Main Bearing Noise

^ Damaged or worn main bearing noise is revealed by dull thuds or knocks which happen on every engine revolution. This noise is loudest when the engine is under heavy load.

^ Excessive crankshaft end play is indicated by an intermittent rap or knock sharper than a worn main bearing.

^ The following are causes of main bearing noise:
- Low oil pump pressure
- Thin, diluted, or dirty oil and/or filter
- Excessive main bearing clearance
- Excessive crankshaft end play
- Out-of-round crankshaft journals
- Loose crankshaft pulley
- Loose flywheel or torque converter
- Loose main bearing cap
- Belt pilling