Recently I did the heater core flush as the heat was pretty much gone. Had very good results with another brand CLR like liquid that I diluted and let it sit for about 15 mins and then flushed with water and a shop vac. Well heat is back but I believe there is air in the system because when I start driving in the morning I can literally hear the coolant slowly fill the heater core as the pressure raises in the cooling system. I bled the system as described in the manual but I think thats good for the engine. The temp of motor is fine and the heat works. In another thread someone mentioned that the motor must be running to bleed for the heater core. How is this done? I have 2000 1.8T ATW motor just for the record.