I’m not a car guy. I want to be. I’m learning. I learn by making friends with mechanics and absorbing their information. I had a car a few months ago with some overheating issues. (Got it resolved. No water in my coolant at all, using straight concentrate in a brand new, empty radiator, like a dingus. 🤦🏼♂️) But before I fixed it, someone said it might have been the thermostat. I asked a mechanic friend of mine about it. (I haven’t known him long.) He told me he’s been a mechanic for right around a decade and has NEVER seen a thermostat issue cause overheating. Is he just totally out of touch? Or did I misunderstand how the cooling system of a vehicle works? Let me know.
Most thermostats are “fail safe” meaning when they go bad, they are designed to stick open so you end up running too cold. But when people don’t change their coolant at scheduled times, and you start getting alpt of corrosion and scale, thermostats can jam up and fail in the safe or unsafe position causing overheating. Now there are “fail unsafe” thermostats out there, but those are typically performance high flow thermostats, and aren’t typically used on everyday drivers
So in my 15 years of working on many cars(I went to school to become a mechanic but don’t do it as a job) anytime I had a car that was mine or that I was working on the thermostat was never it I’d say 9/10 times it was a headgasket. Now, it’s always possible that the thermostat getting stuck caused it to overheat at first and then the headgasket failed but replacing one has never actually fixed it and I’m talking like 100 times Ive worked on car for specifically overheating. Just saying.