2001 Yukon transmission extension housing leaking ATF

[Jon Abbondanza]

Hello,

I have a 2001 Yukon with the 4L60E transmission.

I was wondering if anyone has ever encountered the leak in the picture. It is occurring where the transfer case mates with the transmission extension housing. I just replaced the transmission, and I put a new gasket between the Trans extension housing and TC when re-installing. I've checked all the nuts for tightness and they are all extremely tight on the studs.

It looks like the gasket is not doing it's job, perhaps it tore on installation? It was made out of paper.

Also, why would ATF be in that extension and continually flow? When I had removed the transfer case, I did not notice a large amount of ATF in that location. Should ATF fill that extension housing? Isn't that what the rear trans shaft seal is supposed to prevent?

I'd appreciate any advice or experiences anyone could lend on this.

Thanks!

 

[afpj]

What was the torque spec for those bolts on the transmission tail? I don't recall they are high torque items, especially with a paper gasket. Also, I cannot recall if that surface required gasket AND sealant, or just gasket...I'm pretty sure it didn't have sealant from the factory, like the oil pan, but afterwards some places (like the corners of the oil pan) sealant is needed since we don't have the same alignment stuff the factory does. Also you mentioned shaft seal..was it replaced? Just putting it out there as a starter...much more knowledgeable folks may chime in after the weekend

 

[Jon Abbondanza]

Thanks for the reply. The nuts are torqued pretty heavily, so I'm confident that is not the issue. I did not change the rear seal on the trans rear shaft, so that could potentially be the problem.

The problem may be that I did not replace an o ring in addition to the gasket. I am trying to determine if my application needs a gasket AND an O RING...

Again, any knowledge would be appreciated

 

[Rocket Man]

There isn’t supposed to be any fluid coming out of the back of the trans, the rear shaft seal should prevent that. That gasket is just paper because it’s more of an isolators than a gasket. If fluid is coming out of there, it’s because your trans is leaking out the rear seal. Is it a rebuilt trans?

 

[Jon Abbondanza]

no not rebuilt, it was a used one from the yard..it shifts great, and the fluid was bright red.

In retrospect, I should have changed the seals.

I will replace the rear one this week, as well as installing the extension housing o-ring which I found out is required.

O-ring is here: https://www.summitracing.com/parts/ado-1358899/applications/year/2001/make/gmc

At least I don't have to remove the transmission again.

Thanks for the reply.

 

[NoReverseYukon]

Yes, you should have an O-ring in addition to the gasket.

 

[Jon Abbondanza]

So I found out that the o-ring is behind the housing between it and the transmission. So it pretty much is the trans rear seal that is the culprit I guess.

 

[NoReverseYukon]

Since you will be removing the transfer case to install the o-ring, change the seal. If there was fluid in there, the seal is bad.
The ATSG rebuild manuals only say to lube the o-ring with Transgel.

 

[Rocket Man]

So I found out that the o-ring is behind the housing between it and the transmission. So it pretty much is the trans rear seal that is the culprit I guess.

Yessir.

 

[rockola1971]

Your rear tranny seal is leaking and pressurizing the extension housing or the Tcase input shaft seal is leaking. There should be no fluid in the extension housing.