High temp light came on today while idling. Shut the car down, fan was running like a jet engine. Popped the hood, let it sit for a few. The level in the expansion tank was low, and I just put some water in it for now. Funny part is that the car has an aftermarket water temp gauge, but the sending unit for it died recently. Got a spare of that coming in too....

Car is a 2003, already on it's second expansion tank.

Ordered some parts -- this weekend I'll put in:

- new expansion tank
- new upper and lower rad hoses
- new thermostat
- new thermostat housing

and all new coolant. Hopefully that'll straighten it out...

 

I have a tiny radiator leak and find that it will create an air pocket that causes temps to fluctuate more severely in this pressurized system. So I periodically need to just bleed it and add fluid. Bleeding it is simple to do once you know it.

 

Good to know. I've got the Bentley manual, so that should cover it...

 

there is no such thing as a "tiny" radiator leak, i guarantee you it will not stay tiny

 

Very true.

 

I live in SW Florida (fort myers) and i have a autometer mechanical water temp gauge(my car has factory Navigation, not my choice) so the only time i would know there was a coolant temp problem it would probably be too late, hence my install of a mechanical temp gauge. I find it interesting to watch the temp fluctuate between 180-222 degrees, I am older then most of you people on here and 220 degrees makes me nervous! After talking to the head Technician at my local Mini dealer, he tells me this is normal, this was confirmed by a friend i autocross with, he has a 2011 mini, non S running in H stock. (he is one of the best drivers i have ever had the pleasure to watch).
In spite of what they tell me i still kick on the A/C and rev the motor to about 1500 RPM.s when sitting at a light. Turning on the A/C activates the fan, the increased engine RPM's theoretically should move the water faster??? Anyway, this works and the temp falls back to under 200 degrees.

 

I notice the same thing. I have a Scangauge to tell me actual coolant temp. Without the A/C on, the low speed fan won't come on until around 220 degrees F. I know this is fine but it still hurts to watch the temp go this high.