K 2500 Truck 4WD V8-454 7.4L (1990)
Fluid Pump: All Technical Service Bulletins
A/T - Loss of All Forward Ranges
GMC NUMBER:
90-7A-102
GROUP:
7A-AUTOMATIC TRANSMISSION
DATE:
OCTOBER, 1990
CORPORATE
NUMBER:
077135
SUBJECT:
LOSS OF DRIVE, SLIP OR NO DRIVE
MODELS:
1990 C, K, P, R, V, TRUCKS AND G-VAN WITH 3L80 AND 3L80-HD
Figure 1
BULLETIN COVERS (see Figure 1) Some HYDRA-MATIC 3L80 models built from August 1st (Julian Date 213) through October 1989 (Julian Date
304) may lose all forward ranges. This may be caused by an unfinished turbine shaft journal which distresses the stator shaft rear bushing and causes loss
of forward clutch. Changing the Turbine shaft, Forward Clutch Housing Assembly and Pump Cover Assembly will eliminate any future concerns. If
further inspection shows any contamination, the Converter Assembly should also be replaced and the transmission cooler and lines flushed.
SERVICE PARTS INFORMATION
Parts are currently available through GMSPO.
SERVICE MANUAL REFERENCE:
Refer to the Unit Repair Section of the appropriate Service Manual for the proper replacement procedures.