Overheating engine whilst no hot air from heater?

Sounds very much like head gasket problem mate, had this with my Audi A4 recently, heater would go stone cold and temp would rise quite a bit. Tried all the easy things first like new thermostat, flushing the cooling system and bleeding it. Only got worse through a short period of time and eventually blew the head gasket completely ! Sounds like your one is on its way out im afraid.

Colin
October 2008