Engine/Transmission (1998.5 - 2002) Transfer Case Mystery

[Cat Skinner]

Gentlemen,



My rear output shaft seal is leaking. I just changed it today and the leak is still there. The mysterious part is the while the U-joints are spraying the oil on the underside of the truck the weep hole in the bottom of the seal is dry. The outside of the U-joint is slightly wet. This is the latest and greatest seal from Mopar. I'm stumped!



TIA

Cat Skinner

 

[LSMITH]

First thing I would do is check the valve in the vent line to be sure it is clean, if it is not it will puke oil when it warms up. If you cannot blow through it with your mouth something is wrong. Second thing to look at if the seal is not where it is leaking is for porosity in the casting.

 

[Cat Skinner]

L. Smith,

I completly cleaned every inch of the end of the transfer case. How do you pull the vent off? Is it possble for the yoke to seep oil? The inside of the u-joint appears to be wet. Our paving mechanic looked it over and couldn't tell either.



Cat Skinner

 

[LSMITH]

Yes it is possible for the yoke to seep. The inside of mine has gotten just ever so slightly wet and grungy since I got it, but never any oil. I do not know if the yoke is hollow all the way through or not, but I suspect it is. Being hollow would simplify manufacture and not hurt strength. I would guess (again) that there is a plug of some sort pressed into the end of the yoke.



OK, for what I know without guessing, the vent line is a dirty bird to trace. There are several (5) lines off the top of the transfer case, they all go up over the transmission to the firewall. Somewhere between the lift pump and the rear lifting eye on the head one line should seperate out and have the vent on the end. It is tied to the wrap of the other lines so it could be hidden. You can pull the vent cap off when you find it, and blow through it. You can also tap into the line with an extension of vaccum hose and blow back through the line with all of them disconnected on the transfer case to make sure the line is open. I believe, but am not 100% positive, that the vent line is the line furthest forward on the transfer case.



Hope this helps, holler if I can help anymore.

 

[LSMITH]

Forgot to add, welcome to the TDR!!!!!

 

[Roger rodbolt]

Cat Skinner,

It's alway good to check vents but the yoke plug leaking (seeping) is fairly common. I just pull the yoke off the ujoint and use a torch and brass rod to braze the plug sealing area. Seep is permanently fixed. Larry

 

[F-15I Ra'am]

If you have the "Heavy Duty" transfer case. On top of the tailshaft housing is a rubber plug. Fluid will seep out from there and look like its coming from the seal. There is a revised plug availible from Mopar.

 

[B9Mile]

After replacing the rear output seal on mine for the third time (under the 3 / 36 warranty), the dealer decided something must be wrong besides the seal.



They ended up replacing the yoke and the rear extension, with only about 32k miles on the truck. The yoke had a high spot on it that wore the bearing in the housing.



Others have had this problem a couple of years ago but not too many lately.