Worn valves, valve guides and/or valve stem oil seals.

1. Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection.
2. Inspect the valves, valve guides and/or valve stem oil seals. Refer to Valve Stem Oil Seal and Valve Spring Replacement.
3. Repair or replace, as required.

Worn piston rings

Oil consumption may or may not cause the engine to misfire.

Low oil pressure

1. Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing.
2. Repair or replace damaged components, as required.

Worn accessory drive components

Abnormalities such as severe cracking, bumps or missing areas in the accessory drive belt and/or misalignment of system components.

1. Inspect the accessory drive system.
2. Repair or replace, as required.

Loose or damaged crankshaft balancer

1. Inspect the crankshaft balancer.
2. Repair or replace, as required.

Detonation or spark knock

Verify the correct operation of the ignition controls system. Refer to Symptoms - Engine Controls.

Loose or damaged flywheel

Repair or replace the flywheel.

Oil pump screen loose, damaged, or restricted

1. Inspect the oil pump screen.
2. Repair or replace as required.

Excessive piston-to-cylinder bore clearance

1. Inspect the piston and cylinder bore.
2. Repair, as required.

Excessive piston pin-to-bore clearance

1. Inspect the piston, pin, and connecting rod.
2. Replace the piston and pin as an assembly, as required.

Excessive connecting rod bearing clearance

Inspect the following components, and repair, as required:

Excessive crankshaft bearing clearance

Inspect the following components and repair, as required:

Incorrect piston, piston pin and connecting rod installation

Pistons must be installed with the mark or dimple on the top of the piston facing the front of the engine. Piston pins must be centered in the connecting rod pin bore.

1. Verify the pistons, piston pins and connecting rods are installed correctly. Refer to Piston, Connecting Rod, and Bearing Installation.
2. Repair, as required.