evenbbq

Purchased a '96 Cherokee XJ a month or so ago and I've been chasing down a transmission fluid leak. It is most noticeable when driving at highway speed and letting off the gas which results in a puff of smoke from it burning on the exhaust. The hard part was figuring out where it was coming from because there's fluid all over the underside around the transmission from it blowing everywhere. I know 100% it's coming from the bell housing area now because I got a buddy to rev it up for a couple seconds while I was looking underneath and when he let off it was an almost constant drip coming from the bottom of the bell housing. This makes sense of why smoke happens when letting off the gas at speed and it blowing back on the exhaust.

I got worried it may be a seal but found another thread here where it seems to be a common issue with either a blockage in the fluid lines or vent tube which causes pressure to build and fluid to overflow out of the breather tube. It also seemed to happen when in hot climates and the stock radiator cooling just couldn't keep it cool enough which caused it overheat and gush fluid. And lastly there were some reports of it happening from being overfilled which i don't think is my case but will double check.

I've done a flush (twice), replaced the pan gasket and filter, and replaced the line fittings at the transmission. I'm going to check the above possible solutions but wanted to see if you guys knew of anything else to check or had other advice while I was at it.

Specs on the car:
1996 Jeep Cherokee Country
4x4 NP231 AW4
Completely stock (stock wheels/tires, no lift, I mean stock)
200k miles, has 10+ years of service history

Thanks in advance!

dzywicki

I had the same thing happening on my '99. Turned out to be the input seal. Had to drop the trans to replace the $5 seal. Mine had ~120k on it and the seal was hardened and cracking. I replaced all the seals I could while I had it out. Wasn't too bad of a job except for getting the reverse torx bolts out from the top of the trans.
It seems ok until the fluid starts heating up. Once that happens, it expands and hits the cracked seal and then lots of white smoke.

TwistedWrench

Well if its dripping down the outside of the bell, MAYBE an overflow.

From the inside? Input and/or front pump seal. Either way in that case, trans has to come down.

As stated above, thats the time to do a reseal job. Rebuild if its not 100%. Though the AW4 is known to go WELL beyond 200K without issue, especially in a stock rig.

Rambler65

If you pull the trans it's a good time to replace the core plugs on back of the engine and cylinder head while in there.

evenbbq

This evening I checked the three things I mentioned and more or less ruled them out. Took it on a short drive to get the fluid warmed up and while running I could wipe the drop of fluid from the bottom of the bell housing and it build a drop back up within a second or two. It's definitely not dripping down the outside thus would mean it's coming from the inside unfortunately.

Is it worth doing the output seal as well at the same time? What else while I'm in there?

TwistedWrench

Well this is where mightaswellitis can snowball quickly, lol. Heres a off the top of my head list of things that COULD be done. Ya know, since youre pulling the trans anyway.

ALL the seals. Why not? Dont forget the oring at the shifter pawl.

Pulling driveshafts, well the ujoints are a no brainer.

As mentioned before, check the rear freezeplugs. Now's the time...

Disassemble and clean the NSS.

Transfer case? Well, youre gonna be in there anyway.

Trans mount. Duh.

Dont **** with the other sensors if they're working. Unless you get legit Mopars. Then, well, you're already in there.


This is the kind of job that can take on a life of its own if you let it.