Engine - Block Heater Leaks

9230chevy01

GMC NUMBER: 92-6B-71(A)

GROUP: 6B Engine Cooling

DATE: April 1992

CORPORATE
NUMBER: 266201


SUBJECT:
ENGINE BLOCK HEATER LEAKS

MODELS:
1976-92 ALL TRUCKS WITH ENGINE BLOCK HEATER (RPO K05)

THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE
BULLETIN 92-6B-71, DATED APRIL 1992 TO CORRECT THE BULLETIN SUBJECT. ALL COPIES OF 92-6B-71 SHOULD BE DESTROYED.


Some owners of 1976-92 light duty truck engines may experience a leaking condition from the engine block heater. This condition may be caused by the block heater losing torque because the yoke, which secures the block heater, has cracked. This could cause a loss of engine coolant.

The block heater brass yoke may crack due to stress corrosion where it contacts the stainless steel crossbar. The yoke is stressed or cracked from over torquing the hold down screw (Figure 1, "6"). Corrosion in the stressed area is accelerated due to the dissimilar metals.





To correct this condition, a redesigned block heater should be installed. The yoke material (Figure 1 "3") of the block heater was changed from brass to stainless steel. The stainless steel is a higher strength material which reduces the possibility of stress corrosion and galvanic potential.

SERVICE PROCEDURE

Follow the "ENGINE BLOCK HEATER REPLACEMENT" instructions in section 9E ENGINE BLOCK HEATER of the appropriate Service Manual.


CAUTION:
The gasket "O" ring seals between the block heater and the block. Excessive tightening is not necessary. The torque specification is 1.6 - 2.2 N-m . (15.0 - 20.0 lbs.in.)

The revised engine block heater (P/N 10154624) can be used in any light duty truck, gas or diesel engine, where an engine block heater is used.

SERVICE PARTS INFORMATION

PART NUMBER DESCRIPTION QTY/VEHICLE
10154624 Engine Block 1
Heater

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

LABOR 0P. Description Labor Time
R4600 Heater, Engine 0.5 hrs.
Block - Replace