Chaps.

Just replaced my tailshaft seal (where the driveshaft goes into the transfer case) because I noticed a very small leak.

I STILL notice a small leak though! I lubricated the seal, and popped it in evenly etc.

Anybody have any thoughts/advice?

 

I had mine leak also..i put grey rtv silicon around the seal before i installed it....helped for me so far..and i have about 2k since replaced..

 

Yeah... I was thinking about putting some RTV on it, but didn't know how good of an idea that was with how sensitive the T case is.

Did you put it around the outside of the seal, or the inside of the seal? Like... between the seal and t-case, or between the seal and the driveshaft?

 

Actually... nm. That doesn't even make any sense. It would obviously be between the seal and the case. The shaft spins...

 

Between the seal and the case..id also let it sit for a little bit to make sure the rtv hard-ends up..Hope it fixes your leak!

 

I would try what RCevo said, ive never had an issue doing it like that

 

This usually happens when there is a groove in the yoke of the driveshaft. The groove doesn't compress the seal enough, allowing it to leak.
You can put another seal in, and not press it in as far- giving it a new sealing surface.
If you do put another in, make sure you lube the sealing surface well... that way the seal doesn't have to wait for oil to get flung up there to be lubed.

 

You can usually sand the part the seal rides on down quite a bit and the new seal will have plenty of tension left to seal well with the reduced outside diameter, if it's still grooved it will not seal well or for very long. Cut a long strip of emery cloth and get as much wrap as you can, makes the sanding much quicker and more even.

If the yoke is fine and the leak is around the outside some rtv or even epoxy like jb weld works well, the lower strength quick setting stuff works excellent and will still come off if you need to remove the seal again.

If it's not either of those the seal isn't straight or got slightly bent on install.

 

The shaft on the driveshaft looks fine. It's certainly not a "perfectly machined surface" but I saw no cause for concern frankly.

That said, I'm not sure where the leak is coming from, and I'm not sure there'd be an easy way to even determine that because of the way the system itself operates.

But I'll try popping the seal back out, and scrub the surface of the seating area to be sure it's cleaned up, then try some RTV in there and see if that sorts it out. If not... I suppose I'll try looking at driveshaft bits.

Though... the car only has 65k on it... that'd be unfortunate to have to replace a part at that lifespan.

 

DSMs were recalled by NHTSA because there was a leak out of the tc tail shaft. The oil was going through the plug in the yoke of the u-joint. Some of Mitsubishi's "fixed" u-joints still leaked.

I've never heard of this problem with the Evo but you could be the first.

 

Barney...

If I had to guess, I'd say it's the seal. I don't believe it's coming from the yoke. I'll check into that as well though.

Would anyone happen to have the part number for the yoke for the Evo? I have a 9MR if it matters. Can the yoke itself be replaced?

 

You can tell if the leak is from the yoke because the oil will be flung in a narrow band at a right angle to the driveshaft. If you see a black line on the exhaust and to a lessor degree on the underside of the car in line with the back of the yoke (between the yoke and the spider) that is diagnostic.

What was happening with the DSM's was the engine rocking on its motor mounts was pistoning the output shaft into the yoke. There's a plug in the yoke like a frost plug. The oil was being forced through this plug. Since the tc only holds 0.6 quarts it soon would be dry. The Evo transfercase holds the same amount.

As for buying a yoke I think Mitsubishi only sells complete driveshafts. The yoke for a dsm was $35. Welcome to the new world.

 

Ok, that makes more sense. It's definitely not flinging. It just drips down... I'm gonna need to pop under there this weekend then and RTV her up.

Thanks as always crew!

 

Dudes.

Anybody have any other potential thoughts on this? I've replaced this seal 3 times. RTV, etc. I'm going to have to drop the flipping t-case, and install the seal with the tailside up with the RTV to stop this I suspect.

Just wondering if there have been any new developments in my absence.

 

^ Any updates? I have a client with the same issue.