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Rear T-case output seal leaking


NAXJA Forum User
How do I make this thing stop leaking ? I'm on my second new one and it still leaks, it really dumps when parked on a hill. I fill it til it drips out the top bolt hole. Seems to tight fit on drive shaft input, but it still leaks between shaft and seal.
I was only able to get mine to stop leaking on my 92 by using a factory seal. The after market ones for Kragen, autozone and napa all leaked.
Check the surface of the slip yoke and make sure there's not a groove - you may want to take a caliper or a mike with a knife blade or a pointed anvil and take measurements along the surface. It's a possibility.

Also, make sure you lubricate the seal lip, since it can be torn on assembly if there is significant friction.

Last, I always put a little RTV black around the shell before I install a seal - it helps prevent leaks from groing around the seal instead of through it. Another thing to watch out for...

With all that in mind, I've never had trouble with aftermarket seals (but I'm also really picky about brands - I usually won't use anything but Chicago Rawhide or Timken - unless I have no choice.

The 2 replacements were Timken brand. Slip yoke does have some bulid up of foreign matter,I wasnt sure if some emery cloth to smooth it down would hurt. I'll try that if I go with a oem seal. The seal on the metal to metal contact is what you are saying to seal with rtv ?, it dont appear to be leaking from there.

5-90 are we lubricating the seal with tranny fluid or a grease? The last seal was 4 months old and seemed to oversized and in spots wasnt even touching the yoke. I'm not sure how to check if the rear bearing is causing it to spin out of balance and elongating the hole. I have pushed and pulled for play at the yoke, doesnt appear to be loose, just a thought ?
I changed the rear bushing on an 87, after the third seal, it seemed to do the trick. I changed the bushing out (don´t know where the parts guy got it), before I was told, it´s impossible and the whole tail piece had to be changed out.
some of the after market seals, seal at a lightly different spot on the yoke, than the OEM seal. If the lip of the seal is on a rough or rusty area it isn´t gonna last long. I usually just use a finger full of grease during assembly, packed behind the seal lip, hasn´t caused me any grief yet (been doing it that way on most all seals, for about 40 years).
I stuck a feeler gauge between a yoke and a bushing (just out of curiosity), years ago, on a yoke, bushing and seal that was holding well and got close to 0.003 of play.
A brass brush and a little oil, will clean off most of the rust and a light buffing with Crocus cloth (very fine Emery cloth, 650 grit or finer).
8Mud said:
I stuck a feeler gauge between a yoke and a bushing (just out of curiosity), years ago, on a yoke, bushing and seal that was holding well and got close to 0.003 of play.

The one I put on with only 5 miles is tight as a drum on the yolk and still leaks on level ground. I keep thinking overfill or excessive pressure but I dont know enough about the internals of a transfer case,I've yet to crack one open yet, havent needed too yet. I do know the OEM seal that was leaking a little originally, never leaked as bad as the 2 aftermarket ones. Whats in the tail cone? What fluids is to be circulating in there if any, is there another seal in there that seals of the main body to the tail cone fluid wise? Damn, the tranny and soft plug job was enough right now ,I dont need to be cracking open the transfer case right now not to mention I hate the smell of tranny fluid.
Either will work - but I usually use either a light grease or a moly assembly lube. Smear a little around the lip of the seal, and a little around the first part of the slip yoke to hit the seal - that should make sure the seal gets and stays lubricated. Move slowly and smoothly as you put sealed joins together, so you don't scuff anything.

Take a couple minutes to take those measurements I mentioned - if you have the tools (a dial caliper is enough) to make sure you don't have any "seal wear" to worry about.

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I just replaced mine a few weeks ago with an OEM seal, no problems. I was surprised to find the seal was less than $9. The shaft has got to be clean and smooth for the seal to last. I used 400 grit and carb cleaner and followed up with 00 steel wool to polish it pretty. A little more grease on the seal (it came packed with grease) and some grease on the splines, no leaks, looks purdy. Now if I would just fix the 5 other leaks my driveway could look good again!
Thanks guys, grease and polish sounds unanimous which I have not done either before installation. OEM came with grease on it, timken did not.

Bradlybob - greasing the splines should be done also,huh. I figured since it did not have any on the splines, the t-case fluid lubricated it, not so I take it. Guess I'll goober that up too while I'm back in there. If there was grease on there at one point there is no trace of it now, splines are clean as a whistle.
I don't think that grease is required because the splines are on the lubed side of the seal. I just put it on there because I had it out and cleaned dry with carb cleaner. The grease is just to keep it slick until the oil works it's way into the splines. I use just a little grease, I don't pack it.
Leak stopped !! I like to post this for future search. Timken aftermarket is a different diameter than a dealer one. Dealer seal was a bit smaller diameter giving me the tight seal I needed on the drive shaft.