I came across this wonderful device from China, it is a 3 functions in one and plugs into a standard cigar lighter 12V socket.
There is one snag I attached the thermistor to the thermostat housing, there is a 25 degree difference between what the thermometer reads and the actual water temperature. so when it reads 55deg C the actual temperature is 80 deg C (the thermostat temperature). When the thermostat closes the water pump runs and maintains a constant temperature in the engine.
|Maximum temperature 95deg C|
|New thermistor location|
Here is an Index page for the build