A/T - THM 200/200C, 400, 700R4 Speedometer Leak

SIL 88-21 (May)

SUBJECT: THM 200/200C, THM 400, THM 700-R4

PROBLEM: Leak at the speedometer driven gear




Transmission fluid leak at the plastic speedometer driven gear can be caused by a hole in the driven gear shaft (See Figure).

This condition could be misdiagnosed as a speedometer driven gear seal leak.

Many speedometer driven gears made in 1986 and 1987 have a hole in them, that allows transmission fluid to leak through the center of the shaft.

Check the speedometer driven gear shaft for a hole through the center of the shaft, as follows:

1. Install a hand vacuum pump over the end of the ear (opposite gear teeth)

2. Pump up 10 in.-hg. of vacuum

3. The gage should stay at 10 in.-hg. for at least 30 seconds. If the gear does not hold vacuum, replace the gear.

Note
Check the new gear from parts stock as outlined, before installing in transmission.