Hey guys, so I have a 2010 Mazda 3 2.0 that started overheating a few months ago so I parked it, well I started it yesterday and the thermostat never opened so I put a thermostat in it and topped it off with coolant (barely level with the max line) and expanded until it bubbled over a little and got up to 220f and finally opened up and ran fine and stayed cool so I drove it to work this morning with my scanner hooked up so I could get watch the temp and it never went above 203f. Well today on break I started it and watched the scanner and it got up to 237f, I turned the heat on and revved the motor a little bit and it went back down to 200f and stayed there but the coolant is still expanding in the reservoir (I bled the heater core when I did the thermostat) the thermostat is definitely opening because all of the hoses were cool when I started it and warm when I shut it off. What’s the issue here? Any ideas?
