Engine Components and Filters: Damage Profiles, Probable Causes and Prevention

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ENGINE COMPONENTS AND FILTERS: DAMAGE PROFILES, PROBABLE CAUSES AND PREVENTION

Technical Information AFTERMARKET Contents

1 Introduction 5

2 General topics 6 2.1 Engine wear caused by contamination 6 2.2 Fuel flooding 8 2.3 Hydraulic lock 10 2.4 Increased oil consumption 12

3 Top of the piston and piston ring belt 14 3.1 Hole burned through the top of the piston in gasoline and diesel engines 14 3.2 Melting at the top of the piston and the top land of a gasoline engine 16 3.3 Melting at the top of the piston and the top land of a diesel engine 18 3.4 Broken piston ring lands 20 3.5 Valve impacts at the top of the piston and piston hammering at the cylinder head 22 3.6 Cracks in the top of the piston 24

4 Piston skirt 26 4.1 Piston seizure on the thrust and opposite side (piston skirt area only) 26 4.2 Piston seizure on one side of the piston skirt 27 4.3 Diagonal piston seizure next to the pin bore 28 4.4 Asymmetrical wear pattern on the piston skirt 30 4.5 Piston seizure in the lower piston skirt area only 31 4.6 Heavy wear at the piston skirt with a rough, matte surface 32 4.7 Wear marks on one side of the piston skirt 33

5 Support – piston pin bushing 34 5.1 Seizure in the pin bore 34 5.2 Cratered piston wall in the pin boss area 35

6 Piston rings 36 6.1 Piston rings with burn marks and seizure marks on the 36 piston skirt 6.2 Damage to the ring belt due to fractured piston rings 37 6.3 Heavy wear of the piston ring grooves and piston rings 38 6.4 Heavy radial wear of the piston rings 39

7 Cylinder liners 40 7.1 Pitting on the outer wall of cylinder liners (cavitation) 40 7.2 Snapped off flange of cylinder liners 42 7.3 Longitudinal cracks in cylinder liners 44

2 | © MAHLE 8 Valves 45 8.1 Valve stem scuffing 45 8.2 Distortion at the valve stem 46 8.3 Fracture in the valve groove 47 8.4 Fracture in the valve head area 48 8.5 Valve seat wear 49 8.6 Deformation of the valve head 50 8.7 Hole burned through the valve head 51

9 Bearings 52 9.1 Scoring and contamination at the running surface of bearings 52 9.2 Localized wear marks on the running surface of bearings 53 9.3 Heavy wear marks in the area of the parting line of bearings 54 9.4 Shiny marks, wear or corrosion on the outer surface of bearings 55 9.5 Abrasion or damage to the outer edges of bearings 56 9.6 Heavy wear at all main bearings 57 9.7 Uneven wear pattern at the bearings 58 9.8 Seizure marks at the bearings 59 9.9 Pitting on the bearing layer of the bearings 60 9.10 Porous bearing layer of the bearings 61

10 Filters 62 10.1 Filter leakage 62 10.2 Reduced engine performance due to the filter 64 10.3 Assembly problems with filters 65 10.4 Granules escaping from air dryer cartridges 66 10.5 Disintegrated filters 67

11 Glossary 68

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Fig. 2 Scoring marks and burn marks on the piston rings Piston skirt Support – piston pin bushing

Fig. 3 Scoring and seizure marks in the cylinder bore Piston rings Cylinder liners

Fig. 4a Pitting in the pin bore due to diluted engine oil Valves Bearings Filters Fig.4b Even more visible when magnified: the pitting

© MAHLE | 9 Glossary Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction xesv iudmyrahtecmuto hme u otefollowing the to due reasons: chamber combustion the crankshaft. reach the may and liquid bearing connect- Excessive the the crankcase, pin, the piston head, cylinder the the piston, rod, the ing at load stress abrupt lock an hydraulic compressed, in combustion be results can the fuel reaching nor fuel water or neither Water Since chamber. liquid. by caused is damage This CAUSES PROBABLE on effect an have can This components: forces. numerous enormous generates lock Hydraulic DESCRIPTION lock Hydraulic 2.3 10 REMEDY/PREVENTION h itnrn ado h itncnendsosa vrodfrac- overload an shows concerned piston ture the of land ring piston The lascekijcinnzlsad hnncsay ee them. renew necessary, when and, nozzles injection check Always replaced. be must engine. gaskets an overhauling Defective when gaskets undamaged and new use Always defective a to due chamber nozzle. combustion injection the reaches fuel Excessive gas- defective to due chamber kets. combustion the enters (e.g. water system Cooling intake the water). through via driving chamber when combustion the reaches Water h itnpni broken. is pin piston The broken or bent is rod connecting The deformed or broken is piston The MAHLE © | Fg 3a+b). (Fig. yrui lock hydraulic to due piston vehicle commercial Broken 1 Fig. Fg 1). (Fig. Fg 2). (Fig. vrodfatr rmtetpo h itnt h i bore pin the to piston the of top the from fracture Overload 3a Fig. ls-pve fa vrodfracture overload an of view Close-up 3b Fig. etadboe oncigrddeto lock due hydraulic rod connecting broken and Bent 2 Fig. AL | MAHLE © 11

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston AllgemeineGeneral Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt Thementopics Introduction CAUSES PROBABLE a by e.g., caused, loss oil to contrast etc. leak, in – con- consumption oil oil to of increased referred level is as it the exceeded, If is manufacturer load. the varies stress by recommended the consumption sumption and Oil type normal. engine is the on consumption depending oil of amount certain A DESCRIPTION consumption oil Increased 2.4 2|©MAHLE © | 12 hre n noteitk asg n h xas a system. turbo- gas the exhaust the of and out passage pressed intake being the oil into in and results charger circuit Rising oil carbonized. the or clogged in is pressure turbocharger the at to pipe return due oil passage bearings. The worn intake e.g. turbocharger, the the via in chamber leaks combustion the reaches Oil h lwb ae i h nieventilation. engine the with via together gases the chamber blow-by enters the combustion then the foam oil ultimately or and can mist passage oil oil inferior intake The or foam. old oil Furthermore, of mist. formation oil the in cause resulting pan, engine oil in immersed the is in crankshaft oil the oil, of amount excessive an to Due the via crankcase. chamber ventilation. combustion crankcase the the into in mist pressure oil force excess can pressure in Excess results rings This piston pistons, bores. worn cylinder to and due increases gases blow-by circuit. of oil level the The in leaks thus and result distortion may This in incorrectly. tightened been leak. have bolts this head via cylinder chamber The combustion the reach may the can it and Oil incorrectly, chamber crankcase. combustion installed the or between sealing wedged inadequate broken, in result are rings piston chamber. the combustion Oil If the pump. a into as transported act actively may then piston skirt”, is the scenario, piston case the worst the on sealed In pattern 30). insufficiently wear page is Asymmetrical chamber “4.4 section combustion see the (also and travels line longer straight no piston a the in that mean circuit. rods oil connecting twisted the or through Bent running oil engine unfiltered filter in the resulting of paper, cracking and/or clogging cause intervals the change oil reduces Irregular maintenance.This wear. irregular increased to to due leading ability, e.g. load-bearing – old too is oil The 8). page sec- flooding”, see Fuel (also “2.2 flooding tion fuel ultimately and chamber combustion reach- the fuel ing excessive in resulting fully, closes longer Possible no nozzle nozzle. The injection result: the piston affect incorrect vibrations due resulting head The cylinder protrusion. the wear against hammer Engine can “2.1 piston The section 6). see page contamination”, (also by caused wear combus- increasing the entered chamber, has contamination tion system, intake leaky circuit a oil to the Due via lubricated usually engine. is the due which of e.g. pump, – injection fuel worn the a with to together chamber combustion the reaches Oil hssmo appears! symbol when this ignition the off turn Immediately 1 Fig. as e eto 1. rnlsecpn rmardyrcartridges“, dryer air from 66). escaping page Granules “10.4 components section other see to damage (also causes and system reaches air also compressed oil of the The wear surfaces. running increased cylinder in and con- rings resulting piston This oil, pistons, cylinder. lubricating the the in dilutes can water water plate densed condensed valve leaky of a formation brake, the air facilitate the for used start. are cold compressors a When layer during and particularly metal capacity, wear increased absorption smeared in oil results so-called the A reduces considerably clogged. This are develops. stones honing smeared the is surface the if running of cylinder the sealing in defective layer graphite and to The rings ultimately crankcase. piston and the surface, piston, running the cylinder increased as the such to surfaces, leads contact This the of absorption. wear oil correct run- prevents cylinder honed surface poorly ning a with cylinder pumped the practically of is machining oil Inadequate i.e. pump, chamber. a combustion can as the act distortion into to Extreme piston chamber. the combustion cause even the reach can case, mist this In oil bolts. head cylinder tightened incorrectly caused, and/or distortion old com- cylinder by the to e.g., due between crankcase seal the tight and a chamber provide bustion longer no may therefore rings can piston The and ability wear. load-bearing increased less facilitate display 8). often in- page oils surface flooding”, running Fuel Inferior “2.2 cylinder section and see rings (also with dramatically piston diluted creases piston, is oil the If at flooding. wear fuel fuel, to lead can combustion abnormal An mk xas pipe exhaust smoky A 2 Fig. AL 13 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction failure. engine light catastrophic from to piston ranging the stages, at several damage includes here described damage The engine diesel a DESCRIPTION of land top the and piston the of top the at Melting 3.3 8|©MAHLE © | 18 hsfutcnb igoe i h olwn features: following the via diagnosed be can fault This combustion: Abnormal are There piston. this: the for of causes overload two thermal the to attributed is damage This CAUSES PROBABLE nanra obsincnb asdb ubro factors: of number a by caused be can combustion abnormal An hr sahl ntepiston. the the in around hole a and is along There all marks seizure are piston. there cases, extreme piston In the crown of top piston off the melted at completely seen be can areas visible. Melted is crown piston the at Erosion h i r-amn sdfcie(seilyfrvr o min tem- ambient low very for (especially compression. defective is insufficient pre-warming is air there The i.e. – small, too is protrusion loss. The compression in – resulting being leaky, is are valves rating The cetane – insufficient an with fuel or fuel fol- incorrect the The by – caused be may which misfiring lowing: and delay ignition is There clogged. is system gas stiff. exhaust or The wedged – either is needle incorrectly. nozzle set The is – delivery fuel of start The incorrectly. clogged. – set is is filter delivery air fuel the The e.g. – reduced, is supply air The – be can following: This the rich. of too result is the chamber combustion the in mixture air-fuel The axis. pin piston the in marks seizure shows land top The are nozzles injection the of incorrectly. rate set delivery the and pressure pattern. injection spray The poor a display nozzles injection off”. The “gnawed been has edge bowl The peratures). sd rteei aoiei h diesel. the in gasoline is there or used, Fg 2). (Fig. Fg 1) (Fig. ih pt a to up right – etn ttetpln fadee piston diesel a of land top the at Melting 1 Fig. h xesv eprtr ee ftepso rw a ecue ythe by caused be following: can crown piston the of level temperature excessive The features: following the via identified be can This crown: piston the of Overheating REMEDY/PREVENTION hc h neto oze o n ek,teijcinpesr n the and pressure pattern. injection spray the leaks, any for nozzles injection the manufacturer’s Check the to according timing specifications. and amount injection the Set required the circuit. prevents oil the etc., in residue, circulation gasket as such Contamination, nozzles oil cooling the clogged. in result being such can biofuels, which oil, using soybean of when and risk rapeseed especially a as is oil, there engine case, this the In of long. polymerization too is changes oil between not time has The or detached error). become (assembly has assembled bent, been either is nozzle oil cooling The h nieo biofuels. running on when engine shorter much the is changes oil between time correctly. the functioning that is Ensure valve regulating pressure the sure crankshaft Make the block, head. engine cylinder the the in and channels oil oil the cooling clean Thoroughly the assembling when alignment nozzles. correct to attention Pay necletsryptencnb bevda h o ftepiston. the of top the at observed be can pattern spray excellent An damaged. not is bowl combustion The etdpso rw tadee piston diesel a at crown piston Melted 2 Fig. AL 19 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction .Asml error: Assembly 2. to: attributed in be can and This peaks lands. gasoline ring pressure piston the high the at with of overload knocking combustion mechanical with uncontrolled as in – – results engine delay ignition excessive An engine: Diesel DESCRIPTION lands ring piston Broken 3.4 0|©MAHLE © | 20 aoieengine: Gasoline following: the by caused be can combustion Knocking “knocking”. from as skirt known piston is the combustion and abnormal lands This ring bottom. to piston top the to fractures or vibrations cracks ultrasound-like are consequences to The behavior. as combustion irregular well to as due overheating degree) and angle crank value (default per degree angle bar crank steep per 3–5 bar a 300 to to leads up of This pressure in speed. increase combustion an the in in resulting increase chamber, combustion tenfold spontaneous the approx. sparks, of areas ignition other the at via occurs started ignition been has ignition the Once combustion: Abnormal 1. lock. hydraulic or error assembly an combustion, results abnormal which an overload from mechanical by caused are damage of types These CAUSES PROBABLE hr seoina h o ftepso,tetpln n ntegroove the on and land top the piston, the walls. of top top to the at bottom erosion lands: from is and ring There 1a+b) piston (Fig. broken bottom for to behavior top fracture from of types two are There ihatosrk nietefatr usfo o obto,a the underside. as the bottom, from cylinder to the top into from forced is runs piston fracture the engine of two-stroke fracture a top With to bottom occurs. typical lands ring A piston bore. fractionally,the the protrude of rings front the the cylinder, blocking the thus in piston the of installation subsequent groove.During compressor, the ring in seated a properly not using often quite without are installed they been have rings piston the If necsieaon ffe en injected. being fuel of amount excessive An nozzles. injection fluid. Leaky starting “ether” e.g. aids, starting of use Incorrect nozzles. the of pressure injection Insufficient pressure. compression Insufficient great. too is ratio compression The hot. too is air intake used. The been has rating octane inadequate an with Fuel lean. too is mixture air-fuel The (pre-ignition). incorrect is timing ignition The Fg 2–3). (Fig. ls-pve ftefatr eaiu rmtpto top from behaviour bottom fracture the of view Close-up 1b Fig. abnormal an by combustion caused lands ring piston Broken 1a Fig. rknpso iglnscue ya sebyerror assembly an by caused lands ring piston Broken 2 Fig. sebyerrwt nipito h itnring piston the of imprint an with error Assembly 3 Fig. reasons: following the to due chamber combustion reach the may liquid crankshaft Excessive 10). the page lock”, and Hydraulic “2.3 bearing section the connect- see (also crankcase, the the pin, head, piston cylinder the the piston, rod, the ing at load stress abrupt lock hydraulic an compressed, combustion in be results the can reaching fuel fuel nor or water neither water Since liquid, chamber. by caused is damage This lock: Hydraulic 3. REMEDY/PREVENTION s hce aktfrar-ahndclne ed n nuethe pistons. ensure oversize and for head, less cylinder is re-machined height compression a for gasket thicker a Use leaks. for system intake the Check specifi- manufacturer’s the to cations. correspond which correctly. plugs ignition spark the use and Only carburetor the system, injection rating. the octane Set specified the with fuel use Only defective a to due chamber nozzle. combustion injection the reaches fuel gaskets. Excessive defective to due chamber combustion the enters Coolant water). through driving when (e.g. system intake the via chamber combustion the reaches Water lascekijcinnzlsad hnncsay ee them. renew necessary, when and, nozzles injection gaskets. check relevant Always replace to forget not engine, do an overhauling and when gaskets undamaged and turbocharged new use a Always for pressure charge-air correct engine. the to attention Pay AL 21 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction DESCRIPTION skirt 4.1 Piston 4 6|©MAHLE © | 26 clearance insufficient by caused skirt, piston the at Seizure 1 Fig. h niehsoehae because: overheated has (overheating): engine clearance The of lack a by caused Seizure causes: possible other two attrib- are be There cannot combustion. crown problem abnormal the piston an undamaged, to the are uted piston Since the spots. of hot top the localized and by caused is damage The CAUSES PROBABLE REMEDY/PREVENTION plus diameter (piston size incorrect clearance). the fitting to machined is defect): bore (machining cylinder clearance The of lack a by caused Seizure seizure. rate piston in (cold the load result thermal twice can high piston) at excessively hot an heat cylinder, engine, the with of iron expands cast gray piston the the of of aluminum the Since h itnrnsadtepso igbl r ngo condition. good in are belt ring piston the and skirt. rings the piston of The end the at concentrated been is have seizure they The if as areas, shiny partially polished as show marks seizure The opposite and thrust the on side marks scoring with skirt piston the at Seizure Fan – Thermostat – (V-belt) pump Water – level Coolant – includes: clearance). this fitting circuit, plus coolant diameter the (piston Check piston the on using stated determined values be can the This size. cylinder correct the observe Always incorrect. is ventilation engine The clutch fan. viscous defective damaged a a a or pump, thermostat, water defective a defective V-belt, a torn to or due loose e.g. faulty, is circulation coolant The low. too is level coolant The eeaetecoigsse.Ti loicue h etn circuit. heating the includes also This system. cooling the Deaerate itnsiueo h hutadopst ie(itnsitae only) area skirt (piston side opposite and thrust the on seizure Piston Fg 1) (Fig. Fg 2) (Fig. . . atal hn ezr marks seizure shiny Partially 2 Fig. itnrnswt unmarks burn with rings Piston 2 Fig. skirt piston the of side thrust the on only Seizure 1 Fig. skirt piston the of side one on seizure Piston 4.2 aeto h hutsd is.Ti a etersl ftefollowing: the of result the be can This first. stroke side power ap- thrust the becomes the lubrication during on inadequate parent piston side, opposite the the of on side than greater thrust is the on load the Since CAUSES PROBABLE DESCRIPTION REMEDY/PREVENTION u oboe f rdryfins. dirty or off e.g. broken overheated, to locally due has engine insufficient air-cooled an an for with cylinder finned i.e. The loads, engine used. been the has for ability, lead-bearing suitable not is which oil the Oil of reduced. ability considerably load-bearing therefore The is 8). film page see flooding”, (also water Fuel condensation “2.2 or section fuel either with diluted been nozzle. has oil oil cooling The the hole and/or feeder oil rod clogged connecting a the or in warm-up engine of excessive result oil, the of be level low can a This lubricated. inadequately was wall cylinder The onolpm,adryfle,adfciepesr eifvlei h oil the system. in cooling the valve Check relief pressure a oil. defective by diluted a caused or filter, be pump dirty can a pressure pump, oil oil worn Insufficient pressure. oil. oil refill the necessary, if Check imperative; are checks level after oil immediately Regular load and speed moderate assembly. a at engine manufacturer. the engine the Operate by approved oils engine use the Only in holes clogged. feeder not oil are the that rod check connecting and – oil of supply correct a Ensure necletwa atr svsbeo h poieside. opposite the on visible is pattern wear rings excellent piston An skirt the piston on the marks of burn side are thrust There the on shows only seizure Piston Fg 2). (Fig. AL 27 | MAHLE © Fg 1). (Fig.

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction DESCRIPTION skirt piston the on pattern wear Asymmetrical 4.4 0|©MAHLE © | 30 eto 24Icesdolcnupin,pg 2.Icrettae can travel following: Incorrect the 12). by caused page be see consumption”, (also and oil consumption vibrate Increased angle, oil “2.4 an increased section at causing travel motion, also pumping which a rings, create pistons The gap baking film. large travel, oil gases) a the (blow-by side gases opposite exhaust the hot at which through while pis- appears cylinder, the the of no with side contact piston one that has the means ton This guidance, cylinder. the piston in the straight travels in longer irregularities geometrical to Due CAUSES PROBABLE REMEDY/PREVENTION h o adhsasiyapaac noesd ftepso n is and piston side the opposite of the side on carbon one oil on by appearance blackened shiny a has land pattern top wear The asymmetrical an shows skirt piston The aktrsdems ecendu immediately. up cleaned e.g. be assembly, must engine residue during gasket cleanliness to attention great pay Always speci- manufacturer’s the to fications. according bolts head correctly. cylinder aligned the is Tighten rod connecting the that sure Make (concentricity). installation and prop- machining rod during connecting the erly and crankshaft the line, bearing main the Align position). (slanted bore the cylinder and the crankcase, in the straight finned on not The is angle piston an contaminated. at is positioned cylinder therefore is finned cylinder the of base cylinder The susceptible. particularly are cylinders finned Air-cooled se- Caution: (incorrect torque). tightening incorrectly incorrect tightened or been quence have bolts be head e.g., cylinder can, The which shells. bearing bearing slanted worn by a angle. caused displays an line at bored bearing been main has The end rod or connecting twisted, the or because bent – is rod connecting the because not – are rod connecting arise, the deviations of Alignment end’ ‘big parallel. and end’ ‘small the in bores The deposits irregular with land Top 2 Fig. Fg 2). (Fig. Fg 1). (Fig. ttepso skirt piston the at position) (slanted pattern wear Asymmetrical 1 Fig. otnos hn iea h yidrbore cylinder the at line shiny Continuous, 2 Fig. of constriction to liner due cylinder skirt the piston lower the at Seizure 1 Fig. . itnsiuei h oe itnsitae only area skirt piston lower the in seizure Piston 4.5 REMEDY/PREVENTION small. too being cylinder the of end the at diameter bore the in stones, result honing can the of travel idle with e.g. machine, honing set incorrectly distortion. An cylinder of risk higher a es- is – there unevenly – cylinders and/or finned incorrectly with tightened pecially are bolts head cylinder the If to: attributed becomes be liner can cylinder the This inadequate, constricted. is groove gasket the in space the If following: the from result may which and bore piston cylinder the the between clearance insufficient by caused are marks These CAUSES PROBABLE DESCRIPTION ideadbto,as ntodrcin,drn n fe honing. after and during directions, two in top, also the bottom, at and bore middle cylinder the Measure correctly. machine honing the Set can gaskets. clearance together the liner of with cylinder the lack insert Subsequently a time. good that in detected ensures be This cylinder first. wet gaskets install distortion, without cylinder liners or clearance of lack a prevent To spec- torque tightening ifications. the to according bolts head cylinder the Tighten aktrsdewihhsntbe removed. been not has which residue gasket or slipped, has which gasket a sealants, additional of gasket, application thick) the (too incorrect an of application the bore cylinder the in edge shiny area continuous, skirt a piston is lower There the in shows seizure sharp-edged A Fg 2). (Fig. AL 31 | MAHLE © Fg 1). (Fig.

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction DESCRIPTION surface matte rough, a with skirt piston the at wear Heavy 4.6 2|©MAHLE © | 32 REMEDY/PREVENTION an to due separator. either mist oil contaminated dirty is a oil and/or The crankcase culprit. ring, uncleaned top the the is than oil worn more engine is nated ring control defective oil the a and and/or ... leaks to due intake filter. either air common is missing the or This cylinders. via the chamber all of combustion ring, system control the oil the reached than has worn more nation is ring top the ... damaged and are ... cylinders the all or several If which debris or leak assembly. a to prior by removed either not caused was is This one above. of from system i.e. intake ring, cylinder, the control via oil chamber the combustion than the reached worn has more nation is ring top the and ...... damaged is cylinder one only If wear: of types several between distinguish to ring piston possible the is of Depend- amount it wear, the contamination. and by cylinders damaged caused of number wear the to on ing due is damage of type This CAUSES PROBABLE h roewlsso xa wear. axial worn. show heavily walls wear. are groove radial ring The control show oil and the gap of end faces large The a have rings skirt. piston piston the The on marks scoring fine are There removed. pattern partially wear is wide profile matte, machining a show The skirt piston the of sides Both temperatures. ambient low behavior, at starting particularly incorrect and performance poor provides “2.4 engine The section see 12). (also page oil consumption”, of oil Increased amount increased an requires engine The laspyatnint lalns uigassembly. during cleanliness assembly. to to attention prior pay manifolds Always intake the and crankcase it. replace the necessary, Clean if and, filter air the Check leaks. for system intake the Check h itnskirt piston the at contamination by caused Wear 1 Fig. contami- contami- contami- Fg 1). (Fig. . ermrso n ieo h itnskirt piston the of side one on marks Wear 4.7 n crn marks scoring and pattern wear shiny Wide, 1 Fig. REMEDY/PREVENTION DESCRIPTION hstp fdmg a aetefloigcauses: following the have can drastically damage wear. thus of component film, type engine oil This increasing the and dilutes ability oil load-bearing the its in reducing fuel of amount excessive An CAUSES PROBABLE h niei worn. is spark engine defective The a – e.g. system, ignition the in occurred has defective. are error rings An piston – several or ring piston One – small. too is protrusion The – incorrectly. set is timing The leaky. – is gasket head cylinder The – leaky. is valve A conditions: – following the This to misfiring. attributed in be result can can which low, too is pressure compression The head, cylinder injection. the uncontrolled hammers causing piston the protrusion, excessive an to Due a to due example filter. fuel for incorrectly, clogged functioning are nozzles injection rich. The too is enrichment start cold The incorrectly. set is system injection The marks burn some even and marks scoring show rings piston piston. The whole the the around of and length skirt entire piston the along marks scoring lengthwise deep, are shiny There and wide is pattern wear The hc h pr lg n,i eesr,rpaethem. replace necessary, if and, plugs spark the Check conditions. intervals extreme shorten in and accordingly intervals, maintenance filter fuel to adhere Always dimensions. installation observe Always nozzles. etc.). injection enrichment, the start Check (cold correctly system injection the Set plug. crn ak n unmrso h itnrings piston the on marks burn and marks Scoring 2 Fig. Fg 1). (Fig. AL 33 | MAHLE © Fg 2) (Fig. .

DESCRIPTION Introduction

A depression has been worn into the piston ring lands and/or the top land (Fig. 1).

The surfaces of the worn area are shiny and smooth (Fig. 2).

Further damage includes the impact of piston ring fragments on the top of the piston (Fig. 3). General topics The piston ring of the worn groove is fractured (Fig. 4a+b).

Fig. 1 Heavily worn piston ring groove PROBABLE CAUSES The damage is caused by a piston ring fracture or by piston ring vibration.

Possible reasons are: Top of the piston and piston ring belt

Assembly error: The piston ring was not fully inserted into the piston ring groove during assembly and broke while being pushed into the cylinder. Piston skirt Knocking: The piston ring fracture has been caused by pressure peaks during knocking (Fig. 4b).

Fig. 2 Piston ring vertical clearance:

Ring belt with shiny surface The piston ring grooves are worn. Support – piston pin bushing

The piston ring is worn.

The thermal overload of the engine reduces the material strength, and the grooves are worn out. Piston rings REMEDY/PREVENTION

Always use a ring compressor during assembly.

Check the piston ring grooves for wear prior to assembly. Always use a new piston if the piston ring grooves are heavily worn. Cylinder liners

Fig. 3 Damage to the top of the piston due to individual fragments of the ring insert

Fig. 4a Piston ring fracture caused by

knocking Valves Bearings Filters

Fig. 4b Close-up view of a piston ring fracture

© MAHLE | 37 Glossary Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction DESCRIPTION rings piston and grooves ring piston the of wear Heavy 6.3 8|©MAHLE © | 38 REMEDY/PREVENTION an to due either separator. contaminated mist oil is dirty oil a The and/or crankcase culprit. ring, uncleaned top the the is than oil worn more engine is nated ring control defective oil the a and and/or ... leaks to due intake filter. either air common is missing the or This cylinders. via the chamber all of combustion ring, system control the oil the reached than has worn more nation is ring top the ... damaged and are ... cylinders the all or several If which debris or leak assembly. a to prior by removed either not caused was is This one above. of from system i.e. intake ring, cylinder, the control via oil chamber the combustion than the reached worn has more nation is ring top the and ...... damaged is cylinder one only If wear: of types several between distinguish to ring piston possible the is of Depend- amount it wear, the contamination. and by cylinders damaged caused of number wear the to on ing due is damage of type This CAUSES PROBABLE rae i osmto” ae1)i oncinwt oso per- of loss a with connection in formance. 12) page consumption”, oil In- “2.4 creased section see (also consumption oil walls increased groove displays the engine and The rings piston the at wear axial heavy is There millimetres. several by increasing gap end wear radial heavy exhibit rings piston The laspyatnint lalns uigassembly. during cleanliness assembly. to to attention prior pay manifolds Always intake the and crankcase it. replace the necessary, Clean if and, filter air the Check leaks. for system intake the Check hscnrsl nthe in result can This 1). (Fig. contami- contami- contami- Fg 2) (Fig. . ev xa erpriual ttetpring top the at particularly wear axial Heavy 2 Fig. itnrn ihhayrda wear radial heavy with ring Piston 1 Fig. ev ailwa ihrltvl o xa wear axial low relatively with wear radial Heavy 1 Fig. rings piston the of wear radial Heavy 6.4 crn ak n unmrso h itnrings piston the on marks burn and marks Scoring 2 Fig. REMEDY/PREVENTION DESCRIPTION hstp fdmg a aetefloigcauses: following the have can drastically damage wear. thus of component film, type engine oil This increasing the and dilutes ability oil load-bearing the its in reducing fuel of amount excessive An CAUSES PROBABLE nerrhsocre nteinto ytm ..adfciespark defective a e.g. system, ignition the in occurred has defective. are error rings An piston – several or ring piston One small. – too is protrution piston The – incorrectly. set is timing The leaky. – is gasket head cylinder The – leaky. is valve A conditions: – following the This to misfiring. attributed in be result can can which low, too is pressure compression The cylinder injection. the uncontrolled hammers causing piston head, the protrution, piston excessive an to Due a to due example filter. fuel for incorrectly, clogged functioning are nozzles injection rich. The too is enrichment start cold The incorrectly. set is system injection The scuff- with marks. seizure combined possibly or skirt, ing piston the of scoring heavy is worn. possibly There are ring control oil the of low. relatively faces also The is walls groove the of wear axial rings. piston The the of wear axial slight only marks is burn There partial show rings piston the of surfaces running The wear radial heavy exhibit rings piston The hc h pr lg n,i eesr,rpaethem. replace necessary, if and, plugs spark the Check conditions. intervals extreme shorten in and accordingly intervals, maintenance filter fuel to adhere Always dimensions. installation observe Always nozzles. etc.). injection enrichment, the start Check (cold correctly system injection the Set plug. Fg 1) (Fig. . AL 39 | MAHLE © Fg 2) (Fig. .

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction itrina h av tmi asdb ehncloela.Ti can This overload. following: mechanical the by to attributed caused be is stem valve the at Distortion CAUSES PROBABLE DESCRIPTION stem valve the at Distortion 8.2 6|©MAHLE © | 46 REMEDY/PREVENTION ota h av ri n h itnmvmnsaen ogrsyn- longer no are movements impacts. piston valve the in resulting and chronized, train observed valve been the not have that markings so the i.e., incorrectly, set is collide. timing valve is The the springs and valve piston the of the speed and insufficient return piston. the the engine at the impacts of valve over-speeding in At result can setting valve incorrect An fe ahnn h yidrha,awy hc h av depth. valve the check always or head, belts cylinder the timing machining After replacing when device chains. clamping the renew Always correctly. timing speed. the rated Set the above engine the running Avoid correctly. clearance valve the Set insufficient. is depth damaged. valve been The has chain clamping or belt defective timing a The to due jumped has chain device. the or belt timing The h av edhsbe npe off snapped been has bent head is valve or The curvature slight shows stem valve The Fg 2–3). (Fig. Fg 1). (Fig. irto rcuewt rcuesraea h av stem valve the at surface fracture with fracture Vibration 3 Fig. npe f av head valve off Snapped 2 Fig. stem valve Bent 1 Fig. lne pigsikn noeside one on sticking spring Slanted 4 Fig. ribs the at keepers valve the of Deformation 3 Fig. fracture/bend- (overload stress) groove ing the in broken base Valve 2 Fig. groove valve the in Fracture 8.3 valve deformed Heavily 1 Fig. fault: assembly – structure fracture Coarse the of this: overload for mechanical responsible by are caused conditions Two be valve. only can damage of type This CAUSES PROBABLE off deformed snapped are been keepers has valve it The or fracture groove a exhibits valve The DESCRIPTION norcl netdvlespring an valve by inserted caused incorrectly head cylinder the at Marks 5 Fig. iefatr tutr emtyfault: geometry – structure fracture Fine REMEDY/PREVENTION prto hscnla omtra aiu n h av being valve the and fatigue material to lead off. snapped longer can During seat. this the strikes valve valve operation the the when and between stem area valve valve the transition the and the between head at right contact occur perfect will slight a bending to at piston, due train the longer stem valve no valve the is the head in to valve fault angle the geometry if a example, by structure. For fracture caused system. fine is a fracture by fatigue characterized The fracture, fatigue a is There to valve 4–5). the (Fig. cause snap can or moment fracture bending on at This moment stick retainer. bending will spring large it valve a angle, the in results an This at compressed. positioned when is side spring one repairing valve after the shortly occurs If and engine. error the assembly an to struc- due fracture is coarse This a ture. by characterized fracture, overload an is There ttevlestem. stress valve bending the in resulting at freely, rotate un- cannot worn valves usually the are that keepers so evenly valve Old keepers. valve new use Always system. train valve the installation. Check during correctly springs valve the Position off. snapped operation being longer valve During the valve. to lead the can at this also moment can bending keepers valve slight used a of cause application the or arms rocker Slanted Fg 3). (Fig. AL 47 | MAHLE © Fg 1–2). (Fig.

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction REMEDY/PREVENTION to attributed be can This bearings. result-the edges, at following: outer the pattern the wear at uneven or an bearing in the ing of center the surface con- in high the create either irregularities at pressure These irregularities pins. crank geometrical the by and/or rod caused necting is damage of type This CAUSES PROBABLE bearing the the of on center only the either in – only patterns or wear edge uneven show bearings several or One DESCRIPTION bearings the at pattern wear Uneven 9.7 8|©MAHLE © | 58 h oncigrdi etdet yrui ok( lock hydraulic 10). to page lock”, due Hydraulic bent “2.3 section is rod connecting The yidial rn h rnsatpins. crankshaft the grind Cylindrically them. installa- align to necessary, prior if rods and, connecting tion the of angle correct the check Always concave sur- or tapered the convex, i.e. properly, either re-machined is face been not have installation. to pins prior crankshaft aligned The been not has rod connecting The nvnwa ttebaig,tebaiglyrhas layer removed bearing partially the been bearings, the at wear Uneven 1 Fig. etcnetn rod connecting Bent 3 Fig. Fg 1–2). (Fig. Fg 4). (Fig. i.3 Fig. losee also ; nvnwa ttebearings the at wear Uneven 2 Fig. hp eitosa h rnsatpins crankshaft the at deviations Shape 4 Fig. tapered concave convex mrnso h i edrholes feeder oil surface: the outer of the Imprints at – bearing installed Incorrectly 4 Fig. crankshaft the to welded Bearing 3 Fig. bearing spun and worn Heavily 2 Fig. bearings the of surfaces running the on marks Shiny 1 Fig. bearings the at marks Seizure 9.8 REMEDY/PREVENTION stages. various in occurs damage bearing This DESCRIPTION l h ernsaedamaged: are bearings the All damaged: is bearing One just whether damaged. determine are to bearings important the of is all it or damage one of lubrica- type inadequate this by With caused is tion. above described damage bearing The CAUSES PROBABLE ern eti lsdadolcno ec h bearing. the reach cannot oil and closed is seat bearing ul oe atclrrs folcodn n hscogdolfeeder oil clogged thus and clouding oil holes. of risk bio- particular of use a The poses lubrication. fuels inadequate cause holes feeder oil Clogged are hole bearings feeder these oil If the holes. orientation, feeder incorrect oil the with has installed bearing the of half one Only pin. bearing melts the layer to lining welds the cases, extreme some In black then and bearings blue turn the first lubrication, inadequate with operation bearing continuous the During on marks shiny very is indication first The hc h i ee n,i eesr,rfl oil. refill necessary, if and, manufacturer's biofuels. level using oil the when the to Check intervals change according the regularly oil shorten – the filter specifications and and oil bearing the the of Replace engine. holes the feeder in to holes oil attention feeder the Pay of specifications. alignment the to correct according bearings the Install vehicle. the of position slanting excessive an or – oil, of level valve, insufficient limiting system, an pressure pipe the – oil at the fault in a leakage or a pump – oil leaky or defective a e.g.: damage, – There this 12). of for page lack reasons consumption”, numerous general a oil a are Increased be must “2.4 there section bearings, see the (also of oil all in seizure is there If Fg 2) (Fig. . Fg 3) (Fig. Fg 1) (Fig. n h bearing the and AL 59 | MAHLE © Fg 4) (Fig. . fthe of

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction niefe itr(KL): filter fuel Inline occur: leaks following the connection, at leakage the More- normal vehicle. the Besides the engine. the of performance at detectable poor is wear or partial over, liquid of loss sudden a is There DESCRIPTION 10.1 10 2|©MAHLE © | 62 ftefle oncini ek,tefloigasml rosmyb the be may errors assembly following the cause: leaky, is connection filter the If withstand cannot it load. incorrectly, pressure installed dynamic been the has filter spin-on load fuel dynamic the is radius if transition the at crack the of cause The (KC): filter spin-on Fuel CAUSES PROBABLE h itrhuighsbe cracked been has housing filter The – (OC): filter spin-on Oil piece. connecting the and in resulting hose hose, the fuel between damaged water a partial to is due connection there line or corroded the at is corrosion housing filter the Either (KL): filter fuel Inline radius. transition the at trans- crack or longitudinal verse a is there housing, filter the At (KC): filter spin-on Fuel h oecap r ihee insufficiently. tightened are during fittings. clamps the hose slipped to The connected or – correctly not replaced are hoses been The not – has the porous, to is due o-ring occur The can – connection line errors: the assembly following at protective leakage the or to Corrosion due occur can leaky. filter damaged or removed the being film of filter clamp retaining and the aluminum the between corrosion contact housings, aluminum With h iheigtru a norc hnisaln h filter. the installing when incorrect was torque tightening The re-used. been has o-ring old An incorrectly. fitted position is slanted o-ring a The in installed been has filter The hr scorrosion is There – assembly. -ighuighsbe uhdout pushed been has housing o-ring itrleakage Filter Filters Fg 4) (Fig. . eutn ntefle being filter the in resulting 6), (Fig. Fg 1) (Fig. Fg 3) (Fig. swollen , n/rcracked. and/or Fg 5). (Fig. Fg 2) (Fig. Fg 1) (Fig. n/rthe and/or e.g. , aktdmgddrn assembly during damaged Gasket 3 Fig. o oprsn wle itr(et n e itr(right) filter new and (left) filter Swollen comparison: For 2 Fig. by caused overload to fluctuations due pressure housing filter the in Crack 1 Fig. aae hed u oa norcl ntle filter installed incorrectly an to due threads Damaged 5 Fig. aae otn h eut Corrosion result: the – coating Damaged 4 Fig. REMEDY/PREVENTION (OC): filter spin-on Oil otc orso u odmgdinsulation damaged to due corrosion Contact 6 Fig. lasuenwsas(-ig,cpe-lmnmwashers). copper-aluminum filter. (o-rings, the seals tighten new to use tool Always extraction special a use not engine. Do the for recommended filters use Only intervals. change the to adhere Always used been has engine the for approved been not has which defective. filter oil is An pump oil – the in valve limiting pressure The reasons: pressed– following been the has to o-ring due the torn or or swollen out or cracked is housing filter The lasahr oteasml instructions. assembly the to adhere Always limiting pump. pressure oil the the replace of to valve advisable is it necessary, considered If h itrhsntbe ihee yhn u ihaseilextraction special a with but hand by tightened been not has filter long. The too is – intervals change between time The causes: following – the have can filters spin-on filter. oil the at installing Corrosion when incorrect was torque tightening The – incorrectly. fitted is o-ring position. slanted The a – in installed been has filter errors: The assembly following – the to attributed be can leakage filter Oil correctly. tightened been not has filter The icretapplication). (incorrect ol n h orso rtcinhsbe damaged. been has protection corrosion the And tool. AL 63 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Filters Support – Top of the piston General Glossary Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction oncigrod connecting type Clamp Circlip pressure Charge-air rating Cetane gas Blow-by Biofuels Biodiesel Anti-freeze rotation of Angle rate flow Air compressor Air air Additional 11 8|©MAHLE © | 68 Glossary o i ntepso,as nw sa‘press a as fit’. known also piston, the in pin piston the fixing for required Circlips longer no rod. thus are connecting the of the in end’ pin ‘small piston the clamping for used Rod bore. pin the in pin piston the fixing Clip performance. engine or torque engine the also mixture air-fuel constant a engine with therefore the to and pressure charge-air fed increasing (turbo- with rises mass air compressor The the charger). after Pressure performance. ignition greater diesel indicates of rating cetane higher quality A fuels. ignition engine the of measure A pistons. the via crankcase the reaches which gas Combustion biomass. from produced Fuel fat. veg- animal or from oil but etable oil – crude fuel from diesel produced common not unlike – is Biodiesel water the engine. in the protection corrosion as and well as bearings pump, the a for as serves lubricant additionally It point. boiling increasing the and freezing from water cooling the preventing physical Thus water. the the of properties changes It additive. Coolant tightening torque. are specific a bolts to addition anti-fatigue in tightened the which by Angle pipes). or (filters medium a through flowing liter/hour) unit: (measuring air of quantity The vehicles. commercial in systems brake air compressed for air ates gener- which compressor Engine-operated leakage. a at system the entering Air itn clearance Fitting fracture Fatigue Fan tool Extraction Erosion gap End center Dead nozzle oil Cooling piston the of alteration Contact enrichment start Cold oil) (engine Clouding o osdrdhere. considered not at diameter ° cylinder 20 and diameter piston largest the between difference Dimensional stress by cycles. caused component a of Fracture elec- separate motor. a tric via or clutch, viscous a engine via the by radiator. driven mechanically the is fan at The air fresh blowing Propeller the damaging of protection). (risk corrosion for filters not on removing, tool for screwing The used OCS. be only MAHLE: should at filter Name oil or caps. filters spin-on removing for Tool to gases. due hot or surfaces liquids component on Damage when installed. ring piston a of ends the between Gap center. dead bottom = position lowest center; dead top = highest position cylinder: the in piston the of Position piston. improved the of ensuring cooling the thus into channel, injected cooling is circular a oil with engine pistons the channel, For circuit. oil the from oil engine with piston inner the injecting directly permis- by observed the is level temperature that sible ensures which tube Bent vice-versa. opposite and the side to thrust the bottom from and center top dead the in piston the Changing concentricity. optimal for mixture air-fuel richer a require fuel. engines with Cold mixture air-fuel the of Enrichment accordingly. is shortened changes not oil between veg- time the with if oils engines etable diesel operating when occur can This oil. sud- engine the which thickens denly chains molecule of linking The .Agaht otn ttepso is piston the at coating graphite A C. AL 69 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction 0|©MAHLE © | 70 rating Octane fatigue Material sensor flow air Mass profile Machining ability Load-bearing probe Lambda (timing) Ignition stones Honing Honing value Heat Granules operation Gas-fuelled delivery Fuel ihotn aig twl aeahigher a have knocking. engine will to it resistance rating, has octane fuel If high a applies: auto following to The ignition). (tendency to knocking ability engine gasoline’s resist of measurement The excessive to overload. due mechanical material the to Damage the setting for mixture. air-fuel required optimum air, intake measur- the for ing system intake air the in Sensor condi- tribological tions. the optimizing for skirt piston the at profile rotation defined Precisely film. oil the of Stability for gas system exhaust concentration. the gas controlling exhaust and analyzing the in Sensor plug. spark the via ignited air- is engines the gasoline for which mixture fuel at crankshaft the of Position process. to honing the used execute stones) (grinding tool grinding The use. in istics character- consumption aid oil and and span, lubrication life good give will which bore cylinder the on lines cross-hatch put is to Honing used (re-boring). re-sizing in or facture ma- manu- during the either bores, cylinder in of chining used process final the is Honing plugs. spark of Index dryer air. air the from water the absorbs which in substance Hygroscopic gases). fermentation or etc.) CNG, gas (LPG, natural autogas, usually with petrol, (not operated gas mainly engine Combustion engines. diesel for fuel injected of Amount mae ea layer metal Smeared marks Seizure phase Regeneration Protrusion pump) (oil valve limiting Pressure Polymerization Pitting seizure Piston protrusion/retrusion Piston fracture Overload Over-speeding side Opposite edt nrae i consumption. oil increased can to stones; lead honing clogged or worn to due honing during arising compression Material contact excessive with pressure. or lubrication out with- long too for other each against rubbing parts metal moving two by caused Damage valves. control is via phase introduced regeneration The air tank. dry air of the from backflow a with from granules removed dryer is air water which in phase The cylinder the and head. center) dead top the at (piston piston the of top the between Distance pan. oil to the pump oil the from back by directly circuit oil feeding oil or the in peaks pressure excess pressure general prevents which Valve oil. engine sud- the which thickens denly chains molecule of linking The piston the in leads holes material. small that of corrosion creation the localized to of form A pressure. contact excessive with long or too lubrication without for other each against rubbing cylin-der the and piston the by caused Damage face. block the of top the below is piston the that means Retrusion the face. of block Protrusion top the center. above is dead piston the top that means at rest at is when it face block travels cylinder piston the the above/below that distance the is This very by caused overload. strong component a of Fracture gear. low clutching too a when to arise shifting after e.g., can, rpm speed. High rated the above engine the Running the during stressed stroke. power less is which side The AL 71 | MAHLE ©

Support – Top of the piston General Glossary Filters Bearings Valves Cylinder liners Piston rings piston pin bushing Piston skirt and piston ring belt topics Introduction 74 | © MAHLE © MAHLE | 75 www.mahle-aftermarket.com