For 1990-2009 cars

Cause | Correction
--- | ---
Low oil pressure. | Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing.
Loose and/or worn valve rocker arm attachments. |

1. Inspect the valve rocker arm, bolt, and pedestal.
2. Replace the valve rocker arms, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

Worn or damaged valve rocker arm. |

1. Inspect the rocker arm for wear or missing needle bearings
2. Replace the valve rocker arms, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

Bent or damaged push rod. | Inspect the following components and replace, as required:

• | The valve rocker arm.

| Replace the valve rocker arms, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

• | The valve push rod.

| Replace the valve push rods, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

• | The valve lifter.

| Replace the camshaft and valve lifters. Refer to Camshaft Replacement.

• | The valve lifter guide.

| Replace the valve lifter guides. Refer to Valve Lifter Replacement.

• | Inspect the top of the pistons for valve contact. If the top of the piston shows valve contact, replace the piston and pin assembly.

| Replace the piston and pin assembly. Refer to Piston, Connecting Rod, and Bearing Removal.

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

• | The valve rocker arm.

| Replace the valve rocker arms, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

• | The valve push rod.

| Replace the valve push rods, as required. Refer to Valve Rocker Arm and Push Rod Replacement.

• | The valve lifter.

| Replace the camshaft and valve lifters. Refer to Camshaft Replacement.

• | The oil filter bypass valve.

| Replace the oil filter. Refer to Engine Oil and Oil Filter Replacement.

• | The oil pump and pump screen.

| Replace the oil pump and pump screen. Refer to Oil Pump, Screen, and Crankshaft Oil Deflector Replacement.

• | The engine block oil galleries.

| Refer to Engine Block Cleaning and Inspection.

Broken valve spring. | Replace the valve spring and spring shim. Refer to Valve Stem Oil Seal and Valve Spring Replacement.
Worn or dirty valve lifters. | Replace the valve lifters. Refer to Valve Lifter Replacement.
Stretched or broken timing chain and/or damaged sprocket teeth. | Replace the timing chain and sprockets. Refer to Camshaft Timing Chain and Sprocket Replacement.
Worn engine camshaft lobes. |

1. Inspect the engine camshaft lobes.
2. Replace the camshaft and valve lifters, as required. Refer to Camshaft Replacement.

Worn valve guides or valve stems. | Inspect the following components and repair, as required:

• | The valves.

| Refer to Cylinder Head Disassemble.

• | The valve guides.

| Refer to Cylinder Head Disassemble.

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.

| Refer to Cylinder Head Disassemble.

• | The valve guides.

| Refer to Cylinder Head Disassemble.