The car is a 2008 Cooper S.

I installed a STRI X-line water temp gauge and a STRI X-line oil pressure gauge.

To install the water temp sending unit I used a hot link water temp port adapter in place of the stock coupling on the upper hose. I lost about 8 oz of antifreeze while swapping the couplings and I put about 8 oz of new antifreeze in the resevior.

I ran the car in the garage for about 20 minutes and all seemed OK. On my way to work this morning the temp gauge started indicating 230 degrees and the gauge started flashing to let me know the temp was hot. I turned on the heater and the defrost and I get very hot air out of the vents. The temp rises while while the engine is running and the car is moving and the temp goes down a little when the engine is running and the car is not moving.

My first thought is that I need to burp the system but I am confused by the heater working and the cooler temp while not moving.
Another thought is that the new gauge is not accurate.

Is there a way to test the accuracy of the gauge?

Were is the bleeder for burping this system and are there any special things about the R56 I need to know when bleeding the coolant. I am familiar with bleeding a coolant system on BMWS.

Thanks,
John Hoffner