Hey fellas,

I was installing my nerf bars over christmas and noticed that my output shaft of my transmission is wet. It appears that the rear tranny seal is leaking, is that normal for the alli? oh by the way I only have 11,000 miles on her.

Not normal for 11k on the clock. I would take it in and let the stealer fix it.

has anyone else had this problem?

has anyone else had this problem?

2WD or 4WD?

If 4WD its the T-case seal. This seal is different from the 2WD output seal on the back of the Alli.

It happened to me. Very slow leak that accumulated near the back of the pan. The dealer fixed it. I didn't understand exactly what they did but it did require parts that took about a week to order from Allison. Hope your fix is faster.

has anyone else had this problem?

Mine is the same :mad:

my leak is coming from the output shaft by the rear drive shaft.

If it is driver's side rear, may be from the vent on top of trans. Seeing a number of them in the cold climates and the word from the General is to drill a small hole in the dipstick tube just below the rubber seal on the stick. Again I know this applies in cold climates and not sure if it would apply across the board. Can chk. in the new year when I go back to work.

To chk. the vent you will need a mirror and a flashlight. Driver's side rear straight up from the shift cable.

Hope this helps.

its been pretty cold (-5 last night) here in new mexico the past couple weeks. I'm going to run it by the dealer tonight and have them take a look at it. How long should it take for them to replace the rear output shaft (if thats the problem)? I need my girl back to haul some coal.

its been pretty cold (-5 last night) here in new mexico the past couple weeks. I'm going to run it by the dealer tonight and have them take a look at it. How long should it take for them to replace the rear output shaft (if thats the problem)? I need my girl back to haul some coal.

Since your truck is 4WD, its the T-Case output seal. I have heard there have been problems with these leaking. Its not part of the Allison though, as the T-case bolts up to the Allison trans with a gasket. This puts the rear output shaft,seal, and yoke a good distance behind the transmission and its vent.

i called the dealer yesterday and they said to bring it in next week. I'll keep you posted.

Mine's getting the new output seal today. The leak covered the ABS module in fluid. Pretty painless aside from having to wait a day for the part.

Got my truck back today and it was the out put shaft seal for the t-case.

Not sure what year yours is but I have an older one and the yoke that is on the rear of the tranny / driveshaft yoke that is the slip yoke is made in two pieces the Y or the piece that the U-joints are mounted to then the piece that slides into the transmission. I had mine replaced about 33 thousand miles ago then it started leaking again.......I just took the u joints off, welded the seam at the center of the yoke put on new u-joint then slid her back into the transmission. The man at the Chevy Dealer told me it is a poor design.....I believe it! They actually press these things together and expect them to hold oil? Anyway, waiting to see how the weld does.

So far I haven't had any issues since (knock on wood) but ill keep you posted as well. Im sitting right now at 53k miles

I just noticed the rear seal of my T-case has a slow leak. I assume it should be covered under the powertrain warranty, so I will need to bring it in. It seems to me this should be an easy area to make reliable, but I guess not.

you're correct its under warranty... I also believe there was a tsb on this issue as well

Good to know. Thanks timoloco.

No problem