Coolant Temperature

[HYRYSC]

Have had my 2020 Rubicon 3.6 for a bit over a year now and have put about 16000 miles on it during that time and they have been flawless.

However I was driving the other day and just flipped over to see the coolant temperature and noticed that it was hovering right around 220. A bit warm for my liking but the gauge on the side was still showing a bit below the mid mark.

When I push it pretty hard it gets a bit over 230 before dropping back down. I have noticed that normal driving through town typically yields pretty average temperatures but once it hits over 215 or so, it seems to stay pretty high regardless.

I have read a bit about this and it seems that the engineers (or at least the folks that write the specs) don't have any issues with these temperatures and have up to 235 as normal operating temperature.

I offroad this regularly and it has never gotten hotter than this but I still think this seems pretty high.

What are your experiences

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[smlobx]

What you see is pretty normal. I was going up a 7% grade yesterday fully loaded with my overlanding gear and hit 230 for an extended time but as soon as I crested the hill it dropped back down…

 

[ATL_Rubi]

You’ll also find that after running at a steady temp for say.. 10 minutes or more, then coming to a stop, the coolant will rise. I easily see 230-240 during Atlanta traffic in the height of summer. I’d worry more about oil temp than coolant

 

[JohnWick]

Normal operating range, non issue.

 

[RickF]

Do you have a Tazer on it? If so, pressing these two buttons simultaneously will turn the radiator fan on high, which always brings coolant temp down to 185 within a minute. Perhaps it's unnecessary, but I do this often, especially before leaving it parked with the engine so hot.

 

[ShadowsPapa]

However I was driving the other day and just flipped over to see the coolant temperature and noticed that it was hovering right around 220. A bit warm for my liking but the gauge on the side was still showing a bit below the mid mark.

That's nothing. A thermostat isn't even fully open before that point.
Don't freak out over the numbers because now we can see them.

I have posted diagnostic info from TSMs in the past showing that some vehicle stats aren't fully open until about 225 degrees.
Running too cold will reduce oil life and result in sludges and acids.

With a 50/50 mix of antifreeze (coolant) and water, and a working pressure cap you are not going to see boiling until you hit about 261 degrees or so.

Apparently a lot of guys have never really worked a gas engine hard.........

~225-230 is nothing to worry about.

 

[RickF]

That's nothing. A thermostat isn't even fully open before that point.
Don't freak out over the numbers because now we can see them.

I have posted diagnostic info from TSMs in the past showing that some vehicle stats aren't fully open until about 225 degrees.
Running too cold will reduce oil life and result in sludges and acids.

With a 50/50 mix of antifreeze (coolant) and water, and a working pressure cap you are not going to see boiling until you hit about 261 degrees or so.

Apparently a lot of guys have never really worked a gas engine hard.........

~225-230 is nothing to worry about.

Helpful to know. Thanks.

 

[willys 41]

Have had my 2020 Rubicon 3.6 for a bit over a year now and have put about 16000 miles on it during that time and they have been flawless.

However I was driving the other day and just flipped over to see the coolant temperature and noticed that it was hovering right around 220. A bit warm for my liking but the gauge on the side was still showing a bit below the mid mark.

When I push it pretty hard it gets a bit over 230 before dropping back down. I have noticed that normal driving through town typically yields pretty average temperatures but once it hits over 215 or so, it seems to stay pretty high regardless.

I have read a bit about this and it seems that the engineers (or at least the folks that write the specs) don't have any issues with these temperatures and have up to 235 as normal operating temperature.

I offroad this regularly and it has never gotten hotter than this but I still think this seems pretty high.

What are your experiences

I have posted this many times how I struggled with getting my coolant temps under control.
The way your cooling system works is.
The thermostat starts to open at about 190 and is fully open at about 212.
The problem is with the radiator fan and when it come on.
The fan comes on at 221 at about 15% fan speed and at 231 about 75% fan speed.
This is to little to late.
The only solution I have found is the RPM Extreme JL Fan controller.
For the last 3 weeks I have put the RPM Extreme JL Fan controller to the test in Vegas, Sand Hollow and now in Moab.
For the first time I hit 212 for just about a minute put most of the time about 190 to 200.
My oil and coolant temps are down by 25 to 30 degrees.
Run this simple test. When you see high temps turn your A/C on full blast and you will see you temps drop. Turning on your A/C your radiator fan will run at a high rate of speed keeping your temps down.

http://www.rpmextreme.com/Product/311/Jeep-JL-PWM-FAN-CONTROLLER.aspx

 

[Hootbro]

Yeah, normal. Just me, but if I had bought it used also, I would be doing a coolant replacement. No telling how they may have topped it off possibly with wrong coolant and or tap water.

 

[Chadnutz]

I'll add to this discussion... On Wednesday I stopped on my gravel road and got out to take a few pictures of the damage an invasive pest (pasture mealybug) is doing to my field. When I got back to the running with A/C jeep I heard the fan running louder than I've ever heard before. I turned to the digital gauge and it was at 110°C and falling fast.

The next day I was heading to the coast and I noticed it was running around 100°C down the highway. Mind you this was a brutal day. Feels like temps were around 117°F. I got stopped on the highway and the temp crept up to 117°C. The fan went to jet engine mode again, but the temp would not come down. I pulled over and cycled the engine and heater about 5 times. When it was less than 100°C I added 1/3 gallon of rain water (that's what I drink and therefor what I had). When I started it again the temp dropped to 85°C and didn't run as hot anymore.

When I got to a restaurant I asked AI if there are audible warnings and there are. A red dash warning, an audible warning, A/C off at ~122°C!!!, and a derate somewhere around there as well. I didn't hit any of those things. Crazy that the engine can run that hot. I work at an engine testing facility, and we never run anything that hot. I added a little more water after eating and then added a little more after it sat overnight. Now I need to monitor coolant level because I should not have to add any. Note that I have 126k miles and I have changed the coolant once. Maybe I didn't fill it completely. I don't smell any coolant and I part on an epoxy garage floor and never see liquid on the ground other than A/C condensate.

I don't understand why, even with the fan on jet engine mode, it couldn't bring the temp down from 117°C at idle. Yes I was on a hot highway, but the engine had no load. Not sure how 1/3 gallon fixed that. You can imagine I had anxiety the rest of the way. Breaking down at night out of town would have sucked.

 

[ShadowsPapa]

I'll add to this discussion... On Wednesday I stopped on my gravel road and got out to take a few pictures of the damage an invasive pest (pasture mealybug) is doing to my field. When I got back to the running with A/C jeep I heard the fan running louder than I've ever heard before. I turned to the digital gauge and it was at 110°C and falling fast.

The next day I was heading to the coast and I noticed it was running around 100°C down the highway. Mind you this was a brutal day. Feels like temps were around 117°F. I got stopped on the highway and the temp crept up to 117°C. The fan went to jet engine mode again, but the temp would not come down. I pulled over and cycled the engine and heater about 5 times. When it was less than 100°C I added 1/3 gallon of rain water (that's what I drink and therefor what I had). When I started it again the temp dropped to 85°C and didn't run as hot anymore.

When I got to a restaurant I asked AI if there are audible warnings and there are. A red dash warning, an audible warning, A/C off at ~122°C!!!, and a derate somewhere around there as well. I didn't hit any of those things. Crazy that the engine can run that hot. I work at an engine testing facility, and we never run anything that hot. I added a little more water after eating and then added a little more after it sat overnight. Now I need to monitor coolant level because I should not have to add any. Note that I have 126k miles and I have changed the coolant once. Maybe I didn't fill it completely. I don't smell any coolant and I part on an epoxy garage floor and never see liquid on the ground other than A/C condensate.

I don't understand why, even with the fan on jet engine mode, it couldn't bring the temp down from 117°C at idle. Yes I was on a hot highway, but the engine had no load. Not sure how 1/3 gallon fixed that. You can imagine I had anxiety the rest of the way. Breaking down at night out of town would have sucked.

1/3 of a gallon is a lot.
It's possible there was air in the system.
1/3 of a gallon - that tank would have been empty.
The fact you added only water = NOT good. You need to check now for proper mixture or get it back up to 50/50

Beware asking AI anything - best to read the owners manual for facts.

230 is getting up there, but seriously, not panic time at all. Too many people freak out and think that over 220 is bad. It's not, not for modern engines. Even my 4.0 used to run at 215-220 F

 

[Chadnutz]

Yeah it looks like 50/50 has a higher boiling point than water alone. We don't get concerned with freezing very often around here. I need to see if I did change it and maybe I just didn't check the level after getting up to operating temperature.

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