainder of these tests. Put the stand s under the frame, not th e suspension members. R ota te each front wheel a nd fee l for more than li ght drag. If yo u get much more drag at o ne front w hee l than the other, yo u have a brake-system problemeither a bad caliper or something wrong wi th the

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CHASSIS

236

hydraulic system, such as a crimped tube or even a bad m as ter cyl ind er. Equa l o r no drag o n both front tires ? Switch them left to ri ght. If the pull is in th e opposite direction, get new tires. Even if the pull changes somewhat, but not necessa ril y all the way in th e oppos ite direction , the tires sti ll are the most probable cause of the pull, and a new pair mi ght be wort h a try if nothing else pans out. If yo u're lu cky, howeve r, th e pu ll will go away and you can pat yourself on the back for a cheap fix. Stop here if you're checking for a cause of torque steer. Let's try one more thing for a tire-related pull. If th ere's no change after th e fronttire swap, next switch the wheel o n the driver's-side front w ith the one on th e driver's-side rear. If th a t makes a significant change, get a replacem ent for the tire now at the driver's-side rear (the one o riginall y at the passenger's-s ide front). If the trea d p a ttern

or amount of wear is sign ifi can tl y different between new tires and th e rest that yo u have, yo u may ha ve to simpl y repla ce a ll four tires.

Memory Steer When toe is correct, and th e car pulls in the sa me direction as th e las t turn , yo u 're dealin g w ith mem o ry stee r-almost a lways caused by binding in the suspens ion on that s id e of the car. On a MacPh erson-strut suspension, it's a good bet that the binding is in the upper strut mount bearing. Sometimes, yo u can feel roughness in the mo unt by reaching up from undernea th and resting yo ur fin gers o n it, whi le a helper cranks the w heel back a nd fort h (fro nt end up on safety stands). More often, you' ll have to pull th e strut for a better test of the bea ring. Check for binding in the bearing after yo u've pull ed th e strut (Fig. 5) . No luck? It might be a binding

ti e- rod end , but that's not lik elyth ey ge nerall y ge t slo ppy rath e r than bind up. G ive the t ie rods a shake and a twi st to c heck. Also unlikely but possible is a binding ball joint. You m ay need to disconnect it to confirm this. It's poss ible th a t the binding is in th e steerin g gear. As a fin a l test, yo u ca n di sconnect th e ti e rods. With th em co nnected a nd th en disconnected, yo u sho uld be a bl e to feel the difference by turning the steering wheel in each direction with the engine off. Unfortunate ly, not a ll a lignment shops are as m eth odi ca l as th ey cou ld be. And some shops wi ll tell yo u th a t "a ll front-wheel-drive ca rs d o th a t. " But unl ess the pullin g probl e m has been th ere since the day you r eceived th e ve hicle, it isn 't generic and yo u should conduct a careful road test and und e rbod y in spection. (I

I

J SOLVING

STEERING

PULL PROBLEMS

237

MODERATE

Diagnosing and Repairing Wheel Vibration MISSING BALANCE WEIGHT

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t long las t it's the wee kend a nd yo u're hea ded for th e mo unta Il1S .. . o r the desert ... or th e shore. Anyw here o ut of town. And for the fi rs t time in weeks yo u ca n po int yo ur hood orn ament at the horizon instead of the license p late in fro nt of you and actu ally achieve the sp eed limit o n the interstate. Yo ur hand s shake w ith glee . Actu a lly, that's not glee, or even hea lthy anticipati o n. Nor is it so me un speaka bl e neuro logica l sy ndrome. It's a vibra ti on that isn't even pe rcep· tible at lower speeds.

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Maintain Your Balance A simp le w hee l balance w ill cure

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238

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mos t vibrati o ns. But if that doesn 't cure the p ro blem-or if it cropped up sud denl y wit hin a reasonab le tim e after a w hee l ba lance- yo ur problems may go deeper. Begin by cra n kin g th e w hee ls ove r to the steering stop a nd loo ki ng a t the insid e o f the rim . It's customar y to split the a mo unt of the ba lance weights betwee n th e in sid e and o ut· sid e of th e rim. If a we ight (eve n a n o ld o ne) has co me off, tha t co uld be th e prob lem . T he we ig ht shou ld leave a clear o utlin e, so yo u' ll know exactl y how mu ch is mi ss in g (Fig. 1). If th e ba la nce we ight was a dded recently, yo u ca n take it back to the shop for a rep lace ment.

(Fig. 1) Missing wheel weights will leave marks on the rim. Check the inside of the rim , too .

Also in spect the rim-in side and ou tsid e- for any da mage . Loo k for packed mud on the inside of th e w hee l. Also look at the tires-i f yo u see any bulges or uneven wear of the ti res, co nsider them in the " pro ba bl e ca use" ca tegory. Not hin g o bvio us? Take the ca r for a tes t dr ive . W hen the vibra ti o n occ urs, is it w hil e yo u're acce lera ting t hro ugh a bend ? T hat mea ns it's both torqu e a nd speed se nsiti ve . W h en yo u pull back to yo ur garage, insp ect th e axle shafts, loo king for da mage

CHASSIS

(Fig. 2) With the wheel off the ground, shake it in and out to check for a loose wheel bearing. Then check for loose tie·rod ends. to th e boo ts. Constant ve locity jo in ts can wear out. But if the boots are intact, th e clamp s are ho lding them at each end, and there's been no loss of lubrica nt and no intru sion of road film, t hen th ey' re pro babl y in good cond iti o n. If the vibration is not related to torqu e, shift into Ne utral and let the ve hicle coast a t th e problem speed. Still ha ve the vibration? It's speed sensitive pure and simpl e. This could be the source of your troubl es , even if th e wheels are bal a nced and t he tires are good. It's not a powertrain or dri ve lin e iss ue.

Keeping Your Bearings Ja ck up th e front wheels by the control arms , so the y' re off the ground , and support them with safety stands.

DIAGNOSING AND

Grasp each wheel , ho lding it first at the sides, then at the top a nd bottom. See if yo u ca n rock th e w hee l in and o ut a nd if yo u can fee l a n y loose ness, whi c h indi cates a loose wh ee l or worn wh ee l hub bearin gs (Fig. 2) . To replace wheel bearings on front-drive cars, yo u've got to remove the wheel hub. Tbis job requires a slideha mm er pu ller, a tool typ ica ll y ava il a bl e from the rental Peg-Bo ard of many a uto parts stores, and a torque wre nch capab le of the high torque usually required for the retain in g nut (often well over 200 ft.lb .) . Fro nt-drive whee l bear in gs (a nd th e front bea rings on many reardrive cars) are well-sealed and often are life- of-thecar w ithout lu brication. Howeve r, if yo u've been

REPAIRING WHEEL VIBRATION

on a lot of secondary roads, or g lanced off a curb bard eno ugb to bend a rim , they could be worn or damaged. If yo u have an o ld er rear-drive car it probably ha s ad justab le front wheel bea rings, a nd finding a lo t of COTTER PIN

(Fig. 3) Remove the cotter pin to retorque a loose front wheel bearing on a rear-drive car.

239

(Fig. 4) Total radial runout at the tire tread should be no more than .050 to .060 in.

free play in th ese is not surprising. To adj ust, remove the cotter pin, tighten the wheel bearing nut to abo ut 20 ft. -lb . to sea t the bearings, and back off so th ey're just free but have so little p lay that yo u rea ll y can't fee l it (Fig. 3) . Then lin e up the slot in the spindle w ith the nut and insert a new cotter pin.

Steering Your Way Yo u may not fee l free play in a fro nt w hee l (front- or rear-drive), but try rocking it in and o ut with a bit more effort, but no t eno ugh to move the steering linkage . That co uld demo nstra te free play from wear in the tierod ends or ball joints. If yo u're not sure where the free play is, pry up on the bottom of the tire and watch the ball joint to see if it has free play-Y< in . is a lot. To check a ti e-rod end jo int for looseness, try to flex it by hand. A good tie-rod en d sho uld feel sn ug, but not immob il e or stiff. On rack-and -pini on steer ing, it's a good idea to check the tie rods' inner sockets. They're covered by the steering rack boots, but yo u can sq ueeze the boots to hold the inn er joint. J ack

HOW IT WORKS

Rack-and-Pinion Steering There are several types of steering systems, but the rack- and-pinion has become the most popular because of its simplicity and precise response. It's used primarily on passenger cars and also on late-model sport utility vehicles. The rack is a shaft with gear teeth, and it meshes with the pinion, a gear at the end of the steering wheel shaft. The rack is horizontally installed between the front wheels and is connected by a tie rod at each side to a steering knuckle, the pivoting structure to which each front wheel is attached. The tie rod has a flex joint at each end that allows it to flex and pivot in transferring steering wheel motion from the rack to the knuckles. As the steering wheel is turned to either side, the pinion rotates and moves the rack to that side, pivoting the front wheels in the same direction.

240

PINION INNER SOCKET

,~

CHASSIS

up th e fr o nt end to take th e w eight o ff th e fr o nt wh ee ls. H a ve a fri end slo wl y turn the steerin g wh ee l a pa rti a l turn to eac h side , w hil e yo u feel for looseness.

Look Out for Runout Just because yo u can 't feel a lot of fre e play o r "wobble" in a wheel doesn't mean there isn 't eno ugh to cause vibration. It doesn 't ta ke a lot to be responsible fo r o bj ecti o na bl e vibration at speeds o f 60 to 70 mph a nd abovea ny devia tion from a trul y circul ar spin is ca lled runout. It can be vertica l (updown ) or hori zo ntal (in-o ut ). Th e o nly prac tical way to ch eck fo r r un o ut-fro nt or rea r-i s w ith a dial indi ca tor, a nother tool yo u ca n rent at ma ny pa rts stores. T here a re severa l different check s to make to pinpoint the so urce of t he run o ut. Mount the indicator o n something heav y that won 't mo ve, such as a n a nch o r plate o r wheel hub/knu ckl e. Positi o n the plun ger fo r the spec ific runout chec k. Exa mpl e: Fo r a radi a l runout test, rest it aga in st a good ti re tread groove. Sl o wl y turn the tire a nd measu re the am o unt of runo ut, ignoring jumps in th e plunger that res ult from th e shape o f the trea d or minor imperfections in it. If there a re fac tory sp ecifications fo r run o ut, use th ose . If yo u do n't have specs, see if th e runout is a bo ut .050 to .060 in.-thi s measurement is consid ered rul e of thumb (Fig. 4) . The tire a lmost surely isn't th e issue, although there is precision equipment that can chec k a tire fo r heavy spo ts. We kn ow- yo u d o n't have it and ca n 't rent it. Most profes siona ls do n't have it e ith e r, which tells yo u how co mmo n it is. To iso late the source of the runout, check it a t the wheel w ith the plun ger o n an underside horizonta l surface. Ignore minor imperfecti o ns in th e wheel finish (p a int, w eld , tin y dings) th a t ca use th e plunger to jump in sta ntan eo usly. If th e runout is over .045 in., th e wh ee l sho uld be replaced. If radia l run o ut isn 't ba d, check la teral run out with the plunger aga inst the sidewa ll, even if the in-out roc king didn't show anything. O bvio usly,

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igno re an y p lunger movement fro m ra ised lettering, etc. If th e J'L1I10u t is over .045 in. , it's too much . H ere aga in , isola te the run o ut by checkin g at the wh eel with the plunger against a vertica l surface . The r ule-of-thum b specs are the sam e as for radia l run o ut. Wh en th e run o ut a t th e whee l is excess ive, a new w hee l norma ll y is the a nsw er, but no t a lways . R emove t he wh eel a nd c heck r uno ut o n th e wh eel hub (Fig. 5) . M a kin g a la te ra l run o ut check is an obvi o us procedure beca use th ere's a hub face aga inst which you ca n rest th e plunger. For a ra di a l check, it may be m o re difficult if th e top surface o f the hub isn't reaso na bl y smooth beca use yo u have to use th e threa ded edges of th e studs, a nd , typ ica ll y, th ere a re o nl y fo ur o r fi ve of th ose studs. So it d oes ta ke so me careful mea suring to see if there's a significant a mount. You have / to look fo r the pea k rea din g a t eac h

DIAL INDICATOR

(Fig. 5) If radial or lateral runout is high, check both runouts at the hub to rule out a bent rim.

stud to be sure yo u're measuring at the o utermost p oi nt. Unless almost a ll th e radi a l runout is in the bolt circl e, a nd tha t a mount is a t least .030 in. , go fo r a new w heel. Repl ac ing the hub and bearing on a fr o nt-dri ve is no t a qui ck a nd easy jo b. It ca n ta ke a co upl e of ho urs to check o ut the p ossible ca uses of highspeed vibration, and you ma y be tempted to take th e car in for wheel a lignment to see if tha t helps befo re yo u spend time o n a ll th ese other things. So rr y. Unl ess there's some evidence of wh ee l mi sa li gnment (s uc h as irregula r tire wea r), a w hee l a lignment is no t go ing to help at a ll. In fa ct, until yo u first isolate a nd correct the cause of the vibra tion , a lignm ent wo uld be a was te of tim e a nd money.

tI

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---DIAGNOSING

AND

REPAIRING WHEEL VIBRATION

241

ReplaCing A Steering Rack

I

t's a c risp morning as you ca refu ll y back yo ur car down the driveway. A quick turn of the w hee l as th e front tire clears th e curb w ill sw ing yo ur car up th e street. But th e steerin g wheel is stra nge ly stiff. In stead of swinging th e car's nose aro und , yo u run stra ight back, knockin g over a tras h can across the street. Fo rtunately, th e damage is sma ll : a cr unched $14.95 rubb ish barrel a nd a sli my mess to pick up in yo ur second- best su it. "W hat happened?" you wo nder as yo u pop the hood. "The belt's still there a nd the fluid 's up-although it does look black . Ma ybe the belt just slips until it warms up. " After tid ying up across the street a nd tid ying up yo urse lf, yo u try back ing o ut aga inwi th both hand s on the w hee l. T he steeri ng feels fin e now- no groans a nd plenty of power steering boost. If the belt is 4 yea rs o ld or more, go a head and change it because it's due a nyway. Bur do n't be shocked if the p rob lem returns the next chill y mo rn ing. Power steerin g th at awake ns slow ly o n cool da ys has so-ca lled " mo rning sickness." It wo n 't go away. It's ca used by wear in side the steering assem bl y (a.k .a. the "rack"). The fluid 's black, meta lli c look is a resu lt of metal worn from the inside of the ho using. The fluid is abras ive, and the wea r w ill wo rsen wit h time. The rack is shot-replace it and use th e opportunity to flu sh the jun k from the pump a nd lines.

Can I Do It? Swapp in g a rack is simp le in so me cars, nas ty in others. For exa mp le, a rear-drive car's rack, if bolted in fro nt of the fro nt crossmember, is usua ll y easy to cha nge. But it's more cha ll enging in a fro nt-dri ver w ith the rack bo lted to the subframe behind th e L we rtra in or aga inst the fir ewa ll.

242

CLAMP·TYPE TIE ROD PULLER

STEERING ARM

(Fig. 1) Disconnect the rack's pinion shaft from the steering column.

Should yo u do it yourse lf? A shop manual may tell yo u how tough the job will be, but not a lways. O ne Gen era l Motors ma nu a l says yo u have to lower th e front subfra me 3 in . to get eno ugh clea rance to slip o ut the rack. Maybe, maybe not. Legions of tec hnicians just t w ist a nd w iggle it through th e existing space with no problem. But yo u should still check the service man ua l. For one thing, it' ll let yo u know if there are nuts and bolts that mu st be rep laced w ith new o nes, fo r safety's sake, when cha nging the rack . You w ill also wa nt to know th e torq ue va lues for all fasteners. Are there any O-rings involved ? Th ey' ll need re pl acing. T he ma nual will tell yo u. Befo re chi cken in g out, look at a rep lacement rack. Yo u' ll see t he location of bolt holes and the fluid pressure and return lin e ports- the on ly fluid lin es yo u' ll need to disconnect a nd rea ttac h at th e rack . Safely support the car a nd check cleara nces. If

(Fig. 2) Use a special puller to remove the tie rod end from the steering upright.

you find you can't grasp everything you need to work o n from under the car or by reaching aro und th e engin e, yo u may o pt to send the job o ut. Lastly, befo re dec iding, talk w ith peop le w ho kn ow the jo b, such as th e front-end pro w ho' ll align the car after yo u've swapped the rack, or a di smantl er at a loca l sa lvage yard. They may know legitima te sho rtcuts.

Doing It Ready to go? It w ill help if yo u remove th e front w heels for better access to the w hee l we lls. Break a ll the lug nuts free before using the jack . Lift th e car and support it safely on sta nd s. T hen, unbo lt the clamp that con nects th e steerin g co lumn to t he pinion shaft (Fig. 1). Detach the outer tie rod end s. Yo u may need to use a spec ial tie rod end pu ll er to get the tape red bolt to re linqu ish its grip on the steering upright (Fig. 2) . If yo u're re using the o ld o urer

CHASSIS

ti e wd ends, d o n't ta ke th em o ff th e knu ckl es w ith a for k-type remover-it co uld d a mage t he g rease sea ls. Use a pull er-t ype remover. Better ye t, yo u pro ba bl y ca n leave them in th e uprights. Just loosen the ja m nuts and turn th e ti e ro d s w ith a pipe w rench. Th e rods w ill un screw fr o m t he ends-cl oc kw ise o n o ne sid e, co unterc lock w ise o n th e o th er. Unbo lt th e rac k fro m th e chass is. Now yo u ca n di sco nn ect th e fluid lines a nd ca ptu re th e powe r stee rin g h ydra uli c fluid as it drains.

Flushing In spite of hav ing di gested co nsid era bl e am o unts of crud , ma n y powe r stee rin g pumps sur vive mo rnin g sick ness intac t. Still , yo u' ll need to remo ve conta min a tion to prese rve the

REPLACING

A STEERING

RACK

new rac k. H ere's how to flu sh most o f th e junk o ut o f the pump a nd lin es . Di sco nn ect t he return lin e to th e fluid ta n k a nd let it dra in into a sma ll co nta in er thro ug h th e return hose . Thi s is th e lo w -pressure side, usua ll y sec ured w ith a hose clamp . T hen block the ho le. Vin yl vacuum ca ps work well. Next, di sconn ect th e press ure lin e fr o m the rac k a nd a im it into a b ucket. Refill w ith fr esh fluid a nd ta p th e sta rter-it may require pump ing a qu a rt o r m o re to c lea n the line. Ca p o r plug an y loose end s. Now it's time to twist, wi gg le a nd snake the o ld rac k o ut o f th e ve hicle (Fig. 3) . Ex pel a n y min o rs fr o m th e ga rage, as th ey may find the la ng uage necessary to pers ua de the rac k c lea r o f th e ve hicl e un accepta ble.Yo u may

need to unbolt a nd sli ghtl y move so me o ther co mpo nents to ge t th e rac k o ut o f its tunn el. Lift, twi st a nd w iggle in th e new rac k a nd reco nn ect th e fluid lines. It may be ea sier to get a w rench to swing on a fluid line a ttac hm ent once yo u've unbolted th e rac k a nd mo ved it a bit. Also, rea ttac hing th e lin es may be ea si er befo re th e new rac k is bo lted in pl a ce. Use a ta pe meas ure to chec k th e ove ra lli engtb of th e rack a nd ti e ro d asse mbl y. Set th e overall length o f th e new asse mbl y to thi s sa me dimensio n b y t w istin g the ti e rod ends on th eir threa ds. Keep th e rack centered a nd

(Fig. 3) Snake the old rack out of its mounting tunnel after disconnecting the steering shaft, the tie rod ends and the fluid hoses.

243

... until it looks clean. Rea ttac h the pressure lin e. No te: Yo u m ay be ab le to insta ll a n aftermarke t inlin e filter so a ny cr ud yo u mi ss wo n 't harm the new rack . H ave a n alignment sh op rese t the toe-in ad justment or th e car may ha ndle strangely and wear o ut its tires rap idl y.

The Fluid Situation

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STEERING RACK HOUSING

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sp lit the overla p difference between the left and right rod ends as yo u do this , or t he steer ing w hee l w ill be offcenter w hen yo u' re done. Co nn ect a ll th e lines, the steering shaft and the rack-a ttac hment hardware . Use fres h

cotter pins in the tie rod ends' castella ted nuts . Reattach t he front w hee ls. O nce the new rack's in, reconnect a ll hoses exce pt the reservoir return lin e. Poi nt it into a bucket, then refill. Start the car, a nd run fluid thro ugh

T he las t step is bleeding ou t a ll of th e trapped a ir. While th e ca r's still eleva ted o n sta nds, fi ll the reservo ir, idl e th e eng in e a nd steer sid e to s id e, fro m lock to loc k, 10 to 12 ti mes. Be careful to avo id banging in to th e stops. Tan or foa m y fluid con ta in s a ir. Shut down, let it sit 15 minutes, then top off and start again. Repeat until the fluid looks norm al. Don 't forget to properl y torque the lug nuts o n the front wheels afte r yo u've take n th e ve hicle off the jackstands. And it wou ldn't be a bad id ea to cha nge th e powe r steering fluid in a few hund red mi les to get o ut any crud yo u've missed. (i

HOW IT WORKS

Power Rack-and-Pinion Steering

As you turn the steering wheel , a spool valve on the pinion shaft moves relative to ports in the housing. The ports connect to chambers on either side of a piston on the rack shaft. Steer left and the port connected to the chamber on the right side of the piston opens while the other port closes. This lets fluid pressurize the right side of the piston, helping push the rack shaft to the

244

left and pointing the wheels in that direction. (This description assumes the rack assembly is ahead of the axle. If it were behind it, moving the shaft right would point the wheels left.) Wear allows fluid to bypass the piston, wasting steering assist. "Morning sickness" results from light wear that closes up as heat expands the parts. As wear worsens, expansion will no longer take up the slack. Intense competition has driven remanufactured rack prices down. A "reman" unit may be your best bet, since many originals wore out because their shafts bore directly on the inside of their aluminum housings. In remanufacturing, the housings are bored, then hardened-steel inserts are installed in areas subject to wear. You may be able to get a recently installed new or reman rack at a salvage yard.

CHASSIS

---J

EASY

Servicing Brake Discs

Ou' re up to highway speed and suddenly a car cuts across your lane to m ake an exit . Yo u manage to slow eno ugh to avo id a nasty accident, but th e brakes definitely don't fee l ri ght. Th e bra ke peda l has had thi s kind o f vibration fo r a co uple of weeks, but onl y at low speeds. Now it fee ls like you 're stepping on a running chain saw, and the fro nt w heels don't wa nt to go w here you want th em to.

Y

Forget The Guesswork Pull the w heels fo r a cl ose up loo k. With the w heels off, you can inspect the rotor-lining contact surfaces . First look for a crack that goes all the wa y through a ve nted rotor-o r at least through one of its two surfaces. A cracked roto r ca uses severe p ul sa ti on, a nd th e o nl y cure is repl ace ment. Ru st at the ro tor edges is mea ningless, as are moder ate scores in the di sc's surface, or a fe w off-co lor spots on the shin y areas swept by the pads . Be sure to check both sides of th e

SERVICING

BRAKE

DISCS

(Fig. 1) Surface grooves deep enough to catch your fingernail will need to be removed by machining the brake on a lathe.

roto r, however. W hen yo u pull the w hee ls, there sho uld be an access ibl e area on th e bac k side (even if th ere's a du st shield ) w here yo u can in spect th e surface. Severe rusting of the lin ing contact surfaces is a problem . So are thick , deep scores , un even thi ckn ess a nd latera l run out (warping). If the rotors have never been res urfaced , it is theoreti ca ll y p oss ible to have them machin ed to remove signi fica nt rust and deep sco res (a bo ut .06 0 in . deep ). H owever, many la te-m odel rotors a re not ve ry thick to start with, and ca n't ta ke more tha n a .030- in. res urfaci ng. U nl ess the rotor is at least .060 in . thi cker th a n the minimum thickn ess stamped somewh ere on th e roto r, fo rget trying to save it. Buy new roto rs. H ow ca n yo u test th e dep th of a score? If it's thick eno ugh , in se rt the hea d of a dime into it. If the dime

goes in beyond th e top o f the pres ident's head, the sco re is too deep . If a score is too thin fo r th e dime to slip in , it's ha rml ess. Anoth er test is to run yo ur fin gern a il across the surface radiall y. If yo ur nail ca tches, the ro tor needs to be resurfaced (Fig. 1) . If not, yo u're pro ba bly okay, provided th ere's eno ugh thick ness left on a tru e-running rotor. Uni fo rm thi ck ness is criti ca l. Measure eac h rotor with an o utsid e mi crometer at a number of eve nl y spaced po ints aro und th e lining co ntac t surface . A va ri ati o n of .005 in. or more is enough to ca use the pul sa ti on yo u fee l. l atera l runo ut is ca used by a rotor th at's uni fo rm in thick ness, but is wavy. Un even thi ckn ess a nd excess ive run out often go toge th er. Th at is, th e runo ut ca uses th e un eve n wear on the roto r. So if you ca tch it early, th e rotor may pass a thi ckn ess ch eck , but it still co uld ha ve excess ive latera l run o ut. Th e high heat (then rapid coo lin g) fr o m ha rd brak ing is a p rimary ca use of run o ut, but close behind is un even tightenin g o f w hee l lu g nuts. Dirt or ru st buildup betwee n the rotor and hub a lso ca n produce run out (Fig. 2) . To check fo r excess ive runo uti wa rpin g, yo u need a di a l indicator, which yo u can rent fro m many a uto parts stores . W hen yo u pull th e w heels, the ro to rs might be loose on the stud s, so refit th e lug nuts and ti ghten th em securely. In stall the dial indi ca to r, and mo unt it on the susp ension. Th en, aim the indicator plunger at the mi ddl e of the lining co ntact surface, at as close to a 90' a ngle as possible. Set the plunger so it presses li ghtl y aga in st the rotor-lining co ntact surface, th en zero o ut the dia l. Slow ly ro ta te th e ro tor and wa tch the dia l. If it exceeds .005 in ., th e ro tor is no t runnin g true (Fig. 3) .

245

(Fig. 2) Whenever assembling brakes, remove any dirt or rust that might get between the brake and the hub to reduce lateral runout.

Yo u may not have to replace or resurface the roto r. With the roto r off, you can look fo r and remove dirt or rust buildup. If that's not the problem, yo u can try re-indexing the rotor. That is, just remo ve it, rota te it one or two stud holes, install and tighten the lug

nuts and recheck . Alth ough the typica l rotor just slides off the studs with the w heel removed (some advance spraying with penetrating solvent may be necessary), the ca liper has to come off first. First, remove the bo lts that hold the ca liper itself to its anchor frame or

to the suspens io n. Then pry the caliper up, lift it off the frame and wire it to th e suspension. Thi s w ill reli eve any stra in on th e brake hose. Many ve hicles have "fl ip up " ca li pers . Remove o ne lower retaining bolt, flip up the caliper and slide it off a stud. If the brake shoes stay in the anc hor frame, perhaps held by a reta ining clip, remove those nex t. Fin all y, unbo lt the anchor fra me, lift it out and the roto r shoul d slide off. But first, if the rotor is not necessarily being replaced, make a lignment marks on the hub section and the stud, so yo u can reinsta ll it in the sa me loca ti on. If it binds on the hub, that's norma l r ust buildup. Just spray the studs and ho les and hub/rotor joints w ith penetrating solve nt, rock the rotor with a pulling motion and it should walk off. Clean

HOW IT WORKS

Brake Rotor The brake rotor, the disc in disc brakes, mounts on the hub with the wheel, and both rotor and hub are held by the same studs and lug nuts. When you apply the brakes, the hydraulic device called the caliper clamps the brake shoes (also called pads) against the rotor, and the friction material on the shoes stops the spinning of the rotor (and therefore the wheel). The friction material on the shoes causes the energy of wheel and rotor motion to be converted to heat, and the rotor temperature can soar to over 1000 F in a hard stop. That heat has to be dissipated very quickly so that the rotor can cool down for the next 0

246

A typical vented disc brake assembly. The hole in the caliper is for inspecting pads. stop. Because front brakes do about 75 percent of the work in a front-drive car (over 50 percent in a rear-drive), the front rotors have to be able to dissipate a lot more heat than the rear brakes, drum or disc. As a result, the front rotors on virtually all cars today have two con tact layers separated by a vent area, which resembles a paddle fan, to scoop up air. This design not only gives each brake shoe a separate disc, but the airflow through the center provides greater cooling. Some high-performance cars also have vented rear discs.

CHASSIS

(Fig. 3) A dial indicator will show you the total lateral runout-.005 in. is too much.

rust off the hub with ultrafine sandpaper or a wire brush. Clean the mating face of the rotor as well. If you're working on rear discs, they're likely to have a mechanical actuator for a parking-brake function or a drumtype parking brake built into the hub. With the drum type, the rotor itself will have a deep "hat" section to fit the hub, and the inside of that hat is the drum for the parking brake. Normally, with the parking brake off, the rotor just slides off, but if the parking brake has a self-adjusting linkage, it's possible that it's overadjusted and the drum shoe linings are locked against the inside of the hat. In that case, you can reach in from the back through an access hole (in the hub and also possibly through a dust shield ), and back off the adjuster (Fig. 4) . With the type that uses an actuator on the disc brake lining pads, you may be able to just lift the caliper off. At worst,

a rea l bear to remove, so if the ve hicle manufacturer indicates specia l tools or if a press is necessa ry, a rotor ca n be machined on the ve hicl e. You're best off leaving this to a properly equipped pro.

Both Sides, Please

INDICATOR

yo u' ll first have to disconnect the bra ke cable from the actuator on the ca liper.

Installation If yo u need a new rotor, insta ll it stra ight out of th e box. Som e o f the li g htweight rotors, made of a sta mped stee l hub with a cast-i ron brakin g surface, co uld test as warped unl ess yo u check them w ith a ll lug nuts in stall ed and tightened. Note: There are some rotors th at are

Norma ll y, w hat happens to one wheel happens to the other. If one rotor is gone a nd the other is marginal for machining, rep lace both. However, if one is particularl y bad, perhaps the veh icle has been pulling, lea ving the other side pristine. There ma y be uneven brake application, perhaps from a hydrau lic or mechanical problem at the wheel. Trace the cause in addition to correcting the rotor problem. C lea n lug nuts and stud threa ds w ith a mild so lvent and w ipe dry. Don 't lubricate them if the torque specifications are based on clean, dry threads. But a thin film of anti-seize compound normally is beneficial. One of the most im portant tools you can use is a torque wrenc h. When yo u' re re-indexing a rotOt; be sure to reinsta ll the lug nuts and torque them to spec ifications in at least three stages. Use a crisscross pattern for each stage until all are tight. (I

DISC

(Fig. 4) Removing disc-type rear brakes may require backing off the parking brake adjusters first to relieve the tension of the parking brake shoes.

PARKING BRAKE SHOES

SERVICING

BRAKE

DISCS

247

Fixing Suspension Clunks And Rattles t's the proverbial 20 miles of bad road. Potholes compete with ruts for th e privilege of knocking yo ur Freedom Fries out of the bag and OntO the floor. It's worth it, however, for the grea t weekend of backwoods hiking and knocking around. Heading back to civilization without the heavy load of refreshment and food seems eas ier on your car and your fresh ly relaxed psyche. At least until yo u hit the pavement a nd the rattlin g sta rts. Maybe yo u cou ldn 't hea r it on the unpaved road, but every expa nsio n strip on the interstate makes your car sound like a tin can full of bo lts. Something's loose in your suspension. While there 's littl e chance that yo ur car is going to lose something essenti al wh ile yo u' re go ing down the

I

roa d, chassis a nd suspension noises definite ly have to be checked out for safety's sake. Plus, who wants to dri ve a vehicle that so und s like it's abo ut to drop to the pavement? If yo ur car has lots of miles o n itor even if it doesn't, but is "chronologically gifted"-d on't be surprised if some portion of the heavy metal that supports it over terra firma starts compla ining. Unfortunately, finding th e ca use of th e no ise isn 't so easy. The d ynamics of a rolling vehicle, the comp lex na ture of modern suspensions, and the way sounds can be telegraphed thro ugh the chassis and body m a ke it hard to pinpoint the loca tion of a prob lem. If yo u hea r a clunk when the suspensio n works over bumps, the prob-

able cause is excess ive clearance in a join t due to wear. It might be as simple as a loose strut gland nut, or so mething more subtle such as a shrunken, dried-o ut rubber bushing.

Research, Then Bounce As a first step, consu lt whatever litera ture you have avai la ble to see if you can find a Technica l Service Bu ll etin (TSB) that perta in s to the noi se. Apparently, suspension clatter is a popular problem industrywide beca use it genera tes quite a few TSBs. Some of these a lert you to redesigned replacement parts, while others say the no ise is simpl y a cha racteristic of the ve hicl e and sho uld be accepted as norm a I. If no clu es are forthcoming, it's

A worn tie rod end will not only make the steering vague, but can set up a rattle if it's bad

enough. Set the overall length of the tie rod with a tape measure to get the toe-in close enough to drive over to the alignment shop.

248

CHASSIS

Antiroll bar bushings and brackets can loosen up as they wear. Replace the bushings or tighten the fastening hardware.

time to go ha nd s-on. It' ll be helpful if yo u can get a fr iend, preferab ly a hefty one, to ass ist. For front-end noises, pop t he hood, a nd have yo ur comra de press down o n th e bumper o r fender, th en re lease a nd li ft repea tedl y until t he suspensio n is rea ll y working. Whi le he does thi s, listen carefu ll y a nd use a good lig ht to examine the up pe r str ut or shock mounts and th e control arm joints. If yo u hear a nyt hin g untoward, but can't pinpo int th e so urce, pl ace th e end o f a broomstick aga in st yo ur ear a nd touch t he o th er end to suspected areas. Thi s works a lm ost as we ll as a mechanic's steth oscope. Nothin g o bviou s? Then li e down and look underneath w ith yo ur light, even though yo ur fr iend 's stamina may be taxed by t hi s time. The " dry pa rk check," which wi ll unco ve r las h in the steerin g mechanism , is less p hys ica ll y cha ll enging. Have yo ur helper sit in the dri ver's seat, turn the key to unl ock the column, then rock th e steerin g w heel vigorousl y fr o m side to sid e w hil e yo u wa tch th e steering compo nents. There sho uld be next to no visibl e las h. By th e way, if yo u ra ise th e car by the fr a me, t he suspension a nd steering parts w ill be ha nging at a n unnatural a ngle, w hich may mas k th e looseness yo u' re look ing for. So, p lace yo ur jack a nd jacksta nd s under the control ar ms or th e rear axle to keep the w eight o n th e suspensio n components. You ca n uncover the sho rtco mings of upper A-frame or contro l a rm bushings by having a helper ho ld the brakes firml y with the engine idling while shifting fro m Dri ve thro ugh Ne utral to Reverse repea tedl y. Look down over th e fender as yo ur helper does thi s. Som e vehicl es ha ve substa ntial horizontal struts that p ositi o n th e lower contro l a rms fore and aft. These are mounted in la rge rubber bu shings, a nd a ny cleara nce here w ill

FIXING

SUSPENSION

CLUNKS AND

make itself heard . Also, their m ou nting points o n th e frame ha ve been known to rus t away, but thi s causes steering sym pto ms far mo re noticea bl e a nd worrisome th a n a mere nOise. O ld er rea r-wh ee l-drive ve hicl es with a li ve rear ax le a nd coil sprin gs

may have w hat's ca lled a " panh ard ro d " that run s diago na lly from t he chass is to o ne side of the axle ho using . Th e ro d's bu shin gs are a li ke ly so urce of a clunking no ise . Worn-out shocks or struts a re co mm o n c ulprits here. Wh en th e intern a l h ydra ulics wear o ut, the pi ston w ill move w ith o ut the prop er resistance, then stop short w hen yo u hit a bump. W it h shocks, a nother t hin g to check fo r is loose o r dri ed- o ut mo untin g bushings. A groaning noise w hen yo u turn th e w heel typ ica ll y mea ns th ere's a dry joint, likely a t th e idl er or pitma n ar m . T ha t hu sky stab ili ze r bar, the p art tha t helps keep a car level in a curve, is often the source of noise . The links that a ttac h it to th e chassis have bu shings a t both ends, a nd th ere is m ore vu lnera bl e The antiroll bar's attaching links can become loose. Check the bushings.

RATTLES

249

rubber in its mounts. A wo rst-case scena ri o we often see o n unibod y ca rs driven extensive ly in winter conditions: rustedour suspensi o n pickup p o ints. Th e onl y fi x fo r thi s is a trip to th e fr a me shop wh ere new metal can be weld ed on. If thi s is your ve hicle's pro bl em, you ha ve rea l troubl e-because if o ne p o int is ru sted , its sister o n th e oppos ite side is pro ba bl y ru sted also . And proba bl y a bunch of oth er pl aces as w ell. N o w you ' ll have to decid e how much mo ney yo u wa nt to spend on a ship th a t's sinkin g slowl y but surely. It m ay be tim e to retire this vehicl e.

Alternate Sources O f co urse, so me no ises t ha t ema na te fro m under a car d o no t have a nything to do w ith the suspe nsio n or Rusted-out suspension pickup points are an accident waiting to happen. This calls for welding- or the scrapheap.

A loose upper strut cartridge nut can cause a hard-to-find rattle . You may be able to tighten it on the car.

steerin g systems, but it ca n be difficult to ma ke th e di stincti o n. For insta nce, ta ke th e exha ust system-th e muffl er, hea dpi pe a nd ta ilpipe, a nd th e ca tal yti c conve rter. If everything isn't positioned just ri ght, o r the ha ngers are loose o r b ro ken, it's likely th a t there'll be occasio na l LOWER CONTROL ARM

FRAME

250

co ntact, and the res ul ta nt clu nk, betwee n these comp o nents a nd th e chass is o r dri ves hafr. Try fo rcing th e system from side to side (make sure it's cool to the touch ) to see if yo u ca n duplica te the so und. A broken motor mo unt ca n ca use a so li d thum p. O il soak ing may have ca used it to dela min a te, or perhaps a coup le of bo lts are loose . Thi s co ndi ti o n will be sensitive to getting o n o r off the throttle, but wo n't be detected over bumps.

Restoring The Peace W hil e we've seen peopl e try to ta ke up cl eara nce in a deteri ora ted bu shing wi th shim s made of sheetmeta l, screws, etc., th e o nl y rea l fi x is rep lacement. This ca n be more involved and expensive than you might expect, but it's the price of peace . O n th e other ha nd , some repa irs are free, o r nea rl y so . It costs no thin g to ti ghten a strut gla nd nut (put a drop of a naero bi c threa d locker o n it to avoid a rec urrence) , and very little to repl ace shock mo unting o r sta bi lizer ba r bu shings. (I

CHASSIS

DIFFICULT

Curing Steering Wander

Ou're a lm ost enjo ying a lo ng dri ve o n a nice, flat inters ta te. Almo st, because it 's windy and you nee d to saw the st eer ing wheel ba ck a nd forth, tacking li ke a sa ilb oat, to sta y in your la ne. Th at is, until yo u ma ke a shorr res t stop a nd rea li ze tha t there's no wind wha t soever. T he k id s in th e back sea t are screa ming fo r Dra mamin e, and yo u're fatigued after only an hour of driving. There's no doubt about it-you definitely have some steer ing iss ues.

Y

CURING STEERING WANDER

Vehicle-to-pavement interface Before yo u start thin kin g a bo ut expensive repairs, make sure the basic ve hicl e-to-road interface is okay, meaning the tires. First, check inflati on press ures. (Don 't tru st the gauge on th e qu arter-ea ting pump at the loca l statio n-those are often off by as mu ch as 5 pounds. Drop 10 bucks on a good ga uge and keep it in yo ur glove box.) Yo u shou ld check your tire press ures once a month. And th at 's first thing in the morning, cold . The correct pressure is on a

stick er- check yo ur ow ner 's ma nu a l for its exact loca tion. A low t ire on one side w ill make a car p ull in th at direction. This is because its rolling diam eter w ill be sma ller than that of its mate o n the other sid e. Also, th ere' ll be more trea d-to-pa vement drag on the low sid e, p ullin g the car in that direction. If th e p rob lem persists, tr y switching the positions of the r ight and left tire/wbeel assemblies. If tbe car pulls in tb e opposite direction afte r yo u've done thi s, yo u've fou nd tire troub le. 251

PSSST!: Low tire pressure will cause a wheel to pull.

Check your tires' tread-wear patterns. For examp le, if a front tire's tread tends to disappear along the outboard edge, it's likely that the camber setting at that corner is too positive, and any pull probably will be toward that side.

Geometrical considerations Camber refers to the tilt of the tire from the vertica l, and this has a profound effect on directional tendencies. Zero camber means the centerline of the tire is perfectly perpendicular to a level surface. If tbe top of the tire tilts outward from the body, camber is said to be positive. Going too far in this direction wi ll cause a pull to that side because the tire itself forms the shape of a cone. Don't run to the alignment shop just yet . You can get a pretty good idea of camber by using a carpenter's level, a lthough you'll need to be parked on a perfectly level space. We used two 35mm film canisters held to the edge of the leve l with rubber bands. The canisters served as feet that we placed at the top and bottom of the wheel 's rim. Keep in mind that most vehicles wil l have a degree or two of negative camber. Here's where ride height comes in . As springs or torsion bars sag with age, camber changes. Replacing coil springs or adjusting torsion bars can bring alignment back into specs.

(IRS ), the thrust line is determined by splitting the toe-in angle of the rear wheels. For example, if the left rear w heel is toed in at 4' and the right is toed at zero, the thrust line is 2' to the left of the centerline. In an id ea l world the two lines coincide. But given a veh icle's size, This side up: A quick camber check can be done with a level and two simple spacers.

manufacturing tolerances, wear and abuse of daily driving, they often do not. If the deviation between the two is great, your vehicle wi ll dog track. Besides having a steering whee l that's not at center when you're going stra ight, another obv ious clue to dog tracking is if you see four distinct tracks in the snow or rain when driving straight. This is just about impossible to correct without professional 4-wheel-

Woof! Even if the front wheels are perfectly aligned and tires properly inflated, you may still have to steer constantly in one direction or the other to keep the vehicle going straight up the road. The problem is that the rear wheels are also trying to steer the vehicle and overtake the fronts. This condition is common ly referred to as dog tracking. Technically this occurs when your vehicle's " th rust line" and centerline are too far apart. On vehicles with solid rear axles, the thrust line is perpendicular to the rear axle. On vehicles with an independent rear suspension

252

CHASSIS

a lignment equi p ment. O n IR S cars, ta pered shim s are typ ica ll y in sta ll ed unde r t he rear stub ax les to reco ncil e the thru st lin e a nd centerlin e a nd to restore ha rmo ny. With solid rea r axles, the rep air will require repl ac ing the rear links o r strai ghtening the fram e.

Wanderlust If yo ur ca r doesn't have a definite pull to o ne sid e, but instead a sloppy, undi sc iplined tendency to wa nder a ll over the place, the fi rst thin g to think about is w ear in the steering a nd suspenSIOn. Direct observation is the bes t wa y to find thi s, but yo u' ll need a helper. With the ca r sitting with a ll w hee ls so lidl y o n the p avem ent, have him or her unlock the steering co lumn , th en rock the w heel vigorously back a nd fo rth while yo u stick your hea d undern ea th a nd inspect w ith a lig ht. (Needl ess to say, do thi s w ith th e engine off. ) With a pa rallelogra m steerin g system-th e kind with a Pi t ma n a rm coming o ut of the steering box- yo u ma y see the idler or Pitma n ar m moving up a nd down. Or yo u m ay no tice slo p in the tie-rod ends or p erha ps m ore ro ta tio na l acti o n goin g in to the steering box th a n co ming o ut. W ith rack-a nd-pinio n steering, pay spec ia l attentio n to the inner ti e-rod ends, and ma ke sure the rack hou sing itse lf is firml y mo unted. Another w ay to inspect is to slightly raise o ne tire off the gro und (pl ace the jack under the lowe r co ntro l a rm , then have yo ur ass ista nt rock th a t tire side to side, th en to p to bo tto m, while yo u ta ke a look) .

Steering bag? With the recirculating-ball steerin g boxes typically fo und on big do mesti c rwd cars, pickups and SUVs, las h w ill gradua ll y develop betwee n th e wor m a nd sector gears. Yo u ca n elimin a te thi s pro blem by d oing an "over-center adjustment." Yo u' ll find a n adjusting bolt o r screw sticking out of the top of the steering box . With the w heels as close to the straight-ahead pos iti o n

LOOSE: Minor adjustment to the clearance of a high-mileage steering box can tighten up the steering.

LOOSER: Worn tie-rod ends let the wheels wander, making steering vague.

as yo u ca n get t hem, loosen th e locknut, then turn the screw cl ockw ise to reduce las h . D o not overdo this o r yo u ca n reduce interio r tol era nces too much , ca using da m age . Yo u'll know yo u've gone too fa r if the steering w heel stays w here yo u p ut it instead of returning to a stra ight-a head positi o n under no rma l roa d forces, es pecia ll y when coming o ut of a rurn . Las h m ay exist in the joints th at a ll ow the steering co lumn to tra nsmit th e helm sman's co mmands to the

gea rbox. T he uni versa l va ri et y typ ica ll y las ts fo reve r, but the rub berized textil e type, fo ndl y kn own as a "rag jo int," often deteri o ra tes to th e po int a t w hi ch th ere's excess ive pl ay. Deteriorated upper contro l arm bushings can ca use serio us steering pro blem s, a nd proba bl y a lot of clu nking to boot. Look down on them w h ile your helper ho lds the brakes a nd shi fts from Dr ive to R everse a nd back . You' ll see and hea r excess ive movement .

9

J I

L -_____________________________________________________________ _

CURING

STEERING WANDER

253

254

CHAPTER SIX

Interi •r and Ext rl Re-Covering Your Seats / 256 Replacing Your Cabin Air Filter / 260 Replacing Your Rearview Mirror / 263 Repairing Your Rear-Window Defroster / 266 Keeping Your Windshield Clear / 269 Detailing Your Car / 272 Aligning Body Panels / 275 Prepping Your Car For Paint / 278 Repairing Windshields / 282 Finding and Fixing Water and Air Leaks / 285 Storing Your Car / 288 Drying Out Your Flooded Car / 291 Repairing Paint Chips / 294 Polishing Your Car / 297 Repairing Plastic Bumpers / 298 Hushing Interior Squeaks and Rattles / 302 Removing Bumper Stickers, Window Tinting and Pinstripes / 305 Freshening Up Your Musty Interior / 308 Fixing Hood and Trunk Latches / 311

255

MODERATE

Re-Covering Your Seats t's Sa turd ay ni ght, and yo u're tak ing th e in- laws o ut to dinner. Unfortun ate ly, the dog has been digg ing-unbek nownst to yo u-for bones he thinks are hidden und er the back seat. The ens uing di vo t leaves your spo use's mother sitting at a considerab le angle a ll the way to Denny's. Morning finds yo u duct-tap ing large and sI11 a ll chunks of foam rubber bac k into p lace. Late morning find s yo u ca llin g uph o lstery shops, followed by a qu ick ba lancing of the checkbook to see if yo u can afford it.

I

.

:

..•. ••• J'

....

--HINGE COVER

Rolling Your Own The one-size-fits-a ll covers yo u've seen a t the di sco unt department stores are certainly in expensive, but they look like covers more suita ble for lawn furniture. And you know that going to the loca l car upho lstery shop is like ly to cost yo u a minor fortune . "Basica lly, yo u have three choices, " says Randy Smith of Brougham Seats Inc. , "s lipcovers, re-covers or getting the damaged seat pa nels replaced at an uph olstery shop ." A fo urth choice also ex ists: Get replacement sea ts of an acceptab le cover fro m a wrecking yard. If all seats have been damaged, consider this p oss ibi lity. Slipcovers, which are designed to slide over the car's origin al seating materia l, range in price from $25 for the di scou nt store cheapos to $400 for custom- fit covers designed specificall y for each ve hicl e. O ne company, Performance Products, even sell s slipcovers for Toyota trucks and Ford Explorers th at are made from scubad iving wet-suit neop ren e. As the nam e implies, slipcovers sl ip over th e ex ist ing cover. They're typica ll y held in p lace o n back-seat and front- sea t bottom cushions with flex cords that attach to both sides of the cover und er the cushion . The covers for front-seat back cushions snap on

256

(Fig. 1) Start removing t he front -seat top by removing the cover over the hinge.

(Fig. 2) Once it's completely disconnected , pull the bottom bolster free of the frame.

or are held by Velcro at the bottom w here th e seams can't be seen. Headrest covers attach sim ilarly. Ca ution: If your vehic le seats have side airbags, covers cou ld affect their dep loyment. Re-covers are des igned to complete ly rep lace the origina l factory seat coverings. " It's no t a do-it-yourself project," says Smith, whose company mak es them. "They can only be

purchased by up holstery sh ops, and they're normally installed in fairly new cars and trucks fo r customers w ho want to upgra de their car's interior, say from vinyl to leather." T he cost ? Typica l insta llation prices range from $1500 to $3000, depending on the vehicle. The third option-having an up ho lstery shop repa ir a vinyl, cloth

INTERIOR AND E X TERIOR

(Fig. 3) Rear-seat bottom cushions usually just clip in at the front.

or lea th er pan el on a seat-might actua ll y yield th e most attractive result and may eve n be the least ex pensive option, if the da mage or tearing is limited to a single pane l o n a bottom seat cush ion or seatback. You ca n save add iti o na l mone y by taking the seat out yo urself, removing the hard-pla stic sk irrs, sp litting the back from the bottom cushion and deli vering the damaged cushions to the shop for repair. Of course, the drawback is th a t yo ur car w ill be out of commission for a while if th e work needs to be don e to th e driver's sear. If you ' re planning to go thi s route, chec k with th e upholstery shop first so it can order matching material a head of time, then mak e a n appointment to have the work do ne to reduce yo ur vehicle's downtim e.

Seat Removal and Disassembly Repa iri ng a n upholstery pa nel is not eas il y tac kl ed at home, bur yo u ca n remove a nd disassemble th e sea ts. And w hile you don't necessa ril y ha ve to remove the front seats to install the slipcovers, the finish ed job wi ll look better and smoother if yo u take t hem out and th en separa te th e cushions before putting on the covers . If yo u're doing a ll the sea ts, remove the front seats first so you' ll have room to maneuver the rear-seat cushio ns from the car. Doing it this way is especially critica l on 2-door vehicles . Most front seats are bolted to th e floor pan at a ll four corners . Begin by removing any plastic covers (Fig. 1) and th en remove the bolts (Fig. 2) . On power seats, disconnect th e wires to the seat motor before lifting out the

REAR-SEAT BOTTOM CUSHION

sea ts . Ca ution : If yo ur vehicle has si de airbags in the seats, refer to a factory service ma nual for instruction s on how to disable them safely, as well as how to reconnect the system. Typica ll y, rear-seat bottom cushions must be removed before th e back cus hi on can be removed. Most bottom cushions are " hoo ked " to the floor pan in fro nt (Fig. 3) . Firm ly pushing the seat cushion rearward and th en lifting upward disengages the cushion from the hooks so the cush io n can be li fted o ur. The back cushi o n is usua ll y bolted to th e rear bul khead near th e bottom of the cushi o n, w hil e th e top of th e back hooks to the top of th e bulkhea d. Remove the bolts a nd li ft upward to remove the rear cushi o n. With the seats mi ss ing, yo u' ll want

to pick up loose change, petrified food a nd other materials. Now is also a good time to give the carpet a thorough vacuuming and even a shampooing if it's gotten rea lly disgusting. To disassemble the front seat, remove th e hea drest by sliding it from th e sea tback. You' ll probably unbolt the sea t top at the hinge pin. First, remove a ny hard-plastic skirtin g. If the seat has a reclining lever near the bottom cushion, yo u ' ll a lso ha ve to disconnect the reclining mechanism from the seatback (Fig. 4) . After t hat, unbolt and se parate the two cushions.

Installing Slipcovers If the foam cush ions are damaged, this is the time to patch or replace them. If th ere are chunks missing, yo u can simpl y carve matching pieces

(Fig. 4) Disconnect the seatback recliner mechanism from the seat carefully.

RE-COVERING YOUR

SEATS

257

(Fig. 5) After you've removed the front seats from the vehicle, the new seat covers can be tugged over the seat bottoms.

from uph o lstery foam to fit, gluing them to the existing foam in the cushion with contact cement. Because durabl e material s are thicker and a tight fit makes for a better look, th e more expensive th e slipcovers, the harder th ey are to insta ll. Begin by sliding the cover onto the bottom cus hion first (Fig. 5). You may need a n ass istant wi th strong fingers to help yo u pu ll on the cover and get it aligned on the sea t. Once the cover is in pl ace, mo ve to the unders ide of the cushion w here yo u can draw the fl ex cords to the other side. Attach

' '.

l 258

-.

',. t.'.. ",:.

,'Jr! '

....

(Fig. 6) After the cover is on, add the elastic cords and connect the S-hooks.

INTERIOR

AND

EXTERIOR

th em to the eyelets in th e cover w ith th e S-hooks that a re provided w ith th e cover (Fig. 6) . To ensure tha t th e fle x cords stay in place, crimp the Shooks closed with pliers (Fig. 7) . Next, slide the slipcover for the back cushion into place and snap o r Velcro the bottom. Insta ll the hea drest covers an d a ny fo ld-d own ar mrest covers. Before reassembling the sea t's back and bottom cushions, make sure the sli pcovers are properly fitted with no gaps or loose corners. If there are any, readjust the covers on the cushions until the gaps disappear. After the seat cushions are reasse mbled, rea ttach th e recliner mechanism and reinsta ll the plastic skirt. • The Driver's Seat, The rear-sea t slipcovers fo r 1400 G lades Road, both the bottom and back cushBoca Rato n, FL 33431; ions insta ll with flex cords in a (561) 368-7966. manner similar to the front-seat • ] C Whitney, bottom cushi on. After the cords 1 ] C W hitney Way, are in p lace, crimp the S-hooks LaSa ll e, IL 61301; with pliers and reinsta ll the (800 ) 469-3894. cushi ons in the car.

(Fig. 7) Crimp the S-hooks with pliers before reassembly.

Another suggestion is to take • Performance Products this opportunity to Scotchgard (Ford Exp lorer, Toyota the new fabric while the seats 4x4s, Porsche), are still out. This water- and 8000 H askell Ave., dirt-proofing treatment is ava ilVan N uys, CA 91406; ab le at yo ur loca l disco unt store (800) 553-2840. in the automotive department, o r at the auto parts store. It's a simple aerosol can, and yo u can avo id cleaning up overspray if yo u use it o utside the car.

Reinstalling Seats When reinstalling the rear seats, make sure the lap and shoulder belts are properly routed thro ugh their seat openings . Also, make sure any hooks and fasteners are firmly engaged (Fig. 8) . When reinstalling th e front sea t, be sure to torqu e th e mounting bo lts to th e proper spec ificat io ns. Properly route the sea tbelts and then make sure th at both th e sliding track and reclining mechani sms work properly. On electric seats, reco nnect the moto r w ires and then run the seat through its full range of adjustments to ensure the connections are correct. 9

RE-COVERING

YOUR

SEATS

FRONT-SEAT TOP COVER

· ".1

'.,

' .'

." "

--" (Fig. 8) Install the front· seat top cover in the same way you would pull on a big, heavy sock.

259

EASY

Replacing Your Cabin Air Filter

t's Sund ay and the big basketball game is this afternoon, but yo u ca n forget a bo ut getti ng tickets. So it's time to ga ther the crowd and dri ve to the sports bar. Minutes into the rid e, the windshield is so foggy, yo u've got to hit the Defrost button. But w hy? The panel is set to o utside ai r for heater operation, and there a re no smokers in the car. You put your hand over the defroster o utlets and there's hardl y any a irflow. When yo u turn the blower switch to high, the noise leve l goes up but the a irfl ow is still weak . M ay be yo u need to change the cabin a ir filter. If it's plugged, the passenger compartment mi ght as well be a sealed cabin- and with a carload of friends th e glass will fog in minutes.

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Filter life depends on th e a ir q ua lity in yo ur area, but a yea r, or 12,000 to 15,000 mil es, typica ll y is the reco mmended repl ace ment inter va l. Ca bin air filter? In th e late 198 0s and earl y 1990s, onl y some Europea n lux ur y ca rs had them. It's more co mmon on newer ca rs. In ma ny premium ca rs, there may be two filters, even three. Sometimes they're para llel (side by side), sometim es they' re in se ries (one after the oth er, w ith so me space in betwee n ). So metimes th ey ' re nowh ere nea r each other.

Locating the Filters A ca bin a ir filter may be in the outside a ir intake, visibl e with th e hood up and perh aps a cover lifted. O r it will

(Fig. 1) Underhood filter covers are often held in place with plastic button fasteners, which need to be pried up carefully.

be under the das h in o ne or both of two genera l locations: • Above the bl ower in th e back section of the o utside air intake, a locati on well protected from moisture. • Between the bl ower and the rest of the H VAC case. If the owner's manua l doesn't tell yo u th e loca tio n, and yo u ca n 't see it w ith the hood open, check behind the glovebox-perhaps yo u'll see an o bvio usly re mova ble (with a spring-ta b or simil ar reta iner) rec tangular plas tic cover. Next, look under the das h (on

INTERIOR AND EXTERIOR

reins ta ll the a ir intak e scree n , as we ll as a ny cove r over the fi lter element. If th e gas ket sur face aro un d th e screen does not sea l, or if th e cover (actu a ll y a shield , in mo st cases) is not reinstall ed, rainwater can flow in to the fi lter, sa tura tin g it.

(Fig. 2) If any debris has contaminated the filter plenum, vacuum it out and then wipe with a damp rag.

both the driver's and passe nger's sid es) for a removab le plasti c cover in the HVA C case. If yo u ca n remove its cover, look in side the HVAC case. Still no a nswer? Buy th e fi lters, something yo u ha ve to do a nyway. You've got two choices: • Buy th e factory filters a t th e dea lership at full price. T hi s way, yo u' ll know for sure w ha t th ey loo k li ke a nd get some id ea abo ut how they have to be in sta ll ed. Yo u' ll a lso find o ut how man y yo ur ve hicl e has . The parts department sho uld have a diagram to show yo u w here the filters are located in th e ca r. • Buy aftermarket filters th a t co me w ith step-by-s tep in structi o ns fr o m a n a uto parts store. The odds of th e or igin a l equipment parts com ing wit h instructi o ns are extremely slim. Do a ll a ftermarket filters have them? No, but if yo u' re shopping at a parts store, yo u sho uld be able to check in the boxes o n th e shelves. Also, th ese parts proba bl y will cost less .

Replacing the Filters in the Air Intake Th e filter in the outside air inta ke (eve n if th ere are other filters) ta kes care of most of the dust a nd

REPLACING YOUR

CABIN

AIR

FILTER

In the Case, above the Blower If the filter is in the ca se

po ll en , so it's likely to p lu g first. T he typ ica l proced ure begin s wit h remo ving th e air in take sc reen, which is held by "Chris tm as tree" pla stic fas teners. If the " tree" has a center pin, pry it up w ith a thin-blade screwdriver a nd then w iggle the tree o ut of th e ho le (Fig. 1) . If the tree is a singlepi ece design, yo u' ll have to pry it o ut. Most o f th e time, it w ill brea k a nd yo u' ll have to rep lace it (b li ster packs of rep lace ments are sold in most a uto parts stores). If there 's a r ain/snow defl ecto r over the fi lter, remo ve it, th en ext rac t the element. The fi lter element may be held by a pl as tic ta b, o r it may slip into a reta ine r ho usin g th a t yo u will reuse w ith th e new element . Some du st may have gotten aro und o r through the filter. Use a vac uum cleaner to clean the outs id e air inta ke duct (Fig. 2) . Be careful when you

above the blower, m ost likely it is behind th e glove box . Removing th e glove box ma y be easy, but yo u m ay no t have to remo ve it a t a ll. Ma ny filters (s uch as on most Hondas a nd Toyotas) are just a bove the blower behind the glovebox, a nd yo u' ll have to drop it for access. In the best of cases, yo u ca n fl ex the sides of th e box so the pins clear the das h, th en pi vo t the box down for cl ea rance. In oth ers, the entire glove box asse mbl y has to come o ut, wh ich mea ns removing a number of retain ing screws, not all of which are visible.

Replacing Midcase Filters T he midcase filters may not a lways be easy, but remember, the setup was designed to a ll ow filter rep lace ment, so do n't ass ume the worst. There are pull tabs taped in pl ace in GM seda ns that have two or th ree fil ters in the same HVAC case located

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above the gas pedal. Pull a tape to release the tab, then pu ll the tab to withd raw the filter. D itto for the others. All filters need perimeter sealing, so air flows only through the filter element. With side-by-side filters, the sea ling may be a simpl e foam rubber strip . Or there may be interlocking guides. O n many cars the filter will come straight down and hit the floor without clearing the HVAC case. Nothing'S wrong. Most of these filters are flexible, and yo u have to bend them to get them o ut and the new ones in.

How to Buy Even if the filter location is access ibl e, th e toughest job ma y be getting the right rep lacement filter. One of th e most common complaints among professionals is th at the aftermarket catalogs have n't kept up w ith the year-to-year changes, particularly w ith filters th at fit under the dash where the space prov ided may have changed.

If a ve hicl e has more than one filter, yo u may not find both in the same box, especia ll y if they are in different locations. And they may have totally different part numbers. T hi s is particularly true if one filter is in the air intake and others are in the HVAC case. The o ne in the air intake is more

li kely to be a simple particulate filter, one that just traps sma ll particles. The one und er the das h is m ore likely to have a charcoal layer for odor control. No matter what the origina l equ ipment element is, the aftermarket one is more likely to be a partiClllate filter, ra ther than the more sophistica ted type with a charcoa l layer. Should yo u get the charcoa l filter, which may cost a lot more? If you're in a dense ly populated area with slow-mov ing traffic, or your carpool partner fancies Mexican food , the extr a cost is worth it. If yo u're not fac ing an odor pro blem, you may save money with a low-cost particulate-onl y replacement for an original equipment filter with a charcoal layer. An aftermarket particulate element does fi lter finely eno ugh to remove pollen as well as dust particles, so if pollen and dust are your major concerns, save your money. G

HOW IT WORKS

Cabin Filter The cabin filter is a type of air filter that in some respects-such as pleating to provide a lot of surface area in a small package-may resemble an engine air filter. However, it usually is made of different materials, the main one being a charcoal layer in many elements. Like some engine air filters, the dust and pollen filtering element is electrostatically charged, which means it's made with fiber particles that have been given either a positive or negative static electrical charge. Airborne particles are negatively or positively charged, so they are attracted to the oppositecharge fibers. In addition, the filter performs "mechanical filtration."

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This means that fiber material with pores of a specific size will trap particles larger than the size of the pores. The charcoal filtration layer removes odors. The charcoal is "activated," which means it is treated with chemicals and heat to give it specific odor-control properties. Each manufacturer has its own recipe, based on tests with individuals who have "sensitive noses," including people who work as perfume testers. Charcoal traps odor-causing gases by adsorption (not absorption), holding them on the surface of the material. Because charcoal is porous, each pore is an exposed surface, so the filter has a very high capacity for trapping noxious gases.

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