Worn or loose rocker arms

The rocker arm bearing end caps and/or needle bearings should intact within the rocker arm assembly.

Replace the valve rocker arms as required.

Stuck valves

Carbon buildup on the valve stem can cause the valve to not close properly.

Repair or replace as required.

Excessively worn or mis-aligned timing chain

Replace the timing chain and sprockets as required.

Worn camshaft lobes

Replace the camshaft and valve clearance adjusters.

Sticking lifters

Replace as required.

Malfunctioning camshaft position actuators - improper oil viscosity or contamination.

1. Verify correct oil pressure. If low, inspect the bottom of the oil filter for oil filter drain back feature. Refer to Oil Pressure Diagnosis and Testing : LE5 or LE9 .
2. Isolate the noise to a specific camshaft position actuator. Disconnect the electrical connector on the camshaft position actuator solenoid valves and start the vehicle. If noise is gone, repeat procedure to limit to an individual actuator. Refer to Camshaft Position Intake Actuator Replacement : LE5 or LE9 or Camshaft Position Exhaust Actuator Replacement : LE5 or LE9 .