Cooling System - Engine Cooling Fan Drone

GMC NUMBER: 88-T-20


GROUP: 6B - Engine Cooling

DATE: June, 1987

CORPORATE
NUMBER: 866202

SUBJECT: ENGINE COOLING FAN DRONE

MODELS: 1988 C/K WITH 4.3L (VIN CODE Z), 5.0L (VIN CODE H), AND 5.7L (VIN CODE K)

ENGINES WITH OR WITHOUT AIR CONDITIONING (A/C)


Some 1988 C/K trucks with 4.3L, 5.0L, and 5.7L engines with or without air conditioning may experience a "drone" noise caused by the fan shroud vibrating. The drone is usually most pronounced at or just above idle. On units equipped with air conditioning, this bulletin applies to only those vehicles experiencing a drone with the air conditioning in the OFF position. If this condition is encountered, it can be repaired by replacing the fan clutch. Use the procedures in Section 6B-Engine Cooling for fan replacement

PARTS INFORMATION (/= And/Or)

Part
Number - Description Application Quantity
22073415* Clutch - Fan C/K 1,2,3 with 4.3L, 5.0L, 5.7L without 1
A/C/KC4/VO1/VO2

22068662 Clutch - Fan C/K 1,2,3 with 5.0L with GU2/GU4/GU6 and 1
KC4/VO1/VO2/A/C

22073409** Clutch - Fan C/K 1,2,3 with 5.0L with GT4/GT5 and 1
KC4/VO1/VO2 A/C

C/K 1,2,3 with 4.3L, 5.7L with GT4/GT5 and 1
KC4/VO1/VO2/A/C

22073403*** Clutch - Fan C/K 1,2,3, with 4.3L with GU2/GU4/GU6, and 1
KC4/VO1/VO2/A/C
with 5.7L with GU4/GU6, and 1
KC4/VO1/VO2/A/C

* P/N 15548580 or P/N 22054876 can be used optionally with P/N 22073415

** P/N 15550738 or P/N 22008968 can be used optionally with P/N 22073409

*** P/N 15548575 or P/N 22008956 can be used optionally with P/N 22073403