Suburban 3/4 Ton 4WD V8-305 5.0L (1986)
Fluid Pump: Customer Interest
A/T - THM 700-R4 Pump Whine or Moan
GMC NUMBER:
87-T-32
SECTION:
7A - Automatic Transmission
DATE:
February, 1987
SUBJECT:
PUMP WHINE OR MOAN NEW TEN-VANE PUMP DESIGN
MODELS:
1985-87 LIGHT DUTY MODELS WITH THM 700-R4 AUTOMATIC TRANSMISSIONS
(MD8)
Whine or moan on a 1985 through 1987 (before 1986, Julian date 301) THM 700-R4 transmission may be caused by line pressure instability in a
seven-vane pump design. A ten-vane pump design to provide stable line pressure is now used on all 1987 THM 700-R4 models and available to service a
1985 through 1987 model transmission.
Figure No. 1 - Transmission Identification
DATE OF CHANGE (Figure No. 1)
October 28, 1986, Julian date 301, ten-vane pumps for all 1987 THM 700-R4 production and service replacement transmission assembly (SRTA)
models.
SERVICE ACTION
When using the ten-vane pump body assembly to service a THM 700-R4 transmission, mate the new pump body to the pump cover taken from the
transmission's existing oil pump.
