Engine Noise Under Load

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

Cause	Correction
IMPORTANT: A cold piston knock which disappears in 1.5 minutes should be considered acceptable. A cold engine knock usually disappears when the specific cylinder's secondary ignition circuit is grounded out during diagnosis. A low rumble/knocking may indicate a crankshaft or piston, lower engine concern.
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 Detonation/Spark Knock in Engine Controls - 5.7L.
Loose torque converter bolts	Inspect the torque converter bolts and flywheel. Repair as required.
Cracked flywheel - automatic transmission	Inspect the flywheel bolts and flywheel. Repair as required.
Excessive connecting rod bearing clearance	Inspect the following components, and repair as required: The connecting rod bearings The connecting rods The crankshaft
Excessive crankshaft bearing clearance	Inspect the following components, and repair as required: The crankshaft bearings The crankshaft journals The cylinder block crankshaft bearing bore