I was just thinking outside the box here, I can't get my jeep to cool down on the highway, I know it weights a lot, 5500-6000 lbs, I did all cooling upgrades I can,
Now I was thinking what if I cut out the bottom of the radiator core support and re-fab it to hold a bigger radiator and bigger fans.
Trucks pull all kinds of weight no problem like mine, it never gets hot, what if I add one like it??

 

What have you done for upgrades? What year is the Jeep? The bone stock cooling system is more than capable of cooling a 4.0 on the highway (or 2 mph on the trail). My XJ that weighs close to the same as yours has a bone stock cooling system and stays at 210* all the time no matter what I'm doing.

People dump tons of money into cooling systems and it'll usually hurts more than it helps.

Are you running dual electric fans?

Something else is wrong with the system.

 

1997 109k miles had motor check for leaks, all good.
Flex lite radiator with the 3 e-fan setup, new hoses, hood vents, waiting for that Flowkooler water pump, tried 195,180,160 stats, timing good, jeep runs really good, trails around town fine, highway good, add a small hill, it goes up

 

Sorry highway good FLAT

 

There ya go. Put a mechanical fan back on it with a good shroud. Mechanical fans move significantly more air than e-fans. If you want an upgrade use a ZJ fan clutch.

 

Will try it, and let you know soon, as I am heading up to the mountains at the end of the month, 4 day trail camping trip, last time I made it half way, pulled over 10 times to let it cool down, then went back home and got my YJ

 

When I drive in deep and soft sand it feels like my XJ weighs 5000 pounds.
Running 2000 RPM and going 8 mph.
The ZJ fan clutch was the fix for me, to move more air at low speeds, but your issue is highway cruising.
Could be the radiator has clogged orifices. Is it a 3 row? They like to clog up due to the smaller passages.

edit; Didn't know you had e-fans. That is likely the issue, judging by reports from other users.
I swear by the ZJ clutch and think it will serve you good. Usually will not work with a 3 row radiator.
NAPA part #272310
Advance #215149

 

I flushed it a few times then added the new aluminum radiator, it helped a little just took a little longer to get hot

 

3row

 

The ZJ clutch sticks out about 1" further towards radiator. I can get an exact measurement if you might have the room.

 

Can you, will try it

 

Are you running shrouds on your e-fan setup?

 

Yes what it came with

 

5/8" longer
XJ clutch overall thickness = 3"
ZJ clutch = 3 5/8"
With my 2 row radiator there is only 5/8" gap between it and fan clutch.

 

Will try it, will see