David Breceda

I was wondering if anyone has had this issue or give me some points on fixing it

I have a 2016 JKU 3.6, when I'm running at highway at 60m/h and the RPM are steady at 2,000 my jeep starts to overheat, and more when going over a little hill, I do not have this issue while going off-road or anything, only when I'm driving on normal speed. I already replaced the fan, thermostat, antifreeze and hoses.

The only way I can cool it down as soon as it starts to go up, is by having the heater on blast, and just there it will start to cool down little by little

Any ideas on what it could be, thank you! if you guys need more info, I will gladly let you know anything

resharp001

So you're not losing coolant at all? Your reservoir is always a constant level? You have no air in the cooling system at all I presume. What kind of coolant temperatures are you seeing? 240°+??

David Breceda

Not at all, coolant level stays the same, and no leaks as well, also so far, I have already taken all the air bubbles out of the cooling system

This is a picture I took today on my drive I had to turn on the heater on blast, just to cool it down

karls10jk

What does the front of the jeep look like? And just curiosity- what coolant did to use when you replaced it?

David Breceda

For the coolant I used mopar OAT, I went to the dealership to purchase the right one, as I read that some other coolants can cause overheating issues on the jeep, hope I used the right one

This is how the front end looks

Just to point out, I removed the winch and the KCs for a week to test it out, and it still overheat

resharp001

Those steering stabilizers are askin for trouble.

Anyhow, you used the right coolant. Certainly you either used pre-mixed or concentrate and watered down to 50/50. So this is an issue that the jeep had been working fine for an extended period of time, and just now it's started to run warm out of nowhere right? It's really hard to tell with that needle given the angle of that picture. Usually that is sitting just a bit right of center on my jeep. It's helpful to have something like a Jscan app to monitor actual coolant temp readings as that needle is just kind of a dummy till it really starts running hot. You don't have great airflow with the grill and accessories, but many of us have just as bad flow. The thermostat you used was actual Mopar unit right?

David Breceda

Hope this picture helps, yes, it was running completely fine, then out of nowhere it started to overheat on highway, the new thermostat wasn’t mopar, would you recommend to swap it for a mopar one? Forgot to mention, when driving at night, I really don’t have the issue at all, just a couple of times so far, but it is really weird if it happens

resharp001

My preference for something like a thermostat is factory part. Not to say some aftermarket thermostat is the issue as you were having this issue prior to that, but there are some aftermarket parts (like sensors and such) that I don't like to 2nd guess so I stay factory. when it's happening vs. not is quite odd (day vs. night, normal driving vs. wheelin). Not like you're running screamin' RPMs in 100° weather at the moment which is when I was having a few issues up here in DFW. Hard to think there's anything wrong with the water pump as that wouldn't be selective to when it was causing an issue or not, and if the coolant sensor was on the fritz you'd see a code about that.

Sixty4x4

I would guess that the airflow through the rad is compromised by perhaps turbulence. Take all that eyebrow stuff off and the spot lights and run same speed. Amazing how airflow can be disrupted easily. Also ensure the rubber seal between hood and grille is in place still.

Tjmiller01

I had the same issue and never really noticed coolant low since I think it was sucking back in from the overflow and I didn't notice. Replaced water pump/thermostat/flushed systems/used MOPAR OAT (From Rockauto) but still would climb at times. Took to CO and first day ran great going up Iron Chest, but then got really bad coming down. Ended up being a blown head gasket and I think the engine braking coming down the mountain made the blown head gasket worse (had to coast down difficult trail strapped to a J/L behind me after we keep getting air in system (opened bleader on thermostat housing but keep getting air due to blown head gasket)). Once home w/ Jeep, took apart and had heads planed (could see where it was barely blowing by the gasket). Got running again and it was getting hot right away. Pulled the 'new thermostat' and could see wax on it. Turns out I got it so hot coming down mountain that the wax in the thermostat came out and so now it was stuck closed (put on a pot of boiling antifreeze in kitchen and wasn't opening even at 220degs). New thermostat and 'burping' 3-4 times and all good.