G 20 3/4 Ton Van V8-305 5.0L VIN H 4-bbl (1984)
Fluid Pump: Customer Interest
A/T - THM 400 No Gears or Slipping In All Ranges
Number:
84-136
Section:
7A (VIIc)
Date:
June, 1984
Subject:
NO GEARS OR SLIPPING IN ALL RANGES
Model and Year: ALL TRUCKS WITH THM 400
TO:
ALL CHEVROLET DEALERS
Some 1984 THM 400 transmissions built between February 1, 1984 and March 31, 1984 may experience no gears or slipping in all
ranges. Refer to the chart below for model and serial number applications affected..
When servicing any 1984 THM 400 transmission which is listed in the chart below and exhibits the above condition, you may find
either the forward clutch snap ring mislocated or out of its seat and some seals blown out of their seat.
Reverse Boost Valve Bushing
If these conditions are found they may be caused by a sticking reverse boost valve in the reverse boost bushing. It is very important to
visually inspect the reverse boost bushing which is located in the oil pump assembly for possible mismatching of the inner diameter.
Refer to the illustration letters "A" and "B" for examples.
If the reverse boost bushing is like letter "A", the bushing and valve must be replaced. Order service package 8625902 which contains
the following.
Service Package 8625902 contains:
1
-
Regulator Boost Valve Bushing
1
-
Regulator Boost Valve
Model
Serial Numbers
Model
Serial Numbers
FA
9745 to 12760
FN
2372 to 2873
FB
8498 to 11466
FP
9960 to 12837
FC
1027 to 1051
FQ
1714 to 1860
FD
7065 to 9425
FR
1069 to 1119
FE
1003 to 1004
FT
1255 to 2050
FF
3610 to 4254
FV
8735 to 12185
FH
1701 to 2057
FW
11270 to 14565
FJ
6335 to 7739
FX
1949 to 2146
FK
1136 to 1401
FY
1608 to 1833
FM
34782 to 47400
FZ
1178 to 1225
MF
43420 to 49554
