Can you run ATF in a Manual Tranny?

1991 Cherokee 4.0L with AX-15 and NP231 with SYE and F8.8 rear. The motor and tranny have been rebuilt and has 8,000 miles on them. I rebuilt the t-case about 3 weeks ago and it has 500miles on it. I just got the rear driveshaft 4 days ago and had been running around town previously with just the front driveshaft in 4hi and no signs of breakage or anything leaking. I install the new rear driveshaft and 2 days later I start leaking around the tranny and t-case.

The reason I ask is because for some reason I think the t-case is pumping ATF into the manual tranny through the input shaft of the t-case and output shaft of the tranny. I assume there is a seal going or on its way out in there. When i remove the fill plug of the tranny redish brown color fluid comes POURING out for a second simmilar to when you first remove a drain plug. The tranny is over full with the added ATF. The t-case is also loosing fluid. There is fluid leaking from where the t-case and tranny bolt together.

Will ATF hurt my 5 speed in any way? Will it hurt to drive it a 100 miles so long as everything has fluid? I am out of town at the moment and want to fix this at home if possable.

Thanks,

AARON

That's weird. I'd say the ATF probabaly isn't good for the AX15.
There's a weep hole on the AX15 adaptor housing on the passenger side near the bottom facing forward. Usually if the output seal on the AX15 is going you will get transmission fluid leaking here. To my knoledge it is there because there is no input seal on the NP231. Why or how your 231 could be pumping fluid into the AX15 is beyond me.

Jes

The input shaft of the tranny has a pilot bearing for the main shaft right at the end of the splines. I think that that bearing is allowing ATF to seep past and then flow along the splines into the tranny. At least thats my guess.

AARON

Won't hurt

The atf won't hurt the transmission. In fact there are some people who run it in their ax-15s instead of the regular stuff without any problems (Tom Houston are you out there?). But as to your question, no, it won't detrimentally affect your tranny.

Thanks guys. What is the benifet of running ATF instead of regular gear oil in there since the topic has surfaced.

Thanks

AARON

ummmm AX15 has been proven to be picky when it comes to regular oil that it's supposed to have.... the battle is whether it's GL3 only or are some synth ok... and now you wanna run ATF in it??????? Look on the OEM forum for AX15 (or just run a search) as this was discussed pretty recently....

Kejtar

There is a seal in Transmission adapter between t-case and trans

What could've happened is that when you re-installed t-case, you accidentaly damaged adapter seal. what you need to do is to replce that seal and when installing t-case carfully push it when splines are engaged. Dont forget to lube seal with some traany goop. Good luck. I had the same problem, but not that severe ....
Pit.