4x4jeepmanthing

I would like to add a bigger trans cooler and I was curious about some things before doing so.
Ive read that a cooler of at least 13000 btu is what I need to look for, this had me wondering if there is a point where a bigger cooler just isnt going to gain me anything, Is there a known break for cooler size and does it matter if I delete the rad cooling lines to just run a trans cooler? For example is a 16000btu... cooler not going to work any better for this application or set up?
so far im leaning towards 13-14000btu stacked plate cooler.

If you know of a good set up (btu to solo cooler) please fill me in, thanks!

bluejeep2001

Not trying to be a jerk but..why do you think you need a bigger tranny cooler. I have had 2 jeeps for the last 20 something years..the old 92 stroked at 250 ..died at 347. for the first 150 it had a stock tranny cooler and then I added the standard 7x9 6 tube and i dont think I ever had any transmission issues right up to the end. My 01 got the tranny cooler around 150 also..stroked at 175 and now has 255 also with no issues. I don't have a tranny temp gauge so I have NO idea what the temps are but the fluid never seems brown or black or burnt. I don't offroad on them but I do tow a 6000ib boat 20 or 30 miles several times a year on both for the past 20 years. While troubleshooting some higher coolant temps I found something interesting that I NEVER knew but it might be common knowledge.. The upper coolant line, the metal line with the flare connection is the coolant return line to the tranny. I always assumed that was the pressure line so I had my aux coolers hooked up backwards for all these years. Jeep recommends that the flow goes through the main/radiator cooler first and then go thru the aux cooler. Now...where is your aux cooler located, Im sure those btu numbers are dependent upon good airflow. In front of the mechanical fan is prob best because its always running but that preheats your coolant cooling air a lot and then it still has to get thru your condenser and then finally thru the radiator..anywhere else and it only gets good cooling air if the aux fan is on or your at highway speeds

4x4jeepmanthing

No sweat, Im not stroked but its engine #2.hopefully a stroker some day. Im also on 35s and high alpine highway has her running hot and Im just trying to add something that will help keep the trans alive, 250000ish on her now. Im not too worried about impeding air flow to the radiator. I was thinking that bypassing the trans too it, that it may even cool a little better without having to perform cooling for the trans as well. If I wired the electric fan to be switched on manually then I can aid the rad even further. This has been recommend by some that run strokers for optimal cooling.


While doing this upgrade it would allow me to add a trans temp gauge, this brings up a good question on where that should be installed (pre/post) cooler, any preference? pre seems like it would be more telling, no?

bluejeep2001

I think the sensors are supposed to be in the outlet line to the cooler. I think 165 is the standard temp. Remember...you can't make heat disappear. If you bypass the direct cooling in the radiator...then you just make the fluid in the aux cooler hotter and now the air going over your radiator is hotter. Its probably better for your tranny to have an aux cooler but im sure it brings your coolant temps up some. If its not july or august your radiator can easily handle it...if its the heat of summer it probably struggles like the rest of ours do

00t444e

I got a Hayden 405 cooler on mine, not sure what the BTU rating is but my trans temp hasn't gone above 190* since the install, before it would get up to 220* in normal driving. The correct way to plumb it is from the transmission into the radiator, out of the radiator into the bottom of the transmission cooler then back to the transmission.