Trans cooler for overheating

I've searched and read a lot about overheating XJ's but have a question. My XJ runs nice and cool even with the A/C running on max until I start to put it under load. Climbing, towing that kind of thing. If I let it just sit and idle it cools right down. I have a manual switch on the electric fan and leave it on all the time. New water pump, thermostat, and fan clutch. I have a two core radiator and the trans cooler is in the radiator as per stock. I'm trying to figure out if a three core would help or perhaps a remote trans cooler or perhaps both?
Any input?

Hallo. You can put an extra trans cooler in front of the existing radiator.
On my '92 it was OEM. Do you have problems with the cooling? Maybe you ask too much of the engine. :yap:


'92 XJ

How is it towing on the flats? Pulling a trailer up the Cajon Pass at 70mph on a 90 deg day is quite a "workout". An external trans cooler will certainly help.

Coolant correct mix?

Radiator cap correct pressure and good condition?

Do you have a fan clutch and is it working properly?

Yes towing up Cajon it gets very hot but my goal is not to do that but to be able to leave the A/C on all through a trail ride on a 90 degree day. I know these things run hot...would a three row radiator and an external trans cooler be worth the money and effort?

Saudade said:

How is it towing on the flats? Pulling a trailer up the Cajon Pass at 70mph on a 90 deg day is quite a "workout". An external trans cooler will certainly help.

Click to expand...

Yes it gets hot towing on the flat but it is acceptable. I won't be towing with it anymore so now I'm just trying to get it as good as I can for trail running in warmer weather. On a run in Johnson Valley yesterday it was OK, but I'd like to get it to run at 210 or under with A/C on rather than going up to 220 when climbing or in deep sand.

When my rad blew I put in an all metal 2 core. Did a complete flush (heater core too). I can run up the Cajon pass or Grapevine no problem now (even did a few runs to Vegas). Mine's a 2wd so I don't wheel with it. Most of the wheelers I read go 3 core with good results and a manual switch for the electric fan so they can turn it on anytime.

Toss in a HD ZJ fan clutch, NAPA 272310 for $44 and see if you still think you need the radiator.

I have a manual switch on the electric fan and leave it on all the time.
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Your ageing the E-fan unnecessarily (IMO) Or let the stock system do it'd job. It;s a lot better at it then mamy give it credit for. The addon trans cooler would be a real plus. They can stock with one when you got the towing package.
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I'm trying to figure out if a three core would help or perhaps a remote trans cooler or perhaps both
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How big of a trailer are you dragging along? The factory recommends 5000 LB with a towing package. (addon trany cooler)
How much towing you want to do?
How fast you want to go, Slow down a bit and pick a lower gear on the bad hills. The XJ will downshift on it's own but (IMO) It needs to downshift sooner for heavy towing. It will make a big difference in over heating.

If you want other upgrade ideas,
The 96 E fan (((((MAY))))) be an upgrade for you. Please check on the year for that. It should have more blade then yours. Get new E-fans. They tend to slow as they age. Also get a Jeep fan they ar very proven. Have a dependable performance level. Unlike SOME of the Ebay poop.
The ZJ clutch fan as listed above.
Trany cooler also above.
Venting the hood will help with engine bay temp when at very low speeds.
Then a rad upgrade, There are 1000 of post on that. I, not going to start again. LUCK

I am in the same boat as the OP. Went this weekend and towed a buddy's YJ for about 70 miles. My 91 XJ 4.0/auto has a new water pump, thermostat, new rad, engine has just over 500 miles on it. Got up to about 230 towing the YJ and got that high on the trails too. The outside temp was about 80. If I ran the heater, the temp dropped dramatically, down to the 190 range. But that was less than comfortable inside. Coming home the outside temp was about 67 and it was raining, and I had the same problem. When not towing, it never gets over 190. I hate to restrict the air flow through the radiator by adding a trans cooler, but I also don't like the temps.

I just installed a B&M trans cooler and trans temp sensor....along with a 3 row rad and a hesco water pump....thing was still over heating when going up long gentle grades or when sitting in traffic for a couple minutes in 90+ degree heat (with the E fan on the whole time).

I installed a heavy duty clutch fan for a 97-98 Grand Cherokee (there is a write up on here somewhere....do a search). and I have not had the temp get above 211 driving around tucson in 100+ degree heat. I really think its your best bang for the buck.

The trans cooler is also well worth the money IMHO.

Thanks all. This thing used to overheat going to the store I now I can wheel it so I'm making progress. Sounds like good steps will be heavy fan clutch and trans cooler. Since I just put a new fan clutch on, (not heavy duty) I'll start with a trans cooler.

ZJ fan clutch ftw. Some say a 3 core can hinder air flow through the radiator. I've been running a CSF 3 core for quite some time with no issues. Even drove 3200 miles round trip to Moab last month and wheeled out in 90*+ heat for a week with no issues with 33's and 3.55 gears. As far as a tranny cooler goes i've run the B&M stacked plate before with decent results. My latest setup is a fan mounted trans cooler from Derale. Saved my ass on the trails. Its set to come on around 180* and shut off at 170*. I also hooked up a toggle to the fan on the cooler and the rad. Remember that adding a cooler in front of your AC condenser and rad will only hinder airflow.

P.S. I mounted my trans cooler behind the bumper .