635csi /heat when stoped / cold when take off

[jazzfor3]

Hello all,

I just bought a 85 635csi. When I let the car warm up and I have the heat on it gets hot like it should in the car. But as soon as I take off it just blows cold air. Can someone please help.......

Thanks,
-Chris

[slyhog-22056]

Same problem I had with my 633.... fill the cooling system with the heater control valve on hot not running until the water comes out of the bleeder screw on the t-stat housing, fill the resevoir to about 1/2" above the seam on the tank. REMOVE the small hose going to the radiator from the overflow tank and poke a 3/32 drill bit in the plastic bib on the radiator to clear it out. then add water until it comes out this hole. Put the hose back on and run the car with the heat on till it is warm, crack open the bleeder until all the bubbles are gone then close tightly, make sure there is coolant flowing through the small hose to the fill tank. dont over fill it . It seemed like my radiator was clogging the small hole up and everytime It got hot I knew what do do. If you round off the slot on it and cant get it to tighten, remove and make another one with a hacksaw.