1998 xj new jeep owner. I live in the mountains in Colorado. My jeep is constantly overheating. Just replaced water pump, and while I was at it I put in a 160 thermostat. After about an hour it will idle at about 210, I drive down the mountain (mostly cost) and it will go down to about 180. But once I drive back up it goes right back to 210 and once I park it will start boiling. Sometimes enough to raise the gauge into the red. Possibly related, but when I changed the water pump, it only took 1 1/2 gallons to fill up, when i thought it took 3 gallons to fill. I have no oil loss, nor white smoke, so I dont think i have a blown head gasket. Any advice would help

 

98 xj new jeep owner. I live in the mountains in Colorado. My jeep is constantly overheating. Just replaced water pump, and while I was at it I put in a 160 thermostat. After about an hour it will idle at about 210, I drive down the mountain (mostly coast) and it will go down to about 180. But once I drive back up it goes right back to 210 and once I park it will start boiling. Sometimes enough to raise the gauge into the red. Possibly related, but when I changed the water pump, it only took 1 1/2 gallons to fill up, when i thought it took 3 gallons to fill. I have no oil loss, nor white smoke, so I dont think i have a blown head gasket. Any advice would help

 

How old is the radiator ? and check the fan clutch and check the coolant is it clean ?

 

I used to have the same issues fan clutch was working, water pump wasn't leaking. T-stats are cheap and available anywhere. I think factory calls for 195 degree. I put in a 180 but it ran too cool so put back in a 195. I installed a 3 row aftermarket radiator. That was 15 years ago. I paid less than $100 for the radiator on Ebay. I've had Chrysler techs tell me to use the factory water pump as opposed to a re-man which I also did. Not sure they're available anymore though. Never had an issue since. RockAuto had a 3-row but they want about $260. imho, that's a lot to pay for a radiator. I'm sure you can find a cheaper 3-row if you shop around. The factory XJ radiator is too small i my opinion.Ebay has a bunch under $100. There's a bunch on Amazon under $150


Not sure why "Radiator" is linking to ebay in my post. I didn't do that

 

Sounds like the complete cooling system needs some TLC. First thing that comes to mind as far as your problem goes is it could be the fan clutch. But it just doesn't take that long to completely redo the whole system.

 

Have you made sure to bleed the coolant system for air? That could explain the boil when parked. 210 degrees is about right for a 4.0 warmed up/under load (FSM puts the operating range between 160 - 218 degrees)

Park you jeep on an incline nose up, let it cool, check your coolant level. Cycle the engine a bit, check again, let it get warmed up, check it again, fill if necessary. Rinse lather repeat.

That kind of stuff is what keeps our forum running, it auto populates as you post and is part of the advertisement revenue for the folks that run the forum.

 

My 95 would only take about 1.5 gallons on each pass when I flushed it, so that doesn't strike me as abnormal.
I would definitely heed the advice of the previous posters - start with a good burping of the system and while you're at it, double check that your coolant/water mixture is in spec. (50/50 erring on the side of more coolant than more water) You can get one of those floating ball testers at your local parts retailer without blowing a ton of cash.
If that doesn't correct the issue, you can try an upgraded radiator.

I'm not sure how the elevation affects the cooling system (you mentioned CO), but it might be worth looking into to see if there's anything that needs to be different due to the atmospheric conditions you're driving in.

 

Yup, three row radiator, new fan clutch, new water pump and 195 degree thermostat. Yearly flush and cleanout and thermostat replacement. Refill with new 50/50 antifreeze. Also replaced electric fan with higher air volume fan and made sure that it is working based on thermo switch without a/c running.

Did this 10 years ago and have not had an overheating problem since.