A/T - Oil Pump Modifications
Number: 85-9Section: 7A (VIIc)
Date: Oct., 1984
Subject: NEW OIL PUMP DRIVE SHAFT AND SPACER ASSEMBLY, PUMP SHAFT BEARING AND SEAL ASSEMBLY AND CONTROL VALVE AND PUMP ASSEMBLY
Model and Year: LATE 1984 MODEL THM 125/125C ALL 1985 MODELS
TO: ALL CHEVROLET DEALERS
Starting in May, 1984, a new oil pump drive shaft and spacer assembly, pump shaft bearing and seal assembly and control valve and pump assembly went into production on all THM 125/125C transmissions built in the United States.
The new parts provide easier and improved assembly procedures.
FIGURE 1 - FORMER OIL PUMP DRIVE SHAFT AND SPACER ASSEMBLY:
FIGURE 2 - NEW OIL PUMP DRIVE SHAFT AND SPACER ASSEMBLY:
The former parts (Figure 1) are not interchangeable with the new parts (Figure 2) listed above for the following reasons.
FIGURE 2 - NEW OIL PUMP DRIVE SHAFT AND SPACER ASSEMBLY:
1. The new oil pump drive shaft and spacer assembly has a thinner spacer and a longer bearing journal diameter to accommodate the new pump shaft bearing and seal assembly (Figure 2).
2. The new pump shaft bearing and seal assembly was also made longer in length to accommodate the seal as part of the bearing assembly (Figure 2).
3. The new control valve and pump assemblies were changed to accommodate the new oil pump drive shaft and roller pump shaft bearing and seal assemblies.
Refer to Chart 1 for the serial number breakpoints. If the transmission being serviced has a serial number smaller than the number shown in chart 1, it will have the former parts (refer to the 1984 parts list book). If the number is the same or larger, it will have the new parts (refer to Charts 2 and 3 for new part numbers and model applications).
FIGURE 3 - U.S. Models-Serial Numbering:
FIGURE 4 - Canadian Models-Julian Dates:
IMPORTANT: ALL THM 125C transmissions built in Canada will have these new parts beginning start of production 1985. Some models THM 125C transmissions built in Canada are also built in the United States and can be distinguished from each other by their nameplates. The U.S. models have serial numbers (Figure 3) and Canadian models have Julian Dates (Figure 4).
CHART 1
NEW OIL PUMP SHAFT AND SPACER ASSEMBLY, PUMP SHAFT BEARING AND SEAL ASSEMBLY, AND CONTROL VALVE AND PUMP ASSEMBLY
SERIAL SERIAL
MODEL NO. MODEL NO.
CA 2921 EN 4986
CB 240974 EW 1656
CC 1787 HC 2355
CE 83327 HM 3147
CF 8695 HS 20389
CT 4840 HX 7171
EF 7651 HY 33059
EI 7493 PD 2762
EK 11230 PE 70659
EL 4824 PF 34901
EM 3343 PG 69397
EQ 14460 PJ 9033
EB 3452 PW 90895
EP 2433
CHART 2
PART NAME P/N MODEL
OIL PUMP DRIVE SHAFT
AND SPACER ASSEMBLY 8643764 ALL
PUMP SHAFT BEARING
AND SEAL ASSEMBLY 8643762 ALL
CHART 3
NEW CONTROL VALVE BODY ASSEMBLIES STARTING WITH SERIAL NUMBERS SHOWN IN CHART #1
P/N MODEL P/N MODEL
8652251 CE 8652257 EW
8652255 CA, CB, CF 8652262 HC
8652263 CC, CT 8652418 HM
8652412 EB 8652259 HS
8652421 EF 8652414 HX
8652416 EI 8652261 HY
8652410 EK 8652254 PE, PG
8643419 EQ 8652265 PD
8652417 EL 8652268 PF
8652256 EM 8652267 PJ
8652269 EN 8652260 PW
8652415 EP