Valve: Testing and Inspection

^ A light tapping at one-half engine speed, or any varying frequency, may indicate a valve train problem.
^ These tapping noises will typically increase with engine speed.
^ Before attempting to diagnose valve train noise, check for the proper oil revel and thoroughly warm up the engine. By doing this you will bring all engine components to a normal state of expansion. Also, while sitting in the drivers seat, run the engine at various speeds and listen for abnormal noise.

The causes of the valve train noise may include the following conditions:
^ Low engine oil pressure.
^ Worn or faulty oil pump
^ A loose or plugged oil pump screen Loose valve rocker arm attachments (causing excessive valve lash)
^ Worn of damaged valve rocker and bearings
^ Worn valve rocker arm and/or pushrod
^ Broken valve spring
^ Sticking valves
^ Valve lifters worn, dirty, or faulty
^ Broken valve lifter guide
^ Camshaft valve lifter lobes worn.
^ Worn valve guides or valve stems
^ Worn or damaged valve keys Bent pushrods
^ Excessive play in the camshaft timing chain
^ Bent, broken, or damaged timing chain sprocket teeth.