A/T - Fluid Leaks From the Speedometer Driven Gear
Bulletin 87-7200-2Date May '87
Ref.No. 87-122-7200
Corp. Ref. No. 777118R
SUBJECT: FLUID LEAKS FROM THE SPEEDOMETER DRIVEN GEAR/ADAPTER AREA
MODELS AFFECTED: 1986-1987 VEHICLES EQUIPPED WITH THM 200C (MV9)
FIGURE 1 - EXTENSION AND ASSOCIATED PARTS:
BULLETIN COVERS
Transmission fluid leak at the plastic speedometer driven gear (44, Figure 1) can be caused by a hole in the driven gear shaft. This condition could be misdiagnosed as a speedo driven gear fitting leak (43, Figure 1).
FIGURE 2 - CHECKING DRIVEN GEAR SHAFT FOR VOID OR HOLE:
SERVICE ACTION
When servicing a 1986 or 1987 THM 200C transmission for a fluid leak around the speedometer driven gear fitting or cable, check the speedometer driven gear shaft for a hole through the center of the shaft as follows: (Figure 2)
1. Install a hand vacuum pump over the end of the gear (opposite gear teeth).
2. Pump up 10 in.-hg. of vacuum.
3. Gauge should stay at 10 in.-hg. for at least 30 seconds
- If gear holds vacuum, inspect the seals in the adapter
- If the gear does not hold vacuum, replace the gear*
* NOTE: Check the new gear from parts stock as outlined before installing in transmission.
SERVICE PARTS INFORMATION
Refer to GM Service Parts Operations (GMSPO) Catalog for current speedometer gear based on transmission model and year.