Coolant temp concern

[wingnut60]

Bone stock 21 Sahara HA. Was climbing trails in San Juans yesterday not having any problems. Stopped for restroom break, left engine running. Noted that fan was running loudly at idle, causing me to check digital temp gauge--showed 222d. Have never been concerned to watch the digital option, just the analog gauge--which showed same spot as always, just under half. Continued the trek, dropped to 4L to hopefully reduce strain on engine. Temp continued to climb to 235 at highest reading. Coolant full, no leaks/steam noted. On downhill sections, would expect it to lower, but stayed above 220. Got back to level highway running, temp dropped to 195-200. This is a daily driver, towed behind MH, have never been concerned about temps, tho have occasionally run thru the digital readings and nothing unusual. Problem? Certainly not a mechanical expert, any ideas?
Thanks,
Joe

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[John VonJeep]

Totally normal behavior. I see 235 from time to time on hill climbs. Then the aggressive cooling settings kick in and it goes back down to the 220s, where it sill sometimes stay for a while if we’re doing things that are steep and slow.

 

[Byrds8]

Definitely normal in my Jeep. It always comes back down but even down the interstate doing 80mph I'll see it hit up there and then drop back down. The fan doesnt kick on to 235 and I believe the thermostat doesnt fully open til 212.

 

[roaniecowpony]

Sounds typical of my 3.6L.

235F is pretty hot. But it's typical. I don't like it and I'm taking steps to prevent that high of a temperature. My preference is to keep it below 225F peak temps

 

[C.Sco]

Concur with the others above. Pretty normal, especially on long uphill tugs with a lot of weight in the vehicle.

The only real solution that can help keep it from climbing too high (245-ish is where I start to get nervous) is a fan controller to kick on the radiator fan at full blast earlier. Either the RPM Extreme one (which is only for the 3.6) or you can use the Tazer JL to manually kick on your fan at full blast with your steering wheel buttons.

People have tried all sorts of other tricks, mishimoto radiators, swapping out fans for more powerful ones, adding coolant additives, adding or changing the baffling, ventilating the engine bay more, etc, and the only thing that really seems to have any effect at all is to override the fan to kick on at full blast earlier. Otherwise, the factory default is the fan only comes on at 100% after the coolant temp has already reached 230+. If, instead, you can get the fan to kick on at 100% while the coolant is still only 200-210, it will take a lot longer for it to hit those extreme 235-245 temps.

You wouldn't think the fan makes any difference at highway speed, but oddly in these vehicles the fan is absolutely essential even at highway speeds; without the fan sucking in air, very little air gets through the radiator, even when you're doing 70mph.

 

[Bob Burd]

I see roughly 20 degrees difference between idle/stopped and freeway speeds, so it can't all be fan.

 

[PBosch]

Bone stock 21 Sahara HA. Was climbing trails in San Juans yesterday not having any problems. Stopped for restroom break, left engine running. Noted that fan was running loudly at idle, causing me to check digital temp gauge--showed 222d. Have never been concerned to watch the digital option, just the analog gauge--which showed same spot as always, just under half. Continued the trek, dropped to 4L to hopefully reduce strain on engine. Temp continued to climb to 235 at highest reading. Coolant full, no leaks/steam noted. On downhill sections, would expect it to lower, but stayed above 220. Got back to level highway running, temp dropped to 195-200. This is a daily driver, towed behind MH, have never been concerned about temps, tho have occasionally run thru the digital readings and nothing unusual. Problem? Certainly not a mechanical expert, any ideas?
Thanks,
Joe

I do not like it, but I see 220 to 230 every day, and I drive it very gently

 

[roaniecowpony]

I do not like it, but I see 220 to 230 every day, and I drive it very gently

That's really an issue, because it leaves little room for a temperature excursion from hard acceleration, hills, 4wd operation, etc..

 

[Willys41]

Bone stock 21 Sahara HA. Was climbing trails in San Juans yesterday not having any problems. Stopped for restroom break, left engine running. Noted that fan was running loudly at idle, causing me to check digital temp gauge--showed 222d. Have never been concerned to watch the digital option, just the analog gauge--which showed same spot as always, just under half. Continued the trek, dropped to 4L to hopefully reduce strain on engine. Temp continued to climb to 235 at highest reading. Coolant full, no leaks/steam noted. On downhill sections, would expect it to lower, but stayed above 220. Got back to level highway running, temp dropped to 195-200. This is a daily driver, towed behind MH, have never been concerned about temps, tho have occasionally run thru the digital readings and nothing unusual. Problem? Certainly not a mechanical expert, any ideas?
Thanks,
Joe

Unfortunately that is normal. However there is a solution.
RPM Extreme fan controller.
I have been running one for over a year now and it is a game changer keeping your coolant and oil temps about 25 degrees cooler.
Factory is set up. Your thermostat will start to open about 190 and is fully open about 212 degrees however you rad. fan comes on at about 15% fan speed at 221 and 75% fan speed at 231.
With the RPM Extreme fan controller my temps average 188 to 195 and the highest I have seen is 212 pulling a mountain pass from 4000ft to 8000ft.
Its one of the best mods I have made.

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

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