All Models

Check for incorrect valve clearance. Adjust as necessary.
Check for worn valve stem or guide.
Check for weak or broken valve spring.
Check for warped or bent valve.
Check for worn piston, ring or cylinder bore.
Check for worn connecting rod bearing.
Check for worn main bearings.
Check for loose connecting rod nuts.
Check for low oil pressure.
Check for worn crankshaft bearing.
Check for worn crankshaft journal.
Check for loose bearing cap bolts.
Check for excessive crankshaft thrust play.