Hello all, I have a 2015 Ram Big Horn 3.6L, I am having overheating issues with the truck, figured it was just time to replace the thermostat but still having problems after replacing it, some days it doesn't overheat and some days it does, when it overheats, I lose heat and it blows out cold air. if I keep the engine revs past 2k it cools down and back to normal blowing out hot air but after several mins it will start to overheat again and blows cold air. when it does run normal and don't overheat the temperature gauge sits at 1/4 and don't go past that, before it's always been in the middle of hot and cold. it's fine on the freeway doing 65+ mph its mostly on city and back roads where I am not going fast. it's very odd and I was hoping someone had a similar problem and figured it out. I would really appreciate any help or ideas on this. it's now winter and cold lol. Thanks.

 

Your loosing heat issue makes me think your low on coolant. When the thermostat opens the radiator is less resistant than the heater core so all coolant flows to the radiator and not the core or through the engine resulting in overheating. Did you get the coolant bleed out good after changing out the thermostat?

 

I took the cap off and let it warm up until no more air bubbles were showing, that's how I was told to do it. so hopefully I did it right lol

 

I guess Im not sure how to correctly bleed these. Usually just find the highest point on the engine and remove the hose or bleed screw and let the air out while filling then crank it up and top it off good to go usually