http://www.up.ac.za/academic/mae/research/design/diesel-lube1.pdf

DIESEL ENGINE FAILURES DUE TO FUEL WITH INSUFFICIENT LUBRICITY

Although the majority of soot produced during combustion exitsthrough the exhaust, some passes through the rings of thecombustion chamber and enters the engine oil. As long as these sootparticles remain suspended in the oil and are not allowed toagglomerate they pose little risk to engine parts.

It is up to the motor oil’s dispersants to keep soot particlesdispersed. However, in high soot conditions, dispersants can become quickly depleted. Once this happens the soot particlesrapidly agglomerate to form particles with diameters well over a micron.

Effect of SootAgglomeration

Diesel Engine CarIC: 3.0 MD: 75 DP: 75Very high quantity of soot due to a long draining period

Diesel Engine CarIC: 0.5 MD: 28 DP: 36Poor dispersancy due to a coolantleak

Hydraulic ShovelIC: 0.3 MD: 60 DP: 12Feeble dispersancy; poor enginecooling

TruckIC: 1.1 MD: 85 DP: 16The combustion is correct but thedisper-sancy is slightly degrading due to oil oxidation as the result of a tiring engine

Gas EngineIC: 0.2 MD: 65 DP: 7Poor dispersancy due to an extended drain interval

Marine Diesel EngineIC: 0.2 MD: 59 DP: 8High lubricant contamination withheavy fuel

Worksite TruckIC: 0.8 MD: 95 DP: 4Good combustion and gooddispersancy

CENTRIFUGE

CENTRIFUGE

K2 GS500 Right PistonThe right piston just removed during engine overhaul. Nice big carbon deposits here.

Figure 2. Valveguttering ortorching

Figure 3. Valvewith severelyrecessed (worn) sealing face

Figure 4. Valve deck from a Caterpillar3512TALE natural gas engine showingvery low to absent varnish andsludge

Figure 5. Cylinder head from a Caterpillar 3512TALE natural gas engine showing very low depositsafter 8,824 hours

Figure 7. Oil pan shows very low to absentvarnish and sludge

Figure 8. Piston undercrown shows extremely low varnish deposits

Figure 9. Piston ring zone from a Caterpillar 3512TALE natural gas engineafter 8,843 hours shows extremely lowcarbon deposits.

Figure 10. Piston liner shows very low polishing