For 1990-2009 cars

Cause | Correction
--- | ---
Plugged oil filter | Replace the oil filter.
Low oil pressure |

1. Verify proper oil level.
2. Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing .
3. Repair or replace, as required.

Loose and/or worn valve rocker arm attachments |

1. Inspect the valve rocker arm stud, nut, or bolt.
2. Repair or replace, as required.

Worn valve rocker arm | Replace the valve rocker arm.
Worn pushrod guide plate | Replace, as required.
Bent or damaged push rod | Inspect the following components and replace, as required:

• | The valve rocker arm

• | The valve push rod

• | The valve lifter

Improper lubrication to the valve rocker arms | Inspect the following components and repair or replace, as required:

• | The valve rocker arm

• | The valve push rod

• | The valve lifter

• | The oil filter bypass valve

• | The oil pump and pump screen

• | 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 camshaft lobes |

1. Inspect the camshaft lobes.
2. Replace the camshaft and valve lifters, as required.

Worn valve guides or valve stems |

1. Inspect the valves and valve guides.
2. Repair, as required

Stuck valves Carbon on the valve stem or valve seat may cause the valve to stick. |

1. Inspect the valves and valve guides.
2. Repair, as required
3. Use GM top engine cleaner GM P/N 1050002, (Canadian P/N 992872) to eliminate carbon deposits following manufacturers instructions