1. Cylinder Block Service

1.13. Bearing Failures

LO 8-13: Outline the scope of cylinder block service and describe common service operations.

 

Bearing Failures
Most bearing failures are caused by problems with lubrication Figure 96. Bearing failures are indicated by:

  • A drop in lubricating oil pressure
  • Excessive oil consumption (excessive oil thrown onto the cylinder walls)
  • Noise levels of knocking sounds that are reduced during a cylinder cut-out procedure

Bearing roll-ins are performed during engine overhaul. Because the crankshaft is not removed when the engine is repaired in chassis, the upper main bearing shell must be pushed out and another bearing rolled into position.

   Fig08_96

FIGURE 08-96: Causes of bearing failures.

 

Measuring Crankshaft End Play
Occasionally, crankshaft thrust bearings may become excessively worn or even broken. A sudden, sharp release of the clutch or a driver’s foot resting on the clutch can apply excessive force against the thrust bearing, leading to premature wear or breakage. The result is a slipping clutch or difficulty adjusting a clutch, with the free play continually changing after a manual adjustment. Crank position sensor fault codes may also be logged if end play is excessive. Insufficient end play can be the result of a misaligned main bearing cap.

To measure crankshaft end play, follow the guidelines in Skill Drill 8-5.

 

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