Lower Engine Noise, Regardless of Engine Speed

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 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 - Vehicle . 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 . 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.