- General Information

There are four steps to diagnosing engine noise. You must determine the following conditions:
^ Type of noise.
^ Determine the exact operating condition under which the noise exists.
^ At what rate, and at what location in the engine.
^ Compare sounds in other engines to make sure you are not trying to correct a normal condition.

Identify the type of noise. For example, a light rattle or low rumble.
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 noise). Try to determine the rate at which the noise is occurring.
^ Engine flywheel contacting the splash shield.
Reposition the splash shield.
^ Loose or broken crankshaft balancer or drive pulleys. Tighten or replace as necessary.
^ Excessive piston to bore clearance. Replace the piston.
^ Cold engine knock usually disappears when the specific cylinder secondary ignition circuit is grounded out. Cold engine piston knock which disappears in 1.5 minutes should be considered acceptable.
^ Bent connecting rod.
^ Improper oil viscosity. Install recommended oil viscosity for expected temperatures.
^ Excessive piston to bore clearance.
^ Excessive piston pin to piston clearance.
^ Excessive crankshaft end clearance.
^ Excessive crankshaft bearing clearance.
^ Detonation or spark knock. Check operation of ignition controls or knock sensor circuit.
^ Loose torque converter bolts.
^ Exhaust leak at manifold. Tighten the exhaust manifold bolts and/or replace the gasket.
^ Excessive connecting rod bearing clearance.
Replace bearings as necessary.
^ Excessive piston pin clearance.
^ Excessive crankshaft thrust bearing clearance.
^ Bent connecting rod.