Need advice from 110 degree plus climate TJ owners

iamloganjames

iamloganjames

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Joined
Apr 19, 2020
Messages
72
Location
Scottsdale, Arizona
My TJ has had every single component replaced in the cooling system within the last two years. Highest vein count Mopar radiator, Mopar water pump, stant superstar 195° thermostat (per Jerry's advice), new copper heater core, new hoses, new fan clutch (twice because the first one was lazy). I have spent big money trying to make this jeep run as cool as possible. I have a big trip planned this summer where temps will be 105°+ and I won't have another vehicle with me. Just my buddy in his dual sport bike. My 4.0 runs slightly above the 210 mark on the guage with the AC on. The other day, at 65mph, the guage was so high that the needle was completely to the right of the zero for 210°. Picture is from the trail before. It's been higher than that.

For those of you in AZ or any other extremely hot climate, is this normal? Will I boil over or am I at a higher risk of cracking my 0331 casting head when running at these temps? I am nervous about taking this jeep out too far from civilization after seeing these temps this summer.

Does anyone have any remedies, or ideas to get my temps lower? Or should I even be worried? Thanks.

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I don't live in AZ, where it gets crazy hot, but it's been over 100F every day for almost 2 weeks. I have a stock 2006 LJR that runs just fine in the heat. Stock and original motor, water pump, radiator, fan, and plumbing. I don't know what it is, but I think there is something else wrong with your Jeep. Maybe something simple like the radiator cap or something else like a bad thermostat. I'm sure there must be a shop in Phoenix that specializes in heat related issues, isn't there? Good luck finding your gremlin.
 
My 99 got just past the zero, and the obd2 data showed that as 235. I think you're right to be concerned, but I don't have a good suggestion for you. A new radiator fixed mine.

Have you tested for combustion gases in the cooling system? Given your 331 head, you may already have a crack.
 
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Seems high but I'm no expert. I'm just down the road from you in Gilbert and my TJ rarely eeks above 195. Recently, coming back from Payson, pulling the longest grades with ac on at freeway speeds, it never went above 200.

Radiator and hoses were replaced about 7k miles ago due to a pin hole leak in the radiator. Other than slowly losing coolant level, even then, it still ran the same.

You might call Letzroll Offroad and see what they say. They're not a radiator shop specifically, but are well known locally as one of the very few go to expert shops for our jeeps.
 
I think of the dash gauge as a rough estimate. If you have an OBDII reader, what is the actual ECT reading? It sounds like you've got your cooling system in good shape. If it's still on the higher side, you could try a HD fan clutch.
 
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L J said:
I'm not certain but I believe the TJ gauges are closer to idiot lights than true gauges. You can buy an OBD2 Bluetooth dongle off Amazon and use an app like Torque to read the coolant temp and see how closely it correlates to the gauge.
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I've heard about that in terms of oil pressure. They switched the guages to read 40 all the time unless under or above a certain value. But mine reads true because it's before a certain year, I want to say it was 2002. Either way, I have a scan guage II in my Camry. Ill see if I can move it over and get a digital display from the ecu reading.
 
iamloganjames said:
I've heard about that in terms of oil pressure. They switched the guages to read 40 all the time unless under or above a certain value. But mine reads true because it's before a certain year, I want to say it was 2002. Either way, I have a scan guage II in my Camry. Ill see if I can move it over and get a digital display from the ecu reading.
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The ect gauge is somewhere in between. It's definitely not just sitting stationary as long as the temp is acceptable, but the response is nowhere near linear either.
 
My 06 has never run that high. With all the parts you have replaced, make sure you have all the air purged out of the system. Having air in the system can cause it to run hotter than normal. I have experienced this in 2 of our 3 TJs after doing cooling system work. There’s lots of info on here about air in the cooling system.
 
Check your exhaust header for a leak as well. That was the errant bit that caused mine to get warmer than I'd like.

Also make sure your rad cap is good. That one's an easy change.
 
I’m in the Midwest and my gauge usually hovers around the middle.

I’ve always thought that the temperature is fine so long as it’s not in the red.
 
Matt131 said:
My 06 has never run that high. With all the parts you have replaced, make sure you have all the air purged out of the system. Having air in the system can cause it to run hotter than normal. I have experienced this in 2 of our 3 TJs after doing cooling system work. There’s lots of info on here about air in the cooling system.
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When I filled the system I pulled a vacuum with a tool that I borrowed from a friend. Was able to hold the vacuum. Then, used the vacuum to suck the coolant (Valvoline Zerex G05) into the system. There shouldn't be any air. Hence why I'm at a loss here. I feel like I've done literally everything I can.
 
Alright everyone. Thank you for all the ideas! I am going to move the scanguage over tonight to see what the actual temp is. But since a lot of y'all are running cooler and think there may be an issue, I am also going to check for combustion gas at the rad cap. Hoping I don't have to tackle a cylinder head job this summer. Last time I pulled a TUPY casting, it was off a junkyard WJ and it was 110° out. Was trying to get ahead and have that head ready for when mine cracked. Or maybe just do it in advance. But i had it magnafluxed and found out it was already cracked. Hence why I still have the 00' head on my jeep.

Ugh.
 
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Would a vented hood help him? Even one from a yard as a summer/non monsoon season hood-

Just asking for his benefit.
 
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jjvw said:
If the needle is pointing straight up at 210, you don't have a problem to solve.
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I was just noticing mine is just below 210 and I’m in nowhere near the climate - At the same time appreciate where he’s coming from and his concern.
 
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AndyG said:
Would a vented hood help him? Even one from a yard as a summer/non monsoon season hood-

Just asking for his benefit.
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Andy, I would absolutely love to vent the hood. But this jeep is too clean to be cutting up or putting a mismatched hood on. Wish my jeep was a trail rig sometimes, because then I could make stuff work without caring how it looked.
 
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iamloganjames said:
Andy, I would absolutely love to vent the hood. But this jeep is too clean to be cutting up or putting a mismatched hood on. Wish my jeep was a trail rig sometimes, because then I could make stuff work without caring how it looked.
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Note the junkyard back up hood idea- sort of like a set of trail wheels

Im all for not cutting up a nice one too-
 
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