I know on the R53's there was a valve by the thermostat, but how does one bleed any air from the cooling system in an R56?

 

Run the engine with the radiator cover off, it should burb the system. If there is not rad cap, i never looked. You have to fill it from the expansion tank, which is hassel. run the car with the expansion tank open it will purge it'self.

 

This diagram shows a vent screw (#8) in the thermostat housing:
http://www.realoem.com/bmw/showparts...31&hg=11&fg=35

 

Another way to do it is turn the temp control to max heat and run the fan on high. The air bubbles will pass through the heater core and vent through the system.

Hope this helps

 

You probably have worked it out but you access the bleed screw by the large connector on the thermostat housing. Put the fan and heat on HI.

I just had my rad replaced after a deer encounter but they failed to reconnect the top hose and my trip home ended in a cloud of steam... and I'm a bit steamed. Tomorrow will reveal if there was damage. no temp light but I think the sensor is in the thermostat housing and that would have been reading air. They apparently removed the hose to bleed air out of the heater. Regretting trading my 03 for an R56...

 

Definitely wouldnt remove that plug while the engine is running. I would run the engine for a few secs with the rad cap off then shut off and bleed . Repeat until no more air comes out. R56 engines heat up fast so be carefull