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Discussion Starter #1
Just pulled the transfer case to swap out the Allison. Put it back in and now it is leaking from the bottom of the rear driveshaft seal.

This case was rebuilt and had the pump rub fix installed last year and has never leaked.

I checked the fluid level and replaced the seal hoping maybe the seal just got dinged, but still leaks. U joints are only a year old and the is no wobble in the shaft. Just dripping out the bottom of the seal.

Any ideas? Maybe a plugged vent?
 

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There's a spring inside the seal, that might have come out of it's groove. I'm pretty sure that happened to me, and the fluid slowly came out the rear seal and I didn't notice it until the TC started growling...


You may be able to put the spring back in place (maybe also smear some grease on it as well to hold it in) or replace the seal without needing to remove the TC from the truck.
 

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Leaking around the drive shaft or outer metal flange? Weep hole orientated right. Did you use any RTV Sealant.
Sometimes people go through 3 or 4 before they have any luck.
 

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Discussion Starter #4
Leaking around the drive shaft or outer metal flange? Weep hole orientated right. Did you use any RTV Sealant.
Sometimes people go through 3 or 4 before they have any luck.
Leaking from the lip touching the DS yoke. I did rtv the outside lip of the seal and it is not leaking there. Weep hole I was not sure on orientation and put it at 3 o'clock.

I did have it sitting upside down for a couple days while doing the trans, hoping maybe just got a bunch of fluid in cavities and that is draining back into that part of the housing. Looks to me like the fluid level should not be that high and that this seal should only need to deal with splash fluid. Have only driven it about 10 miles, going to just try and put a few miles on it and check the fluid level.
 

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Weep hole I was not sure on orientation and put it at 3 o'clock.
The seal weep hole is supposed to be facing down to the ground. 6 o’clock
 

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FWIW...

On my 2006 that seal has seeped since it ran out of warranty. I replaced it when I did the TC pump rub fix proactively. That new seal began to seep in about a year. The fluid when full will be high enough to sit against that seal when the truck is sitting level. When about a 1/2 pint low it won't.

My 1990 K1500 seal always seeped from new. Dealer replaced it 4 times and me 2 or 3. It never stayed dry.

I've learned to check the TC level often and when the seep becomes a leak creating persistent drops, I replace. But I gave up expecting a 100% seal.

And yes, the seep is where the seal (rubber and spring) meets the yoke.
 

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Discussion Starter #7
Looks like I have it fixed, for now at least.

Swapped out the $6 seal for a $50 one from Napa.

Also while looking at the driveline it looked like the angle of the trans and TC was a little lower than before. When we rebuild the trans we used the updated transmission extension housing that goes between the trans and TC. Thinking the mounting tabs on this one might be slightly different than the original I used a a spacer to raise it about 3/8".

Now I get no leaking.
 

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When we rebuild the trans we used the updated transmission extension housing that goes between the trans and TC. Thinking the mounting tabs on this one might be slightly different than the original I used a a spacer to raise it about 3/8".

Now I get no leaking.
Normally quality parts are the same. I would of never made the height change. Hope it works out.
 
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