For 1990-2009 cars

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.