Valve Train Noise Diagnosis

A light tapping at one-half engine speed, or any varying frequency, can indicate a valve train problem. These tapping noises increase with engine speed.

Before attempting to judge valve train noises, thoroughly warm up the engine. By doing this you will bring all engine components to a normal state of expansion. Run the engine at various speeds and listen for engine noise with the hood closed while sitting in the driver's seat.

After major engine repair or long periods of non use, "Lifter Clatter" at initial start up is normal. This should go away after 10-15 minutes of operating the engine at 1500 rpm. Operating the engine in this manner will purge all air out of lifters.

CAUSES OF VALVE MECHANISM NOISES
- Broken or weak valve spring(s)
- Sticking or warped valves
- Dirty, stuck or worn valve lifters
- Damaged or improperly machined camshaft lobes
- Insufficient or poor oil supply to valve train (low oil pressure)
- Excessive valve stem-to-guide clearance
- Worn valve guides
- Missing or mispositioned lifter guides
- Oil drain back from engine block. Install oil filter with internal check valve.