MG Car Repair: MGB or Midget Heater control valve, heater control valve, piano wire

Question
Barrie,
Again thanks for your sharing of knowledge!
Nest problem...the heater control knob on the dash by the shifter will turn when disconnected from the line going to the valve on the engine block. Will not function when that line is reattached.
My next step is to disconnect the line on the block and lube the line. If this doesn't work I suspect the valve to be faulty or rusted? How should I proceed to correct the problem?


thanks again in advance for all your help
pete

Answer
Hi Pete.  (1) Often the heater control valve on the engine gets stiff, in which case you need to either free it or replace it.  If you disconnect the cable you should be able to operate the lever with one finger.  (2) Another problem is the inner wire rusts inside the operating cable.  If you bend both ends of the wire straight you should be able to extract the inner, squirt oil down the tube, then re-insert the wire into the tube.  (3) The third problem is usually a result of (1) or (2) above.  When you operate the knob, the mechanism sticks and you just end up bending the wire.  Try to remove every kink in the wire.  If it is too badly bent, use a length of piano wire as a replacement.