tranny leak

[woodman1]

My 63 seriesIIA has a tranny leak. It seems to be coming from the shift rails on top of the tranny. The tranny shifts good, I was wondering if anobody elae has had the same problem.

[gudjeon]

I've used o-rings, factory seals, and I have even heard of someone using slices of heater hose. I have never had much success at keeping oil from escaping here. Perhaps someone else has had better luck. Other makes of tranny with shifter rails made in a similar way all leak in a similar fashion.

I let mine weep away. But mine has the swing away tunnel and tranny dipstick, so its easy for me.

[Tim Smith]

I just did this on a transmission over the weekend. I am planning to make a writeup of the process but really, it's pretty simple.

• Just get some 5/8" heater hose
• Cut a slice off that is the same depth as the original seals
• Cut it in half (if you don't have the shifting rods out of the box so you can just slide them over the rods)
• Slide them onto the shifting rods and pack them back into the location of the originals with the cut facing up
• Pack it up and you should be done

The purpose of this fix is to replace the original seals with some soft rubbery ones. The heater hose fits the bill and it's cheap. You may have a hard time squeezing them home on the transmission but do your best and you should be fine. You will also experience hard shifting for a short while but as they wear in, the shifting should get easier.

[jac04]

^^ I tried the 5/8" heater hose, but I wasn't able to get it to fit into the recesses. I tried & tried, but it wasn't going to happen. I ended up using a piece of Subaru PCV hose that I had left over from a project. Now they leak just a little (although not as bad as the original seals, which let oil constantly flow down the sides of the gearbox). I'm going to be in there to re-do the detent seals, so I may give the selector shaft seals another shot with the heater hose.

[Tim Smith]

It is a tight squeeze for sure. If you were to loosen the top of the transmission, you should be able to slide them in. Then put the retaining clips on the front of the selector rods and then tighten down the top of the transmission again. Don't loosen the top up too much though unless you pulled the selector springs and balls out. Otherwise, you'll loose one inside.

I have to admit, I cheated and had the whole transmission out and the selector rods in my hands when I did it. So I didn't need to slice the hose in half either.

I also applied grease to the new seals and the exit holes of the selector rods which has probably helped with the tight shifting action. Being that this is my first time with this trick, I'll judge my method by the success. This transmission will only be run for a month as a test period and then I will pull it and put it up for sale.

By the way, it's a 1 ton transmission. Zoom zoom!

[jac04]

I have to admit, I cheated ...

Yeah you did!

Any tricks for keeping the detent seals from leaking?

[Tim Smith]

This is what it looks like when you cheat. Old ones on the left, new are installed on the rods.



As for the detent springs, I used a high vacuum grease. Not really going to make a positive seal but I expect it should keep the leakage down. Better than stock any way.

[jac04]

Tim-
How much of a PITA is it to pull the top cover off to install the shift rod seals without splitting them? Looks like it might be tough to get the cover to seal again since you don't want to get too much sealant around the shift rods and foul them. Then you also have to deal with the gasket at the back surface of the cover - what are the chances of that gasket NOT tearing? Just wondering if it's worth it or if I should just live with the nuisance leak from the shift rod seals.

Any recommendations for the shift rod seal retainers? They seem very flimsy & easy to bend. I wonder if making a thicker 'heavy duty' set would help keep the seals from leaking. Maybe I'll make up a set in my spare time (aka that time between 9pm and 6am).

[Tim Smith]

Well, getting the cover on and off shouldn't be too tough with the transmission in the truck. Of course you need the tunnel cover off and the center battery box out to get access to all the bolts (I think there are 6 in total). But if you cherish your gaskets, don't even think about doing this unless you have the transfer case off. The central studs are tight and you won't be able to slide the cover down along the rear facing gasket without crushing and ripping it. I would suggest pulling the studs but they are a really tight fit and I bet you would have some trouble getting them to thread home.

I'd say, don't try to pull the top but rather remove the four bolts on top that hold it down. Leave the other two on the back face but loosen them. With that, you should be able to get say 1/16" which really is all you need to shove them in.

Mind though, I haven't tied this myself. I cheated.

[jac04]

Thanks Tim. I may just leave it alone. I know what you mean about just breaking it free to get the seals in, but I bet I would never be able to get the cover sealed again. Right now (rebuilt trans as received from RN), the gasket at the back has RTV on it and the horizontal surface has Hylomar. If everything was Hylomar I'd give it a shot.

[Terrys]

I can't imagine why LR thought the ring seal around the side detent springs would seal up any oil leaking out the center of the spring. In the past I squeezed in a dab of RTV into the end of the spring with success.
It's almost a sure thing you'll tear the rear gasket taking off the cover, and I just cut it at the horizontal joint with a razor, and used a thin smear of Hylomar.
The only time I ever replaced the selector rod seals was when I did a total rebuild, and used new seals, un-slit. The compression plates are thin but looking at the top half, it didn't appear to bulge out at the center rod.
I sprayed carb cleaner into the center (top) detent hole and used a magnet to get the ball out, but even if it falls in, a flex magnet will usually find it ( and a bit of other metal debris too)

[jac04]

I can't imagine why LR thought the ring seal around the side detent springs would seal up any oil leaking out the center of the spring.

If the L-shaped retainer puts enough compression on the detent seals, then they *should* seal against any oil coming thru the center of the spring. Mine were loaded up with Hylomar and still leaked. When I removed them, it looked like one end of each seal was cut with a hacksaw (jagged & uneven). Maybe that's why oil was pouring out of them.
I have another set coming from RN, but they are backordered at the moment.

I now have to decide if it's worth the trouble to pull everything apart just to install new un-slit selector rod seals. Probably not, since it will most likely still leak a little, which is where I'm at right now. If I can stop the oil flow from the detent seals I'll be happy.