Hey all - long story short, bought my 95 4.0 AX15/NP231 two years ago and the TC was skipping and dry as a bone, so I rebuilt it. Turns out it's been leaking slightly for quite some time.

I figured it might be the input shaft seal since that's the side that it looked to be coming from - it's even pooling in the heads of the bolts on the bottom of the tranny mount. But when I got the crossmember off, there sure is ATF all over the passenger side of the crossmember (same side as the input shaft BUT it doesn't look like it's leaking from that side of the TC.

It DOES look wet and dirty around the front output seal, so here's a theory - is there any chance that if the front output seal is leaking, the front driveshaft might be slinging the ATF over to the other side, which is why it's pooling over there?

Would be great if I could get this figured out without having to actually pull the TC - but I'll do what I have to! Thanks a lot.

 

You might have a leaky front input seal if it is leaking where the transmission
and the 231 join. Check the AX15 too. Its rear output seal can leak, as can
the joints between the parts of its case.

I repaired a leaky NP231 front output seal recently. It was losing half a liter per month.
If it, or the front input seal is leaking, you'll have to pull the TC and fix it or else
just remember to fill it regularly.

My NP231 has leaked in a number of places over the years - the drain plug
until I replaced it, at the O-ring for the speedometer gear, at the rear output seal,
at the front input seal, and in the silicon gasket holding the two halves together.
I think the worst leak was the front output seal, though.

If the transmission mount is soaked, then you'll risk ruining it if the leak problem
isn't solved. That happened to me several years ago.

 

get a good look at it and figure out Exactly where its coming from. Not impossible to change the seal while in the jeep, you would definitely need to drop the crossmember to say the least for ease of access. In any case you could spray and wipe it down with brake clean and then fill it back up and look for fresh fluid drip/seapage.

 

JMO if you have already done a rebuild in the past just pull it and do all new seals and recheck the internals.

 

Thanks for all the good advice, all. Got a little further into it today; dropped everything down a few inches to have some room to work and I discovered that the breather hose was broken right after it got off the little pipe from the TC; then about an inch later, the hose was worn almost completely through on one side. Best theory I've got is that I just got unlucky when I put it back together and managed to get the hose caught under something to where it pinched and eventually even tore the hose.

I don't even have 3000 miles on these seals, but I know if the TC couldn't breathe, that could force fluid out of it. Think I need to do all new seals?

 

Just fix the vent for now.

 

Well if I've learned anything, it's that Cruiser knows what he's talking about I got her all put back together this morning and will watch it closely.

It's a pain getting that crossmember down since it's aftermarket and part of my Iron Rock 3-link. It's three separate pieces that bolt together - the long arms connect to the side pieces, and the middle section is removable so you can drop the tranny/TC without having to remove the long arms, which is great, but it's a challenge to get to all those bolts. Definitely worth it to stop this leak!

 

Update: got everything back together and it still leaked, so it wasn't the breather hose. Ended up pulling the TC, and looked like it was coming from the input seal even though the seal looked good, so replaced that seal (after buggering up the first one by not seating it right, then going BACK to the store for another one) and it's been leak-free ever since! MAN is it nice to have this solved. Thanks for the help, all!