2004 TJ 4.0 overheating at idle after cooling system overhaul

Jacob Boehmer

Jacob Boehmer

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Joined
Jul 17, 2020
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Location
Queen Creek, AZ
Im new to the forum so hopefully I am doing this correctly.

I recently overhauled my cooling system on my 2004 4.0 TJ with 140,000 miles. This includes all new parts: Mopar water pump, Stant 195 thermostat, all new gates hoses, ron davis Racing 2 row aluminum radiator, stant 18lb radiator cap, Murray fan clutch, prestone flush, and thermocure flush (flushes drained from engine block drain with heater core flushed each time also). Coolant level has been checked multiple times at rad cap after properly filling and is always right up to the cap when cool. My radiator is not blocked as I also just had my A/C overhauled with a new condenser.

My jeep runs cool (205F) at 60mph+ Even with it being 110F outside. My “overheating” issue only happens at idle and slow speeds where my temp gauge will get to 220-230 and the engine starts running rough. Any suggestions on what could be causing it to idle hot? Thank you!
 
Welcome to the Forum,

One thing comes to mind since your not using the OEM rad, is the original fan shroud in place.
 
Test the fan clutch to see if it's a bit stiff to rotate by hand when she is up to temps. I'm not a big fan of anything Murray produces
 
I really wanted to go with a Hayden clutch but the local parts store only had Murray. Is it possible that the new fan clutch is defective? It has resistance and “Seems okay”.
 
I've used Hayden and it works. I have the Advance Auto carquest brand, another relabeled part. #215160
 
Jacob Boehmer said:
I really wanted to go with a Hayden clutch but the local parts store only had Murray. Is it possible that the new fan clutch is defective? It has resistance and “Seems okay”.
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It is possible to get a bad clutch out of the box. Are you getting decent resistance she up to temps ?
 
That is not your system, it is simply too damn hot outside for low rpm operation.
In Florida heat, 10 minutes in parking lot with AC blowing and i am looking at stable 240 degrees.

Ever see on long uphills bunch of semi trucks parked on the side, cooling off, and few that push all the way through? Those that keep pushing are very likely with iron cast engines...

...there are also a few that read too much of "The Little Engine That Could" and their story does not end so optimistic, but we ignore those :)
 
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eastbloc said:
That is not your system, it is simply too damn hot outside for low rpm operation.
In Florida heat, 10 minutes in parking lot with AC blowing and i am looking at stable 240 degrees.

Ever see on long uphills bunch of semi trucks parked on the side, cooling off, and few that push all the way through? Those that keep pushing are very likely with iron cast engines...

...there are also a few that read too much of "The Little Engine That Could" and their story does not end so optimistic, but we ignore those :)
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I thought of this... some sort of engineering limit. I used to never go over 212F with my leaky CSF radiator and rust stained coolant though haha. Also, I believe the 4.0 is a cast iron engine
 
Ask the guys who routinely off road in Death Valley and other balls-hot locales, the TJ's stock cooling system is more than capable of cooling in triple-digit temps. Something is wrong if you are running 230+ at idle, even if you are in AZ. My bet is on that aftermarket radiator.
 
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bromel said:
even if you are in AZ. My bet is on that aftermarket radiator.
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I agree, even with a busted radiator cap my stock system did fine in Death Valley 110+ heat. Sure, it could be something else but there have been plenty of threads about aftermarket radiators not working well.
 
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eastbloc said:
That is not your system, it is simply too damn hot outside for low rpm operation.
In Florida heat, 10 minutes in parking lot with AC blowing and i am looking at stable 240 degrees.
Click to expand...
Your system has a problem then, Florida doesn't get that hot. We wheel the deserts of SoCal with the OE Mopar radiators without any problems at all. Aftermarket radiator? Bad fan clutch?
 
bromel said:
Ask the guys who routinely off road in Death Valley and other balls-hot locales, the TJ's stock cooling system is more than capable of cooling in triple-digit temps. Something is wrong if you are running 230+ at idle, even if you are in AZ. My bet is on that aftermarket radiator.
Click to expand...
Its an $800+ locally made racing Radiator. The material and craftsmanship is better than any aftermarket radiator. I know this means nearly nothing if it is a poor design for the application though. I do run 200-205F on the freeway though. Wouldn’t this mean my radiator is working correctly?
 
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