With 150K on our 91 745T I knew I was living on borrowed time with the original heater control valve still in service. I changed it this morning and found it to be a simple task compared to the 240 series.

The plastic piece on the old valve was not brittle but no matter how hard I pressed on the accuating arm the valve would not seal. It was only slowing down the flow of coolant to the heater core. I'm sure someone will correct me if I'm wrong but if you are trying to cool the cabin with your air conditioning system it can't be good to have 195 degree coolant flowing through the heater core. That alone might be reason enough to change out an old heater control valve as summer approaches (or at least it normally approaches at this time of year ! ).

Randy