T90 leak found. Please give advise...

I degreased and pressure washed the tranny. Filled it up and drove it. Major leak found coming from the "tubes" on the top that the "shift slides, or rails" ride in. Can this be fixed, or do I need to rebuild or replace the tranny. I'm trying to do this as inexpensively as possible. Here's the pics...

 

see Rick Stivers guide to rebuild the T90. He made a plate to cover the shift rails. I do believe there is more info elsewhere on the net about this.

Paul


http://www.willystech.com/wt/T90RebuildGuide/T90rebuild.htm

 

Dennis,

The good news? You don't have to rebuild the tranny.....

This pics shows a cap I made from a piece of aluminum stock. And can be done with just the shift tower off the tranny.....


The trick is to get the surface of the shift tower flat enough to form a good seal. It will fit in a mill for a quick surfacing, so if you know a machine shop have them do it. Also have them drill and tap a 1/4-20 hole between the shift rail holes to allow you to bolt the cap on the ends. And while you have the tower off and at the machine shop, I'd suggest having them doing BOTH ends. (ask how I know... )

Now the bad news....you have to disassemble the shift tower to grind a "oil return groove" in the bottom of the shift rails. On mine, the end with the metal "plugs" had an oil return groove in the tower casting itself, but not on the other end. (The groove is to ensure that you don't hydrolock while shifting.) You will need to grind this groove into the bottom of the shift rail. I used a Dremel tool to accomplish this, so it's not terrible to do.

The Rick Stiver's guide has a section on the shift tower. Most difficult part was the %&#@+$ spring that pushes against the shifter "ball"....

Let us know if you need more help...

 

So there was / is supposed to be caps on this? I wonder what happened to the originals??

 

There is only 1 cap out of the 4. I will put everything back together so I can drive it. I go on vacation at the end of June. I'll take care of it then. Thanks for the help guys

 

I bought my caps from Walck's. The caps fit in the front end. The rear holes are smaller. I think originally the front were the only ones that were capped (according to the pics in the manuals I have) .

642757 Cap, shift rail $0.95

http://www.walcks4wd.com/cj5/cj5_01.html#transfer

 

My 2 intact caps leaked. I ended up putting plates fore and aft to keep it from leaking. FWIW, If yer gonna pull the tower, cap both ends off with the plates.... my $.02

 

I plan on it Thad. If there are caps already, do I still need to journal the inside if I put a plate in? I'll do it, but not real clear why...

 

On the front end of my T90, there were recesses for the caps. These had return grooves machined into the casting from the factory. This isn't the end you need to worry about. Plate it and it'll be fine.

However, the rear of my T90 didn't have caps, nor were there recesses for any. The factory did nothing to prevent oil coming out these holes. Also, there are no return grooves in the rear end of the tower. If you simply plate it off, the theory is that oil will build up inside the holes, and eventually, you won't be able to get it into 1rst or 3rd gear. Also, if you simply hole-cap the rear holes off without grinding the return groove, the caps will eventually pop off, allowing the oil to do sully the underside of your Jeep. Grinding a return groove ensures that the oil will be able to drain back into the case.

Of course, your T90 may be different, so investigate first by looking inside the tower's shift rail holes to see for yourself.

For more in depth reading, check this link...
http://mvpimages.net/cgi-bin/willys...+T90&x=0&y=0&searchmethod=1&searchresults=500

The pic I linked to in the first post is no longer up, nor do I still have it, but the thread is worth reading.

HTH

 

Not trying to be picky, but don't the shift rods move to the rear in 2nd & R, not 1st & 3rd?

 

Yes they do. But I knew what he meant

 

Thanks Thad, I get the picture now. I'll talk to the few machine shops we have in Norwalk and see if they can help

 

Guess my lysdexia was acting up again....

 

http://www.earlycj5.com/forums/showthread.php?t=13431&highlight=T90+cap

Judging from your pictures, you have the early T90 shifter tower. Here's a side by side pic of the 2 different style of towers. you have the one on the left.
http://www.homestead.com/willyspickupfaq/files/BothTowers2.jpg

The older one is taller and heavier, and in my opinion, is the stronger of the two. the older one does not have caps stock in the rear, but does in the front, thus there are groves machined to prevent hydrolock only on the front end. The newer style tower has caps in both ends, thus groves machined in both ends as well. You can see in the pic the recesses cut into the rear shift rails for caps on the later version.

When rebuilding my T90, I had the choice of going with either tower. While it was more work to file the groves in the rear of the earlier tower and capping the ends (as opposed to just capping the ends on the later tower) I spent the time on the earlier tower cus i think it is the stronger of the two.

 

What I have not seen anyone mention.....

What I have heard happens is the tranny gets overfilled, then you go four wheeling up and down hills...... the overfill causes oil to build up in the shift rail tubes, then when you shift the end plugs get pushed out and PRESTO, leak. My T90 had this leak when I got it. Bought the caps, put them in, made sure the level was right and never had another problem. Switched to a T18 about a year later.

My point is the caps are cheap, buy enough to fix yours, plus a spare or 2. Put em in and check the oil level and evaluate, you may find the problem is fixed, quick and easy!

 

In theory, going up and down hills shouldn't matter anymore than when you are driving on flat land. either way oil will work it's way toward the caps. As long as the caps are well sealed (adding the plate to the caps as mentioned above definetly helps to seal) then the groves machined in the tower will be the easist route for the oil to flow. no groves (or a clogged grove), and the oil will want to pop a cap off when shifted. But when a clear grove exists, the oil will be forced through that grove and back into the transmission.

The most common leak on the T90 when going down a steep grade is out of the front bearing. The stock bearing is of an open design, and while the retainer is there, it is easily overwhelmed by a steep enough decline. And when yhat happens, you run a risk of oil getting on your clutch and pressure plate. not good. that is why I ran a sealed bearing on the front of my T90 as opposed to the stock open bearing. The only modification that has to be done is to seal the oil return passage, cus with a sealed bearing, oil will not get out, thus no need for it to return. Plus if you don't seal it, this will be your source of a leak. No sealed bearing is used on the rear of the T90, as it shares oil with the dana 18.