Need help sealing Transfer Case to Transmission

[YukonRog]

Okay so I've discovered the terrible design of the 4L60E tailshaft when mating to a Transfer Case Adapter. There is no external seal on the transmission so the adapter "tunnel" fills with ATF. I've been scouring the internet and found others with the same problem. There is some discussion of a "grey silicone". I don't believe it's RTV. Can anyone tell me what it is? Mine actually had some on it when a remanufactured transmission was installed! I have some Permatex Transmission Sealer that's supposed to be impervious to ATF. Should I use that? I am actually considering tapping a small hole in the bottom of the adapter so I can remove the plug and drain it once in a while! Need some advice please.

 

[randeez]

The Grey stuff works good, ive used to seal import trans cases back together a few times with no issues. The 6l80/4l80 use a paper gasket between the two.

eerrr maybe i misunderstood? youre trying to keep fluid from getting into the adapter from the transmission? its sposed to do that i think , it sucks and im not sure what, if anything, will happen plugging it up at the back of the transmission

 

[exp500]

Two seperate issues. Tailshaft seal leaking, replace seal while Tcase out. For gasket sealant- Try Motoseal and put on very thin with a roller or similar.
If the adapter fills up, it will push into Tcase, not good.

 

[YukonRog]

There is no seal to replace on the transmission output shaft. From what I've been reading, it's designed that way. They all fill with ATF! Doesn't make any sense to me. Is there a drain hole maybe I'm not seeing where it can drain back into the pan? Here's the interesting thing, the transfer case case side had the grey stuff on it and it just popped off. The other side of the gasket where it meets the adapter has nothing, and I can't get it off! Stupid design. Maybe it's to relieve pressure?

 

[exp500]

Two choices-https://www.rockauto.com/en/moreinfo.php?pk=1839182&cc=1412244&pt=8636

More Information for GM GENUINE 8677268

Buy a factory manual and save yourself some headaches.

 

[swathdiver]

My memory isn't the greatest but I think this area is supposed to be dry and only becomes fluid filled when one or the other seal fails. Precision Transmission's youtube videos talk about this relationship as does the shop manual.

 

[mpope2]

There is a large o ring if I remember correctly that goes in the extension housing. Other than that, there is a paper gasket between the t case and transmission extension housing. There is no need for any type of silicone/RTV

 

[OR VietVet]

@rockola1971 may chime in with suggestions but make sure to check as many you tube videos as you can, like the one @swathdiver suggested.

 

[swathdiver]

@rockola1971 may chime in with suggestions but make sure to check as many you tube videos as you can, like the one @swathdiver suggested.

 

[OR VietVet]

Exactly why they are Transmission Specialists.

 

[YukonRog]

My memory isn't the greatest but I think this area is supposed to be dry and only becomes fluid filled when one or the other seal fails. Precision Transmission's youtube videos talk about this relationship as does the shop manual.

Yeah I've watched a lot of videos lately. Like that guy Richard. Is he ill or retired now? How about a photo of that page from your manual buddy?

 

[swathdiver]

Yeah I've watched a lot of videos lately. Like that guy Richard. Is he ill or retired now? How about a photo of that page from your manual buddy?

Richard is around. He was off for surgery and a vacation but he's back to work.

No difference between tail adapters, same o-ring and seal.

 

[YukonRog]

Richard is around. He was off for surgery and a vacation but he's back to work.

View attachment 349825

No difference between tail adapters, same o-ring and seal.

Hey Thanks! Glad to hear he's okay. He's a good ol boy. And I like pictures. Kinda what I expected though. Poor design in my mind. I believe they put a seal in with a snap ring on the 6L80E?

 

[swathdiver]

I believe they put a seal in with a snap ring on the 6L80E?

I don't recall.

 

[swathdiver]

Hey Thanks! Glad to hear he's okay. He's a good ol boy. And I like pictures. Kinda what I expected though. Poor design in my mind. I believe they put a seal in with a snap ring on the 6L80E?

About 72 seconds in have a look.

 

[YukonRog]

About 72 seconds in have a look

Pretty funny, I just watched that video a couple hours ago! This is not a great photo, but it shows the snap ring holding the seal in a 6L80E. Waay better idea.

 

[YukonRog]

So just going over some things, I found this write up and I believe there's a typo at the end where he recommends the ATF fluid type. It says Dexron III, or IV. Shouldn't it be VI? What do you think?

https://www.thedieselpage.com/reviews/tcase.htm

 

[OR VietVet]

So just going over some things, I found this write up and I believe there's a typo at the end where he recommends the ATF fluid type. It says Dexron III, or IV. Shouldn't it be VI? What do you think?

https://www.thedieselpage.com/reviews/tcase.htm

If the write up is old enough, maybe Dexron VI was not out yet. I used Dexron VI and it covers all the preceded it.

 

[Fless]

If you have the NVG246 transfer case it takes Auto Trak II fluid. Your owner's manual should list what it takes.

 

[YukonRog]

If the write up is old enough, maybe Dexron VI was not out yet. I used Dexron VI and it covers all the preceded it.

Yes Sir, I found this (attached) so it was correct I guess. For a time, you could use IV. I saw it as a typo for VI. Which is backwards compatible.

Dexron IV was an upgraded version of Dexron III, which was used by GM only briefly. ... It is also the specified ATF in certain non-GM models that use GM transmissions, such as BMW.