85 4x4 transfer case output shaft leak

I've searched the forum for some mention of my specific problem and didn't find one. Forgive me if there is and I missed it.

I have an 85 power ram 50 with the diesel and the km-145 trans and case. I have a persistent oil leak at the front output shaft. Three different folks at different times have replaced the seal to no avail. I was one of them so you could say at least two of the people knew what they were doing. The universal joint at the transfer case end of the drive shaft was replaced in the hopes that movement of the joint was the culprit. I'm at a stopping point on where to go from here. I've read that some vehicles have a vent on their cases, but I couldn't find one on mine. The shaft did not have any irregularities on the seal surface that I noticed either. The leak occurs when the truck is parked also. The wrong seal is an option, but three folks getting it wrong seems unlikely, plus, when I did it, the seal squeegeed the shaft tightly (I apologize for the imagery). Does this problem ring a bell and recall a simple solution to anyone?

Any input would be appreciated.

Do you have a center support bearing on a split drive shaft? These can get worn out and sag causing leakage. You say it leaks when it sits also, if the seal was correctly placed then sitting wouldn't make it leak, but residual oil from it leaking while you were driving would drip after you stop. The seal your buying, is it OEM? How did the replaced seal look when a new one was installed. Was there wear?

i believe the part # you speak of is MD712012 Drivetrain : Transfer Case Output Shaft Seal. no mention of a transfer case vent in "the" mitsubishi manual. you also mentioned "Three different folks at different times have replaced the seal to no avail" so thoroughly inspect where seal seats into the case (may need sealant) due to scored case. also...is this a stock height truck?...as the truck height increases (or differential moves down & away from case) the driveshaft angle increases & is no longer fully inserted into case. also swop out fluid if viscosity is in question, transfer case lube is "GL-4 SAE80W or GL-4 SAE75W-85W" per "the" mitsubishi manual.

The front shaft doesn't have a support bearing...and you're right, it would drip what was leaked during driving after stopping for a while. However, I let the truck sit for three days after driving and it still dripped steadily...enough to make me think that it was still leaking after driving. Also, the shaft and case was inspected by a mechanic and he said there is no movement to either. I doubt the seal was oem, if fact, I know the seal I installed was not. The new seal I pulled out was pristine looking...so much so I wish I had been more gentle so I could use it again.

The "scored case" theory is front and center now. Without a clogged vent to explain a leak due to case pressure I'm left with case or shaft scoring...absent the failure to install the seal correctly, that is. What kind of sealant would I use on a scored case? The truck height and fluid viscosity is both oem. I have the shop manual, and I agree with ragtime regarding the "comprehensiveness" of it.

There is a way to fix a weeping seal if it's new by removing the spring that runs around the inner edge of the seal and trimming the spring length back by a few coils (I saw this on a youtube video by jafromobile - he was salvaging a newish seal that had began to prematurely leak) It was done by finding the end join of the spring and 'unscrewing' it, taking a pair of fine wire cutters and inserting the end of them into the bigger diameter end of the spring, then gently clipping 2 to 3 coils off and reinstalling it. It effectively made the spring slightly shorter, pulling the seal in tighter onto the shaft it was installed around. Don't know if this is a recommended way of dealing with a new seal that's leaking, but if you're going to pull it out you only will be investing time into trying this (hey, if it works...)

sounds like you wish to put an oem back in it?:Attachment 11104Attachment 11105MD712012 $15.00 shipped

Ragtime, you have an oem seal? That's semi impressive. Yeah, I'll take it. I'll paypal you.

As far as the spring shortening goes, I'm gonna try it...on an oreillys seal.

Thanks for the help all.

lg

Hi ragtime, did it work? Thx, greg

It took a while to sort this problem out, however I did have some success. The spring shortening thing can work. I practiced with a ruined one I had from an old seal. I didn't use that method because I came across a diameter increaser called a Speedi-sleeve. Another company calls theirs Redi-sleeve. It's a malleable metal sleeve you bang on the drive shaft to the point where the seal contacts the shaft. It seems to work. I hesitate to call something fixed before 20,000 or so test miles, but it's not leaking now.

Hi Guys,

I'm having the same issue with my 92 mighty max 4wd. I've replaced the seal three times with a National 223608 seal. Running Napa 80w90 gear lube. I've also installed a sleeve on the shaft. It's to the point where every 500-1000 miles I lose about a 1/4 quart of oil. Does the OEM seal make that big of a difference? I'm about to change it again... this time I can try the spring trick mentioned above.

Thanks for any advice.

Cheers,

Resurrecting an old thread because I have the same t-case leak, but it's not the front seal (which I've replace at least twice). The problem is that the gear lube leaks from around the soft plug in the u-joint end of the slip yoke. It drips off the yoke/u-joint, not from the seal dust cover which is to the rear of the u-joint. Ten months ago I packed heavy grease into that end of the yoke. It didn't leak until a week ago.
So without replacing the soft plug, what can be used to pack or coat and seal the plug from the inside to stop the leak and still unsure proper slip yoke operation?