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Discussion Starter #1
What does everyone do to keep their JK 3.6L engines from getting exorbitantly hot? Im constantly at 240 to 246* when highway driving with AC on. Then this past weekend I was pulling my Turtleback returning from the North Rim and hit 255* (the tattle light comes on at that point, just FYI). While Im not worried about that being too hot for the short amount of time it was at the temp, I just done like the fact it gets there so easily.

Climate at the time: Pulling up/down/around 4000-5000 feet south of Flagstaff to Phoenix. Ambient temperature was pushing 105* or so. Running 4.88s right around 3200 RPMs. With AC temp would pop up to 240-244* and on a long incline pull reached 255* for about 5 minutes.

Anyone have any feedback?
 

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Well the first I would say is slow down a little, drop the rpms. The other thing to do is move to a better radiator. I am running a aluminum one, holds 1/3 more coolant than stock. Rarely do I see the 230's even when pulling. But the first one failed, but it looks like the second one is a keeper. The other thing I did based on some reading was flush the entire system and switch to green antifreeze. Seems these newer antifreezes don't play well with aluminum radiators and may be the reason the first one failed.
 

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@TerryC6
I really appreciate your sharing this info about your larger capacity radiator.

But as far as the green coolant goes (which is no doubt a great coolant as well), most of the manufacturers have dumped it over 20 years ago and using the new pink stuff ever since.

This is basically DexCool, with minor to no changes among manufacturers. DexCool got a bad reputation in the late 1990's, but is used since - with great success in millions and millions and millions and millions and millions of cars for the past 20 years or more.
 

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@TerryC6
I really appreciate your sharing this info about your larger capacity radiator.

But as far as the green coolant goes (which is no doubt a great coolant as well), most of the manufacturers have dumped it over 20 years ago and using the new pink stuff ever since.

This is basically DexCool, with minor to no changes among manufacturers. DexCool got a bad reputation in the late 1990's, but is used since - with great success in millions and millions and millions and millions and millions of cars for the past 20 years or more.
And it may be just fine for stock radiators but after reading an article by Champion radiators and the way my first radiator failed I made the swap. I will need to change more often but otherwise we will see how it performs.
 

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Discussion Starter #5
@TerryC6 - yes, lower Rs would work as well. Thanks for the reminder. Those are always welcome from time to time. I was pushing fairly hard this trip as I had my English Bulldog with me (with no back windows in) so wanted to get to the house AC as quickly as possible.

What failed with your aluminum radiator with the DexCool-ish antifreeze?
 

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@TerryC6 - yes, lower Rs would work as well. Thanks for the reminder. Those are always welcome from time to time. I was pushing fairly hard this trip as I had my English Bulldog with me (with no back windows in) so wanted to get to the house AC as quickly as possible.

What failed with your aluminum radiator with the DexCool-ish antifreeze?
It sprung leaks everywhere and pretty much all at the same time. Here is the article I was referring to:

https://shop.championcooling.com/articles/What-Coolant-Color-Do-I-Use
 

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I'm very surprised about the article.

Were these cast iron engines that they had their radiators running with? Because where else could all that rust come from and why is this blamed on the coolant IN the radiator?

Indeed that rust stuff looks very much like the rust sludge that was found in the earlier cast iron GM engines in the early "problem" days of DexCool.

For the record, I'm running DexCool with 50/50 TAP water in one of those "problem" GM cast iron engines for about 20 years with no problems (*). Just to prove all the DexCool stickies and class action lawsuits wrong and show how the issues were part of owner's failure to intervene and letting a small issue becoming engine failure. Pentastar - sounds familiar?

(*) I had to change intake manifold gasket to a revised material, the original material was harmed by DexCool. No more problems since.
 

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The only thing I know is my radiator started leaking like a crazy all at once. Welds on both sides just like the picture they show. Now I have only had the green stuff in this new radiator for about 6 months, we will see if the same thing happens.
 

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Good info here. I would also add: Have you checked your thermostat? Those temps you're seeing are very high.
 

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What does everyone do to keep their JK 3.6L engines from getting exorbitantly hot? Im constantly at 240 to 246* when highway driving with AC on. Then this past weekend I was pulling my Turtleback returning from the North Rim and hit 255* (the tattle light comes on at that point, just FYI). While Im not worried about that being too hot for the short amount of time it was at the temp, I just done like the fact it gets there so easily.

Climate at the time: Pulling up/down/around 4000-5000 feet south of Flagstaff to Phoenix. Ambient temperature was pushing 105* or so. Running 4.88s right around 3200 RPMs. With AC temp would pop up to 240-244* and on a long incline pull reached 255* for about 5 minutes.

Anyone have any feedback?

I was having a similar issue in my 18 Jk. I'm running 33s on 3.21s, and after going to Jeep beach, I had mud caked on to my radiator pretty bad where I had to limp it to my apartment. Then, after fixing what I thought the problem was, for some reason I kept overheating on the highway. Only going about 62-68 (and anything faster), I would easily hit 249° on the coolant. So then I removed my grill insert that I've had almost since I got the Jeep. And now on the highway I don't go over 230 unless I'm hammering on the skinny pedal. Also, since then, I've put a winch in front of my grill and haven't had any issues. So first make sure that your radiator is completely free of debris like bugs or mud. Second, if you have anything blocking airflow to your radiator, remove it and give it a test drive. I would suggest doing this before getting any kind of aftermarket radiator to try and save you a few hundred bucks.
 

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Holy cow! The most I ever saw was 244 while towing a heavy trailer at GCVW in Vermont/New Hampshire. Granted it was “only” 90F and altitudes in the 1,000-1,800 Ft range. 4,000 RPM in 3rd, uphill at 55 mph.

Temps went right back down to 230 as soon as I hit a flat section.

You may want to change your thermostat and flush your coolant and see if that helps before moving on to more drastic measures.
 

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that does seem high. I just pulled my Aliner ranger 12 to and from Moab and had plenty of hot weather and driving from Missoula to Moab there are a lot of hills/passes. I drive 70-75mph with the trailer in tow and never got over 242* and that is only going up hills. on the flats mostly under 212
 

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Discussion Starter #13
Maybe I do have a cooling issue in general then. Im constantly at 220-230* just normal cruising around in our 105* weather. Sometimes I can keep it around 210-215* but in general it runs warm.

Would going back to the OE style "open" grill help? I have a grill with the mesh inserts to help keep the rocks out.
 

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Maybe I do have a cooling issue in general then. Im constantly at 220-230* just normal cruising around in our 105* weather. Sometimes I can keep it around 210-215* but in general it runs warm.

Would going back to the OE style "open" grill help? I have a grill with the mesh inserts to help keep the rocks out.
that would be the first thing I would try
 

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I have a 2017 Wrangler Sport Unlimited, never had any overheating issues even in Atlanta traffic. When I went home to visit in the mountains about 2 weeks ago, coming home to Charlotte, mine started hitting 230. It has always ran around 215 in hot weather. Ive replaced the radiator, cap, heater core, fan, fan clutch, thermostat, complete flush, new Freon in AC. Its still is hitting 228-230. Im running a 3" lift with 37's. Im stumped at what else to check except for the coolant temp sensors. Any ideas?
 

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^^^

:welcome: to the Forum..:wavey:

Did you bleed off the air from the cooling system?

Did you remove your Air Dam?

Do you have air flow CFM blocked to your Radiator (grill inserts, lights, winch, Etc)?

Are you keeping your radiator clean externally?

All of the above will add to higher engine coolant temps.

Keep in mind that your cooling fan doesn't kick in until 226 degrees. When your a/c is on in the recirculate setting, then your engine cooling fan will always be running.
 

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