Hello.
my son and I are new to Jeeps, and just bought a 2000 XJ that needs a few small mods to finish. It runs and drives, just don’t want to take off road until we finish upgrades to driveshaft. We are fine with this part.

The reason we need help is possible overheating in the Phoenix heat. If we drive even under a small load, 50mph slight uphill with AC on, it will go up to 220 and slightly over, and twice the coolant boiled out of the overflow bottle. It never blew out of the radiator cap or stopped running. Coolant boiling out of overflow bottle was quite worrisome. If it goes over 220, we turn on heat and slow down and it goes back to 210-220. Being that it’s 108 degrees outside, you can imagine it’s not fun driving with the heat on. Since this is going to be partially a daily driver for my 16 year old sun, I want to try to improve this.

The previous owner upgraded cooling system to new 3 row radiator, electric fan with Dakota controller, v8 mechanical fan upgrade, high flow water pump, new 195 thermostat and housing, and all new neoprene hoses. and trans cooler. It has a 505 performance upgraded 4.0nengine. You would think that with these upgrades, it wouldn’t get hot..... but again at this temp the coolant boils out of the overflow bottle. I have been reading a lot of posts on this and the common theme is they run hot and it’s fine, but is it safe to go over 220... doesn’t seem so and I don’t want to blow the head.

Thanks in advance for any input from someone who lives in a hot climate. I don’t want to blow the head by overheating it. -Nick

 

We have quite a few members who wheel in AZ. They seem to think the stock cooling system in good repair is all you need for anything except lots of slow rock crawling.

Here's are a couple of dirty little secrets:

• Rows in your radiator mean very little. A well designed two row will cool better than a poorly designed 3 row.
• High flow pumps are highly overrated. If the coolant doesn't have enough time in the radiator, it won't cool. It's called, "dwell time", and it's hugely important.

As to your question, no, not safe to keep running over 220. You have a cooling problem, and it needs to be solved. Think about this: If your stock setup can handle that kind of use with zero overheating, why can't yours?

I'd start with the T-stat. Pull it and test it on your stove with a thermometer. Make sure it is opening all the way. That's the easiest and cheapest thing to test.

If that's good, I'd ditch the high flow pump and put a stock on one there and see how that works.

This is all assuming it has been well flushed, of course. If the interior of the cooling jacket is crusted with scale, it's not going to cool well.

 

Factory Mopar stat and make sure the radiator cap is holding pressure.

 

Toss the highflow pump into the garbage or sell it to someone who thinks it will work. Put a stock replacement pump on there. For reasons mentioned in prior posts

The OEM thermostat has a "jiggle valve" you can modify aftermarket thermostats that don't have this by drilling a SMALL hole in the 12 oclock position of the flange.

I'd toss the 3 row or again sell it to someone who thinks it'll work and drop a Spectra in there. If you can find it/afford it the OEM "HD" cooling radiator from Mopar is probably the best. Later models used a thick single core earlier models used a dual core setup. They're very hard to find anymore, Chrysler stopped making them years ago. Most find the Spectra unit to be perfectly capable of keeping a Jeep cool.

Make sure you have a good fan shroud as well. Without it the belt driven fan wont' draw air though the radiator core and will pull it though the path of least resistance which is from around the radiator. The 4 cylinder XJ fan clutch is the one most people use for an upgrade fan clutch, I keep one on the shelf for mid summer trail runs. I do get a 1ish MPG drop in fuel mileage when using it. I spent the money on an actual OEM Mopar fan clutch from Jeep (not a 4cyl a regular 6cyl clutch) and it's been working like a champ. A lot quieter too lol.

 

Thanks for everyone’s advice!

It has a manual temp gauge, and is much more accurate than the dash gauge (compared to an Infrared thermometer). Main fan and electric fan both have shrouds.

we had previously changed the fluid, but decided to start with a flush. Got some chunks out, and much better now. Maxed out at 210 temp up a hill with full A/C on and an outside temp of 110 (record temps today for May)

will check thermostat and get a standard pump this weekend.

Thanks again!

 

I live in LA and it gets hot here also I used the Champion 2 row all aluminum , I'v had it now for about 3 years and it does keep it cool but if you use a 2 row it does work better with a high volume water pump .

 

I'd hang loose on the water pump for now. Maybe flush it again? Get the Mopar stat for sure.

 

If it's a new flowkooler pump it's not going to out flow the radiator lol.