GM Astro/Safari 1985-1996 Repair Guide

Knocking Main Bearings


When the main bearings are constantly making noise, replace or repair the following items or systems, as necessary:

Oval shaped crankshaft journals.
Loose torque converter or flywheel mounting bolts.
Loose damper pulley hub.
Excessive clearance of the main bearings.
Excessive belt tension.
Low oil supply to the main bearings.
Extreme crankshaft end-play.