GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

Low oil pressure

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

Worn or damaged valve rocker arm

    • Inspect the rocker arm for wear or missing needle bearings
    • Replace the valve rocker arms as required.

Improper lubrication to the valve rocker arms

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

    • The valve rocker arm
    • The valve lash adjusters
    • The oil filter bypass valve
    • The oil transfer tube
    • The oil pump and pump screen
    • The engine block oil galleries

Broken valve spring

Replace the valve spring.

Worn or dirty valve lash adjusters

Replace the valve lash adjusters.

Stretched or broken timing chain and/or damaged sprocket teeth

Replace the timing chain and sprockets.

Worn engine camshaft lobes

    • Inspect the engine camshaft lobes.
    • Replace the camshaft, valve lash adjusters, and rocker arms as required.

Worn valve guides or valve stems

Inspect the following components, and repair as required:

    • The valves
    • 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:

    • The valves
    • The valve guides