highsierrajk

So about a month ago, I bought a 2011 2dr JK with about 90k miles on it. For the first few weeks we had no issues, and the coolant temperature always stat where it should be, according to FIXD. This past weekend we took it on a trip. The entire way up, the engine coolant barely got over 150 degrees Fahrenheit (again according to FIXD). When we got up there, we sat in a McDonald's parking lot for about 20 mins and began overheating (coolant boiling), the next day it overheated again. We did some research and found our thermostat could be stuck open, so we replaced that today, but even after idling for over 30 mins, we never got above 180 degrees. From what I've read, these temperatures are low? But of course, I could be misunderstanding something. I'd also like to add the fan never turned on even when we were boiling, although the fan will turn on when we run the AC. Does anyone have an idea what our issue could be?

Thanks in advance!

Lars

(also sorry if this is the wrong section to post in)

tjkamp

Not sure on a 3.8 liter where the temps normally are, but my 3.6 (which should be a hair hotter I believe), has a 203degree thermostat (factory), and idles in my drive way around 212, going down the highway, it fluctuates between 213-226. After the tranny and running gear all get heated up it idles around 217. Towing or long hill climbs will bring it to 230 where the fan kicks into high speed and knocks it back down to around 210.

If the fan runs with the AC, but does not come on when the temp goes up there is likely a problem with the temperature switch, or sending unit, or a fan relay. The temps you are describing are way too low for any modern vehicle, would assume there is an issue wit the sending unit.

All my temps are based off of my Aeroforce Gauge. What is FIXD?

tjkamp

Ok, so the FIXD is reading through the OBDII the same as the Aeroforce does. I'm pretty sure even if your thermostat had been removed you would be getting higher temps than that. I would suspect the temperature sending unit is faulty, however, I know if the sending unit acts this way on the 3.6 it should throw a code for it, I'm not sure about the 3.8 though.

Maybe someone else will know.

highsierrajk

We got some sort of thermostat related code, I may try replacing the coolant temperature sensor (might be the root of the problem?). Otherwise, we have an extended warranty so I could take it into the shop and let them sort it out.

Thank you!

resharp001

Swapping the coolant temp sensor at the same time as changing a thermostat is not bad protocol. Very basic question, but you are 100% certain you got that sucker completely bled after cracking open the system to swap the thermostat before?

Cindy McCuen Johnson

Hey guys my JK is overheating. Have to run AC full blast to get fan to kick on. Replaced the pump, thermostat, cap and last week oil filter housing unit. We even drilled holes in the thermostat. Nothing seems to work. Was hoping someone has changed out their fan for a more powerful one and if so what kind. Any suggestions would be appreciated.