I have a leak coming from the secondary pump. The small unit on the righthand
side toward the back of trans.

The leak is from a seal that is behind the cup that is retained by a circlip.
So my question is can I remove the circlip and cup to replace the seal with
the trans in place? Photo of assembly attached.

Thanks

Attached Thumbnails

 

I have a leak in the same area. Once I decided to do something about it, and replace whatever seals are replacable in that area. All I could find at usual online parts places at the time was a large o-ring that goes right behind the cup shown in your photo

I managed to replace the o-ring without lowering the tranny on my '81 SD -- it's a tight spot, but it's doable (be careful with that small hex nut on the side -- it's got a plastic seal inside). The leak remains, unfortunately, so there's more to this than just this o-ring (I am positive that it's coming from the secondary pump area).

I was just checking out AT seals at Fastlane, and see another seal now that's also for the secondary pump, Fastlane PN J5070-74119:

I remember that seal being inside the pump when I was messing with it, around the pump piston I think. So this could be worth a shot.

Apart from those two, no other seals are sold individually by usual online retailers. There's an "overhaul kit", which claims to have all seals in the tranny, but it's pricey, and to be usable likely requires a detail AT manual which I lack.

Anyone else has advice on what seals to replace???

How did this shake out in the end? I have the same leak.