Seems like a common thing these days. I started with replacing my oil cooler because it was leaking and could smell the oil burning off. Shortly after I did the water pump because it was coming apart. While I was there I replaced those two plastic idler pullies with metal ones and changed the thermostat. Precautionary since I was in that area and hadn't done a thermostat. Flushed the radiator, heater core and burped. Still when at idle temp is normal. While traveling the temp rises. Never gets above 3/4 but cools when I comes to a stop. Ugh.
Overheating at highway speeds
- Thread starter noahs2015jk
- Start date
You probably won’t believe this but I have a 2015 was doing the same thing. Finally the new mechanic pulled the new thermostat that he installed and found that it was not opening all the way causing a flow issue. He put a new one in after testing it and BOOM! No more overheating on hwy or in town. Gauge stays in the middle. Pull the stat and stick it in boiling water and see if it opens all the way. I’ll bet it doesn’t. Hard to believe after new engine, 2 water pumps, 2 radiators, heater core flush, and countless stats.
Trust me I believe it. Can't rely on replacement parts anymore. I will give it a shot
kevinhomuth
New Member
Update: Over heating solved, found water pump gasket seal torn and also discovered Napa brand thermostat which I installed had .285” less throw and .110” smaller diameter than the OEM thermostat. So aftermarket part was choking off a lot of flow. I have since learned there are 2 aftermarket thermostats that the socal dealers are using when they can’t get the oem one from their suppliers which is the Gates and Doreman products.
kevinhomuth
New Member
Sorry should have been more clear, I tracked down an OEM Mopar version at a dealership in Ontario CA. It was $100 but once I put it next to the Napa one it was shocking how much different it was in terms of throw and ID measurement. Once I replaced the water pump with the new gasket it still over heated at high speeds but seemed to be better than it was. But last night I took it on the freeway after installing the OEM T-stat and burping most of the air out and drove 85mph at over 4000rpm and never got past 231 degrees which would have been impossible before. I was getting easily to 260 at 3000rpm at 75mph now even runs at 205 around town.
I have similar issues with the overheating. My 2015 jk will only overheat going more than 60mph, as well as up hills. I just got it diagnosed from a mechanic saying that the cooling fan is not drawing enough power at higher speeds to keep the temp down. I am going to try and repair it myself.. any updates on anyone else’s issues??