2002 Yukon XL Denali Transfer Case Leak

[Tatonka]

I need some advice on where to look or what to fix on my 2002 Yukon XL Denali transfer case. I purchased the Yukon back in October 2019 it has about 180K miles but has been a 3 owner truck and not abused. I have been slowly going through things and fixing various issues. About a week and a half ago I decided to change the transfer case fluid as I was hearing a faint whine at interstate speeds. The fluid was low but I filled it back up with the 2 quarts and the whine went away the truck was riding like a new one.

A day or two later I noticed fluid on the ground and at first thought that I might have over filled the T-case. So I watched for a couple of more days, I checked the fluid level last Friday and it was way down. I refilled and took brake cleaner and cleaned everything under the truck looking for the leak. I finally narrowed it down to the Transfer Case rear output shaft seal. At first I thought it could be the dreaded pump rub but the case was dry at all the pump rub points and only the output shaft was wet.

So after watching countless YouTube videos, yesterday I pulled the drive shaft and replaced the rear seal with one from AutoZone. It was not that hard of a job but after driving a few miles I checked it and I still had the same leak. I went and got a new rear seal this time from Oreilly's that was specifically for an AWD GM transfer case. I came back and redid the entire job, this time it went a lot faster but again the rear shaft is still leaking. Not as bad as before I started but it still leaking.

Anyone have any advice on what to do next?

 

[OR VietVet]

What did the yoke sleeve look like that slid back in the seal? If that surface is fouled up it will not seal. They make repair sleeves for that problem but I hate them. New part for sure if is not in pristine surface condition. Plus, you should make sure to add grease to the seal contact surface, where the seal rides on the sleeve, that protects the seal surface when you reinstall the shaft. How did you install the seal? Use a seal driver to install straight in or tapped in with a small hammer around in a circle? Should use the installer tool if you have one or can get one.

You got lucky on the transfer case pump rub problem.

 

[Tatonka]

What did the yoke sleeve look like that slid back in the seal? If that surface is fouled up it will not seal. They make repair sleeves for that problem but I hate them. New part for sure if is not in pristine surface condition. Plus, you should make sure to add grease to the seal contact surface, where the seal rides on the sleeve, that protects the seal surface when you reinstall the shaft. How did you install the seal? Use a seal driver to install straight in or tapped in with a small hammer around in a circle? Should use the installer tool if you have one or can get one.

You got lucky on the transfer case pump rub problem.

I looked over the yoke sleeve and did not see anything that looked to be a problem, the surface was clean with no nicks, grooves or even dirt. The sleeve lined up and slid back in without any issue both times. I did not add any grease to the sleeve surface, all I did was wipe a little motor oil on the seal side in contact with the case itself. I was wondering if any gasket sealer could be used between the case and the seal?

I reinstalled the seal with a "Vegetable Can" believe it or not. One of the videos on YouTube showed how that was the perfect size for the seal. None of the auto parts store close had a seal driver. After installing the seal I did go back with a small punch and tap all the way around the seal.

Since it looks like I am going to have to pull it all apart again, how much grease should I put on the shaft? Do you know if the seal could be taken off and used again?

 

[OR VietVet]

New seal, never reuse a seal, IMO. Just a thin film of grease on the seal surface and a thin film on the sleeve. You can even clean the seal seat area dry and use grease there as well to help with the seal install. Install with a vegetable can? I would not but you do what you are going to do. Call parts stores about a tool rental for that. Get a good quality seal as well. I am not a fan of National seal seals. Others here will disagree. I like this one: https://www.rockauto.com/en/moreinfo.php?pk=2473008&cc=1381069&jsn=3450 or this one: https://www.rockauto.com/en/moreinfo.php?pk=1842238&cc=1381069&jsn=3453

 

[Tatonka]

New seal, never reuse a seal, IMO. Just a thin film of grease on the seal surface and a thin film on the sleeve. You can even clean the seal seat area dry and use grease there as well to help with the seal install. Install with a vegetable can? I would not but you do what you are going to do. Call parts stores about a tool rental for that. Get a good quality seal as well. I am not a fan of National seal seals. Others here will disagree. I like this one: https://www.rockauto.com/en/moreinfo.php?pk=2473008&cc=1381069&jsn=3450 or this one: https://www.rockauto.com/en/moreinfo.php?pk=1842238&cc=1381069&jsn=3453

Thanks for the info. I guess I know my project for tomorrow. Buying a new seal and pulling the driver shaft one more time!

Here is the video

that shows how to use the can as a seal driver. It was not what I really wanted to do but it was better than trying to tap it on with a hammer.

 

[OR VietVet]

Did you check that leak area on your yoke? Long time since I have paid attention to that area. The alcohol is a good fluid to check with.

 

[Tatonka]

Did you check that leak area on your yoke? Long time since I have paid attention to that area. The alcohol is a good fluid to check with.

That area is not wet. But I have planned to try to seal it over.

When you see the fluid from the leak it is on the end of the transfer case. There is no evidence that fluid is getting slung from the yoke.

 

[OR VietVet]

That seal driver idea works pretty good and most auto parts stores will not have the seal driver for that. I always used to use a big socket. Either way it should be driven in even and not taped in with a flat punch in a circle. You can also use a thin film of sealer around the metal edge of the seal instead of grease. Let sit and cure before road test.

 

[Tatonka]

That seal driver idea works pretty good and most auto parts stores will not have the seal driver for that. I always used to use a big socket. Either way it should be driven in even and not taped in with a flat punch in a circle. You can also use a thin film of sealer around the metal edge of the seal instead of grease. Let sit and cure before road test.

Thanks for the advice. i will let you know how it goes

 

[Tatonka]

OK it has been a while but I finally figured out where the leak was....

It was actually the dreaded transfer case pump rub and not the rear seal. BUT, the leak was not coming from the side but directly on top of the transfer case. For now the temporary fix has been to clean the area with brake cleaner and JB Weld the area. So far it has held over 1,000 miles, fingers crossed it will hold longer.

I went over and above the JB Weld directions, after cleaning the area I lightly sanded the area cleaned it again, I let it dry for an hour, then used the JB Weld. I let the truck sit over night, and then added a second coating to the area and let that sit over night. I was not exactly what I wanted to do but right now with the way money is it was the best I could do.

Another tip I want to pass a long. When tapping in the rear shaft seal I could not find a seal press at any of the local auto parts stores. A YouTube video suggested a soup can, while this did work it was not the best way I found. I dug through my tool box and found an old oil filter socket. It spilled right over the seal and with the beveled edge I was not worried about it cutting or ripping the seal.

I hope this helps anyone else that has a transfer case leak