GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

Low oil pressure

    â€¢ Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing .
    â€¢ Repair or replace as required.

Loose and/or worn valve rocker arm attachments

    â€¢ Inspect the valve rocker arm stud, nut, or bolt.
    â€¢ Repair or replace as required.

Worn valve rocker arm

Replace the valve rocker arm.

Bent or damaged push rod

Inspect the following components, and replace as required:

    â€¢ The valve rocker arm
    â€¢ The valve push rod
    â€¢ The valve lifter

Improper lubrication to the valve rocker arms

Inspect the following components, and repair or replace as required:

    â€¢ The valve rocker arm
    â€¢ The valve push rod
    â€¢ The valve lifter
    â€¢ The oil filter bypass valve
    â€¢ The oil pump and pump screen
    â€¢ The engine block oil galleries

Broken valve spring

Replace the valve spring.

Worn and/or damaged valve rotators

Replace the valve rotators as required.

Worn or dirty valve lifters

Replace the valve lifters.

Stretched or broken timing chain and/or damaged sprocket teeth

Replace the timing chain and sprockets.

Worn timing chain tensioner if applicable

Replace the timing chain tensioners as required.

Worn engine camshaft lobes

    â€¢ Inspect the engine camshaft lobes.
    â€¢ Replace the camshaft and valve lifters as required.

Damaged, broken, or dirty, balance shaft sprocket teeth if applicable

Inspect the following components, and repair as required:

    â€¢ The balance shaft gear
    â€¢ The camshaft gear
    â€¢ The balance shaft rear bushing

Worn valve guides or valve stems

Inspect the following components, and repair as required:

    â€¢ The valves
    â€¢ The valve guides

Stuck Valves

Carbon on the valve stem or valve seat may cause the valve to stay open

Inspect the following components, and repair as required:

    â€¢ The valves
    â€¢ The valve guides