Thanks for reply. There is also a screw-in type plug unit on top of the thermostat housing - sure it's not that one? Presumably I just unscrew the unit and replace with new - seems difficult to get to though. Also I presume coolant will have to be drained first.
Ford Escort 1.8Si R reg. Everything in the heating system seems to work as normal. Fan kicks in as normal when sitting in traffic. The only problem is that the temperature guage is not registering the engine temperature. Can anyone point me to the part I need to replace.
Thanks.
Engine at operating temperature. Standing at front of car. Two pipes on engine side baking hot. Two pipes on other side of (is it the 'heater diverter valve') box to the bulkhead - left one pretty damned hot - right hand side one fairly warm.
Coolant level normal. Hot/cold dial on dash seems OK but I don't think you can get to any connections behind this knob! There is no resistence when turning. I think it must be an electronic device rather than opening/closing a flap.