Cause  | Correction  | 
|---|---|
Worn or loose rocker arms  | Repair or replace the valve rocker arms, as required.  | 
Worn or bent push rods  | Replace the push rods.  | 
Sticking valves Carbon buildup on the valve stem and/or seat can cause the valve to not close properly.  | Repair or replace, as required.  | 
Excessively worn or mis-aligned timing chain  | Repair or replace the timing chain, camshaft retainer, and sprockets, as required.  | 
Worn camshaft lobes  | Replace the camshaft and valve lifters.  | 
Sticking lifters  | Replace, as required.  |