04 Gr. Cherokee 4.0 - Complete cooling system replacement and still overheating!

My daughters 2004 Grand Cherokee (4.0) a week ago Friday threw a code - said Thermostat, so I replaced the thermostat, OEM 195, easy job. Drives for a week all is fine. Last Friday it overheats - she has it towed to my house. No leaks, system is full, pressurized, all looks fine. When she bought the car 3 yrs ago it was loaded with stop leak, which I told her was a big concern but it was too late. But that was 3 yrs ago and it's been fine. My first thought is that when I changed the t-stat and replaced a lot of coolant that it stirred stuff up inside and maybe the t-stat was stuck. Took it out, looked fine, put it in water, heated, it opens fine, etc, cabin is smokin hot, etc. Reinstalled t-stat, new gasket. On to plan B - radiator, was original, and with all the stop leak thinking ok that has to be clogged and the problem. Replaced it yesterday, refilled the system again, still overheating. Water pump is only item left , showing no signs of beinig bad, not weeping, pulley is true, no noise, but replaced it anyway. Refill again, STILL overheating. UUUUGGHHHH......

I do not think it's a head gasket as shows none of the expected signs such as exhaust vapor, no coolant in the oil (its clean), no oil found leaking, idles fine, starts fine. Not likely a temp sensor as that would throw a code and there are no codes. Now - the only thing I've noticed is that the electric fan doesn't seem to be turning on until it's pretty hot past the 195 -210 operating range, and I don't know if the fan is functioning at full capacity as it's not my car, but the fan is essential to cool if just sitting idling but would that alone cause an overheat? There's nothing left as there are not that many moving parts to a cooling system. Again for the past 3 yrs the car has been fine - no issues, and even a week after t stat change.

Would REALYY APPRECIATE and insight here as I'm at wits end on this one. The only good news is it's easy to work on, but I'm tired of working on it.

THANKS!

 

welcome - hope we can help - jeep WJ old world and pretty simple, anyway I think this WJ was a good model,

Lets get started, ALWAYS post the code numbers. Devil is in the details.

Yes the elec fan comes on @ 220deg F - yikes thats a concern to old timers like me, but that is the design.
And I think this high temp is uncommon and concerning to you. .

TMI:
Thermostat - something so simple and old world, you would think they got it figured out BUT no aftermarket quality makes this a crap shoot.
Did you burp all the air out of system? My old school trick prop the T'stat open with an asprin when refilling.

The water pump - well I have seen them erode the impeller resulting in no more flow/pumping.

Be sure all shrouds are there, Water pump is spinning, system is burped.
If you remove water pump look at impeller blades. There is a R stamped on them indicating a reverse and the new pump should match removed pump if has the R or look at direction of blades they need to match .

 

Welcome to the forum @MDB1056 . Your in awesome hands with awrench.

But just food for thought. It has over heated several times now. Once it overheats. It is susceptible to over heating again. As you mentioned. Leak stop is like a cancer causing agent. It will clog and block the small cooling channels in the motor.
I owned a 2000 XJ with a 4.0. Basically the same motor. I cooked the motor once. And it was never the same. Blew a leak in the radiator, and in an emergency. I threw in a bottle of stop leak. Bottom line. Over heated again. And cracked the block.
$5000 later. Had a Jasper remaned motor dropped in it. Hope your daughter doesn't have to go that route.
Good luck....

 

Thanks much @Awrench and @JKBob 25. All the shrouds are in place, iof there is a trick to burping air out let me know. I've parked it uphill and run it with the cap off until it quit gushing. Again ALL components are brand new and working. Agree stop leak is terible stuff and told her at the time to walk away when that was known but they bought it anyway I would think that the coolant swap at initial tstat install and then the, following full radiator flush process would have cleaned out anything still in there and then again wiht the water pump being last the system agaion got drained and filled. Again it starts fine, runs smoothe, no common signs of gasket or block issues. Will check at the temp the fan comes on as you noted 220 is trigger. Looking for any other insights here as something is clearly still going on. Thanks much!

 

did you replace the radiator? I thought it was new...
Get a bottle of radiator cooling flush and use before we open it up to ck water pump.

What exactly are your concerns, what is the issue, remember a dash gauge is not a calibrated instrument, a guess at best.

The system will set a code for temp and elec fan issues, May not turn on CEL but will set a code.

 

@Awrench thanks. Yes radiator replaced Sunday followed by water pump yesterday. Did the bottle if radiator flush earlier Sat before deciding to replace. The Efan is now not coming on so that’s next but as it was kicking in last couple of days and this was still happening I’m not sure it’s that as the main issue but it needs to be addressed. Sitting idling in my garage the car if allowed will heat to the danger zone . I turn it off in advance of course and have external fans then blowing on it to cool quickly. Temp sensor if bad would throw a code I believe and there are no codes active or stored.

 

trying to follow along, symptom are temp gauge rises to High (red) area, E fan is not coming on?

remember the E fan will not activate till ECT = @220deg F.
TRY -
selecting AC or defrost did fan engage*?
Do the key on off trick to access codes.
>> https://www.youtube.com/watch?v=PyHTNhsTZXs

As I mentioned before Thermostats are problematic - they cant get them right esp aftermarket brands. IDK

Search around this site - lots of helpful information.
http://wjjeeps.com/service/cooling.htm

*AC on to check fan is NOT a complete test- just a thought I had. Can't get to manuals now to check 'logic' the PCM uses.

 

@Awrench - many thanks. Didn’t know those jeeps stored on board. Will check when I get home and see what shows. Nice looking Jeep in the clip- exact match to my daughters. Must be a popular color combo etc. I did read elsewhere the efan is a two speed fan which is helpful- as even when this one did come on it seemed low speed and not the high speed whooshing I’m used to hearing when efans engage. I’m leaning more and more to the fan now

 

TMI, fans are PWM (pulse Width Modulated) meaning variable speed - the PCM controls the speed...

 

Problem solved. We missed the obvious up front. Issue was the fan. replaced today with new Dorman assembly - super simple - plug & play, and all is well. I missed that regardless of all the other components if there's no air movement through the radiator the car will overheat. It didn't occur to me until after the water pump. Not knowing the vehicle I didn't know the fan or if / when it runs etc. So my daughter has a COMPLETELY new cooling system of thermostat, housing, radiator, cap, water pump, and fan. Should be good for a while. All in parts total is only about $290, and all with lifetime warranties. Interestingly learned also that the fan is connected somehow to the AC working well as when this was going on the AC would only start to cool then shut down and blow warm. With this fixed it runs fine now. Really have to say that this 04 Grand Cherokee with the 4.0 is a pleasure to work on compared to SO many other vehicles as everything is easy to get to which makes a HUGE difference.

Thanks so much for the traffic - especially @Awrench. Hope this might help out someone else that has a similar issue. No doubt I'll be back her efor help with another issue. GREAT forum!

 

Glad you got it - hope you got a "good daddy"

Help me follow the repair -
in your first post you said the fan would come on. Yet you laser focus on the fan in above summation - what why was the clue?

Also did you try the key on off to check codes? Any codes appear?

I told you the WJ is not a bad vehicle to work on - seriously there are a lot worse, keep in touch if anything else needs the daddy touch...

 

Youre correct the fan did appear to be on at times early in the process but not on at many other checks. Also when on it seemed in my opinion slow, and not the larger WHOOSHING sound you exepct with e fans kicking on. But as not my car I didn't know what was normal. After it not coming on when heating past 210 after other repairs that's when it started to register, and when I found a post off the web about hotwiring to check and gave it a try. In retrospect the fan should have been a key focus up front as again without air through the radiator there's no way to keep an engine cool. Simple.

I did check codes on the car, still nothing (says donE) which I asume means no codes. I'm sure I'll be back to the forum soon with something else, bit it should NOT be a cooling system issue!