moparado

My first post here. 2000 XJ, np242 Transfer case, automatic, 6 lunger.
Caution, long story!
I searched for this issue here and else where and found nothing close.

Had the transfer case rebuilt a little more than a year ago by a reputable shop. A very reputable shop.
At first i noticed a greasy fluid around the front of the drive shaft near the Tcase output.
I chalked that off as excess grease from the new U-joint.

Then slowly but surely as time went on, i noticed drops on the floor. It was definitely tranny fluid. The leak sure looked to me at the time that the source was the Tcase output seal.
The rebuild was still under warranty so i took it back to the shop. On the hoist, the seal area was dry as a bone. In fact all around the Tcase it was dry as a bone.
However there was a ton of tranny fluid coating the the bottom of the floor pan exactly where the parking brake cable exits above the Tcase.

Took it back to the shop and again the Tcase was dry as can be all around.
But the area at the parking brake cable area was drenched. Also checked the vent and its surrounding area and it was dry also. The area around the tranny output seal was also dry.

Could the leak be coming from the transmission somehow, maybe the vent tube? Its got 325K miles on it and the transmission pan area is also dry. Checked the fluid level and it appears OK.

The shop and myself are at a loss on this one. The shop would be glad to rebuild the transmission but couldn't prove it was causing the leak.

Any ideas?

CCKen

Is the TC oil level okay? If the transmission fluid level okay?


Wash everything down with solvent and let dry. Drive slowly (so as not to create a whirlwind under the Jeep) a bit then see if the fluid is on the cross member under the transmission mount. See if it's coming from the small rubber plug on the left side of the TC by the shift lever (see pic), or from the mode select switch.


The TC adapter has a weep hole in its bottom that allows fluid from the transmission to drip out if the transmission output shaft seal in the adaptor is leaking and if the TC input shaft seal is leaking (see pc).



.

moparado

Thanks for the reply Ken.

Its been wiped down twice, driven a while and then back to the shop hoist. In both cases, the only wet area is the floor board approx. above the front of the Tcase. The wettest area is where the parking brake cable exits the cabin.

I and the shop tech checked the transmission fluid. It seemed ok but there's a lot of fluid and a leak could be hard to detect.

I checked the Tcase fluid by injecting a small amount of fluid in the fill hole and it immediately came gushing out. I know not the best way to check it. Next time i'll stick my finger in the fill hole to get an accurate level check.

If the output transmission seal is leaking, its not evident at the adapter weep hole as its dry as can be from the Tcase output to the bell housing. The weep hole could be plugged causing a build up of fluid then spraying it out at the floor board?

On the hoist we both checked the entire area above and below the Tcase, adapter, trans. pan and bell housing. First thing we looked at was the vent fitting area and it was also dry.
Whatever's going on, it sure looks like fluid is being sprayed upward at the floor board exactly where the parking brake cable exits the cabin.

Only thing i can think of is the vent tubing might have a pin hole leak spraying fluid up towards the floor board. But i can't see that much pressure develop in the Tcase and the vent tubing seemed dry also.

This thing has got me puzzled.

CCKen

The parking brake cable/floor entrance is directly above the TC output shaft seal. The VSS is nearby.


My output shaft seal is leaking a little bit and the parking brake/floor area is wet from the leak but the slinger on the output shaft is dry. This can fool you. There's a gap between the slinger and the output shaft bearing retainer that the TC fluid may be getting past. Only OEM output shaft seal must be used. Aftermarket seals are NFG. Ask the rebuild shop what seal they used.


If the TC breather vent fitting is plugged, it may be pressurizing the TC enough to push fluid out anywhere it can get out, including past the VSS adaptor o-ring.


Below is a pic of the TC vent fitting. It is located on the right side of the bell housing by the trans dipstick tube. Mine was plugged so I replaced it with a front differential vent fitting with a 5/16" ID rubber hose and extended it up the firewall - same with the AW4 vent fitting (see pic).


TC vent fitting:



.
New vents extended up the firewall:



.
I suggest you remove and check the TC vent fitting and check it by using mouth pressure/suction to see if it's stuck. It can be freed up using electronic spray cleaner, followed by some silicone spray to lube the internal workings. The best bet is to replace it like I did.


It may be a good idea to wash the area clean with solvent, like brake cleaner, then put the Heep up on a hoist with someone in the driver's seat. Start the engine and put it in drive while people look for the leak.

moparado

Thanks again Ken for taking the time with this.

Don't know this for a fact but the shop likely used a 3rd party rebuild kit.
Gonna copy your last reply and show it to them regarding the OEM seal.
I did notice the leak after the re-build but it got worse as time went on.
Also seems worse in hot Summer weather.

Got a lot of things to check now, unfortunately i'll have to wait til the weather gets better. The XJ is not my daily driver and its basically in semi-storage in my pole barn for the Winter.

moparado

Follow up.
Well i followed CCKen's advice and replaced the seal with a Mopar seal and slinger.
A few months later, no leaks. Thanks.

Apparently the shop who rebuilt my Tcase either used the wrong seal, crappy seal or damaged it when replacing. They also re-used the old slinger which was banged up a little.
Worse, when i took it back there twice, they had no idea what the hell was going on.
And its supposedly a reputable transmission shop.

Arlow Brown

Don't lose faith in your shop just because they were unable to diagnose your problem often times and mechanic will know what they've done and they will go over there work time and time again and not find the simplest of mistakes sometimes it just takes another person looking at it to figure out what you did wrong