Engine - Vibration
88chevy11Number: 88-221-6
Section: 6
Date: MAY, 1988
Subject: ENGINE VIBRATION
Model and Year: 1985-88 G VAN WITH 4.3L ENGINE
TO: ALL CHEVROLET DEALERS
Some 1985-88 G Vans equipped with the 4.3L engine and automatic or manual transmissions may experience vehicle vibration under different driving conditions. Vehicles equipped with 3 speed automatic or manual transmissions and lower gear ratios (3.42/3.73 etc.) may experience a vibration, "drone" condition, at highway speeds while vehicles with 4 speed overdrive transmissions and higher gear ratios (3.08/3.23) may experience vehicle shudder and low speed vibration conditions.
If a 1985-88 G Van experiences a vehicle vibration condition that cannot be repaired using normal diagnostic procedures, a new engine mount P/N 17989409 (2 required) has been released to address this condition.
Use engine mount replacement procedures in section 6A4 of the appropriate service manual.