Transmission Leak Help

[64tantruck]

I believe I have found my tranny leak on my 64 (TH350) tranny. Looks to be leaking at the speedo cable area. Is there a seal in the cable area that can go bad? Does the cable it self leak fluid?
Cable is pretty cheap thru LMC approx $17.00, wasnt sure if there were any O rings in that area etc...

Thanks,
Glenn

[Chevy Fleetside]

I got this from another forum but I kinda knew it anyway..

From under the car check to see if
The retainer which holds speedometer cable to the transmission has an "O" ring which is probably leaking... If this is where the problem is it is an easy fix......
Remove retainer, 1 bolt, and slowly pull on cable to remove retainer.
There should be an "O" ring, or a grove for one, near the outside of the retainer.
Replace and reinstall....clean area around and watch for leaks.
No, you don't have to remove transmission to replace this "O" ring.....
Good luck

[64tantruck]

Thanks Chevy fleetside. So the speedo cable doesnt leak itself, just the o ring behind it. I did remove that bolt, (7/16) pulled it out and started to get a face full of fluid. Ill check tonight that O ring. I assume, local parts shop would have one I can match up to.

[tincan1966]

There is also a smal o-ring inside the speedo adapter. When you pull the speedo gear out of the trans, the gear will slide out of the adapter. Inside there is a small oring-these are known to become brittle and leak, also.If memory serves, most auto parts places will have a "speedo drive seal kit"

[Tx Firefighter]

Originally Posted by tincan1966

There is also a smal o-ring inside the speedo adapter. When you pull the speedo gear out of the trans, the gear will slide out of the adapter. Inside there is a small oring-these are known to become brittle and leak, also.If memory serves, most auto parts places will have a "speedo drive seal kit"

It's actually a lip seal. The lip seal goes inside the gear housing and keeps the fluid from leaking around the gear. Then there is an o ring around the housing that seals between the housing and the case.

It's best to shotgun this repair. The gear is plastic and gets worn. The housing gets worn too. A new gear and housing will solve it once and for all. The new housing will come with the seal and o ring included.

Also, support the cable with a clamp on the frame if not already set up like that to keep it from hanging and bouncing under the truck. That wears the gear and seal quickly.
Posted via Mobile Device

[tincan1966]

Originally Posted by Tx Firefighter

It's actually a lip seal. The lip seal goes inside the gear housing and keeps the fluid from leaking around the gear. Then there is an o ring around the housing that seals between the housing and the case.

It's best to shotgun this repair. The gear is plastic and gets worn. The housing gets worn too. A new gear and housing will solve it once and for all. The new housing will come with the seal and o ring included.

Also, support the cable with a clamp on the frame if not already set up like that to keep it from hanging and bouncing under the truck. That wears the gear and seal quickly.
Posted via Mobile Device

thank you for correcting that, I knew "o-ring" was wrong.....

[Tx Firefighter]

It's all good. A lip seal is like your wheel bearing seals or front seal on the engine. It has a hard outer circumference with a tapered wedge shaped seal on the inside.
Posted via Mobile Device

[64tantruck]

Thanks to all for the info. Went to both AutoZone and Advance with no luck. Ended up stopping at TruValue and poked thru the rubber O ring parts and found a Kohler 63-12789 part number fits perfect, infact a little snug, but no leaks. Will check tomorrow after work, as I left some fresh cardboard under the truck. I also took the advise to secure the speedo cable to the frame.
Thanks Again,
Glenn