Dana 18 Leak Troubles

I have been trying to stop seeping oil from my D18 xfer for two years with little luck. All seals and gaskets are new (X2).

I notice the xfer is always overfull. The loss of oil is noticed in the xmission and I do the refills there, but the leaks are in the xfer. It looses about an eighth of a cup if oil a week just sitting in the garage. When I drive it, it will lose that much in a day.

I know the xmission and xfer share oil, but should the xfer always be overfull?

Any insight would be great. Thanks.

 

Can you determine where it is leaking from? Did you put sealant on the splines when you put the front and rear yokes on?

 

It's leaking from around the parking brake - could be the rear output shaft, but I covered it in ultra black and let it sit for 24 hours before filling the xfer. The backplate of the parking brake is damp with oil. It drips off the bottom of the back plate and the three or four lowest bolts on the bottom access plate.

It use to leak at the speedo shaft, but I think I have that fixed.

 

Just what did you cover in RTV?

Pop off the E-brake assembly, remove the rear output yoke, replace the seal, and then reinstall the yoke using a skim coat of RTV on the inside of the yoke splines. That should do it.

 

The yoke splines are what I coated in RTV. I replaced the seal at the same time. I can try it a third time.

Also, is it normal for the xfer the be overfull all the time?

 

Hmmm - had not given that much consideration. I need to take a look at that.

 

The transmission and transfer case shouldn't be sharing oil. That's your first problem.

 

If the yoke has a lot of wear at the seal surface it doesn't matter how good the seal is. Sometimes it takes a new yoke. If the yoke uses a felt backer that needs to be there also. You can permatex both ends of the intermediate shaft without removing it if you use a little brakeclean and work it in while turning the end of the shaft.

 

The felt is in place. When I had it apart there did not appear to be excessive wear but.... I took a look at the intermediate shaft and there appears to be some seepage there. Not sure that it is enough to account for all of the oil. I'll try the permatex after I clean the crud off well and see what happens at that spot.

 

If it seems like you have a bigger leak, then look very closely at the case between the intermediate shaft and the corner of the pan. Rare, but these cases do crack there especially if it has been run without the torque mount in place( thats the side mount on the passesnger side that keeps the case from twisting).

 

mine seems to be doing the same thing. it's a slower leak, but a leak nonetheless.

on mine it looks like it's leaking from the front shaft output, but it's definitely transmission fluid leaking. my jeep is a daily driver, and it took three months for all(ish) of the oil to leak out of the transmission.

when i went to fill it up, the transmission was empty (or damn close) and when i pulled the fill plug off of the t-case, oil started dribbling out. topped it off and it drives just like it used to.

 

No cracks that I see.

Think I'll drain the xfer and xmission and re RTV the rear output as well as both end of the intermediate shaft and see what happens.

Thanks. I may need some more advice in a week or so - fingers crossed.

 

Re the level in the transfer case, all the Borg-Warner 3-speeds (not the T-150) share oil between the trans and TC. The oil seeks its level - whatever it is, that's its level.

From empty, you fill both to the bottom of the fill plug. I would then put more oil in the trans after it levels out, but I'm not sure if that's needed or not. If you pull the fill plug on the TC, oil comes out. I don't think the 'overfill' in the TC will matter though, wrt leaks.

Patrick, I'm surprised that there is no seal in your adapter plate. The parts book calls for one in all T18s, wide and close ratio, Jeep PN 939335. Maybe it's something peculiar to 1971, with the D18 - my book doesn't go back that far.

 

So it's not really overfull, its just level since the xmisson is higher. My only thought is the oil might be at a level that would cause it to leak in places that were not designed to hold the oil.