Replaced my thermostat this past weekend on my 2015 JK. Prior to replacement my engine temp never got over 200 degrees (digital gauge) unless we were trail riding and working the engine pretty good (never got over 220 degrees on trails), reason I replaced the thermostat this weekend. Also note I have never heard my electric fan kick on prior to thermostat replacement.

Ok, new thermostat engine is running around 212-217 while running maintained speed of 60-65. Idling around red lights, drive through, etc the engine will cool down to at around 205 but can slowly work it's way up to 230 if running around the parking lots in 2nd gear under 2500 rpms, elec fan kicks on and she cools quickly. I burped the cooling system by performing heat and cool down cycles and adding coolant after each cool down cycle. Radiator and system is completely full now and no air.

What is common engine temps you guys are seeing? I bought the Jeep used so I have no history other than the cooler temps it was running with the old thermostat.

 

The 3.6L just seems to run warmer. Over 200* is normal, and IMO, anything up to 230 isn't abnormal. Mine regularly runs around 220*. I'd say the odd thing is how you were running so cool previously.

 

Yeah, I'm not sure as the old thermostat looked great, clean, no surface corrosion, etc. Good thing is I think she is dial in now.

When do you notice your fan kicking on? What condition or running cycle?

 

Before this last axle swap, I ran 5.13 gears with auto tranny and 37s. Most of my driving was interstate and I'm in Texas, so running 3k rpm things would heat up. Over the summers I'd keep a VERY close eye on things. One day I decided to test things in the driveway and just let that sucker idle away. It seemed my fan would kick on ~224* (+/-...it's been a while so this is just what I generally recall) and it would turn back off when temps dipped around 210*. I think up over 232* that sucker turned on airplane mode and prepared for takeoff.

 

Yeah, when mine hit 230 I was like what the heck is that sound lol,,,

 

I have had 3 JK with 3.6's and EVIC so I can monitor the temps. On long hot climbs at highway speeds I will hit over 240F especially when pulling a trailer.It will cool right down tho as soon as the grade is topped. just running around 200-212F. seems like the fan kicks in around 224 too but I can remember for sure as it it does not kick in all that often. I know my Tstat opens at 203F tho as when I first take off in the morning I can watch the coolant temp rise up to 203 and as soon as it hits 203 it immediatly drops down and then climbs again til hits 203 and keeps doing this until it is pretty steady.

 

My 14 manual ran around 195-210 on the hiway, and I pushed it as high as 248F beating on it in the snow trying to climb in deep snow, my 18 auto that I have now tends to run around 200-215 on the hiway and hasnt got over 238 doing similar driving and pulling a trailer through the rockies etc., my trans always runs around 168-172 once warmed up but spikes to 200-210 when put in P or N.

 

you will find when you put it in park you are actually reading your coolant temp not your tranny temp even tho you have it on the tranny temp in the EVIC. Not sure why it does that but it does and it is normal.

 

Factory thermostat is 203. Mine usually runs around 212-217 at idle in the drive way. 217-224 going 70 down the highway.

Fan come on at 224, turns on high at 230 (sounds like a tornado and flattens the grass in underneath it in the driveway).

I have an Aeroforce Gauge and monitor oil pressure also. The oil oil pump doesn't come out of high gear on initial warm up until temp hit 208 or a little higher, depends on if I am accelerating or not, it will delay slowing the oil pump until the throttle position is where it wants it.

Happy Jeeping!

 

Thanks everyone for the details.