My T-case is leaking down my rear driveshaft making one hell of a mess under my truck. Not to mention dumping all my fluid to help burn it up. I replaced the rear dust seal twice (yeah I had a jackass moment before I figured out it was just a "DUST" seal) and also have checked the vent tube that runs up firewall. The output shaft inside the housing isn't loose and the housing isn't leaking where it bolts to the case. So I figured its obviously coming from inside. I printed a breakdown off of drivetrain.com and the only seal I can see is labeled as an oil pump seal so I guess that's what I need to change? Has anyone done this? What r yur thoughts? Am I on the right track? Can I do this while the t-case is still in the truck? Thanks in advance and any help or tips would be greatly appreciated.

 

Those T-cases can be a bugger to stop leaking. They seem to eat seals. And it is the output shaft seal too. As you've noticed, the dust cover is only a dust cover. I've had to change my seal once and then it was clean for about 20,000 miles but its leaking again. I understand that there's other reasons why it can leak, like a leaking plug on the output yoke, or the yoke bushing is worn. If yours is 2wd then there is a rubber seal behind the yoke bolt that could be leaking.

 

Seems to me, The output seal was also the dust seal. It was all one piece and sealed against the slip yoke.

Have you check to make sure the slip yoke is smooth and doesn't have a bunch of burrs and hard crusted on dirt that tears that seal up, or a groove worn into it from the seal?

 

KATOOM: Its a 4Wd and it has an output splined output shaft that the driveshafts slip yoke slides onto. Maybe the bushing is worn in there? Does it seal the fluid? Or am I not following??


kazairl: The seal looked like it only had one lip on it and it rides on the slip yoke. The rubber part of the seal is roughly 2" out from the metal part that drives into the housing and has a hole molded into it from the factory just as the one that was originally leaking and the 2 ive put in since do. Thats why Its not making sense to me that there would be fluid up to this point. Wouldnt it just run out that hole? even if you installed it on top wouldnt it still sling out? I have checked the slip yoke twice, it was clean when i pulled it, but I still took some super fine grit and "dusted" it VERY LIGHTLY to make sure I didnt change the size. I cleaned it afterwards to make sure there wasnt any metal dust. There were no visible grooves and I couldnt catch a nail on it.

Thank you both for your responses.

 

Ok So I found a seal off my old 241 DHD. The lip that extends out is indeed the dust seal. However, if you look at the other end of the seal there is a lip seal on the inside that rides directly on the slip yoke. This is what keeps the oil in. Or is supposed to.

I converted mine to a 271 and run a flanged output so I don't have to worry about leaks.

 

This is right. There's dust seal and a oil seal. As I mentioned before, I've read many threads where guys just cant get theirs to stop leaking and it sounded more like a seal problem or possibly installation error.

I also converted a T-case but it was a NP205. Worked great and if I remember right, there was enough depth where the seal went that I was able to install two seals back to back.

 

the bushing on the end of the output shaft housing wear causing this to happen as well. Mine was doing this for a while and thats what took care of the problem and the internal oil seal.

 

Forgot about that^. It would be a good idea to buy a new bushing and replace that. If it is worn it will allow the slip yoke to wobble around and cause leaks.

 

This is true but the wobble would have to be substantial, and the designed clearance already gives it a "loose" feel which could be construed as bad. With that said, its not something I'd look past if you just couldnt get seals to last very long.

 

I will definitely look into all of these when I tear it down to look into it. I really appreciate all of the responses and the great info