Worn or incorrectly adjusted valve rocker arms

The valve rocker arm and rocker arm rollers should be intact and in the proper working condition.

Adjust or replace the rocker arms, as required.

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 components

Replace components, as required.

Worn camshaft lobes

Replace the camshafts, as required.