Could use some help from the Auto tranny folks ????

[karstman]

Here is the situation. A friend has a 92 YJ with an auto (TF999 ? ). Last weekend we installed a NP231D from JB Conversions. SYE was already installed in the new case so it was a direct bolt-in replacement. All went well until the next day he noticed ATF dripping where the case and tranny mate. Yesterday he pulled the 231 and replaced the rear seal of the tranny (original seal with 183,000 miles) with a new one. Still leaks. Today we pulled the 231 again and replaced the front seal and retaining plate. Still leaks. All the seals are new, the case is new, and the tranny never leaked prior to installing the new case. There are clear polished marks on the input shaft of the 231 where it appears the seals are riding. Both the new and old 231 input shaft were measured and are the same OD. Tranny fluid is to the full mark and clean. It appears to begin leaking ~after~ the jeep is turned off. We ran it in drive with the 231 in neutral for about 15 minutes at varoius speeds and no leaks. Shut it off and drip....drip...drip.... that originates at the weep hole in the bottom of the tranny tailhousing.

Anyone have any thoughts or suggestions? We both feel it's the rear seal of the tranny but can not figure out why the thing is leaking.

TIA,
mark

[karstman]

Anyone ??
It is still leaking and getting worse. We are going to pull the case again tomorrow and replace the rear seal of the tranny...again

Going to check for any run-out on the 231 input shaft while we are at it.

later,
mark (scratching head)

[Scott Hill]

I think there are 2 seals on the rear of rhe tranny one on each side of the adapter. it sounds like both went.

when he drives does it empty the tranny into the t-case??



when Robert Yates reads this he will be able to help you.


Scott

[karstman]

2 seals ?
We only replaced one. Hmmmm....
It is leaking into the void between the case and the tranny, but not into the case itself. It actually drains out a very small weep hole in the bottom of the tranny tailshaft adapter.

thanks

[William]

Having just been in there.. I got some advice from my Brother:

You might want to think about polishing the shaft with some type of materail, it may have a bur or imperfection on there that causes it to leak. Also, I had some residual after I put the case back on that took a little bit to clear out. Remember that the seal will have some build up when you put the seal on. Also, make absolutely sure you got the right seal. I bought one from Napa that was completely wrong, the dealer one seemed to be a better fit. You might want to also put a little fluid on the shaft before you re attach so that it will slide in smooth, and perhaps not push the seal off a little to cause a leak.

One final bit, you might want to triple check that the tranny is not overfilled. That can cause fluid to shoot out at all possible angles.

[Robert J. Yates]

I would have offered some advice if I had any actually experience with this - my problem at the time was with the t-case itself, not the adapter or seal. I do however concur with 2 things that William offered;

First, the use of fine emery cloth to debur the shaft and secondly, using a bit of atf on the seal when installing it.

[William]

One other thing on the seal. There is usually some paint on it (mine was green) make sure that it's not rubbed off or scraped when you put it on. The paint is actually a material that helps the seal close the gap. When putting the seal on, put it on smooth and even, don't hammer it at an angle. Not that you'd do this, but maybee the seals are getting maligned while being put on.
I'm trying to apply my poor quality wrenching skills to your senario to pinpoint any problems.

[karstman]

Thanks guys. We did not de-bur the shaft, but the seal was lubed before the case was installed. It will get de-burred this time just to be sure.

Is there a concensus on whether there is one seal or two? All I saw behind the seal was a bearing. We did not remove the tailshaft adapter, just replaced the rearmost seal.

Thanks for the help.
mark

[RockYJ]

Kartsman was the case ordered for an auto tranny Jeep? The front input of the t-case's are different lengths. If this is the case I think it would leak quite a bit. If a manual tranny t-case is put in the input wont reach the seal completely. There should not be run out in the shaft of the new case. Rocky

[karstman]

Thanks for the help folks. Here's what ended up happening for anyone interested.

RockYJ - yes it was the correct case, 23 spline, long input shaft.

We pulled the case on the 4th in the morning. Cleaned and cleaned and cleaned the tailhousing of the tranny then drove in a new seal. Put the case back in and went for a drive. Shortly thereafter had the tell-tale drip...drip...drip...

So...we got some UV dye just to be 100% sure it was the tranny. Dye showed up clearly so we pulled the case again. Replaced the rear tranny seal again, using RTV around the perimeter of the seal and the tranny tailhousing. Put it back together and it still leaked. Ugg.....

Took a VERY close look at tranny fluid level again. It was exactly at the "Full" line. Dipstick has 3 lines on it. "Add 1/2 pint", "Safe", and "Full", with about 1/2" between "Safe" and "Full". I suggested removing enough tranny fluid to lower it to the "Safe" level. My buddy kindly disagreed and we called it an evening, with him totally disgusted and planning to take it to the dealer on Friday morning to pick a brain or 2.

Friday morning he took it to the dealership to chat with the techs. They claim this is fairly common and when it occurs they RTV the weep hole shut and RTV the case and tranny mating surfaces. The void between may fill with some fluid, but it will not hurt anything. ???

I left for Paragon and my buddy proceeded with the above procedure. No more drip. Then....while enroute to Paragon with his YJ, the tranny vent began weeping ATF when the coolant temp reached 230 or so when climbing highway hills. He kept a close eye on the ATF level and proceeded with the trip. It stopped venting fluid on Sunday and has not leaked since. Fluid level is now between the "Safe" and "Full" level. Seems that his tranny is particularly sensitive to fluid level and my best guess is that the slight "overfill" was creating too much pressure for the seal to handle. I have not idea why the pressure would not be releived via the vent...???

Well...that's it. The good thing is that we have the case removal/install down to ~20 minutes each way

later,
mark