Transmission Fluid Leak

[Thornton93]

Hello, '87 v10 700R4 NP208. I have a leak coming from my slip yoke and for the life of me can't figure why or how it's leaking. Already replaced output shaft seal and still leaks. Plain as day can see it's coming from middle of slip yoke. Any help would be appreciated.
Thank you!

 

[yevgenievich]

There is a hole in the middle of the yoke on some models for venting and another seal internally. Generally I have seen it to be fine to eliminate the other seal and the hole in the middle of the yoke. It is also possible that the cover closing the hole simply is leaking if it is a sealed yoke model.

 

[74 Shortbed]

Probably needs a new O-ring, or just plug the hole with JB Weld..

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[ripandtear]

leaking yoke

I noticed after changing almost every seal on my D train that I had a bit of ATF leaking from my YOKE not the tail shaft seal but from the center of my yoke. So I stick my finger in there and there is not weep hole or anything in there. After much research and learning. I pulled it back off and popped the Ujoint apart cleaned it up and it was obvious that at some time there was something pressed into the hole. After much research and pondering I slapped on my JackofALLTrades Hat and welded a washer over the hole and then welded a bolt (short bolt) into the hole. No problems since.

 

[74 Shortbed]

That's one way of doing it..

 

[HotRodPC]

Seems you have your answer already.

One other tidbit. What can happen is, the old seal becomes very hard and can cut a small groove in the yoke. In this case, replacing the seal won't fix the leak. It's more common on the front seal though and the groove is cut into the snout of the torque converter. The fix is after replacing the front seal, put a washer in between the flywheel the bolt lugs so the snout is riding on a differnt part of the seal and pushing the converter a bit further into the transmission.

Being a 4x4, you don't have a 2 piece driveshaft but in the event it is the rear seal and has cut a groove into the yoke, you can sometimes have enough slip at the carrier bearing to move the driveshaft further into the tailshaft and the yoke is now riding on a different spot of the rear seal.

 

[Honky Kong jr]

Or the bushing ***** the bet and the slip part doesn't sit square and pulls down on the lip and and oblongs the seal