My '83 245DL Wagon runs on the hot side, 2/3 of the way toward "H" on the gauge when I'm at 65 MPH and interior heat is on "cool" You ask "now you see it" if his temp drops markedly when running the car heater--definitely so in my situation. What does this mean? Is it the radiator (original, is clean but has minor "fin rot") or the water pump, in your humble opinion? I do lose some coolant from around the seal atop the water pump (between it and the cylinder head).

I've got a turbo (colder) thermosat installed which helps somewhat but this 240 runs hotter than others I've had. By the way, if I replace the pump, do aftermarket models come with necessary gasket and seals? Should I buy the pump from the dealer? I was stranded twice in 140s with blown water pumps and want to avoid the curse.

Frank Richards