How Diesel Engine Works

8/14/2019 How Diesel Engine Works

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HowDieselEnginesWorkandWear

Engine ystems. Cooling. Lubrication. Fuelr Air lntake& Exhaust. Electrical

Thisbulletingivosan ovorviow f diesolengines,how heywork and typicallywear,plus he commonwarnlngsignsot engi;" problems. Tho objectives to give you a thoroughunderstandingf nginesand h6lpyouefiectivelymarxetCatrpillaro roductsandyour dealership's ngineBepairOptions'


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Plslonwlth normal woar o^ r lqhl , abnormalwear on le l t ,EngineWearHand n hand with he d scussion f how enginesworkis how they wear. For our purpose,we wi l lc lassi fyenginewear nlo two categories; ormaland abnormaenginewear.Normal {earoccurs n al englnes, As pa(s push,sl ideand work againsteach other, wear occurs.Nornal wear s that wl_ichwe e'pecl ou.ingeng;neoperation, The normalwear tems n a dieselengineinclude he p ston r ings, cyl inder iners, alvesandvalveguides,main and rod bearings nd i f equipped,turbocharger earings nd seas,

Abnormalwear s an y wear oth6r han that fromnormalengineoperation, General ly, bnormalwearresults rom lncorrectmaintenance r operatingtechnique. Using he wrongoi l , oxtonding i l changesintervals, ol maintaininghe coolantcondit ionerconcentrat ion, nd inadequatemachinewarm-up aretypicalpraci ices hat cause abnormalwear andpremature ngine ai lure,t is important o understandhat there are only ivemajorwear tems in a dise engine,and they re wor th. cyl inder iners. prston ngs

. vaves, guides,and seats

. main and rod bearingsa turbocharger earings nd seals

lf lhese wear parts are replacedbefore they wear out approximately80%of majorengine ailures an beeliminated.ar ln9showlnqabnorhal war.


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These parts are relatively nexpensive, andheads, blocks, crankshafts and connecting if replaced on a timoly basis, expensive components lik cylinderrods should nevr n6ed replacement.

War rems r6prac6dwh6n ropaklng b6lor6lal lure (ontho lsl t ) . P6rts oplacodaltsr la l lur (on ihor lgh0. Thlnkol ihunnscossary costs sssoclaled wlth alter lallure rpahE.

RepairBeforeFailureThisconcept s the basis or the management trategyof repairing efor ailure. Lt's look at a quickcomparison etweonbeforeand after ailure epaksso we cloarlyunderstand ow ropairing efore ailurebonefits h customer.In our after failurexample ho customer gnores horepair ndicators nd continues peratinghe 6ngineuntila main bearing ails causingmajor damage o thecrankshaft. In fact the damage s to the point hat thecrankshaft annot be used as a core or aremanufacturedrankshaft addingslbstantiallyothe ropair osts,In our before ailureexample he ongine s maintainodcorrectlyand th repak ndicators re monitored.when an S.O.S report warnsof bearingwear heengine s promptly cheduledor repair beforemajorfailurocan occur. Tho nexpensivoearings re

replacedand thereother components,Using his xample,benofitsof repairing

is no damage o the crankshaft rlet's summarizehe customorbefore ailure.


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Nobody knows Cat equipmnt d6sign and wear trendsas w6l las Cat erpi l lar nd Cat Dealers. They regularlypool informatjon to develop wear trends for accuratelyinterpreting S.O.S lest results. Olher oil analysisprograms simply don't have this critical information.The bottom line is, S.O.S is the only program thatcan determine whn wear trends go from acceptableto unacceptable indicating problem.LJsed 6gularly, S.O.S can catch problems early sothey can be fixed n minirnal ime and with minimalcosts o the customer.EngineRepair ndicatorKit

One of the oasiest ways to determine the overallcondit ion f an engine s 10 periorm some simplechecksor tests. That s the purpose or the EngineReDairndicatorKi t (ERIK).The ki t includes he basictools needed to evaluate the engine condition anddetermino i a before ai lureoverhau s needed,or i ifurtherdiagnosiss required.

The kit is convenient and 6asy to use, ln the kit aresuch tools as:Tempraiure Fecordr LabelsCoolant ConditionerTest KitFiher CutterCrankcase Pressure Gauge

Also ncluded s helpful i terature uch as an OverhaulEstimator orm, EngineEvauationWorksheel ndSpcial nstruct ionshat give you the basic nformationneeded o completea lhoroughengineeval!at ion.Dealer alesmen r f inding he kit usful n buidingcrdibility and professionalismwith thelr custon]ers.Now et 's look at each oi the dieslenginesystemsindividual ly.

l. CoolingSystemOver40%of engineailures esult romcooling ystemproblems. Of the live syslems, ho coolingsystem sthe mosl criiical o engine iie.

Over 40/oof enginefailuresare due to coolingsystemproblems.

Thocompon6ntshatmakeup he cooling ystemincludeh6 ollowing.T6mperature Thermostat9aug6


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a Water Pump- Thewaterpump provides ontinuouscirculation f coolantwheneverhe engine sturning. Waterpumpson Cat enginesaregenelallygear driven,excepton the 3208,3j 14,and 3116Engineswhichhavobelt drivenwatoroumos.a Radlator Th6 radiator ransfrsheataway romth6 coolant, owerino oolant emperature, Coolantflows hrough he radiator ub6s whileair circulatosaround h6 tubesproviding transferof heat o theatmosphore.W have hrse stylsof radiators,conventional-style,oldedcore, and the modularcore radrator.

o Coolant Coolant s a mixtureof water,antifreeze(glycol), ndcoolant onditionerinhibitor). orpropercooling,eachmust be maintainedn th6correct9rooortion,. Thrmostgl Technicallyhe thermostat s calledatemperatur egutator. Thethermostatassists nenginewarm-upand h6lpsmaintain ootantandengine empeEtureduringoperation. When he6ngine s cold the thermostat ttows oolantcirculationust through he engin6,bypassinqheradiator to hlpthe nginewarm-up). When heengine s at properopratingemperaturehethermostat pens o allowcootant low through h6radiator so cooling akesplaco). The hormostat

continually pens and closesas the cootanttemperature hanoes,. WaterTemprelureGaug The mperaturegauge ndicateshe temperature f the cootant.The recommendd perating anoo s gnerallybetween 90'-210oF88"-99.C).. Fan- The tan forcesair around he radiator ubesto transferheatout of the coolantand dcrsasecoolant emperaturo. Fansare boltdrivenoff acrankshaft ulley.. Oil Coolers Oil coolers unction o maintain hecorrcct empetature f engine, ransmissionndhydraulic il. Therear two basic ypes: oil tocoolantand oil to air.

Oil o coolantcoolersare used most often orcoolingengineand transmission il. Oil towsthrough ubs whilcoolant towsaround h6 lubspickingup heatand lowednghe oil temperature.

Oil to ajr coolersaro usedmost often or hydraulicsystems,wherea muchgreatar emprature rop stequared, uch as on manyexcavators. Air to oilcoolersare similar n designand principleoradiators. Ak blowsacross he surfaceof oil coolertubesdissipating 6at away rom the oit to theatmosohere.How heCoolingSystemWorks

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The primary unctionof the coolingsystem s tomaintain orrect engine emperature y takingawayunwanted oatgenerated y combustion nd friction.Approximatoly3% of th6 hatnergydevlopedduringcombustions convertd htousabtehorsopower, % radiats irsctlyoff enginesurfacesand 30%out the exhaust. The remaining 0% sdissipated y the coolingsystam.Coolant kculates hroughpassagesn th6 enginecalledwat6ror coolantackets. The coolantabsorbsheat from the hot enginosurfacesand carries t to theradiatorwhr t transfers o the atmosphere,Thecoolingsystemalso hlpsmaintain he correcttemprature f engine, ransmission nd hydrautic ilthrough h6 useof oil coolers. Now et's look n moredetailat how coolant lows hrough he engine.


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Coolant low is iniliated by the water pump thatstarts and continues pumping as soon as theengine s slarted.Coolant circulates through the engjne oi l cooler tocool the engine oil.From lhe oil cooler' coolant travels into theengine block and around the hot cylinder linefspickingup heat and cool ingenginepartsThen it travels through intricate passages in thecyl inder ead(s) pickingup more heat around hecri t ical alve areas.

5. From the cyl indorhead(s) he coolantgoes o thethermostat and on to the radiator for cooling litne engine s cold the thermostatwi l l remainclosed and will recirculate the coolant through theenginebypassinghe radiator.

DiagnosingCoolingSYstemProblemswhich causes the most engine failures problems withthe cooling system or the lubricationsystem? Initiallymost people say th lubricalion system' however thecorrecl answer is the coolng system A coolingsystem that tuns too colcl causos rYlarginalubricationbecause the low tomperature prevnts the oi l fromwarming up so that it can flow and coat partsadequately. A cooling system that runs too hot alsocauses marginal lubricationbcause the hightemoeraiures breal down th oi l properlies so thatoaris are nol orotected correclly. Both cases ofmarginal lubricationcan be traced back to coolingsyst6m proolems

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OIIal norhal oprating emPsrature n the lelt' thlckviscous l l at low 6mperatu16n h6 rlght 'Coolingand lubricationare closely related oecausetempeiature greatly affects lhe oil's ability to lubricatand protect Parts ProperlyGeneral ly, 4ginesare designed o operalebetween190"-21ooF 88'-99'C) - and they wil l not operatewell. or livo up to thoir expcted life, il continually uneither colder or hotter than this. lf the engine runshotter (overheating),or iJ it continuallyoperates oeloliris temperalure (overcooling), the result is the same- excessivoengine woar and damage Let s oxamlnoverheatingand overcoolingand the indicatorsorwarning signs o{ these Problems

Engineswith turbochargrsand aflelcoolers circulateoait ial ton,ot coolant iom th waterpump oirect ly oihe aftercoOrer.Here he Coolanl s used tO ower hair temperature so that more air can be packed in lhecv,inde., This al lowsmore f, lel o be burneda"dc:eateshighereng:nehorsepower utpul ln addlron'some machineshave orqueconverter ndtransmission i l coolerswhichare also cooled byenginecoolant.8


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OverheatingOverheating s by far lhe most wll-known coolingsystem problem. lf l6ft unresolved t will almostalways cause quack,catastrophic engine failure,somgtimes in a matter of minutos.

Indicatorsot Overheatingo S.OrS- high wear metals & oxidation. High readingon temperaturegauge. Crackedcylinderhead. Turbochargerailures. High emperature abel readings

Thls lllustrats rh. hea! bulld-up lgadlng ro a sotzurcondlllon. Nole how h6ar aflcis al l parts torrnlnq th6combusllon chamber, Includlng th6 valvos, luel nozzloand cyl lndr hoad.Without proper cooling, temperatures inside an 6nginewill soar, - spcially around th combustion chamberwhereextremehot spots can devlop, Ovarhatingcausesparts o expandcausingmore friction,andthusmore heat. Tempratures ontinu o increaseuntil he partscannotmoveandwill ultimately oize.For example,a pistonwillexpand ausing heclearance etwoon t and the cylinder iner odecrease o the point hat the Diston eizs n tholiner, Often n thiscas6, the piston s pulledapanfrom the connectingod and pistonpin allowingherod to break hrough he linr andgo through he sideof the engineblock. Catastrophicailur andwithoutpropercooling t takesonly a shon tim forsuch a failur o occur,Overheating lsocaussa brakdown f the oil whichis the mainsafeouard oainstwear. As lsmperaturesincrease, h6 oil thins out, destroyingts lubricatingqualities. In this hinnedout state he oil doesn't havethe strength o support h partsadequately. tdoesn'tprovidoa barrierbetwaanmovingsurfacos.The result s metal-to-metal ontactand excessive

Ovrhating ftncausesexcessive r prsmature ingand linerwear,pistonscuffing,and bearing cuffing.Extreme verheating an alsocause he cylinderheadto crack.It's importanto note h6re how ovarheatingan aflectthe entire6ngine. Take or examplea customerwhohad a crackdcylinderheaddue to overheating,roplaced t and then hada pistonseizurea shon mslater, The knownproblemwas he ccked cylinderhead, lt wasasy to diagnose, But unknowno thecustomerwas he additionalDroblem f scuff6dpistons. When h engine emperaturencreasedhepistonsexpanded, nd the oil lhinnedout, causingscutfing. Thesculfingcausod ncreasdrictionwhicheventually ausedone of the pistons o sizo. Bothproblems, he cGcked had and scuffedpistons,occurrodat th same ime, but only ono, the crackedcylinderhead,was diagnosed. Thopoint s to thinkofall the consoquonces f an overheating roblem,beyond he most obvious.S.O.S roportson nginswith ovrheatingypicallyshowelevated oncentrationsf war metals,withnosubstantialncroase n dirt (silicon). kon (cylinderliners),chrome(piston ings)and lead (bearingoverlay) eadingsmay incleasodue to the eflectsofmarginalubricationrom ov6rh6ating. n addition,sinceheatacts as a catalyst o the oxidation rocess,infrared est rsultsmay show elevatedoxidationreaotngs,


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Ell ipt lcal lyhaPod lston t amblonl6mprature n 6f lThs sah plslon at normaloporailnq omPeraruro nrlght.Overcoolingprevents the oil and parts kom getting tothe correct temperature. This is especiallyprevalentduring engine start-up and in low ambient temperatureaoolications, In these situations he oi l is cold andthick and doesn't flow correctly or quickly enough'resulling n marginal lubrication Also' when pansdon't reach the correct operating temp6ralur theydon't sgat together properly - causing wear' Pistonsare a gooclexample lf overcoolingoccurs. pistonsdon't expand to lit correctly in tho cylindor' ln elfctyou have an " out-of -round " lelliptically-shapod)piston moving up and down in a round cylinder liner'The result is xcessivewear around the piston skirl'

OvercoolingOvercooling s less lndorstood than overheating' butthe results can be just as damaqing. Both causo

Indicatorsot Overcooling. Not enoughheat in the cabo S.O.S - high wear metals,no oxidation. Lowreading n temperature auge. Sculfed bearingsor Pistons

lnstead of immediate engine failuro, which is commonwith overheating, overcoolingcauses woar thatorooressesover a longer time. It an engino willnorirally run SOOO ours to overhaul in an application'with overcooling il will typtcallyrun only 6000 hoursOvercooling s harder to detect, but S'O'S is still thebest indicator. The S.O.S results will be similar tooverheating. However' since there is no excessive1 0

heat, there will be no increased oxidationas occLlrsduring ovorheatingconditions ln addition toencouragingenrollment in S.O.S, check lhe followingpoints to help insure the cooling system is operating

Cooling ystemChecksoI

\:Thermostals When he engine s cold thethermostat ssists he engine n lvarming-up ndreaching orrectoperatingemperature uickly Youcan't tell by lookingat the thermostat f it's workingcorrectly,howverhereare some ndicatorshatwilltell vou if it isnt working orrectly. In coldclimates' la thirmostat s stuck open t will ako an xcessivlylong ime for the engine o warm-upand littlaor noheatwill be availableo heat th6 cab. lf thethermostats stuck closed he enginewill overheat lthis case he enginewill be very hot while hs radiatohossand tubesare cool, indicatinghe coolant s nogoing hrough he radiator. lt is importanto remrnoownorsandoporators o neveroperatea Cat enoineor machinewithouta thermostat overheatinganresult.CoolantTempraturGsugo- lf you suspecia taultgaugo,you can placea few temperatureabslson thengineand aadiatoro get an approxamatete-p.ratrrt reading. ll you stillsusped a problamthe servicedepartment an use a ThermistorThermometeror a more accurate eadingandforturther nvestigatronEmohasize ith customershe importance f usingcori""t st"n-rp procedu@s. Remindhgmto notstart ope6ting until he onginehasreached hecorrgct emperature,ndicated y th coolanttemperature augepointingn the gre9n area Alsowarn hem if the gaugepoints n the red area'indicatjng verheating,he machine houldb shutdownor the loads educed mmediately o thoproblemcan be invstigated.


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Cat CoolantConditioner (inhibitor) s the additive thatorevgnts corrosion and cavitationerosion ol parts'baterpillar recommends maintaininga 3-6"/0concentrationof conditioner' regardlessoi tneantilreere concentration A note here is that CatAntitreezealready contains coolant conditionor' so lt lsflOi n"""""u,u t; add additionalconditioner (inhibitor)on ini,iut itt o{ the cooling systom with Cat Antikeeze'However, the conditionerconcentrationshould bechecked regularlyand mainlainedat thei".ommenoiO concentration. Gonerally t is onlynecessaryto add inhibitorat each engine lubricationservice intervat {250 or 5OO ervice meler hours) Besure rhe concentration s between 3-6%' too muchcorrosion inhibitorwill form insolublesalts which cause

Cavtarion roslonwlll pl t and corrodeParissuch as thrsJ.*"-u," i t" .n"-0..r ( top)andcvrinderlner bottom)wtthoLt he neededcondi l 'oner. everecavital ionerosion will pi t and corrode the outer cylinder linersurfaces and surfaces o{ the block next to tne llners'Erosjoncan be very damaging lf not stopped rt caniiog|.;"" "o.pr"*V ,hrough the liner or cylindr block

Encouragecustomers to maintain heir coolanfaccoroirig to the rocommnded procedures in theLutlricationand MainlonanceGuide Also' encouragethe use of Cat Antifreezeand Cat Coolant Conditioner'Both products are formulated to caterpillar"p""'i'c"tion" to provide lhe best proteclion lor Cateouromen(.

Belts and Pulleys - The fan is belt driven off thecrankshaftas are some water pumps catrecommnds about 1" (25 mm) play in the beltsBelts should be checked daily for proper tension anosions ol cracking and wear. The correct positionottits in tne pullev grooves should be as illustrated'The belts should "ride" above the pulley grooves

ll. Lubrication ystemThe engine lubricatingsyslem has three mai,1lunctions: to clean' cool, and lubricate parts'

EngineOil1. Cleans2. Cools3. Lubricates

. Cleaning: Oi l cleans parts by carrying awaydarnagingmotal particles that materializedurrngnormal engino operation Oil also cloans thecylinder walls and carries away carbon ano lacqLrdeposits produced during combust!on'

. Cooling: The second function oJ oi l is to cool parby absorbinqand carrying hoat away

. Lubricating: Thkdly' oi l forms a thin film or layerbetween the surlaces of moving parts to supponand separate them This prcvents metal-to-metalcontact that causes excessivwear'

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The components of the lubricationsystem includ thefol lowing.

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By-pass valv Dlpst lck

. Oi l Pump - The oi l pump operateswhenever heengine s turning o provide ontinuous irculat ion foi l through he engine.

. Oil Cooler - Coolant circulates through the oilcoolor providinga heat transfer, fiom the oil to thecoolant. This lowers the oil tomperature andprotects the oil proprties.

. Oi l Filter - Th oil filter cleans the oil by collecting.aetal particles and other debris that can damageengineparts,

. Oi l Level GEuge (dipstick) - The dipstick providesa method o check the amountof oi l in the engino.

. Oi l Pressure Gauge - The oi l pressure gaugeindicates he pressure in the 6ngine lubricationsystem during engin6 operation,

. Oi l Pan - The oil pan (sump) bolts to the boltom ofthe engine and is the reservoir for the engine oil.

. Oil Fill Pipe - This is where oil is poured into theengine.

How he Lubrication ystemWorks

1. Oil ravels rom the oi l pan (sump), at the bottomof the engine,up through he oi l pump and2. th6n to the oil cooler. Here the oil is cooled byenginecoolant,3. Then the oil goes through the oil filter(s) wheredebris and contaminants are removed,4. Clean oil then movs into th6 oil manilold where itgoes in two directionsi

A. into the engine to lubricate components,such as th6 bearings, g6ars, pistons, lin6rs,valves,6tc.B. and a sm aller low direct ly o the turbocharger.

The oil then returns to the engine oil sump (pan) tostart the cycle again. A bypass valve in the filterbase allows unfilteredoil to by-pass a plugged filterso the engine will always hav6 some oil. When the oilis cold an oil cooler bypass valve bypassos oi l aroundthe oll cooler during start-up.


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Diagnosingubrication YstemProblemsThereare two major Ubrication ystemproblems hatcan causeexcessiv nginewear: inadequatelubrication nd contaminantsn the oil.lnadequateubricationInadequateubrication, r marginalubrication' andevelop rofi a numborof causos. Themostcommon,and the easiest o coriect, is cold enginesta.ts. When h engins s cold, the oil is thick anddoesn't lowwell. l f engine peed r load sincreased efore he oil is warmed-upmarginallubrication ill occur. In effect, the partswill beoperatjngwithoutadequatoil. Followingherecommended tart-Llpprocedureswill eliminatehisproblemand help assure ong engine ife. Note hat inextremelyow ambient emperatures uxjliary ilheatersmay be required.

Lackof Lube ndicators. Lowoil pressure. Scuffedbearings

other calses of inadequateubricationnclucle:wrong Viscosityof Oillf the oil is too thin, it will not coat the partsadequately;and if ('s too viscous, or thick, it will notflow correctly. In either case, the oi l is not providingadeouate protect|on.Not EnoughOilll ther sn't enoughoil in the engine' hereof course'will b inadequate rotctionbetwsenmovingparts.Tho resultwill be almost mmediate nginedamageNotoalso hat even opratingwith a low oil levelcausesproblems. lt allowsair into he system'loweringhe lubrication ystempressurc,which n turnprevents ufficiontubricationo some parts-OvercoolingWhenan engioe uns oo cold it dosn'tget hotenough o boil off waterproducedduringcombustionThe water hen mixeswith othrcombustionby-products ormingacids. The acidsdamageoilproperties ausing nadoquateubrication ndexcessivewear.

ContaminantsnThe OilThe second yp of lubrication ystemproblem scontaminated il . The eading ause s xondedoilchangep6riods. when oil changesaro pushedbeyond ho recommended oriod here is abrakdown f the oil itself and it loses ts ability osuspend ontaminants, omthing imilar o acontaminant verload. Whon his happens,contaminants mbod hemselvsn bearingsurlacsand othermovingpartscausingdamageandwear'

lndicators t Contaminated il. S.O.s - highmetalsor silicon. Contaminantsn usedoil lilters. Scratched earlngs, istonsor rings. Milkycoloredoil (wateror antifreEze)

Dirt and metalparticles re the most commoncontaminants, ut soot, water,and antifreeze lsocontaminatehe oil causingxcessive ngineweal.Note: Contaminatedil is the singl argstcauseorenginecrankshaft earing ailur Btween 0%and80%of 6ll crankshaft earing ailuresare causedbycontaminated il.

Boarlngs on lstt ar6 damagd from d6brls and fallguoionos on rlghl show normal woar'By far, bgarings re the most sensitive ngineparts ooil relatedprobloms,espciallyurbocharger oaringslf a lubrication roblgmexists, he first signwill beworn urbocharger earings. Maindnd rod baringsare the nextmost suscaptible arts. But becausetheyare thicker, hey can often survivmarginallubricationonger han he thinnor, astermovingturbochargr earinos. Thepoint o remmbers; ifboaringwear s a problem, h causwillnormally efound n the lubrication ystm.

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Belore eaving he discussion n contaminated ilhere's ong importantm6ssag6 hat needs o bdiscussedwith ev6ry equipment wner. One of thebsl ways o extndengine ile is to simplychangeoilandfiltorsaccordinOo recommended chedlles.Also o inspect ilters regularly. Thesesimpleprocedures annot b overstressed.Oil FiltersIt's a good practice or ownersand operators o cutopen usad oil filtersand examine he tilterpaperandoil for m6talparticlas.

Hereare some other aras hat can warnoflubrication ystmprcblms,LowOllPressurelf an oil filter plugs,a bypassvalvwillopen and allowunfilterd ii to lh engine. The operatormay noticea slight eduction f plessureon the gauge, orexample, rom 50 to 45 psi (345 o 310 kPa). Whenthe filtor s rplaced, he pressurewillgo back up tothe previousevel. Extremo owoil pressuremayindicatea dangerous roblempossibly ausedby aninsufficient mountof oil, a malfunctioningil pressurreliefvalv6, or worn oil pump gears,Cat Filters and FluidsCaterpillarFiltersand Fluidsar speci{icallydesignedto provid Cat ngins and equipment the bestprotection aoainst excessiv and costly w6ar.

Cat Filtersare manufacturedo meet exactinorequirements f each enginemodel. Th6sespecificationselpprevent he filter rom pluggjngprematurely,uptu ng or passingdamagino ebris.Cat DieselEnginOil s specificallyormulatedoreducdepositsand provide he b6stwearprotectionfor Cat dieselengines. Cdt EnginoOil alsoprovidesoxcellent rotection nd is recommndedor mixedfleets or other brandsof onginos.

: t tCunl.g op6h ol l t l l tors s rh6 bost v lsualch6ck fo rcleloctlng Intsrnal on9ln war,Other han S.O.S, this is the best method ordotecting nternal6ngin6wear. h's a practic hatshouldbe a regularpart of th oil and filterchangeprocodure.SeOoSWe've akeadydiscussedS.O.S as a indicator orsiOnaling ccelerated nginewoar. lt shouldalsobenoted hat it monitors he conditionof the oil. S.O.Sindicatosf tho oil is contaminated r if the orogeniesof tho oil are breakingdown.


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lll.FuelSystemh is the function of the fuet injoction pumps and injectors10 supply fuel into ach cylinder in tho correct amountand at the right time ior efficient combustion. The components of th fuel system include tho following'

Direcl njoct lon nsin. Fuel Tank - The tank is the reservoir for holding

tuet ,. Fuel Trsnsler Pump - The transter pump marntarnsa constant flow of low-pressure fuel kom lhB fueltank 10 he engine uel system. Not6, h transferpump s dif lerent rom he tuel nject ion umps.

. Fuel njct ionHousing Al l engines,except hosewith unit injectors, have a Iuel iniectionhousing thatholds the individual uel injectionpumps (one percyl inder).

. Fuel lnjction Pumps - There is one fuel injectionpump for each cyl indor. Unl ike ho ful t lansforpump which s low pressure, he fuel inject ionpumps operate at high pressure, Injectionpressures an run kom 2,800 o 20,000psi (19,290to 137,800 Pa). Eachpump rneters he correctamountof fuel and pumps t, at a high pressure,through metal lines to each luel injector.

. Unit Injeclors - The unit injector combines a fuelinjectionpump and a fuel injector into oneassembly. Unit njectors l iminato ighpressurefuel lines between the pump and injoctor allowingfor higher uel njoct ion ressures.

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. Fuel Fillers- Fuelpasses irst througha primary,thena secondaryuel filter. lt's critical o haveclan uel for thesehighpressurspumps Someothe clearances etwenpartsare as smallas a temil l ionthsf an nchandevon he smallest ebriscancause amage,

. Water Sparator Waterseparators re used oprotectagainst ust causedby water-contarnlnatfuel. All 3208enginshave waterseparatorsNottheyare not standard quipment n all engins nshouldb used on any enginewhrewater contaminateduel is a problem

. Fuel Pr6ssureGaug6 Thisgaugereads hepressure nerated y the luel lransferpumpdowstream rom the tilters. It a filter becomesplugga pressure eductionwill show up on the gauge.

. Fuel Lin6s- Fuel inesare most commonlydefineas thoso rom the fuel injection umphousing o tiniectors. On orecombustionnd direct njectionngines he fuel linescarry highpressureuelSinceunit njectors ave he injection umpsbuiltinto the inioctorassgmbly, heydo not have highpressurernes,

Sscondarvprrmrng ru6t thor


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How heFuelSystem orksThere are tvrc methods of detivering uel into thecombustionchamber; the first is precombustion,where uel bgins gn it ionn a precombustion hamberbeforegoing nto the cyl ind6r;and the second sdirect injection, in which the fuel is injected direc yinto the cvlinder for combustion.It is also important to understandunit fuel injectorswhich are used on many of the latest model Catengines. lJnit injectors use a direct injection methodof fuel dehvery but they are dif,erent lrom engines

with traditionalprecombustionand dkect iniectionsystems,The fuel travels through all Cat Engines n basicatly hesame way, up until the point of fuel injection. (1) Fu6lgoes from th6 tank, (2) through a water separator,(3) through a primary fuel filter, and (4) into the lueltransfer pump. (The primary filtr can be before orafler the transfer pump). From the transfor pump luel(5) goes to a secondary lilt6r, and then either (6) toa tuel injecdonpump (precombustionand directinjection)or to a unit fuel injector.

Dlrct n lectronEnglne

PrecombustionTheprecombustionhamber PC)system s foundprimarily n older modelengines. Fuel s putled romthe tank by the fuel transferpumpand pumpedthrough he primaryand secondary uel filters o thefuel injection umphous;ngwhere he individualuelpufips are locatgd one per cylindor). The uelinjgction umps orce fuel throughhighpressure uellines o the fuel nozzlesmounted n lhe cylindrhead.A precision rilledholo n the end of each nozzleatomizes uel as it enters h precombustionhamber.As the fu6l begins o ignite, he heatof combustiontorces he remaininguel and air mixtur hroughanorifice n tho precombustionhamber nto he cylinder.Glowplugsar mounted n the PCchamberhousingsto warm he air and assist n startingPCengines, lt'seasy o idontifyPC enginesbecauseof ths etectricalglow plugwiresrunning o each precombustionchamber n the cylinderhead. And, you can easilytell pistonson PC enginesby the steel heatplugmounted n the center on 6achpiston.

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Direct niection

On direct injection (Dl) enoines ful travels from thetank through th filters, pump, and lines to the injeclorhousing he same as on precombustionengrnes.However, instad of pre-ioniting the fu|, directinjection engines inject frlel directly into the cylinder'You can tel l pistonson Dl enginesbecause he lop ofthe piston crown has a conical crater design and nosteel heat plug.Unit njectors

Manyol the latestmod6l Cat engins, ncludinghe35006nd 1.1LiterEngines seunit ul niectors.Eachunit njectorhas a highpressurenjection umpand injectornozzlebuilt-in6ach unit assembly. Theris one unit njoctor or each cylinder.Theyaremounted n th6 cylinderhad. Lowpressuro uel sdelivered rom the fuel transfergumpto aachunitinjoctor, hen through he injectorassembly irectlyinto he cylinder. A rockerarm assembly, imilar othat usod o operate he enginovalvs,operatoshefuel injection umps. By eliminatinghe fuel lines, hinjoctorpresssres an be increased esultingn moreefficiantatomization ndcombustaon.DiagnosinguelSystemProblemsUnderfuelingUndrfuelingccurswhen hero s not snough uel tomeet the powerdemandson the engin6. lt doesn'tnormally auseenginedamagebut will causea lackof pow6r. Most often he cause s a plugged uelfi l ter,and h remedys to simply hange he il ter.

Indicators t Underfueling. Lowpower. Low uel pressure pluggedilter)

CorrectFuelThe typ of diesgl fuel as well as th maintenancoofthe luel is important to the performance and life ol a6n9ine, First, the fuel must be clean _ fr66 of walerand contaminants,and second it must be the corrocttype for the application,

lndicatorsof IncorrectFuel. Difficult starting. Enginecutting out

In low ambient emperatures,iohter uels, iko diesfuel numbor1, are usd o grventproblemsof fueljelling(a situationwhre he fuel coagulatespreventing ufficient low).

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In ar6asoutsideNorthAmerica, t's importanth6townersmatch he TBNnumber(TotalBaseNumber)ol the engineoit to the sutfurcontentof th fu|.Normally BNadditives n th6 engineoil neutlalizeu6lsulfurby-productswhich rosult rom combustion,Howver,f ths concentration f sulfur n the fuol istoo high,or the oil TBN oo low,sutfuricacid willdevlop. Thiscan causecorrosionand 6xc6ssivewearof piston ings,barings, nd liners. To countorsuchproblems ustomerscan change o a higherTBNoil or shonen he oil chanoe ntervals. Note:recommend horteningh oil change ntervals nlyafter horoughdiscussiohwith hs appropriateCatergillar ersonnel.OverfuellngOverfueling ccurswhn oo much uet s injocted ntolhe cylindr. Excossive tackexhaust mok6 s theloadingwarning ign. Therearg manycauses,suchas a high uel rack setting,misadjustgd klful ratiocontrolor faulty uel injector. All involvhe fuelsystemand must be handledby appropriatedealorship 6rvic6oersonnol.

Indicatorsof Overfuelingor IncorrectAtomization. Blacksmoke. Increased uel consumption. S.O.S showing uel In the oil

Plstonallur. du6 o Incorr.ct uot nJ6crtonWhen nconoctatomization r fuol injection ccurs,fuel is Injected nto thg cylindr n a stream nstadofin an atomized tato, This happons f an injsctor spluggedor hasa brokn ip. Instoad t a smooth,completebuhing of th fuI, the liquid gnites nto a

burning trcam of fuel, much ike a cltting torch. Thetempratures et so highand th burning s soconcentratodhat it can actually lt into the piston.In addition, omol the unburned uel runsdown helinrwalls. Thiswashosoff the protective il ,rcducing ubrication nd acclerating ng and linerwearand pistonscuffing.When uel is not atomized orrectly, he combustionprocss akes onger han normal, eavingunburnedfuel in the cylinder. Again, he problemof fu6lrunning own he linerwallsoccurs. This s typicallyfuel systemproblomand shouldbe handledby theservicdepanmnt, The eadjngndicators re;excessivo lacksmoke, a lack of power,and fuelcontamination f th engineoil,lV. Air Intake& ExhaustSystemTheak intakesystemsupplies leanak for enoinocombustion. Ths exhaust ystem akesawayexhaustgasesand h6at, anddrivs he turbocharger.Thecomponentshat mak6up the air intakeand exhaustsystem nclude he following.

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Prcleanel Theprcleaneremoves argepaniclesof dirt and debris. How heAir IntakeandExhauSystemWorksI Air Filters - Usually here are two air filters' aprimary and secondary lilter. They collectcontaminantsand prevent dirt from entenng tn6ngine.

r Air Filter Service Indicator - The indicatormonitorsrestriction hrough the air filters. lt is the mostaccurate method for determiningwhen to changeair f i l tors, Everyengineshouldhave ona Aninteresting act is that changing filters too olten canactuallydo more harm than good - because dirtcan so easily enter the engine during a lilierchange. This maks lhe indicatora very useful andimportantmaintenanceool

a Turbochatger - Exhaustgases drivB theturbocharger which pumps additionalair into lheengineal lowingmore fuel to be bLlrned' herebyincreasing he horsepoweroutput

. Aflercooler - The aftercooler cools the air aiter itleaves the turbocharger but before it enters theengine, This increases he air density' so more alrcan bo packed into each cylinder.

. Air Intak& ExhEuslManifold6 The air intakeandexhaLrst anifolds onnectdkctly o the cylindernead(s),The ntakemanrloldislr ibuteslean irirom heair i l teror turbochargorntoeachcylinder'while he exhaustmanitold ollectsexhaust asslrom each cylinderand dkects hemto theturbochargernd/or o the muffler.

. Mulfler - The mufllerreduces he sound evelandprovides ufticient ackpressure o the engine,soth6enqins broathes'asdesignad.

1 .

2 .

3 .

Air first enters he systemvia the precleaner'Hre argedirt particles re removedThenair moves hrough he

primaryandsecondary ir filters or furthercleanrng'On turbocharged ngins hs spinning { theturbocharger omprgssorwheelpullsair Into nturbocharger.Thecomplessorwheelcompresseshe air (whalsoheats t) and snds t to tho aftercoolor'The aftercoolereduces he air temperaturemaking t moredenseso moreair can b pacinto he cylindrs

4. Thodensecompressod ir movs rom theaitercoolerhrough he air intakemanitold ndcylinder ead(s)5. past the intakevalvs ntoachcylindercombustlon hamber. As the intakevalvescloand hg pistonmovesup n thecylinderheaicomoressgdurther. when lhe piston s nearroo of its stroke, uel is injected nto thecombustion hamber, Thefuel mixeswith hehot, compressed ir and ignites Theforce ofthe combustion ushes he plstondownon the

6. Whn h pistonmovesup again t is on thoexhaust trok. The xhaust alvesopenalloexhaust asesout through he oxhaustmanifo

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The combusr lon ycl

ExhauFt a

TurbochargerperationExhaust ases low hrough he xhaustmanifold ntothe turbineside of the turbochargero drive heturblnewheel. The turbinewheel s connectd y ashaft o lhe compressorwheel, Thecompressorwheelpullsair into he system. Exhaust asesaftrdriving he turbinewheelpassout through he mufflerandoxhaust tack.

On engineswithout urbochargers ir movesdirctlyfrom the precleaner nd air cleaner hrough he intakemanifold nto he cyljndrs. After the combustioncycle, exhaust asesexit hrough h exhaustmanifoldand muffler.Diagnosingir Intake&Exhaust roblemsThe two major problems associated with the air intakeand exhaust systm that can affect engineperformanc and life ar6: not enough air and dirty air.NotEnough ir

lndicatorsot Lack of Air. Blacksmoke. Low power. Hardstarting

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Wh6nair tiltrs becompluggodor there is arestrictionn ths system, ho engine s staNed or ak.The enginecan not efficiontly r completely urn hefuel. Most often his problom s diagnosed y anoperatorwho complains f excessive lacksmokeora loss of power beforeactlal nginedamageoccurs,Tho most commoncausesof air rostrictionnclud6 hefollowin9.PluggodAir Fllirs- Dirty,pluggdair liltersare themost ovorlooked nd yet the primarycausol airrestriction.Thfirst item that shouldbe chcked lther s blacksmokeor a lack of powercomplaintsth6 ak filter. Remmber ir filter service ndicatorsare the mostaccurateway o knowwhen o cnangethe air filters. Theyshouldbe recommendedor allnoines, f not alreadyequipped.

Anythinghat inhibits r restrictsair coming nto hoengin, hrollgh he air filtr, urbocharger raftorcoolor, r goingout, through he exhaust ystewill affect eltici6ntcombustion. As noted betor6' theladingndicators r blacksmoko,which ndicatesunburneduel (du6 o not nough ntakeair) andaloss of power.Dirtyair

Indicatots f DirtyAir. Highoil consumption. Worn:Rings

LinersBearingsTurbochargeransDkt in an enginecauseswear' As littleas oneteaspoonof din can causeseveredamageandpossibly hut the enginedown. Commonproblemsthat can allowdirt in an engine ncludea splitor smpin-hole n a hose,a loosehose or pipeconnectioor a to.n air ilter.Dirt hat onters he enginecollectson the oilycylindlinrwalls. As th piston ingsmovo r'lpand downalong h walls he dirt causes inewear,much ikgsandoapr,on the pislonringgrooves, ingsandcylinder inersurfaces.S.O.S is the bst ndicatorof dirt entry Belorewof the ringsand linerswill causeblowbyand increaoil consumption .O.S willwarn ol an increasensilicon evels alorting he owner o a problem.

M6lf nctioningTurbochsrger - ll turbochargerbearings r sealswear o the point hat turbochargerspeed s reducedor if the bladescontact he housingtherswill be insufficient ir going o th cylindersorcomoltecombustion.PluggedAftrcoolr Any restrictionn iheaftercoolerwill docreaso he amountof air into thecylindors,ExhaustBestrlction A restrictionn the exhaustwillslow ho turbocharger ince t is drivenby exhaustoasos. Thiswill reduc he amountof intakeair goinginto h6 cylinders nd calse a loss of powor. Exhaustrcstrictions an be causedby customized xhaustsystems hal are incorrecttymatched o the engin6'damagedmufflersand pipesandother tems hatrestrictair flow.

Tho ak flltr sorulc6 Indlc.tor


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OilConsumptionndBlowby

t, ,iii

Corroct rlng and llner contact Woar rnd Incr6asod oll consumDtlon

Normalnglne oprat lonon lhe lel t , r lng ahd l lnor w6ar causlns IncreaEed l l consump! lonon ih6 r lght .

Here s a goodplac6 o explainoil consumption nd Blowby ccurswhencombustion sses ravelpast h6blowby. Oil consumplion ccurswhen ubricating il ringsand/orvalvesand valv6guides rom theon the cylinder iner walls s allowodpast the piston combustion hambor nto he crankcase. Thisallowsrings nto he combustion hamberor whenoil passes carbon,soot and othsrcontaminantso mix with heanto he combustion hamberdue to excessive oil increasing nginewear.clearance etween he valvesand *tt q'l::-:-- -,- , other causesof increased ir consumption nd browbyNormallyhe ringscontrol he amountand thickness n"frOa ---- - - -the oil on the linerwall, but if wom, the increasedclearance etween he ring and linsr allowsexc6ssiv6 a worn ulbochargelbearings nd salsamountsof oil in the combustion hamber,.Th oil a worncrankshaft ealsthen burnsalongwith he fuel. As the engineoporates,additional mountsof oil are consumed . worn oil-lubricated ovornor ealscreating h6 need o continually dd oil to the engine. . oil laking nto he ,!el or coolingsystems

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O consumbtton occors on rho lhtak6 s[oko as too much oll ls l6il on lho cyllnd6r llner whn tho plston hovo3downward, B lowby occurs on th compress lon and powor s l roko as aass pass b6tw66n worn r lngs and l lnerc 'V.ElectricalSystemh6 termsoil consumption nd blowbyare ottenusedinterchangeably. o assist n diagnosing ngineproblems,blowby s a more specific erm and iseasier o measure han increased il consumption.Blowby an be checkedby measuring ranKcasepressurewith a pressure augeor by chockingblowbyvolumewith a blowbymeter. Oil conslmption sharder o measlrro ince t dependson goodconsistentmaintenanceocords somethang anycustomers on't have. Also blowbycan be moasuredat any time. wheroasoil consumption as to bemeasured ver sevraldays or weeks, The mportantpoint s oil consumption nd blowbybothrsult romnginewear, and the most common ype ot enginewear s piston ing and liner wear,

Battry Plug

Theprimary unctionof a dieselengine'selectricalsystem s to start the engine. The secondaryunctiois to power ights,gaugsand vehicleelgctricalcomponents. (som6 of the latestnginesn theon*highwayruck marketalso have electronicuolcontrols).It's intgrostingo notothat after cranking dieselengine, he battery s no longrneeded o continurunning ecause her s no ignition ystem equiredfot combustion, s on a gasoline ngine

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MaiorComponentsn the ElectricalSystem. Battery The battorystoreselectrical norgy.a Altrnelor Thalternator reatesolectrical nergyto replenishh6 charge evel n the battery. Avoltage egulator s inside he alternator.. Slartr - The startrmotor s poweredby elctrichyIrom th battery. lts function s to start the engine.. Glowplugs - Glowplugs pr6h6at he air for easierenginestarting. Th6yar only oundonprcombustionngines.How he Electrical ystemWorks

Fot quickerand aasiernginstarts, precombustionsng;nesus lectricalglow plugs o warm and preheatth air in the precombustionhamberbefore cranking.They heat for approximatlyne minute. And even at60"F (15.5oC) emperaturst's a good practice oheat th glow plugs or a short ime. lf notpreheatd,h extreme emperatur hange, romambint o combustion6mper6turo, an cause h6tips of the glowplugs o brak off. Basicallyt'sbttor o h6at hem up graduallywith elctricity hanto shock hemwith combustion eat.

The batterystoreseneroyand provides he pow6rneeded or the sloctrical tarter o crank he engine.As electrical nergy s used out of the battery t hasto be replenished.Tho alternator evelops lectricalenorgyduringmachineoporation o replenishh6battery.

Glow plug uEod tor siartlng prooombustlon 6nglng

Dlagnoslng leclrlcal ystemProblemsBattery

A majorityof electrical ystemproblomsar related othe baltryand most commonly esult rom a lackofmaintenanco.Battarymaintonances very simplekeep he battery illed,clean, and clampoddowncorlctly.ll not securdcorrectlywith he clamps, he battrywill bouncearoundduringmachineoperation ausingthe internalplatesand connectionso crack and breakresultingn a battery ailure. Extremearringcan evncause he cas6to crack, allowing hs fluidto leak.

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Battory erminalsand connections houldbe cl6anandcorrosion-free. on othr hanmaintenance-treebatteries, he lluid levelmust be maintained ccordrngto the Lub.ication nd Maintenance commenclations.i;e lectrolyte oncntration an be checkedwith anhydrometer.This ells howmuchcharge s in theOattery. tf a "dead' baltery s recharged vernightand i; th morningstillshowsonlya low chargeor nochargeat all. the bstlerywillno longeraccplachargeand mustbe replaceo.GlowPlugsHardstarting.crankinga longtim or running oughuntil he enoin s warmodup aro signs hat the glowolrjosmav iot be {Llnctioningorrectly Eachglowolui can be easilycheckedwith an electricalmeter'inJ gtowptugs6r checkedduring uneupsand as areoularpart of each of the engineoverhauls'Alternator& VoltageRegulatorOnco he engine s running, he alternator ervosastnr "t."t|.i""ipo,n"|. source o run lights,gauges'E[4Soanels,and eiectrical omponents, lusreplenishhecharge n the battery. lt is belt drivenofl thecrankshaft.lnside he alternators a voltage egulatorhat limitsthe voltagoutput o the battory. Thispreventsovercharglng.lf a oroblemdevelopswith he charging ystemanalto;natorioht n he cabwil lOo on" This ouldsional he alternators not supplying n adequate"tiu,g", o, " wiro s not connected orreclly ll not.orrJcted, tn. electrical nergywill drainout of thbatteryuntilno morecharge emains'

SlowCrankingSpeedDieselengines equiresufficient ranl(jng po6o odevelop ie highcompression ressures eeded oidnite he fuel. lf th6 cranking peed s slow hee;oine will be hard o start. Beforecalling he servrd"_pun-"nt.h""k th" battryand all connections lfth6 problom s stillnot identiti6d serviceman anItLJx tne "ta.ttr ano moasur he cranking pm olthe 6ngin The starteror batterymay needropalroreplac6mnlOtherMaterialon atEngine& EngineRePairOptions

For moro information n Cat Englnes nd CatEnginRepair ptionscheck he followingmaterialso ERIK EnginRepair ndicatorKit - Parinumber4C3502. lntroductiono DiselEngines TECB6005

(Training ulltin). Guid or Manaoing nginePerlormancePEDP71OlAdvertising rochure). How o PreventEngineFailure PEDP6101(Advortising rochure)o Cat EnginoPartsQuality PELP7901Flipchart). EngineRpairOptions Decisions" PEVN6020(VideotaPe). SchduldOilSamplingSrOoS PEDP7105(Advertising rochure)

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Air FilterService ndicator pEHp9O13(Adv6rtising rochure)Oil and YourEngine SEBD0640(T6chnical ublication)Coolantand Your Engin6 SEBDog70(Technical ublication)FuelandYourEngine SEBD0717(Tochnical ublication)KnowYourCoolingSystem SEBDo5IB(Technical ublication)catelpillar'sMachineLubrication ecommenoaI|ons- SEBU6250 (Tchnical ublication)

Thereare manyoth6r matorials vailabl, heck heI\rarketing rainingMalerialsCatatog TECM005O)ndProductSupportPromotionMatoriats atatog(PEGP9800)or compl6ta istings. (yourdalrshipPromolion nd/or TrainingManager ave hesecatalogs vailabl6.)

ConclusionYou now have a good undorstandingol how dieselengines work, how they wear and the commonwarning ignsof problems.use this knowledge o hlp your customersia develop correct prBventativomaintenancepracticos. choose appropriate nspsction programs. solect the best repair options for their spec.ticsituationAnd, as a last note, remember to always demonstrateand reinforce with cilstomers that your dealership'scapabilitiesand Cat products offer the best vatueavailable.


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lndexN o r ma ls .A b n o r ma l e a r . . . ' . . . . 2Repai r e fore a i lu re enef i ts . . . . . . 3SrOeS ScheduledOil Sampling .. 5ERIK EngineRepair ndicator it .. 6l . C o o l i n gy s t e m. . . . . . . . . . . . . . . 6C o m p o n e n t s . , , . , . , . . 7H o w h e S y s t e m P r k s. . . . . . . 7P r o b l e msI n d i c a t o r s. . . . . . . . 8

O v e r h e a t i n g. . . . . . . . . . . IO v e r c o o l i n g. . . . . . . . . . . . . . 1 0T h e r f i o s t a t s. , . . . . . . 1 0C o o l a n ta u g e. . . . . . . . . . . . . . . 1 0R a d i a t o rF a n . . . . . . . 1 1R a d i a t o r C a p . . . . . . . . . . 1 lW a t e r P u m p . . . . . . . . . . . . l 1C o o l a n t . . . . . .. . . . . . l lB e l t s P u l l e y s . . , . . . . . . . . 1 2l l . L u b r i c a t i o ny s t e m. . . . . . . . . . . 1 2C o m p o n e n t s . . . . . . . . ' 1 3H o w h e S y s t e m o r k s. . . . . . . 1 3P r o b l e msI n d i c a t o r s. . . . . . . . 1 4I n a d e q u a t eu b r i c a t i o n. . . 1 4WrongOil . . . . . . . . . . . . . . . 14N o tE n o u g h i l . . . . . . . . . . . . 1 4O v e r c o o l i n g. . . . . . . . . . . 1 4C o n t a m i n a t e di l . . . . . . . . . . . . 1 4Oil Fi l ters . . . . . . . . . . . . . . . 15s . o . s. . , . . . . . . . . . . . . . . . . . . .5LowOi lP rsssu re. . . . . . . . 15C a t i l t e r sF l u i d s. . . . . . 1 5I t l . u e l y s t e m . . . . . . 1 6C o m p o n e n t s . . . . . . . . 1 6

H o w h eS y s te m o rk s. . . . . . . 17P r c o m b u s t i o n. . . . . . . . . . . . 1 7D k e c tn i c t i o n. . . . . . . . . . . . . 1 8l J n i tn j c t i o n. . . , . . . . . . . . . 1 8P r o b l e ms In d i ca to r s. . . . . . . . 1 8U n d e r f u | i n g . . . . . . . . . . . . . . . . .8C o r r e c tu e l. . . . . . . . . . . . 1 8O v e r f u o l i n g. . . . . . . . . . . . . . . 1 9Air Intake& ExhaustSystem ... 19C o m p o n e n t s. . . . . . . . . . . . . . . . , 2 0H o w h eS y s t e m o r k s . . . . . . . 2 0Turbochargerperation . . . . . 21

P ro b fe msIn d i c a to r s. . . . . . . . 2 1NotEnoughAlt . . . . . . . . . . . . . . . 21P l u g g e di rF i f t e r s. . . . , , . . . 2 2Turbochargerroblems . . . . . 22A f te rcoo le rrob lems. . , . . . . . 22Exhaus tes t r i c t i on. . . . . . . . 22D i r t yi r . . . . . . . . . . . . . . . . . 2 2OilConsumptionBlowby . ., 23E l e c t r i c a ly s t e m. . . . . . . . . . . . . 2 4c o m p o n e n t s , . . . . . . . . 2 5How he SystemWorks . . . . . . . 25P r o b l e msl n d i ca to r s. . . . . . . . 2 5Battery 25G l o w P l u g s .. . . , , . . . . . , 2 6A l t e r n a t o r. , . . . . . . . , , . , 2 6Slow rank ing . . . . . . . . . 26OtherMaterials '. " " 26C o n c f u s i o n " ' . . " ' 2 7

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How Diesel Engine Works

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