TJ Trans cooling ideas

alosix

alosix

Expedition Leader
Still working on getting my TJ to tow the mountains without the overheating issues it had last year.

Part of my issues are very likely the lack of external tranny cooler on the Jeep. I believe that attempting to cool an auto trannying pushing 300-400 degrees is mixing over to my engine temp. It def gets worse any time I'm in a TC unlocked mode going uphill.

So. Looking for ideas on mounting a tranny cooler.

Now for the fun part. I would like i to NOT be in front of the radiator. Trying to keep obstructions there to a min.

Got any ideas? I've considered some pluming with brake ducts, putting the cooler above the engine and getting a Subaru style scoop for it (like the intercooler scoop).

Willing to hear any crazy ideas....

Jason
 
alosix

alosix

Expedition Leader
LandCruiserPhil said:
Remove your trans lines from your radiator and go to a stand alone trans cooler. I have this one http://www.jegs.com/i/Derale/259/13950/10002/-1?CT=999

Damage occurs to internal transmission parts when temps reach 300+ so check your trans temp gauge. At 400 degrees your trans will only last 10 minutes.
Click to expand...

That's the sort of cooler/fan I have in mind. Planning on only using the cooler. I'd do something more creative if I end up living in a cooler climate again but with synth fluid I probably don't need that winter 'warming' of the mixed cooler.

I'm guessing I was probably around 300(no gauge yet). But honestly, the Redline fluid in there is probably the only reason I still have a trans :)...


Edit: And the main thing I need to figure out is.. where to mount the darn thing if not in front of the rad...
 
Last edited:
roadkill

roadkill

Adventurer
you should get a gauge first to see how bad the temps are. what if your overheating issues have nothing to do with the tranny?
 
Black Dog

Black Dog

Makin' Beer.
A lot of the little ricers mount their intercoolers in the front bumper, so that could be an option for you. Or if you aren't worried about tires coming up and mashing into them you could put it in a wheel well.
 
alosix

alosix

Expedition Leader
roadkill said:
you should get a gauge first to see how bad the temps are. what if your overheating issues have nothing to do with the tranny?
Click to expand...

Def working on other things to address that.

But if I'm cutting up my lines to put a gauge in.. I might as well do a cooler. I know it needs it.
 
jim65wagon

jim65wagon

Well-known member
I've seen street rods with long narrow aftermarket coolers mounted inside the c-channel of the chassis.....
 
ntsqd

ntsqd

Heretic Car Camper
Where are you measuring the trans fluid temperature at?
There have been numerous arguments made for various temp sender locations. I'll lay out my logic and let others lay out theirs.
To me the trans is the relatively irreplaceable part. The fluid is a consumable. Knowing the temp of the fluid coming out of the trans will tell you what the converter is doing. That is all that it can tell you because that is the only source for that fluid. The converter can easily be the hottest part of the trans, but it is not the most fragile part - those are inside the trans itself.
Knowing what the temp of the fluid in the pan is will roughly tell you what the temperature of the hard parts in the transmission is, and more importantly, what the temperature is of the fluid being pumped into the trans to lubricate and cool it. The fluid in the pan is mixed from the fluid that has dripped out of the workings of the trans and the fluid that has been returned from the cooler. To me, this is the most important fluid temperature to measure. I understand that Bowtie Overdrives (.com) supplies a gauge with every trans that they sell and the pan already has the sender bung in it. That tells me that they too want to know the temp of the fluid is in the pan.

You do need the fluid to reach at least 170*-175* to drive the condensation out of it. Right now that may not seem possible, but you can end up there. The simple solution is a thermostat.
These are all pretty much the same thing, one just comes with worthless fittings:

der-13011_w.jpg

http://www.summitracing.com/parts/DER-13011/

prm-1060_cp.jpg

http://www.summitracing.com/parts/PRM-1060/

Trans cooler hose is not the same as fuel hose. Fuel hose will only work for a while. Highly suggest using "Push-lok" or "Barb-tite" type fittings with their intended hose (Aeroquip FC332 or equivalent).

As far as location goes, with a thermo-controlled fan you are not limited to in the airflow of the moving vehicle. Can be laid flat under the radiator, laid flat between the frame rails in front of the grill, behind the transfer case & above the skidplate, in the engine bay exiting air through a perforated panel added to the fender liner, hanging off the side of the frame rail just inboard of the rockers, etc.
 
alosix

alosix

Expedition Leader
Ah.. I like those suggestions.

The Jeep is on its 2nd trans (AW-4). Been in there for 80k already. Man how time fly's.

Its currently plumbed with the aeroquip style stuff.

Behind the t-case might just work. I don't tend to whack that area much (used to have a 2.5 gal air tank there). It also seems to be one of the cooler area's under the Jeep.

Jason
 
alosix

alosix

Expedition Leader
Oh, and for the rest of you going 'this guys is nuts, this is only part of the solution'.. I know that :)

Here's the rest of the thoughts:

1.) The Jeep needs a new rad bad. Stock rad on a 1997 TJ with 140k on the clock. Its getting a new one.
2.) water pump was done last year.
3.) A gear change is under consideration. Currently @ 4.10 on 35s with the AW4. But.. the main thing I like about this setup is I can still run 65 mph in 3rd gear when trailering @ 3k rpm if i need to. No OD to build up more heat in the tranny and the Jeep runs good like this. It also affords me decent gas mileage unloaded on flat ground.

It only tends to have issues on longer straight pulls with the trailer. It goes from just a little warm to very warm as soon as I have to downshift to a gear that the computer won't keep the TC locked with. Will be adding a manual TC lock switch to help with that as well.
 
computeruser

computeruser

Explorer
Earlier this year I installed a 26k GVW stacked plate cooler on crossbars welded to the V support in front of the radiator, and plumbed the trans lines out of the radiator - trans to cooler and back, no more use of the bottom tank in the radiator. No problems with overheating, and I'm actually running cooler engine temps at trail speeds than I was before. No problems have been detected in 0* temps, either. And I tow a whole freakin' lot with this setup, year-round, too.
 
ExpoMike

ExpoMike

Well-known member
Though not a direct bolt in like the above post, this is the one I have on order. It's a little cheaper in price but you have to figure out the mounting.

http://www.summitracing.com/parts/BMM-70297/

I have used this one before. It's nice because it is basically self contained. The fan, t-stat switch (turns fan on at 180*) are all on one unit, so just run your two lines and mount it. Once in, you can basically forget about it.

Currently I have a cooler plummed to bypass the radiator and have a temp gauge on the tranny output line (got the wrong line when installing). I also have a temp bypass (similar to listed above) so the fluid will bypass the cooler until at 180*. With all this, I show temps typically with the TC locked up, cruising down the freeway (towing or not) at 160-190*. TC unlocked (climbing a grade) is will come up to 210-230*. Highest I have seen it was 275* and that was high RPM's, 1 gear, in the dunes. Keep in mind, this is the output from the tranny, not the pan temp or after the cooler. I am actually thinking of getting a second temp sensor and putting a switch so I can change between input and output temps. May do that when I put in the new cooler.
 
H

hugh

Observer
Just my 2 cents. The trans needs to be at a certain temp once its warmed up which is why they route it through the rad tank. If on a heavy haul your system is overheating maybe consider 2 options. First add the external cooler in to the line before the line goes through the rad, that lets it bleed off excess heat. That way the rad tank can have some of the heat taken out and it will be better able to do its job. You can grab a cooler at any junk yard from say a 1/2 ford. On my old CJ7 I mounted a fin and tube cooler on the inside of the wheel well on the drivers side. It got enough airflow to make a difference. Also consider adding an oil cooler also to your rig
 
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