How can I keep engine temps down?

[jav_eee]

Try turning your A/C on to get the coolant temps down.

Iirc, the A/C compressor running also helps with cooling the engine in the JL. On very hot summer days if I leave mine off, coolant temps will start climbing to over 225°F and if I leave the A/C on (or on auto) the temps will usually stay below 200°F.

Not sure if this is specific to all JL models, or just the 3.6L, but I recall @mwilk012 explaining this here a few times.

Yeah that doesn't work. I live in deep south Texas so my AC is always on. Still gets up to the 230s in the right conditions (sitting at a light and city stop and go traffic). Only thing that worked for me was the RPM controller. It can be programmed by them to allow your engine to get warmer. I asked for mine to not come on at all until the engine gets to 197.

Here is an example and a question. Driving to California going up the long steep grades of northern cali the oil would hit 240+ and the coolant would hit 235+. I had the A/C going so the fan should've been working full blast. The RPM's were around 3,000-3,500. How would the RPM Extreme have helped me? 2019 Rubicon on 37's with stock 4.10 gears. Not being a smart ass, cause I really would like to not see those temps again. Just a genuine question.

The RPM controller would've turned the fan on and cooled it down. I have one and haven't seen over 210 and that's romping through soft sand (higher rpm). If you want your jeep to run cooler the RPM controller will do it. As I stated above they can program yours to run however you'd like. Want it warmer? Tell them to turn the fan on at 210. It'll cool you way down and you'll probably never see 235 again.

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[roaniecowpony]

Here is an example and a question. Driving to California going up the long steep grades of northern cali the oil would hit 240+ and the coolant would hit 235+. I had the A/C going so the fan should've been working full blast. The RPM's were around 3,000-3,500. How would the RPM Extreme have helped me? 2019 Rubicon on 37's with stock 4.10 gears. Not being a smart ass, cause I really would like to not see those temps again. Just a genuine question.

As I mentioned in this or other threads, I had the same situation in southern CA on a long pass climb in 60F temperatures. My advice to get your temperatures under control is to install three things.

RPM Extreme fan controller. RpmExtreme Jeep JL PWM FAN CONTROLLER :: RPM Extreme This modification will be the most significant in reducing temperatures. It has fan schedules that are moved to lower temperatures.

This is the plastic grill mesh that's clipped on the back side of your grill. Your grill will be the one on the right. The leff is 392 Hemi grill, which is also used on the Gladiator. Note the larger holes. A Jeep engineer at Easter Jeep Safari told my friend to rip all of it out and run without any grill mesh. I decided to use the 392 grill mesh. This allows a lot more air flow.

In the picture below, you see two fans with radiators. Both are factory fans. The original fan on my 2018 3.6 JLUR is a 650w fan on the bottom. Note the narrow cord of the blades. The fan on top is a 850w Gladiator fan with wider blades and more power to turn it. Plug and play. The harness on all the jeeps are the same. You will need to change the z-case fuse from 60 to 100 watts for the fan.

And you can also see the radiator in the top is all aluminum. This is a Mishimoto higher capacity radiator. I installed it, but even without it, but with the other three mods (especially the RPM Extreme fan controller), you'll see a large drop in temperatures.

 

[roaniecowpony]

It also has a bigger grill and radiator.

I think you'll also note that even the JL driver cluster gauge doesn't move much. That gauge is intentionally programmed to not move much out of the center of the range, even when the temparture is running 235F. You have to pull up the actual temperatures to see any change in the gauge.

Once I installed the RPM fan controller, larger grill mesh, 850w fan, and the Mishimoto radiator, my temps run more steady and about 20F lower across all conditions.

 

[Willys41]

I think you'll also note that even the JL driver cluster gauge doesn't move much. That gauge is intentionally programmed to not move much out of the center of the range, even when the temparture is running 235F. You have to pull up the actual temperatures to see any change in the gauge.

Once I installed the RPM fan controller, larger grill mesh, 850w fan, and the Mishimoto radiator, my temps run more steady and about 20F lower across all conditions.

My highly modified Willys. The same. RPM fan controller, larger grill mesh, Put 940w fan, and the Mishimoto radiator.
Coolant and oil temps down 25+ degrees.

My stock Rubicon. RPM fan controller, Grill, 850w fan.
Coolant and oil temps also down 25+ degrees.
The RPM fan controller is the main component keeping the temps down.

 

[roaniecowpony]

My highly modified Willys. The same. RPM fan controller, larger grill mesh, Put 940w fan, and the Mishimoto radiator.
Coolant and oil temps down 25+ degrees.

My stock Rubicon. RPM fan controller, Grill, 850w fan.
Coolant and oil temps also down 25+ degrees.
The RPM fan controller is the main component keeping the temps down.

I think the larger radiator and probably the 850w and 940w fan, are just adding more margin, for when the OEM radiator reaches the limit of its cooling capabilities. But then again, more margin is what we are all looking for after bringing the temperatures down during "normal" use.

 

[Willys41]

I think the larger radiator and probably the 850w and 940w fan, are just adding more margin, for when the OEM radiator reaches the limit of its cooling capabilities. But then again, more margin is what we are all looking for after bringing the temperatures down during "normal" use.

You are probably right.
My attack on the cooling system started with the 850w and then 940w fan motor, grill, and I did not see much difference in temps.
Finely the RPM fan controller. That was the game changing solution.

 

[roaniecowpony]

You are probably right.
My attack on the cooling system started with the 850w and then 940w fan motor, grill, and I did not see much difference in temps.
Finely the RPM fan controller. That was the game changing solution.

same experience.

 

[Pismo61]

How hard is this controller to install?Wiring is not my specialty(soldering)?Suspensions,brakes ECT. Im ok.Didnt see any videos just instructions from the website.

 

[LDSSILLS]

Folks,

I see allot of emphasis on radiators and fans. Which is great. There are many ways to get that engine cooler.

But another way is to install and oil cooler. Its smaller and even with a fan can cost less than a ungraded electric fan alone. There are many varieties, some with fans and others with just fins.

In my experience with tractor oil coolers most will cool engine temps as much as 10 degrees. But average was around 4 with RPMs around 3-4,000. With tractors speeds at 3-6MPH average depending on tilling or harvesting there is not much air going across the radiator as you can image. Also radiator screens get plugged my field debris at times. So manufacturers have leaned to remove heat buy cooling oil as well.

I believe for me if I get a high mounted winch, Ill add an oil cooler to my Rubi to supplement lost air flow to the radiator.

Heres one of the more expensive ones. From Summit racing at ~$150.00

Grandpa Larry

 

[AFD]

Yeah that doesn't work. I live in deep south Texas so my AC is always on. Still gets up to the 230s in the right conditions (sitting at a light and city stop and go traffic). Only thing that worked for me was the RPM controller. It can be programmed by them to allow your engine to get warmer. I asked for mine to not come on at all until the engine gets to 197.

Yeah, I don't idle for too long in my travels, but it absolutely does have an immediate effect on temps for me and without the A/C compressor running at max my temps will stay well over 225F on hotter days, even while moving. I'm thinking my stationary temps were even higher, but perhaps it doesn't provide the same cooling benefits when idle?

Mwilk012 is a service tech here and has described this exact behavior in the JL many times..

https://www.jlwranglerforums.com/forum/threads/average-coolant-temp.114962/

Not saying it's a fix or solution for temps hitting up to 240F in stop-and-go, just that the A/C plays an unusually significant role in the JL's coolant temps compared to other vehicles. The OP mentioned >225F temps with steady driving in a more temperate region than yours, which is why I mentioned it.

Hit the highway on a 90+ day with your A/C and RPM controller off and then compare your temps.

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