Diagnosing Engine Noise

1. You must determine:
- Type of noise.
- Under which operating conditions it exists.
- At what rate, and at what location in the engine.

2. Compare sounds in other engines to make sure you are not trying to correct a normal condition.

3. Identify the type of noise, for example, a light rattle or a low rumble. Determine the exact operating conditions under which the noise appears.

4. Remember, engine noises are generally synchronized to either engine speed (caused by the crankshaft, connecting rods or pistons) or one-half engine speed (valve train noises). Try to determine the rate at which the noise is occuring.