Crankshaft, Main Bearings, and Flywheel
02
040
15
RG,15,DT7461 –19–18MAY00–1/1
Crankshaft and Main Bearing Failure
Analysis
Scored Main Bearing (Diagnosis also applies to
connecting rod bearing.):
• Oil starvation.
• Contaminated oil.
• Engine parts failure.
• Excessive heat.
• Poor periodic service.
Galled or “Wiped” Bearings:
• Fuel in lubricating oil (incomplete combustion).
• Coolant in lubrication system (cracked block, liner seal
failure, or leaking coolant pump seal with plugged hole).
• Insufficient bearing oil clearance.
• Parts not lubricated prior to engine operation.
• Wrong bearing size.
Inconsistent Wear Pattern:
• Misaligned or bent connecting rod.
• Warped or bowed crankshaft.
• Distorted cylinder block.
Broken Main Bearing Caps:
• Improper installation.
• Dirt between bearing and crankshaft journal.
• Low oil pressure.
• Oil pump failure.
Cracked, Chipped or Broken Bearings:
• Overspeeding.
• Excessive idling.
• Lugging.
• Excessive oil clearance.
• Improper installation.
CTM100 (06APR04)
02-040-15
P
OWER
T
ECH
10.5 L & 12.5 L Diesel Engines
040604
PN=211
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