2007 mini cooper needed a thermostat replacement. Did that no other issues lights or alarms on OBD II. just to be safe I drove to work with the OBD hooked up so I could monitor temp (Probably my mistake) and watched as the temp climbed to 220 F turned the heater on and it didn't get any higher and seemed to be regulating as it would go up a few degrees and then back down on highway. In traffic, no issue temp actually drops to the 216 range with heater running full blast. Tried turning heater off and the temp got up to 233 F got nervous and turned the heater back on and it came down into the 220 range. Still no alarms or codes on OBD. Felt like I was going to melt in the FL heat though. Outside temp around 90F. Got home and cooling fan only ran for about 30 seconds temp got down to 216 and I shut off. Can the normal operating temp really be that high? How high would be considered overheated? I have read a lot of posts to try and get to the bottom of this, but cant seem to find a consensus on what the operating temp should be. Running 50/50 mix, 89 grade fuel, no leaks, before and after I drive the expansion tank coolant level is dead in the middle. bled the coolant when I refilled after the I changed that artificial heart looking thermostat housing.

 

220 is my normal operating temp. If I get on it the thermostat opens more and it drips to around 185. I think the fan comes on at 236.

 

The thermostat operates in two stages. Normal operating mode is 104-108C (220-225F). Under high engine load, the second stage kicks in, at 85C (185C). This is activated by repeated wide open throttle use, etc. Some, but not all, models can activate the second stage by turning the AC to max. Later year JCW’s and GP’s only have the second stage 85C for all modes of driving

 

I now have more than 236,000 on my 2007 Cooper. I have monitored the coolant temp since I drove it off the lot. Then, and now, it runs at a steady 215 to 218. The temp sometimes starts to climb when I stop at a light or get caught in traffic. Anticipating that, I'll turn on either the AC or the heater will the car is stopped. I think the cooling system is marginal, and needs to be watched carefully to avoid a meltdown.

 

I couldn't help notice your username. I assume it's actually your name or you're big fan of Robert Crais