GM Astro/Safari 1985-1996 Repair Guide

Knocking Pistons and Rings


When the pistons and/rings are constantly making noise, replace or repair the following items or systems, as necessary:

Misaligned connecting rods.
Out-of-round or tapered cylinder bore.
Loose or tight ring side clearance.
Build-up of carbon on the piston(s).
Piston-to-cylinder bore clearance is excessive.
Broken piston rings.
Loose or seized piston pin(s).