Worn or loose rocker arms

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

Replace the valve rocker arms as required.

Worn or bent pushrods

Stuck valves

Carbon buildup on the valve stem can cause the valve not to 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 lifters.

Sticking lifters

Replace as required.

Improper operation of the displacement-on-demand (DoD) system

Repair as required. Refer to Displacement on Demand (DoD) System Diagnosis.

Cut or damaged oil pump screen O-ring seal which may cause aeration of the engine oil

Repair as required. Refer to Oil Pressure Diagnosis and Testing.