Engine Noise Under Load

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	Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . Repair or replace as required.
Detonation or spark knock	Verify the correct operation of the ignition controls. Refer to Diagnostic System Check - Engine Controls in Engine Controls. 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.
Worn, damaged or improperly installed pistons 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 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.