Engine - Vibration Diagnosis
89chevy30Number: 90-20-6
Section: 6
Date: June 1989
Subject: DIAGNOSING ENGINE VIBRATION
Model and Year: 1988-90 C 1, 2, 3 WITH 4.3L, 5.0L, 5.7L (VIN CODES Z, H, K) ENGINES
Figure No. 1:
Figure No. 2:
Figure No. 3:
TO: ALL CHEVROLET DEALERS
This bulletin is for information purposes only, and should be used as a guideline for correctly identifying transmission mounts on light duty C trucks with gas engines and all automatic and manual transmissions.
When diagnosing 1988-90 Light Duty "C" Trucks for engine vibration, the transmission mount should be inspected to make sure it is the correct application for the mount. The rubber in the mounts uses different durometer ratings, and the incorrect mount could induce a vibration that may not be there if the correct mount is installed.
All the mounts can be visibly identified, and Figures 1-3 show the correct applications for the mounts.