So I got my jeep, it's a 96 4.0 with 193,XXX miles. I drive it around base for 2 weeks and it never gets over 210 degrees. I flush the radiator and put new coolant in it. I put one jug of the stuff thats NOT 50/50. I think its the concentrate. one jug and filled it with water after the flush. Today I drive to the next town over 45 miles through the mojave it almost broke 100 degrees outside today. On the way there it was runnin 220-240 and on the way back it just touched the red before I got home. Its through the mountains and goin downhill it stays around 210, but as soon as I go uphill it gets hotter and hotter. I'm lucky it leveled off.

I keep hearin' that cherokees are hot under the hood, but what can I do?

Exhaust manifold is new, the thing runs damn good for 200,000 miles. I just don't know why it would run so damn hot.

 

is the electric fan coming on? it should kick on about 220.

 

my jeep also seems like it runs hot. you cannot even touch the hood after a little bit of wheeling. gauge stays right on 210 at all times. time for some hood vents maybe

 

while i was flushing it it kept coming on about when the guage ran 210.

 

If it's only getting hot when under load going uphill, then it's more likely to be a coolant flow issue versus an airflow issue. Maybe a clogged radiator or a failing water pump...how nasty was the stuff that came out when you flushed it? Could have broke some gunk loose that is now restricting flow. I would say definitely replace the rad and water pump if they're original.

Just out of curiousity, how does it do at an extended idle?

 

when I flushed it a bunch of rusty water came out, I rinsed it till clear water came out then used the flush, then refilled with coolant/water.

The radiator is not original, it was in a wreck and the radiator had to be replaced when it was 3-4 years old. Its a metal one and it was the "heavy duty" one says my mom when she replaced it.

 

Mine was full of rusty water too last year when I bought it and rad was shot, sprung a leak. Your rad is still 10 years old, so I wouldn't rule it out. What about the water pump? Isn't it easier when stuff just breaks completely so you know what to fix, LOL.

 

its only been today that I have had the problem. I drove it around all day after the flush and it was normal. Today was a hot bastard and when I idled it with the AC on it got a little hotter then normal. It was only hot under load up hill as soon as I got level it stopped getting hotter. When I was goin uphill and turned the AC off it helped a little but not alot. I pretty darn sure the E Fan works, during the flushing process I made sure it was at operating temperature and it stopped and started a few times that I noticed.

What about the fan clutch? How is it operated? Is there a way to lock it up permanent style???

 

Its possible its an air gap in your coolant system. Purge the system again, i.e. turn the heater control on full heat and open the radiator cap when its cool. let it run until the thermostat opens up and you should get a little air out of the system. Top off the coolant and the overflow bottle and put the cap back on. Test it again. Normal temp for the 4.0 is 210. I believe the fan clutch engages around 220, and you should hear it lock in with the louder fan noise. keep a check on the temp and coolant level, and burp again if necessary. Those air gaps can fool you at times. Good luck!!

 

X2 on the possible air in the system. But on the fan clutch, it does not engage instantly at a certain temp. It has some kind of viscous material inside that gradually engages the fan as the clutch gets hotter. Even when it is "fully" engaged, it is only spinning at something like 70-80% of engine speed...it doesn't actually lock completely.

Here's how I figured out that my fan clutch had gotten weak. Let the engine run at idle up to 210+ giving the fan clutch time to absorb as much heat as possible to get it to engage. Then with the hood open so you can see it, turn off the engine and watch how quickly the fan comes to a stop. My old weak fan clutch would continue to spin for 3-5 seconds and therefore was not engaging much anymore. When testing my new fan clutch the same way, it stops instantly with the engine, spinning less than one revolution after engine shutdown.

 

If it is an all metal rad, you can have it cleaned out. A rad shop can take it apart and clean all of the path ways in it. If it's 10 years old, and rusty water came out of it, that doesn't sound good to me. BTW, rust will not rinse out. Hope you get it fixed up!!

 

Put a switch on your AC fan so you can run it any time you want!

 

so I "burped" it and quite a bit of air came out. When I opened the cap the level of fluid bobbed up and down spilling a little bit out every time and after a while I checked and it had went down quite a bit. I filled it and after a while longer bubbles came out again.

I hope this fixes it.

Is this something that I have to repeat? Is there a way to stop this from happening in the first place?

 

You should check it in the morning when cold and then again when it has cooled down after driving to see if the level varies with temp. Another thig that I didn't see mentioned was the fan clutch. It being probably 10+ years old may be slipping too. It is worth checking.