Separate expansion tank
WARNING: This page is about a different car, the 2002 BMW Z3 and 2001 BMW Z3. However, it is still accessible from the selected car via links, so may be relevant.
No bleed screws on radiator and thermostat housing!
All bleeding occurs through the vent pipe which leads to the connection on the expansion tank.
Courtesy of BMW OF NORTH AMERICA, INC.
Coolant system is vented during the filling procedure.