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 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.

 

[birdyhues]

You may want to consider adding a drain plug to you transmission pan or replacing the pan with one that has a drain plug. Makes it much less messy to service. Also you can just drain and fill the transmission to keep the fluid clean.

I like this idea. Will look into this for next time.

 

[birdyhues]

Just came back to report that a new transmission pan gasket and several attempts at getting the hard-to-reach bolts tight enough did the trick. Thank you all for helping. @KDizzle, did rou figure out what was going on with yours?

 

[KDizzle]

Just came back to report that a new transmission pan gasket and several attempts at getting the hard-to-reach bolts tight enough did the trick. Thank you all for helping. @KDizzle, did rou figure out what was going on with yours?

Yessir! Turned out the selector shaft was indeed damaged, thus allowing tranny fluid to pass underneath seal. Ordered a used one online and that took care of it, in addition to a new pan gasket and shaft seal. I guess the “caveman” came out in the removal of original selector shaft. Hah!

Glad all is well with yours!