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Discussion Starter · #1 ·
Well, my first summer in Phoenix and I got the Jeep on the interstate with the AC blasting going about 65 -75 on the interstate. It was a toasty 110 degree day yesterday and my engine temp was pushing past 230 heading to 240F. If I turn my AC off it will hold at 230 but for how long is still unknown. I need to see what I can do to keep the temps down. Let me know your thoughts after reading the facts below.

Here are the facts

-Cooling system is stock (OEM AC Delco fan clutch, stock fan, stock shroud, Mopar thermostat, Napa water pump)
-Radiator is an autozone special. Plastic caps with a single aluminum core.
-Radiator cap is 13lbs but I will change to 16 though that won’t solve the problem.
-Once I’m off the highway below 50 mph my engine will start to cool down with AC on.
-Under load, the flap for the cowl air intake is open and dumping in hot air to the cab. If i let off the gas the flap closes and no air comes through, if i accelerate it opens. This doesn’t affect the engine temp but the cab temp.

I’m leaning towards getting a better radiator. As you can imagine, Phoenix has radiator shops so an all brass or even aluminum might be a good option.

The obvious answer is to not drive over 55 mph and not use the AC but that’s not an option for me. Too hot and too much sprawl in Phoenix to not drive on the highway.

~~~~~SOLVED~~~~~~July-28-2020

So I think I have this figured out and now I can drive down the interstate in July in Phoenix, with A/C on. Before I would overheat badly on the highway and couldn't use A/C. I can really tell my fan is pulling air and doing it's job after the radiator change. Here is a list of things done:

-195 Stant Superstat Thermostat
-Thermocure engine flush (twice)
-Mopar temp sending unit
-Flow Kooler water pump (old Napa was leaking)
-OEM Fan clutch from Collins Brothers
-Autozone Spectra Radiator (This is what ultimately changed things in the end)
-Removed winch (have not remounted to check if it overheats)

Things I tried that didn't work:
-OEM brass radiator from '87 YJ, rodded out at shop.
-New CSF three row, brass radiator. It did not work sadly.
-Napa fan clutch but I have not tried it with the new radiator. Might work fine.
-Removed winch at first but didn't fix issue, have not reinstalled.
-Tried 180F Stant Superstat, not a fix really but I could probably run cooler if reinstalled.
-Radiator caps replaced (16lb) but it was fine apparently.
-I had a wire in the lower radiator hose before but hose leaked. New hose is stiff and was told didn't need spring.
 

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I feel your pain im just south of you in Casa Grande. I put in a 3core aluminum radiator new fan clutch 180* stant and mine rides right around 210-215. Not really bad but im usually only at 65-70 for 10-15 minutes. I was thinking maybe because my winch has a center mounted solenoid that it was blocking a little to much air flow. I've thought about pulling the hood off and driving it to see if it helps not for long term but just to see if I need more air flow through the engine compartment.
 

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Discussion Starter · #3 ·
I also have an M8274 mounted in front of my grille. I’m sure it is a factor. I thought about the Poison Spyder hood louver also.

A new radiator might not be a bad option if it keeps the temps around 210-215. I’m way past that now.


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I'd definitely get rid of that autozone radiator. I had one where the tank just split open on me on the trail, dumping all the coolant out. It was only two years old.



I also just had the issue where the fresh air vent was opening under load. Found that the vacuum check valve that's on the manifold was leaking. Got a new one at the parts store for seven bucks, swapped it out and now it stays closed.
 

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Discussion Starter · #5 ·
Good call. I've had this radiator for a number of years. I'll pick up a new check valve at the very least.

Pics because you should. It was still climbing .



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I'm with bolty. If you assume the gauge is accurate, get it to those temps and stop, let it idle and listen for boiling coolant in the overflow. If yes, then i would do the following:

1. Invest in a quality radiator. I was a proponent of AutoZone is good enough until my LJ autozone radiator cracked just like the image on this thread and dumped all my coolant on the 15 freeway at 65mph. I have settled on the Champio all aluminum radiator for the MJ build, and I think Chris has one in his YJ as well.

2. 16lb is dencent insurance.

3. check the block fluid for rust. if it is rusty beyond slight, Thermocure the system when you put the new rad on.

4. 185 tstat woud not be a bad move based upon where you live now.

5. no hood vents. do all that and see if it corrects the issue. if not, remove the winch temporarily to test it without to confirm it's an airflow issue. If you cant solve the airflow issue because you are keepig the winch no matter what, increase the flow rate of the coolant with a hi-flow impeller style water pump.
 

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I'm with bolty. If you assume the gauge is accurate, get it to those temps and stop, let it idle and listen for boiling coolant in the overflow. If yes, then i would do the following:

1. Invest in a quality radiator. I was a proponent of AutoZone is good enough until my LJ autozone radiator cracked just like the image on this thread and dumped all my coolant on the 15 freeway at 65mph. I have settled on the Champio all aluminum radiator for the MJ build, and I think Chris has one in his YJ as well.

2. 16lb is dencent insurance.

3. check the block fluid for rust. if it is rusty beyond slight, Thermocure the system when you put the new rad on.

4. 185 tstat woud not be a bad move based upon where you live now.

5. no hood vents. do all that and see if it corrects the issue. if not, remove the winch temporarily to test it without to confirm it's an airflow issue. If you cant solve the airflow issue because you are keepig the winch no matter what, increase the flow rate of the coolant with a hi-flow impeller style water pump.
Agreed w Luuca

Luuca why not a hood vent? Don't you want to let the hot air escape the bay?
Hood vents wont change block / eng temp... Just the surrounding accessory heat soaks / temps... But I like them...
 

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Luuca why not a hood vent? Don't you want to let the hot air escape the bay?
I'm not luuca but I'm of the opinion that hood "vents" -while surely letting heat out while parked- don't change the amount of air traveling through the radiator at highway speeds one bit. I even suspect that hood vents on a YJ with the windshield up may impede flow at highway speeds.

#1 use an accurate measurement tool and confirm 240 at gauge is 240 for real

#2 a copper 3-row may rectify it

#3 get a fin comb and straighten the condenser fins

#4 that waterless coolant Jay Leno promotes: I don't know but I've read it let's go of heat more readily than glycol, and about the same as water

#5 if you're an automatic get a long, narrow 4-pass transmission cooler. Put it someplace that doesn't let its heat pass into the radiator. If you are set on using the radiator tank trans cooler run it through the passive cooler First before hitting the radiator.

#6 I'm not sure a 185 stat is a cure? By the time you hit 205/210 for real, a 195 (oem) is already quite past fully opened. So if you are /actually/ hitting 220+ you are gaining a btu load in excess of the btu dissipation capacity. The thing about 195-210-ish is that is the optimal design temperature range for this motor to run in. Some newish vehicles actually want 220 for fuel efficiency by if cooling is already struggling then there's absolutely no capacity to safely maintain that.

Insufficient btu dissipation that stabilizes like yours is showing / seeming to do is mostly one thing: the temperature differential of the cooling medium (air) to the substance being cooled (antifreeze) is insufficient. Increasing the flow of coolant /may/ help. But there is also the idea that if a coolant passes too quickly (high flow) it doesn't lose enough heat per given volume during the time of coolant contact. .

Increasing the flow of cooling medium (air) could potentially help but is hard to achieve in a jeep that already is "all in" air-flow-wise.
Increasing the surface area of contact is the most efficient and effective means of transferring heat, so the different, bigger radiator makes the most sense to me.
 

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Very interesting thread


I have an aluminum 3 core radiator. I have an efan that is on a switch and can run forever. I have an auto transmission, with a trans cooler mounted on front of the radiator and also a center mounted winch.

My Temps this summer are ****, and we're just hitting 100 to 103. I ordered a 180 tstat and highway speeds still put me to 215. Around town I sit at a nice 170-180 degrees with the efan on.

Subbed for possible fixes...

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I have to agree, don’t trust the gauge completely. I was also worried because my temps would climb high on really hot days to 230. I have an infrared thermometer and checked the temperature at the thermostat housing, and the top of the radiator where the hose goes into it. Despite the gauge reading ~230, my thermometer only read about 207. I don’t know it it’s the gauge that’s off, or the aftermarket temp sensor is typical aftermarket garbage.
 

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I have to agree, don't trust the gauge - the gauge reading ~230, my thermometer only read about 207. I don't know it it's the gauge that's off, or the aftermarket temp sensor is typical aftermarket garbage.
The way the gauge works: a bad contact/connection can/will make the gauge run high. The sensor(s) are much more dependable than our ~25 year old gauge package.

Try a replacement radiator cap, your cap may be faulty and as a result not letting the cooling system pressurize properly.
This is partly true. If he was actually 230F with a bad cap, he'd be boiling over and/or steam locking.
The pressure cap actually lets you run 220-230 /without/ boiling. Even if it *may* need replacing it isn't the source of the issue.
 

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I have to agree, don't trust the gauge completely. I was also worried because my temps would climb high on really hot days to 230. I have an infrared thermometer and checked the temperature at the thermostat housing, and the top of the radiator where the hose goes into it. Despite the gauge reading ~230, my thermometer only read about 207. I don't know it it's the gauge that's off, or the aftermarket temp sensor is typical aftermarket garbage.
Guessing its the gauge... but sender is easier to replace... I think I have a new unused temp gauge in the garage
 

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Discussion Starter · #18 ·
a single row is probably not enough but first, do you trust the gauge?
I trust it in terms of accuracy, not precision. I'm not looking for the gauge to tell me when we are at 260F. I want to know when I need to shut the engine off so I don't tear it up. Which I think it does a good job of that. Of course, with my 195F Mopar thermostat, it appears to be opening before it hits 210 on the gauge so I'm happy with that. To beat a dead horse, I haven't had a reason not to trust is. My environment changed and using my AC did as well. So, if was faulty for the last 18 years I've owned it, I suspect I would have discovered it sooner. But I've also never lived i the desert before...

I'm with bolty. If you assume the gauge is accurate, get it to those temps and stop, let it idle and listen for boiling coolant in the overflow. If yes, then i would do the following:

1. Invest in a quality radiator. I was a proponent of AutoZone is good enough until my LJ autozone radiator cracked just like the image on this thread and dumped all my coolant on the 15 freeway at 65mph. I have settled on the Champio all aluminum radiator for the MJ build, and I think Chris has one in his YJ as well.

2. 16lb is dencent insurance.

3. check the block fluid for rust. if it is rusty beyond slight, Thermocure the system when you put the new rad on.

4. 185 tstat woud not be a bad move based upon where you live now.

5. no hood vents. do all that and see if it corrects the issue. if not, remove the winch temporarily to test it without to confirm it's an airflow issue. If you cant solve the airflow issue because you are keepig the winch no matter what, increase the flow rate of the coolant with a hi-flow impeller style water pump.
I agree about the hood vents. Heat is heat and it's still coming from the engine compartment.

I'm not luuca but I'm of the opinion that hood "vents" -while surely letting heat out while parked- don't change the amount of air traveling through the radiator at highway speeds one bit. I even suspect that hood vents on a YJ with the windshield up may impede flow at highway speeds.

#1 use an accurate measurement tool and confirm 240 at gauge is 240 for real

#2 a copper 3-row may rectify it

#3 get a fin comb and straighten the condenser fins

#4 that waterless coolant Jay Leno promotes: I don't know but I've read it let's go of heat more readily than glycol, and about the same as water

#5 if you're an automatic get a long, narrow 4-pass transmission cooler. Put it someplace that doesn't let its heat pass into the radiator. If you are set on using the radiator tank trans cooler run it through the passive cooler First before hitting the radiator.

#6 I'm not sure a 185 stat is a cure? By the time you hit 205/210 for real, a 195 (oem) is already quite past fully opened. So if you are /actually/ hitting 220+ you are gaining a btu load in excess of the btu dissipation capacity.

Insufficient btu dissipation that stabilizes like yours is showing / seeming to do is mostly one thing: the temperature differential of the cooling medium (air) to the substance being cooled (antifreeze) is insufficient. Increasing the flow of coolant /may/ help. But there is also the idea that if a coolant passes too quickly (high flow) it doesn't lose enough heat per given volume during the time of coolant contact. .

Increasing the flow of cooling medium (air) could potentially help but is hard to achieve in a jeep that already is "all in" air-flow-wise.
Increasing the surface area of contact is the most efficient and effective means of transferring heat, so the different, bigger radiator makes the most sense to me.
Good food for thought. The condenser is an aftermarket one from Jeepair and it's cheaply made. As in, the fins are far apart and it's new. I have no intention of replacing the $26 Mopar thermostat I put in a few years ago. Still does as it is designed to do. No automatic transmission so I'm good there. See my comment above about my gauge.

The last thing I'll try is removing my winch. Just to see what happens.

I have to agree, don't trust the gauge completely. I was also worried because my temps would climb high on really hot days to 230. I have an infrared thermometer and checked the temperature at the thermostat housing, and the top of the radiator where the hose goes into it. Despite the gauge reading ~230, my thermometer only read about 207. I don't know it it's the gauge that's off, or the aftermarket temp sensor is typical aftermarket garbage.
I may spend the money on a thermometer but the reality is it's overheating regardless of what it says. I would like to know the true temperature but at that point, I might as well replace the stock temp gauge.

As far as rehauling the cooling system...I did that a few years ago. I had a Taurus fan that was not cutting it. I have quality parts other than the radiator.

Thanks for the feedback guys. I am soaking it in.
 

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Wow. Deja Vu. There was a thread almost exactly like this about ~10 years ago. Guy even said "take your winch off."

It's your radiator, bro. That single-row isn't gonna cut it. Replacing other parts is going to be throwing money at a tiger hoping it eats the paper instead of you.
 

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I cant believe no one has said this yet but have you checked your fan clutch? I am sure your not the only YJ in pheonix. Your stock cooling system if working properly should keep your engine at proper temp even with the winch. So this happens at 55mph and over. If your fan is staying engaged and not free wheeling it can actually hinder air flow and the arizona heat has just made the problem show up. You might want to test and make sure your fan clutch isnt seized.
 
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