1996 Trans Leak When Hot
 

Hello,
I have a 1996 Jeep Cherokee 4.0L HO
The transmission is made by Toyota

After a long hard towing session my tranny started leaking fluid to the point it looked like it was raining nder the car.
Immediatly took it to the garage to have it looked at.
Guy cleaned it off, could not detect any leaks, "serviced" the tranny and all seemed well.
Had to return as one of th hoses was apparently rotten inside at the trans connection point and stared leaking....
At this point all seems well.
Drive it on and off, no longer than 5-10 miles all is good.
After average city driving for approx 1/2 hour, I proceeded up a 1/2 mile standard grade hill, upon reaching midway up I notice more gas is required to keep speed up.
At top of hill, Jeep is smoking from tranny leak, and it's raining fluid under car again :(, fraid it may catch fire, if this keeps up.

Take it back, guy thinks it was a burp from breather tube, cleans it off, test drives it, no leaks for a day, then it starts again. Trans guy has pretty much given up I think, and from what I know of him, he's pretty good.

The ol' ATF-4 is breaking me up, not to mention the spots I'm leaving.....

Thanks ahead of time for any thoughts/questions! ~jdk

Sounds like you have roasted your tranny. Is the fluid dark brown and smell burnt? You need to add an external cooler to the tranny lines at the radiator heat exchanger.

how does the vent for the trans look ? is it clogged ?

if it's over full it'll do that too. getting hot inside. trans fluid expands a lot with heat. if it getting hot it will find ways to exit.

Your trans is cooked.

When towing you can't use overdrive and if towing for distance or with a large load you need an external trans cooler.

Also, should have Dex/Merc III in the trans and not ATF 4+

ATF4 is not ok to use in you trans. No matter what TSB you read.
Where is the fluid coming from add a picture?
I just had to re-do a already new pump seal in the bell housing because my vent line had pinched and blew out my seals.
Im guessing its leaking onto the exhaust and creating a smoke cloud?

Also Im not sure the trans is made by toyota who told you that haha

The trans is an AW4 which is also used by Toyota in similar versions. This is a common problem when these trans are over worked. They blow excess fluid out the vent and it hits the hot exhaust causing smoke and oil on the tailgate. Oil level is very important and overfilling will make this worse. As youve said it was run hard towing. This did not help as you have realized. This trans also likes Dexron III. This has been documented often in many threads and other websites. With a fluid change to Dexron III not 4, and to the proper level and not overfilled should get you back to working well. As others have said a good cooler is also recommended. These trans are known to make it to 300K with only fluid changes.

Ron

I would bet its the pump seal around the input shaft I just finished mine..

but AW stands for Aisin Warner
Toyota is not the manufacturer was just makign that clear lol

Aisin (now called Aisin AW) is 30% owned by Toyota. Warner, as in Borg-Warner, AMC's old transmission supplier hasn't been a partner for decades, although Aisin kept the "AW" name.

Thats insane I never knew any of that. Nothing like someone like me talking out of their *** lol

Borg-Warner is also a great manufacturer of excellent turbos :thumbsup:

Except you were correct, Toyota is not the manufacturer. They merely have an ownership interest in Aisin and buy many (if not all?) their trans' from them.

CNF, hopefully you've changed ALL your transmission fluid after the overheat? Once the fluid cooks the next overheat is just around the corner and if the first one didn't cook the trans the second probably will. Overheated fluid doesn't lubricate or cool correctly anymore.
AW4 is tough as nails but this is their one weakness- they don't like heat. (and they tend to run warm as it is). Agreed entirely on Dex III, not ATF4 and adding a nice big cooler.

Did not make it to the burnt stage
 

Thank you for all the replies....Great site/GREAT members!

Was not in OD, rarely use it, cept' in winter.
I was towing a trailer with 4k of shingles split between Jeep and trailer.

Got the Toyota manufacturing thing from my mechanics assistant. Duely noted and passed on!
Thank you for straightening me out! ;)

Oddly enough the fluid never reached the "burnt" stage, just came raining out a pretty red. I think/hope I caught it in time! :blink::blink:

I am looking into a external cooler. Thank you for the suggestion!

Apparently only I was using the ATF+4 not my mechanic, he uses Dextron III

I am going to have them check the pump seal (again) in the bell housing and see if the vent line is possibly pinched.

I had asked them to do this originally but they did not think the leak was comming from there as it only leaks when it gets real warm/hot.

Thank you all again. Your help is much appreciated!! ~jdk

I was having a similar problem, here in the AZ desert the ambient temps get well above 110℉. The fluid would start leaking enough that it would start smoking on the exhaust. I added a cheap external tube cooler when I did the 2 row radiator and almost eliminated the leak now.

4K is plenty of a load to way overheat the trans.

Read my posts on this other hot trans thread that's going on. It has a short writeup on how to put in an explorer plate style cooler that will fix your problem. https://www.cherokeeforum.com/f67/tr...estion-174792/

The leak your all talking about. Does it come from the front of the trans between the motor? I had a leak like that about a month ago, it went away, then today, it started leaking again and into the exhaust