Transfer case rear seal STILL leaking

I have taken apart and put back together the back of the transfer case 4 times now trying to keep it from leaking.

First time I replaced the seal....it leaked.

Second time I replaced the seal and gooped everything including the holding bolts with black silicone maker....it leaked

Third time I remember Brent Mullins saying one time that the Omix rebuild kit seals had the wrong ID and he had the correct ones. He also said if the yokes were anykind of scored, they would leak, so I bought his seals and a brand new yoke. I put those in and resealed....it leaked

Fourth time, I called Mullins back and he asked if I put silicone around the outside of that yoke seal which I didn't....so....I took it back apart sealed it and the splines.....it leaked.

I'm wondering if I just need to give it up and realize its like an old AMF Harley.....It's gonna leak no matter what I do.

 

Yep...did that too. I even waited a day before I filled it with gear oil to make sure that stuff was hard

 

Its somewhere behind the e-brake drum. The only possible locations are the 4 bolts that hold on the speedometer housing or the rear seal. When I took off the drum and yoke, the backer plate was bone dry around those 4 bolts.

 

I feel the pain. I have the same problem, and the same symptoms as described. I have also done everything you describe. I too have pulled my xfer case and either rebuilt or resealed it four times in the last five years.

I wish I had good advice, but I will be watching closely to see what folks come up with.

How much oil do you loose? In a week of sitting in the garage, I'll get a little less than a quarter of a cup on the drip pan. Driving it I will loose that much every day. I love the winter though. It almost makes my leak disappear in the garage

 

Are you using the cloth seals or a new style rubber?
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I'm using the new rubber ones.

Also, it isn't leaking behind the speedo gear housing. Its leaking from behind the e-brake drum. Its somewhere in front of the drum backer plate and behind the e-brake drum up inside.

Funny thing is, its leaking more now than when I was using my old yoke.

It drips probably 5 drops per day. I filled it up to the fill plug hole level.

 

Just to clarify. I remember when I rebuilt the case I had to play around with the shims between the speedo housing and the T/C housing to get the load just right.

I noticed when I had the e-brake drum and yoke all put back together and the big nut tightened, before I bolted up the drive shaft, I remember I could move the e-brake drum assembly in and out just a little. Is it supposed to have that slack?

 

Is there a chance it's leaking from the shim pack? If that's the case, you might be able to to make a one piece shim to eliminate the stack and help it seal better. For example, mine was .076", so I found a piece of aluminum .076" thick, carved it out in the shape of the shim, and cut several circular grooves around the holes that would have oil in them. The grooves held the sealant forming a sort of O-ring. Seems to have worked, although I can't say that the rest of the Jeep is as leak free.

 

Sure would be nice if someone would write up the definitive "How to make your D18 leak free" guide ... with every tip and trick known. Would be a best seller like the last Harry Potter book.

 

The 4 bolts and nuts that hold the flanges for the driveshaft together also hold the drum in place. If the bolts and nuts aren't tight the drum can move around. There should be virtually no movement once the drive shaft is bolted in.
A very thin coat of sealer on both sides of the shims help, as does sealer on the bolt threads that hold the housing onto the transfer case housing, on the splines as mentioned, on the outside of the seal, etc. Sometimes the bore for the seal gets marred and the sealer can fill the gap. Everything must be absolutely clean and oil free. Also make sure the garter spring that holds the seal lip tight against the seal surface on the yoke hasn't popped off. Commonly happens when the seal is driven in. I put a little grease or assembly lube like vaseline or tranny assembly lube on the back side of the seal to keep it from popping off.

 

I finally gave up and built a drip pan. I ended up removing the e-brake drum which gives more room to work and makes accessing the speedo connection much easier. With the drum gone, I had room to make a much better than stock skid plate which I made so I had room to mount the new drip pan below the t-case but above the new skid plate.

The t-case still drips but now it doesn't make a mess on the floor.

 

Just a thought here, maybe a waste of time??

But, have you made sure the vent is open???

I am assuming there is a vent, dont know for sure.

If there isnt a vent ------ maybe there should be one to relieve pressure generated by things heating up when driving.

Remember when car engines switched from road draft tubes on the crankcase, to a closed crankcase??? Oil leaks were a major problem when the PCV screwed up.

 

Good point Mike.
Vent in an 18 transfer case is on top of the front output housing.

 

Yea, I know its not from the shim pack. It would leak from that location; you would see it. It's leaking off the inside of the drum.

How would you know if the garter spring came off? you would have to take it back apart to tell.

This is a crazy idea, but just shooting from the hip here; What if you put on 2 seals? Would there be room to do that?

 

The stock seal is a single lip. There's a double lipped seal available that replaces it. I have the number at home in my file. It fits both front and/or rear output shaft yoke. Other possibilities may be that your yoke's sealing surface is scored or the case is cracked across the seal seating area. I put the felt oil seal inside the case, not on the back of the yoke. That solved my problem.

 

double lipped seal is National Federal Mogul oil seal Part # 473229 per Rick Stivers rebuild guide

 

Like I said, the Yoke is brand new so no scoring