1986 Automatic Transmission Leak

[ChuckN]

I’ll just chime in to recommend the Moroso steel core silicone gasket that @edgephoto mentioned. I bought one and it’s the bees knees.

 

[NickTransmissions]

Heres another guess as to what that "rivet" could be from. Possibly somebody in the past used it for their valve body mod, plugging the hole in the 1-2 bore of the valve body, like most shift kits say to do to hold 1st gear at any RPM. Just a guess based on the size.

Yep, that is also a good possibility. Looks like its the right size. Either that location or the throttle plunger sleeve. Plugging one of those holes allows for WOT 3-4 upshifts.

 

[KDizzle]

You dont need the tool if the pan is already off. Just take loose the 15mm selector shaft to rooster comb nut with a 15mm wrench, tap the rooster comb towards the valve body, pry the band style spacer off the selector shaft with a flat blade screw driver then withdraw the shaft. Then remove the seal with a small pry bar. Install the new seal with a hammer and 15mm deep socket (9/16 will also work). Make sure it's as square in the bore as possible before you pound it in or you'll bend/break it.

After two new seals and going through 24 quarts of transmission fluid, still leaking from

You dont need the tool if the pan is already off. Just take loose the 15mm selector shaft to rooster comb nut with a 15mm wrench, tap the rooster comb towards the valve body, pry the band style spacer off the selector shaft with a flat blade screw driver then withdraw the shaft. Then remove the seal with a small pry bar. Install the new seal with a hammer and 15mm deep socket (9/16 will also work). Make sure it's as square in the bore as possible before you pound it in or you'll bend/break it.

After 2 new seals and about 24qrts of tanny fluid, still leaking. Possibly damaged new seals during install…hard to properly set the seals with exhaust pipe in the way. Or I’ve damaged selector shaft. It’s got a couple of small gashes from a flat head that may be allowing fluid past seal…very small gashes, though. Also, I guess I’ve damaged pan gasket after removing and reinstalling several times. Can’t win for losing. Anyways, thanks for all the assistance. When I figure out the solution, I’ll be sure to post.

 

[KDizzle]

Heres another guess as to what that "rivet" could be from. Possibly somebody in the past used it for their valve body mod, plugging the hole in the 1-2 bore of the valve body, like most shift kits say to do to hold 1st gear at any RPM. Just a guess based on the size.

Thanks for the guess, better than what I can come up with.

 

[Frankenchevy]

Thanks for the guess, better than what I can come up with.

I guess they may be right if it suddenly stopped shifting like it has a shift kit in it…but I know next to nothing about automatic transmissions beyond basic anatomy.