Engine Noise Under Load

WARNING: This page is about a different car, the 2005 GMC Yukon XL, 2005 Chevrolet Suburban, and 2005 Chevrolet Avalanche. 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 - 8.1L.
Loose torque converter bolts or improperly installed torque converter	Inspect the torque converter bolts and flywheel. Verify correct installation of the torque converter. Repair as required.
Cracked flywheel	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