Engine - Knock, Piston Scuffing

91chevy22

Number: 90-433-6A

Section: 6A

Date: SEPT. 1991

Corporate Bulletin No.: 136515R

ASE No.: A1, A8


Subject: PISTON SCUFFING


Model and Year: 1990 CAVALIER, CORSICA, BERETTA AND LUMINA WITH 3.1L ENGINE
1990 LUMINA (APV) WITH 3.1L ENGINE


Condition: Some 1990 J, L and W cars and U-vans (APV) may exhibit engine piston scuffing, which could result in cold engine knock at low ambient temperatures. This condition will not lead to engine failure and is limited to cylinders # 2, # 4 and # 6.

Cause: Premature wear of the pistons due to low adhesion of the tin plating.

Correction: If pistons need replacement due to scuffing, a partial engine replacement is HIGHLY recommended rather than replacement of individual pistons. This recommendation is made since other pistons in these engines might have to be replaced later.

Labor Operation Number: J 1820

Labor Time: Use applicable time