Operating temp?

[Allwhite14]

I have a 2014 JKU automatic, 37s, 4:88 gears. My thermostat was stuck open. I replaced the thermostat. Flushed the system with distilled water. Used Peak OAT coolant. Burped the system. Now my average operating temp is 222-226 while driving between 50-70mph. Ambient air temp outside is 90ish degrees (Florida). Fan works in low and high speeds. I’ve seen 231 while accelerating hard or climbing a grade. Does this seem normal/acceptable?

 

[BLACKJKU]

I have a 2014 JKU automatic, 37s, 4:88 gears. My thermostat was stuck open. I replaced the thermostat. Flushed the system with distilled water. Used Peak OAT coolant. Burped the system. Now my average operating temp is 222-226 while driving between 50-70mph. Ambient air temp outside is 90ish degrees (Florida). Fan works in low and high speeds. I’ve seen 231 while accelerating hard or climbing a grade. Does this seem normal/acceptable?

I don't have the 3.6 so I don't know about the temps. But you could always raise the front of the Jeep up about 6" and remove the cap and let it idle and see if the coolant drops.

 

[Anybodyhome]

Jeep claims the normal operating temp for the 3.6 is between 195-220.
My 2014 JKU 3.6 experienced the same thing a couple years ago and I wrote about it extensively in this forum. Here's what I can tell you:
1. Make sure the t-stat you installed is set for that temp range.
2. If it wasn't properly burped, your temp gauge will fluctuate pretty noticeably.
3. I believe the temp gauge is centered at 210, you're probably okay. But you're running a 4.88 versus my 3.73 and, therefore, turning much higher RPMs. I'm sure this comes into play as well. What kind of RPMs are you turning at 60-70?

If you have an OBD and JScan, here's what I did:
1. Cold start your JKU with the JScan and your phone connected.
2. Wrap your hand around the upper radiator hose and take note of the temp when the t-stat opens (you'll feel the warm water begin to flow in the upper hose. This should occur around 200-205. If so, your t-stat is working as it should.
3. As Black stated above, you should elevate the front end on a curb or something 4-6" higher than the rear. Open the rad cap with the engine running and see how much the coolant settles. You should continue to add coolant up to the top of the radiator with the engine running until it no longer settles. This isn't an immediate thing, either. It may take you 15-20 minutes standing their adding coolant a cup at a time. Putting coolant in as the it settles forces the air out.

 

[Allwhite14]

I elevated the front of the jeep multiple times to burp the system. I Installed an AC Delco thermostat. Not an OEM thermostat. And I’m pretty sure the thermostat is opening at a higher temp than 205. I see temps in the 220s before the temp starts to drop. I need to see if I can find the package for the thermostat I bought. At 70mph I’m running 2700 rpm’s.

 

[BLACKJKU]

I elevated the front of the jeep multiple times to burp the system. I Installed an AC Delco thermostat. Not an OEM thermostat. And I’m pretty sure the thermostat is opening at a higher temp than 205. I see temps in the 220s before the temp starts to drop. I need to see if I can find the package for the thermostat I bought. At 70mph I’m running 2700 rpm’s.

That's the main problem with the t-stats trying to find one that works like it's supposed to. I'll bet overheating issues is the no 1 problem then electrical issues. If you buy a new t-stat put it in a pan of boiling water and see what temp it starts to open before installing it.

 

[Allwhite14]

That's the main problem with the t-stats trying to find one that works like it's supposed to. I'll bet overheating issues is the no 1 problem then electrical issues. If you buy a new t-stat put it in a pan of boiling water and see what temp it starts to open before installing it.

I guess I’ll be pulling the thermostat off and testing it. It’s duralast brand. Not ac delco.

 

[Allwhite14]

I just found a ton of bad reviews on this exact thermostat. People are saying that they fail. And most say that it runs about 10 degrees hotter than OEM. That is exactly what I’m experiencing. Time to find an OEM thermostat.

 

[BLACKJKU]

I just found a ton of bad reviews on this exact thermostat. People are saying that they fail. And most say that it runs about 10 degrees hotter than OEM. That is exactly what I’m experiencing. Time to find an OEM thermostat.

In the last couple of weeks there was alot of discussion and someone found a good one but I don't remember what brand it was. If you have time might look at the bottom of this page where it says Similar Threads.

 

[Allwhite14]

I just ordered an OEM thermostat. Be here Tuesday. I’ll give an update when I install it. Thanks everybody.

 

[Anybodyhome]

I double checked my thread from 2019 about this issue. The OEM t-stat I ordered from partsgeek.com was very reasonably priced, got here in about 2-3 days and it worked!
So, I installed the t-stat, filled and burped for about 20-30 minutes and shut everything off. Cold started later in the afternoon with my JScan connected and my hand wrapped around the upper hose. T-stat opened at about 215-217 and been running fine since. Typical running temp for mine is just a hair above the centerline on the temp gauge- so around 212-215.
But, again, my 3.73 gears are only turning around 2400 @ 70mph.

 

[Anybodyhome]

I just ordered an OEM thermostat. Be here Tuesday. I’ll give an update when I install it. Thanks everybody.

Yeah, let us know!

 

[Danarch]

This seems to be a hot topic. We have two JK’s each 2015, Rubicon 35K and Sahara 105K or so. Each one them will operate 226-230 on the freeway with an incline. Around town driving is usually 212-220 or so. I gave up trying to keep them down around 212. Based on what I’ve read and having two do the same thing figured it’s normal. We will be out the wife comes over the radio “hey Jeep is 230”, I look at mine and say “Mine is about the same” usually within a degree or two. Temp comes back down and hasn’t been issue.

 

[Anybodyhome]

This seems to be a hot topic. We have two JK’s each 2015, Rubicon 35K and Sahara 105K or so. Each one them will operate 226-230 on the freeway with an incline. Around town driving is usually 212-220 or so. I gave up trying to keep them down around 212. Based on what I’ve read and having two do the same thing figured it’s normal. We will be out the wife comes over the radio “hey Jeep is 230”, I look at mine and say “Mine is about the same” usually within a degree or two. Temp comes back down and hasn’t been issue.

Typically, most 6-cylinder engines are good until the temps get well into the 240's and even 250 range.
I suppose if someone really geared up a 6-cylinder for serious off-road stuff, like 4.88 or 5.13s, you could add a larger radiator, a bigger fan, etc.