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tranny cooler recommendation?

O

outlander

NAXJA Forum User
Location
Columbus,Ohio
Ive got a 97 ZJ with 4.0 and 42re transmission.
Its been awhile since ive had an automatic jeep so im out of the loop as far as what aux tranny coolers are the best.(i have the stock one now that runs into the drivers side radiator tank)

Also any feedback is welcome on weather i sould run the aux cooler in parallel with the one that is currently in the radiator or just run the fluid through an aux cooler mounted in front of the radiator?
My thinking is if i use an aux cooler only it should cut down on engine temps because i wouldnt be having hot tranny fluid running into the radiator tank anymore.
Then again it does get cold here in Ohio so the tranny fluid prob helps the motor warm up faster?

Should i run the two in tandem?
 
Standard practice is to run them in series with the fluid passing through the aux cooler first. That way when the tranny is hot is puts less heat into the engine coolant and when the tranny is cold, the engine coolant helps to warm up the tranny fluid.
 
Use a plate style cooler, they are more efficient than the tube style coolers.
Running the setup as already stated by the person before should be fine. If you get a cooler kit it should have line and fittings and some basic instructions on how to tap in and modify current system.
 
Bigger isn't necessarily better, I was doing a lot of high speed driving and thought a bigger cooler might help the tranny last longer. The first cold winter and my shifts got sticky. It would tend to hang in first and second until the fluid got warm.
All around it seems to work out better with the near stock setup and not something over sized. Likely a non issue in warmer climates.
 
PaulJ said:
Standard practice is to run them in series with the fluid passing through the aux cooler first. That way when the tranny is hot is puts less heat into the engine coolant and when the tranny is cold, the engine coolant helps to warm up the tranny fluid.
Click to expand...

I may have always been misinformed, but I thought it was standard practice to put the standard radiator transmission cooler BEFORE the new aux cooler that way the transmission fluid is as cool as it can be before it is returned to the transmission.

http://www.carid.com/images//bm/cooling-systems/pdf/coolers-user-guide.pdf
 
Last edited:
I got my cooler from These guys. Good prices and service I thought. The TruCool HD ones regulate the temperature to avoid over cooling.
 
lazyxj said:
cpefy3 said:
I thought it was standard practice to put the standard radiator transmission cooler BEFORE the new aux cooler that way the transmission fluid is as cool as it can be before it is returned to the transmission.
http://www.carid.com/images//bm/cooling-systems/pdf/coolers-user-guide.pdf[/QUOTE]

You are correct.
The same is stated in the FSM (year 2000)
Click to expand...

I looked again and this is in fact the case on both 97 and 01 FSM and the way it is plumbed in my 97 XJ. On the transmission, the front line is the supply and the rear most line is the return.
Click to expand...
 
My mechanical intuition is telling me to run the fluid through the radiator first and then out to the aux cooler and then back to tranny.
Which is what i intend to do.
Those tru cool coolers are sweet...may end up with one.
 
I won't step into the debate of where to put the aux cooler, instead consider eliminating the radiator cooler altogether. Get a big enough aux cooler with ability to regulate temperature(and filter with temp. gauge while you're at it) and simplify the whole cooling process and eliminate the risk of the radiator cooler failing and mixing coolant into your transmission.
 
outlander said:
My mechanical intuition is telling me to run the fluid through the radiator first and then out to the aux cooler and then back to tranny.
Which is what i intend to do.
Click to expand...
Operating temperature is defined. Colder fluid shrinks seals, resulting in slower and longer shifts, and increased clutch wear. Running the fluid back through the radiator normalizes it. It doesn't matter for SoCal maybe, but Ohio gets pretty cold.
 
If you have any doubts, you could just leave it the way it came from the factory. Unless you are towing and seeing high tranny temperatures, draining the pan and refilling every 10-30,000 miles is probably a good idea. I am not sure about your particular transmission, some have drain plugs and others have pans that must be dropped. Sometimes you can make things worse by trying to fix what isn't broken.
 
Im just trying to make this transmission last a long time because its a heavy son beach and i dont wanna be changing it anytime soon.

Came across a chart that has temps from low to high and resulting tranny life...

Gonna be adding a temp gauge this weekend to see where the temps are so maybe i dont need an aux cooler....we will see.
 
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