Valve Mechanism or Valve Train Noises

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

Light tapping
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.

Abnormally noisy
If the valve mechanism is abnormally noisy, remove the rocker arm covers and use an engine stethoscope to determine which valves or valve train parts are causing the noise.

WARNING: This procedure is not recommended on engines with stainless steel exhaust manifolds because manifold temperature will exceed the flash point of the oil causing a fire with possible personal injury.

The cause of valve mechanism noises include:
- Broken or weak valve spring(s).
- Sticking or warped valves.
- Bent push rods.
- Dirty, stuck, worn or defective 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.
- Worn rocker arms or push rods.
- Broken rocker arm stud.
- Loose or worn rocker arm attachments.
- Missing or mispositioned lifter guides (roller lifter engines).