Loss of heat in the cabin could be an eazy fix as adding coolant to the reservoir and/or releasing any build up air pockets.
Next step could be the thermostat or heater core,....
If the thermostat is gone it will go into the manual mode and stay open as a failsafe not to overheat the engine so your engine would actually be cooler than normal.
This car and its never ending cooling issues aghhhh! Do the whole overhaul and be at peace. Get the all aluminum rad with built in tank, water pump with metal propelers, bulletproof thermostat.
E39 540i Sport
Last edited by Dado 540; 12-13-2010 at 11:10 PM.