Does anyone know what the small plastic 'valve' which is fitted into the return fuel line, and then pushes into the top of a diesel fuel filter, actually does?. I'm going to replace my original filter with a heated fuel filter whilst doing a straight veg oil conversion. I was planning on simply removing this valve and joining the two pipes together.

Does anyone know what the small plastic 'valve' which is fitted into the return fuel line, and then pushes into the top of a diesel fuel filter, actually does?. I'm going to replace my original filter with a heated fuel filter whilst doing a straight veg oil conversion. I was planning on simply removing this valve and joining the two pipes together.

It's a temperature sensitive recirculation valve. Below 15°C, the valve allows the warmer fuel from the return line fuel to enter the filter. This helps to regulate fuel temperature. Above 30°C, the valve is fully closed to the filter.

Provided you have a heated filter, then you can do away with the valve.

Thank you, i shall be removing it soon!