I recently lifted my Jeep (5.5 inches) with 33x13.5 nitro mud grapplers and took it trail riding and ran at 200-210 the entire time but when I had to put it in 4x4 to go through the thick sand it goes up to 220 and sits there for a while then all of a sudden shoots up to 245 and the coolant boils over (brown).

-The Jeep has a brand new water pump
-gutted thermostat(I did this to try fixing the problem but it didn't make a difference)
-the radiator is clean
-recent coolant flush
-electric fan is new
-tires at 12 psi

My next step is to put a new radaiator maybe a cfs 3 row.

I'm sure this is not an uncommon problem and was hoping to get some feedback/advice on the issue.

Thanks in advance!!

 

What year is your XJ?

There are a number of cooling system components working in concert, so it's a little hard to troubleshoot this one remotely. But you're going to want to resolve this ASAP as overheating is very hard on hardware and if repeated, you may have bigger fish to fry like a head gasket repair, warped cylinder head or worse.

How OLD is your current radiator in miles and years? If the currently one is old (even if it appears clean) a new one would be a good idea. And don't forget about that radiator cap; a very important component for maintaining proper pressurization. A new radiator and cap can be sourced inexpensively. Be sure shroud is intact as that is important as well.

I'd replace the radiator/cap, fill with 50-50 fresh coolant, put your stat back in, be sure serpentine belt is snug and see where you are at. Good luck and keep us updated!

 

how old is your clutch fan? and is it working properly?

 

1. If your coolant is brown, your system is NOT clean. See my sig.
2. Have you verified that your fan clutch is good? Diagnosing them is difficult, and you might be better off just replacing it.
3. Have you verified that your electric fan is good? Is it coming on when it should?
4. Forget about "rows". More rows does NOT equal more cooling. Radiator design is much more complicated than that.
5. Forget about fixing this with fancy aftermarket improvements (like a better radiator or all electric fans). You have a basic problem, and it needs to be fixed.
6. If you live in a mild climate, skip the coolant temporarily until you know you have solved the problem. You might have to tear into things again, and if you have to drain it all again, you'lll be glad you did. Once you have verified that the problem is solved, drain the water and replace with a good coolant.

 

The fan clutch I'm sure is the original one and the Jeep has 160k miles same with the radiator. I do believe there is a lot of mineral deposit in the cooling system because even when I put new coolant you can see deposit when coolant over flows and a lot in the walls of thermostat housing

 

It is a 2000

 

 

Step 1. Get rid of those tires

Step 2. Get a new cylinder head because yours is more then likely cracked and that is why your overheating

 

1. It is a weekend toy

2. No signs of cracked head. It will never overheat on road or in idle (210 constant).

Any other thoughts?

 

ALLSTOCKCHEROKEE,

First off. Beautiful Jeep. Very nice.

I've seen these types of symptoms on a few posts in the past. Always makes me wonder if it isn't super heated transmission oil going through the cooler/radiator and pushing it over the edge of what it can do. Most people don't have a transmission oil temp gauge, but I'd be very curious. I would even hit the transmission pan with an IR thermometer to see if there is any possibility this might be happening.

 

If it doesn't do it at idle, it may not be the fan clutch. E fan come on?

 

I would at the very least replace the clutch fan. I think they are around $40 and only take a half hour to replace. Would not hurt to replace the radiator. I would just get a stock radiator from the auto parts. If you want an upgrade get a separate transmission cooler. Better off spending the extra money on that than an expensive radiator.

The brown coolant should be addressed. You really need to flush out the entire system, including the engine and the over flow bottle.There is a coolant drain plug on the driver side of the motor towards the back to make it easy to flush.If your coolant is brown I would guess there will be some gunk built up in the motor....Keep an eye on you coolant level--if you notice you are losing coolant and don't know where it is going, it very well could be the cylinder head.

 

Thanks jordan! I never thought of that! How does the transmission effect the temperature of the motor?

The electric fan is new and on ignition.

 

I read this in Donald Trumps voice.

 

Thanks Mike! The Jeep has never had a sign of coolant loss. Unless it boils over when I over heat in the sand lol... but I think I am going to clean the system as best as possible, put a new radiatior from advance, install a transmission cooler and regear.

Thanks!!