1974 GMC C2500

DON WOODS

MEMBER
1974 GMC C2500
V8
2WD
AUTOMATIC
120,000 MILES

I have a turbo 400 trainsmission on a 1974 GMC 2wd Pickup. The transmission has approx 80,000 miles since a rebuild. I removed the transmission pan for filter/fluid replacement and found two small pieces of metal in the pan ( looked like part of a small washer). A transmission shop said it looked like part of a pressure seal. The transmission has been a little slow to engage in reverse for several years but other wise works very well. I do not know about automatic transmissions but guess its the pressure seal for reverse? Is it possible the transmission will continue working as it does now for a long time or am I looking at short term failure. I drive the vehicle occasionally probably 2000 miles a year for camping/fishing etc. Thanks in advance for your expertise.

1 Reply

PEAR69

MECHANIC
1,482 POSTS

There is no way to tell when this pieces of metal entered the pan. The reverse seal only applies force when the tranny is in reverse. Yes, the tranny will continue to function normaly in forward, but this seal will eventually either cause you to be stuck in reverse or no reverse at all. Considering that the tranny has been acting like there was a problem with reverse for several years, it is likely that the problem occured at that point in time and the pieces of metal were riding around in the pan for a few years now.