FIRST TIME POSTER HERE. I OWN A 1990 JEEP CHEROKEE 2 DOOR 4X4 4.0V6 AND RECENTLY STARTED HAVING OVERHEATING PROBLEMS. SO I DECIDED IT WAS TIME TO REPLACE THE COOLING SYSTEM WHILE THE ISSUE IS AT HAND, WENT AHEAD AND CONVERTED IT TO THE OPEN COOLING SYSTEM USING PARTS FOUND ON THE LATER XJS AND SUCH . STILL OVERHEATING! IVE REPLACED THERMOSTAT AND HOUSING, RADIATOR AND CAP, RADIATOR HOSES, RECOVERY TANK, WATER PUMP, FRESH COOLANT, CYLINDER HEAD AND HEAD GASKET. STILL OVERHEATS AFTER ABOUT 15 MINUTES OF IDLE AND DRIVING ALIKE... ANY HELP WOULD BE GREATLY APPRECIATED AS THIS IS MY WINTER DAILY AND I AM CURRENTLY STUCK DRIVING A 91 FIREBIRD THIS WINTER SO FAR

 

Sure your temp gauge is accurate?

 

same first thought I had... that's a pretty loaded parts cannon without checking that.first

 

Yeah i forgot to mention i did away with the stock gauges long ago. It is accurate as i compared it to a block tester. And i know it is overheating due to the boiling coolant in the overflow tank. but i replaced the head-gasket after pulling the plugs and taking a peek and seeing coolant pooled in cylinder 4&5. pulled the head and sure enough the gasket was done. then had the head checked and found to be warped. i maybe should have specified i did not replace of the parts listed in the op in one sitting. it was all trial and error one thing at a time. From after the initial necessary head gasket and head replacement it was cheapest-more expensive in regards to order of replacing things it could be. But of course to no avail it still wants to overheat. and im kinda stumped. hense why Ive turned over to you fellas. Ive been working on vehicles for a long while now but i will say the renix system on this jeep is pretty cool and very simple system if you know what you are looking at.

 

i would be leaning towards your clutch fan. replace that and get back to us. (if you haven't already)...

 

not the clutch fan.. just replaced it yesterday and still doing the same thing. im at a dead end here. complete cooling system replaced and still overheating. yay lol

 

You said the head was warped, exactly what machine work was done to the head after that? I also did not see any mention of a compression test. Also, I have seen the impeller come loose inside a new water pump.

 

it was used used as a core. i put a brand new head on it from my work. everything I have thrown into this thing is all brand new parts. i work at o'reilly auto parts. get a killer discount, very helpful when owning a jeep. although i have not ran a compression test but wouldn't i notice a slight miss or irregularity. the jeep runs amazing and doesnt skip a beat. just keeps wanting to overheat on me. ill do a compression test after work today and report back.

 

I have had nothing but problems with t-stats these days. Brand new units causing overheat and under heat issues.
Brand names be damned Ive gone thru a half dozen before I find one that actually works right.

Swapping out the t-stat might be your resolution

 

I'm wondering about air flow. Is the cooling stack dirty or plugged maybe not allowing air through?

 

All the additional info really helps!
Pick up a block tester and test fluid at work and check the cooling system again for combustion gas leaking into the cooling system. I find that easier/faster than doing the compression test as a first pass. Things can go wrong on a head and head gasket install. Also, was the block checked for flatness when the head work was done? Bubbles in the overflow tank may indicate that there is still a combustion gas leak into the cooling system.

 

SHES FIXED!!!!!! Thanks for all the help guys. i really appreciate it. Turned out to be my new faulty water pump. warrantied out for another and it runs nice and cool with 0 issues. only problem no is no radio or dome light. replaced fuses. re checked radio wiring to harness. checked fuse on back of radio -"rare but happens" and changed bulb in dome light. both went out at the same time ?

 

another C.R.A.P. victim!!!!!!!

Chinese Replacement Auto Parts

 

How the HECK did you troubleshoot the problem to a waterpump?

 

That's what you get for using cheap china sourced parts from Oreilly's. :}
Lifetime warranty often means repeatedly replacing it until you get one that lasts.