Bmw 316ti overheating?

put a new thremostat back in. did you back flush system (radiator and engine and heater) top get rid of the scale and hard water that is usually caked on? if not drain the system by switching the heater to hot and recurculate then drain all the water and jam the hose in the top and block off out lets till clear water shows then reconnect everything with a new thermostat and gaskets. dont forget anti freeze.