Lower Engine Noise, Regardless of Engine Speed

Cause	Correction
Low oil pressure	Perform an oil pressure test. Oil Pressure Diagnosis and Testing 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.	Inspect the accessory drive system. Repair or replace, as required.
Loose or damaged crankshaft balancer	Inspect the crankshaft balancer. Repair or replace, as required.
Detonation or spark knock	Verify the correct operation of the ignition controls system. Symptoms - Engine Mechanical
Loose flywheel bolts	Inspect the flywheel bolts and flywheel dampener. Repair or replace, as required.
Loose or damaged flywheel dampener	Repair or replace the flywheel dampener.
Excessive piston-to-cylinder bore clearance	Inspect the piston and cylinder bore. Repair, as required.
Excessive piston pin-to-bore clearance	Inspect the piston, pin, and connecting rod. Replace the piston and pin as an assembly, as required.
Excessive connecting rod bearing clearance	Inspect the following components and repair, as required: Connecting rod bearings Connecting rods Crankshaft Crankshaft journals
Excessive crankshaft bearing clearance	Inspect the following components and repair, as required: Crankshaft bearings Crankshaft journals
Incorrect piston, piston pin, and connecting rod installation	Verify the pistons, piston pins and connecting rods are installed correctly. Piston and Connecting Rod Removal and Installation Repair, as required.