A/T - Loss of Power In Drive and Reverse

Number: 84-93

Section: 7A (VIIc)

Date: April, 1984
Subject: LOSS OF POWER IN DRIVE AND REVERSE - THM TRANSMISSIONS


Model and Year: 1981-84 THM 125C, 200, 200-4R, 400, AND 700-R4 TRANSMISSIONS DIESEL ENGINES ONLY
TO: ALL CHEVROLET DEALERS

This cancels and replaces Chevrolet Dealer Service Bulletin 84-93 dated March, 1984 which should be destroyed. This bulletin clarifies engine/transmission combination and removes reference of 9Y6 with 700-R4 transmissions.

Some THM 125C, 200C, 200-4R, 400, and 700-R4 transmissions may experience a loss of power in drive and reverse ranges. If this condition is experienced at approximately 30-35 mph, then it may be caused by a damaged torque converter assembly.

Beginning with 1984 production new torque converters went into production for diesel equipped vehicles. The new torque converters will have the blades brazed into the pump shell. This process increases the ability of the pump blades to retain their position in the pump housing. The torque converters will appear identical except for one (1) type used on the THM 400 transmission which will not have any exterior embossments welded.

When servicing any THM 125C, 200C, 200-4R, 400 or 700-R4 transmissions for a loss of power in drive and reverse, refer to the chart below for replacement part numbers, identification, and model application.


THM Model P/N New Ident. Application by Model

THM 125C 8653936 FH5 1982 Thru 1984 OP.

THM 200C 8638926 CE9D 1982 Thru 1984 OR.

8638927 CG9D 1981 AS, HT, OT.

1983 Thru 1984 OU.

THM 200-4R 8638926 CE9D 1984 OF.

8638927 CG9D 1982 Thru 1984 OM.

1984 OY.
THM Model P/N New Ident. Application by Model

THM 400 8629917 4M 1982 FD, FF, FX, FY.

1983 FD, FF, FR, FS, FU, FX, FY.

1984 FD, FF, FR, FS, FU, FV, FX, MA.

THM 700-R4 8642992 CGAD 1982 9TN, 9TP, 9M6, 9MH.

1983 3MH, 3TL, 3TP, 3TS, 3TZ, 3T8, 3VJ.

1984 4MG, 4MH, 4TL, 4TM, 4TZ, 4T8, 4VE, 4VJ, 4VX.