Lower Engine Noise, Regardless of Engine Speed

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Cause	Correction
Low oil pressure	Verify oil pressure. Refer to Oil Pressure Diagnosis and Testing . Repair or replace damaged components as required.
Detonation or spark knock	Verify the operation of the ignition controls system. Refer to Diagnostic System Check - Engine Controls in Engine Controls. Repair or replace damaged components as required.
Worn, damaged or improperly installed accessory drive belt - severe cracking, bumps or missing segments in the accessory drive belt	Inspect the accessory drive system components. Repair or replace damaged components as required.
Worn, damaged or improperly installed accessory drive system components	Inspect the accessory drive system components. Repair or replace damaged components as required.
Worn, damaged or improperly installed crankshaft balancer	Inspect the crankshaft balancer. Inspect the crankshaft. Repair or replace damaged components as required.
Worn, damaged or improperly installed engine flywheel	Inspect the engine flywheel. Inspect the engine flywheel bolts. Inspect the torque converter. Inspect the torque converter bolts. Inspect the crankshaft. Repair or replace damaged components as required.
Worn, damaged or improperly installed torque converter	Inspect the torque converter. Inspect the torque converter bolts. Inspect the engine flywheel. Repair or replace damaged components as required.
Damaged oil pan, contacting the oil pump screen An oil pan that has been damaged may loosen, improperly position or restrict oil flow at the oil pump screen, preventing proper oil flow to the oil pump.	Inspect the oil pan. Inspect the oil pump screen. Repair or replace damaged components as required.
Worn, damaged, improperly installed or restricted oil pump screen An oil pan that has been damaged may loosen, improperly position or restrict oil flow at the oil pump screen, preventing proper oil flow to the oil pump.	Inspect the oil pan. Inspect the oil pump screen. Repair or replace damaged components as required.
Worn, damaged or improperly installed piston 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.	Inspect the spark plugs. Refer to Spark Plug Inspection in Engine Controls. Verify engine compression. Refer to Engine Compression Test . Inspect the cylinder bores. Inspect the pistons. Inspect the piston pins. Inspect the connecting rods. Repair or replace damaged components as required.
Worn, damaged or improperly installed connecting rod bearing	Inspect the connecting rods. Inspect the connecting rod bearings. Inspect the crankshaft connecting rod journals. Repair or replace damaged components as required.
Worn, damaged or improperly installed crankshaft bearing	Inspect the crankshaft bearings. Inspect the crankshaft journals. Repair or replace damaged components as required.