AW4 transmission cooler

[bmyohn]

What cause overheating in the first place? Lugging the engine,what else? I know when we go snow bashing some guys think 4Hi is better for traction and those are the ones that boil tranny fluid. Whats the sign of an overheated tranny? Some puke fluid from boiling the fluid but I have never seen or herd of an XJ puking tranny fluid when hot. I still carry extra fluid in case but what do you guys think?

We were caravanning out to Indiana, and my dad, who has a Toyota Sequoia V8 was flying. I was trying to keep up with him. He would pass cars, so i would go into the passing lane and hit the gas, it would downshift pretty hard and the RPMs would jump. After driving like this for about an hour. When we hit the mountains in New York. The tranny had enough, it started smoking. The fluid was coming out of the dipstick and landing on the exhaust. We pulled over and let it cool down. Then for the rest of the drive i tried to keep it in OD as much as possible, like getting runs up hills so it didnt have to downshift, that kinda thing.

Carrying extra tranny fluid is good, i keep about a quart in the trunk as well as a quart of motor oil when im DDing. On the trails its different. I usually bring a bunch with me.

 

[altierior]

If you unplug your air conditioner compressor then turn it on AC inside the cabin then your electric fan will come on without running the actuall air conditioning. This just gives aditional air. If you don't turn it on it will eventually come on but I don't like to wait untill it's that hot.

yeah, i know this is an old thread, but i just stumbled upon it.

the above sounds like a great idea. i wonder if there are any downsides/negatives to doing this?

 

[altierior]

If you unplug your air conditioner compressor then turn it on AC inside the cabin then your electric fan will come on without running the actuall air conditioning. This just gives aditional air. If you don't turn it on it will eventually come on but I don't like to wait untill it's that hot.

ok, so flame me if this is a stupid question, but something just occurred to me. it doesn't matter to me how hot it is outside, i never run my AC when wheeling. for a trail rig in which i will never run the AC, is it possible to convert the AC radiator to a trans cooler? i couldn't find any threads on such a mod (the search is how i ended up on this old thread), so i'm guessing not.

 

[jeeperjohn]

ok, so flame me if this is a stupid question, but something just occurred to me. it doesn't matter to me how hot it is outside, i never run my AC when wheeling. for a trail rig in which i will never run the AC, is it possible to convert the AC radiator to a trans cooler? i couldn't find any threads on such a mod (the search is how i ended up on this old thread), so i'm guessing not.

Yes you can use the A/C condensor as a tranny cooler. It will work very well. Some will tell you it will overcool your transmission but nobody has ever posted up any data to support that notion. I personally think you can't run an AW4 too cool.

 

[altierior]

Yes you can use the A/C condensor as a tranny cooler. It will work very well. Some will tell you it will overcool your transmission but nobody has ever posted up any data to support that notion. I personally think you can't run an AW4 too cool.

excellent. i will search around some more on this and other forums to see if someone has done it and posted their results and along with a how-to thread.

 

[clean4drxj]

It is possible to overcool the AW4 and ruin it. If you really want to know the imformation behind this just do the research.

 

[altierior]

It is possible to overcool the AW4 and ruin it.

understood. so the question becomes: will a converted AC radiator overcool it?

If you really want to know the imformation behind this just do the research.

trying, but so far i can't find much pertinent information out there

 

[hubs97xj]

Paste this into Google.

use ac condenser as trans cooler site:naxja.org

 

[altierior]

Paste this into Google.

use ac condenser as trans cooler site:naxja.org

thanks. i must have been using ineffective search keywords.

so it seems to not be a good idea. people ditching their AC have removed the AC rad and installed a trans cooler in front of the engine radiator. a trans cooler is smaller then the AC condensor, thereby increasing airflow to the engine radiator. win-win

 

[jeeperjohn]

I have not done this but if my A/C dies I plan to. I have not seen any useful data that shows the tranny would be harmed by the fluid being too cool. I have asked for opinions from several people I know who specialize in transmissions and they all said you can't overcool an auto tranny unless the temps are well below zero. As much as my tranny gets hot towing and running in sand I need all the cooling efficiency I can get. If anyone has any factual data or actual manufacturer info that says the tranny must be at a certain minimum temperature, please post it up. People have posted info regarding the normal operating range but that is not some kind of limit, it's just the projected temps in a stock system.

 

[xcm]

theory < application, i agree and trust jeeperjohn and his trans peeps. overcooling is a fantasy on an auto trans.

 

[XJWOLF]

How much heat can a cooler really take away. The fluid leaving the tranny is gonna be over 200* in any driving condition. and quickly reheat once back inside the tranny. In SoCal it would never be an issue.

 

[jeeperjohn]

How much heat can a cooler really take away. The fluid leaving the tranny is gonna be over 200* in any driving condition. and quickly reheat once back inside the tranny. In SoCal it would never be an issue.

A good cooler could drop the temp 40* or more. It's really a matter of how much cooling surface area there is. A stock A/C condensor has a whole bunch of surface area.

 

[austinaubinoe]

I highly recommend a plate style cooler. Way for surface area then a cheapo tube type cooler, and way for heavy duty. I got mine at JEGS for about 50 bucks and it came with all the mounting hardware and hose. They cheap ones at advance are still around $35.

I ran it after the rad, until I installed a CSF 3 core. Then I just taped the holes on the new rad and only ran the B&M cooler. I also recommend installing a temp gauge like this:

http://www.jegs.com/i/B-M/130/80212/10002/-1?parentProductId=748099

Once you overheat your AW4 once, you'll never feel comfortable without the gauge!

 

[XJWOLF]

A good cooler could drop the temp 40* or more. It's really a matter of how much cooling surface area there is. A stock A/C condensor has a whole bunch of surface area.

Agreed. It won't cool 200* fluid to 100* and "overcool" the transmission. Unpossible.

 

[kdub41]

why not go with something like this? and mount it in front of the rad?

http://cgi.ebay.com/ebaymotors/Perm...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[Original_MudButt]

why not go with something like this? and mount it in front of the rad?

http://cgi.ebay.com/ebaymotors/Perm...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

That would work as long as you have the room for it.

However, that one is the old school tube and fin type. They do work and with the fan should work okay. But the newer plate style coolers are more efficient.

 

[Talyn]

I used a Tru-Cool LPD 4544 9.5"x11x.75" plate style in my cooler install. http://www.naxja.org/forum/showthread.php?t=1026658

 

[kdub41]

thats a good idea ill probably just use that idea

 

[Kevin108]

I put a 25,000 lb-rated cooler in front of the mechanical fan. It works great.