So I have a 2000 XJ, HO 6cyl and the AW4 tranny. I run 31s with 4.10s. We all know this tranny is known for getting hot. I noticed with weight in the car when I'm going about 80 miles an hour (about 2800rpm or so) on the freeway I sometimes see smoke. Due to fluid coming out from the overflow. I installed a B&M tranny cooler last week to aid the tranny.

I took a trip to Lake Tahoe in ghe Sierras last weekend from San Francisco. With four people and gear I noticed after a long climb into the mountains the tranny got hot and smoking out again. Anybody else have this problem?

 

There's a built in tranny cooler in the radiator, iirc, if the two have crossed fluids from some sort of failure, that's no good. Maybe this had already happened. Have you checked your fluids?

 

What color is your tranny fluid? A nice, fresh red color?

I've been battling that issue for a while now and think I figured it out for myself. What it took for me was bypassing the factory tranny cooler in the radiator and have it routed straight from the tranny, to the B&M and back to the tranny.

Do you currently have the B&M connected in line with the factory cooler in the tranny?

 

my fluid is fine, just replaced TC so its fresh. i believe it is routed on the return line from the radiator.

 

Are you talking about the coolant overflow? If so, I don't see how the tranny is causing that. I'm pretty sure that'd be the engine.

Also, doesn't 2800 rpms at 80mph sound a lil high? Even for 31s on 4.10s.

 

its the tranny overflow and yes around 2800rpm does seem high for my setup at 80mph

 

well maybe you shouldn't have put new fluid in the TC when changing it out. you should have used the old fluid if it was still red. I say this because "MOST" trannys; unless done from new, don't like to have the fluid changed after about 60k.

A varnish develops on all the internals and when the tranny is flushed and new fluid installed you have a 50/50 chance of the the tranny failing because that varnish acts like a protective barrier.

I'm not saying that this is your case; but just putting it out there as a possibility.

I really don't know how the AW4 reacts to later in life tranny fluid changes, but i had a buddy that did a complete flush on a 130k honda accord and not even 3 miles down the road the tranny was smoked. all after i warned him not to do it.

 

The tranny overflow as in tranny fluid starts pouring out and onto the downpipe, causing smoke in the rearview mirror.

My vote is to bypass the factory cooler in the radiator.

I was skeptical to do it at first but am extremely happy I did. Guarantee it'll help you out. You're in CA too so you're in a good climate to do this.

 

I had an issue with some smoke coming out of the rear when I was towing a trailer in the mountains. After a stop and checking everything i believe it was my rear main seal leak spewing oil on the exhaust that was causing this. i could see no other leaks and i don't believe the transmission has an "overflow". If it was going to come from the transmission you would have to have a leak or from the dipstick tube.

 

If you're towing something, you're even more likely to have the transmission to overheat and have fluid pour out and cause smoke. Guaranteed that wasn't coming from your rear main seal

 

If you're towing something, you're even more likely to have the transmission to overheat and have fluid pour out and cause smoke. Guaranteed that wasn't coming from your rear main seal

So it created enough pressure to cause the transmission fluid to unseat the dip stick and leak from my dipstick tube, then reseated the dipstick solidly with no fluid on the dip stick tube? I have no leaks in my transmission, no red fluid on anything. ??

 

there is a vent tube on the top of the transmission........ has to vent pressure.....

 

Ive had the same problem with my 93. In the mountains it was smoking also. I wonder if takine the vent into a vacuum line? Cooler should help.

Ron

 

i drove on stock gears.on 32s n i blew the front seal on the tranny pouring fluid from bell housing from behind the torque converter & i lost reverse and it clicks and grinds in drive :-(

 

yawl keep you're bad luck away from aw4.... only had one issue out of my old trans and that was the front seal started leaking at 190k after being submerged in a mudhole...... but i think it was caused by the main bearings having too much play because the engine dropped oil pressure at the same time.

i have noticed that 90 percent of the overheating aw4s do not have the auxillary trans cooler. just the one in the radiator, also another thing overlooked for high trans temps is plugged filters. with a plugged filter there is little flow causing temps to get up and create excessive case pressure.