T-90 Countershaft Leak - How to stop?

[Ryan_M]

Well I said I wasn't going to rip the transmission out yet again to chase a small leak...but I really had nothing else to work on and it was driving me crazy...so for the fifth time I pulled the tranny to chase a gremlin. The leak is coming from the countershaft on the front of the transmission. It seems this is a fairly common problem but what's the best way to deal with it? I had squirted a little bit of blue sealant (permatex, maybe?) when I rebuilt the transmission a few months back but apparently it that wasn't the best choice. Do I just need to use more of it? Or different stuff completely? Any suggestions? I peeled some of it away before taking this pic.

[athawk11]

Ryan,
I am leaking out the front of my T90 also.  Not sure if mine is leaking in the same place as yours, but when I get around to pulling it, hopefully you will have had success...and will share what you came up with.

You have pulled it 5 times?  Is your tub on?  If it is, please share the steps you are taking to get your T90 out.  I am not looking forward to this.  

Tim

[Ryan_M]

Ryan,
I am leaking out the front of my T90 also. �Not sure if mine is leaking in the same place as yours, but when I get around to pulling it, hopefully you will have had success...and will share what you came up with.

You have pulled it 5 times? �Is your tub on? �If it is, please share the steps you are taking to get your T90 out. �I am not looking forward to this. �

Tim

Hey Tim - I figured you'd respond. When I was whining awhile back about how far I should go chasing leaks you replied. Then, shortly after, I saw your post about your transmission leaking in the same spot. I was hoping you would have fixed yours first so then I could have stolen your solution. Get on it, would ya?? Luckily for me, the tub is off so taking the transmission out is a relatively simple. If I have to do it once the tub is back on I think I'll throw in the towel and find a different hobby.

[Macgraham]

My shaft hasn't leaked yet but it hasn't run yet either. I used GM engine sealant # 12378521. A local machine shop swears by the stuff. If and when I have to pull the tranny again I think a guy could chamfer the end of the shaft and put a fat(but not too fat) Oring that would flatten up against the bell housing. Maybe just an Oring and some sealer would do it. Clean oil free surfaces though. Interested to hear the cure. Mac

[CJPilot]

I did a quick clean up and check of my transmission recently. �One of my main objectives is to stop or at least slow down any leaks. I have not mated it with the bell housing yet. I used some Hylomar Blue (it�s not blue silicon) around the counter shaft were it comes through the case. �I am planning on doing more to seal it but I haven�t made up my mind yet. �One thought was to use permatex sensor safe and apply it generously before mounting the transmission to the bell housing. �I�d also like to hear from somebody that has fixed this leak.

You might have a problem getting your transmission clean enough to get a sealer to stick now that it�s got gear oil on it.

Not to get to far off topic but did your main drive gear shaft have a rubber washer along with the felt washer (seal)? �My new gasket set did not include one. �I think I�ve seen a rubber washer mentioned in other posts


Steve

[Carls_jeep]

You could put a very thin coat of RTV on the front surface of the tranny surrounding the shaft opening. I do mean thin coat. Or, you could use #2 Permatex.

[CJPilot]

Carl , What is the reason to put a thin verses thick coating ? �

Steve

[Ryan_M]

Tonight I coated both the transmission and bell housing mating surfaces with a thin coat of Permatex 2, going a bit heavier over the countershaft indent. Bolted everything back together now we wait and see if any drops appear on the floor. The guys on the 2A forum suggested making a paper gasket. Maybe I'll try that next if the Permatex doesn't hold.

[Carls_jeep]

The reason for the thin coat of sealer in just the area of the shaft is a thick coat would be like putting a shim between the bell housing and tranny. The pressure from bolting the two together may break the ears off the tranny.

By covering the entire surface you spread the force over a wider area. All it takes is a thin coat of sealer between machined surfaces. Most people put to much sealer on and it shows as a bead around the joined parts. If it forms a bead on the outside it also forms a bead on the inside and that can cause problems is some instances.

[Ryan_M]

No bead squirting around the edges.. I spread it very thin except for filling in the countershaft hole roughly flush with the front of the transmission.

[Bob W]

Early 3As and prior used a gasket between the bellhousing and transmission but it was deemed unnecessary and was eliminated.

[CJPilot]

Bob, ��I do now remember reading that somewhere �;D. �I'd guess it must have been due to some bean counters thinking they were engineers.

Carl, �Thanks for the reply. �I don't usually put much gasket cement on anyway. �I do use permatex #2 quite often. I just figured out that the difference between permatex #2 and permatex #2A is the size of the tube, but hey I'm a slow learner. �My new favorite for mating surfaces is Hylomar Blue. I believe it was developed by Rolls Royce. Permatex recently picked up the distribution but it's still hard to find.

Steve

[Carls_jeep]

If you have a large area to put sealer on use a squeegee like the ones for putting on bondo. It will spread a thin coat if your careful.

[ventport]

Would spray on Copper Coat work?

[Carls_jeep]

Probably will. There are some other spray on sealers but it's still easy to put to much on, and very tempting I may add.