Hello,
I am trying to find out how the heater in the round 6.5 type fuel filter operates. As in is it on all the time the motor is on or does it cycle with the glow plugs etc. And on the water in fuel does that just go to a light. Thanks for any help.

 

The fuel heater is operated by a built-in thermostatic switch. The thermostatic switch completes the circuit for the fuel heater element when it senses a temperature below 8°C (46°F).