Engine - Internal Coolant Leaks

9210pontiac01

Bulletin Number: 92-6-16
Reference Number: 136009R
Publish Date: 1/92


Subject: INTERNAL COOLANT LEAKS
(SERVICE PROCEDURE)

Models
Affected: 1991-92 FIREBIRD MODELS


Condition: Some owners of the above vehicles with a VIN F (LB9 V8) engine built before VIN breakpoint NL205439.

or a VIN 8 (L98 V8) engine built before VIN breakpoint NL205712.

May comment on a loss of engine coolant without visible coolant leaks.

Cause: This condition may be caused by an internal coolant leak between the cylinder head and intake manifold at the coolant crossover passages.

Correction: Perform the following procedure:

1. Remove the rocker covers.

2. Remove the intake manifold.








3. Measure the distance between the rocker cover mounting flange and the bottom of the coolant passages (front and rear) (see Figure).

4. If the distance is less than 2.60 inches, replace the cylinder head(s) with the following part numbers.

LB9 V8 Engine, P/N 10159553
L98 V8 Engine, P/N 10159552

Parts are currently available from GMSPO.


Labor Operation: T1800

Labor Time: Inspect both cylinder heads 10.3
with A.C. +.1

Clean part on vehicles with
30,000 plus miles +.3

Replace head (right or left) .6
Replace both heads 1.1