The bimetal valve is built on the outside i.e. it is no longer directly situated on the filter. When heating mode is activated, the hot fuel flows back to the distributor unit and, from there, on to the fuel filter.
Function
Fuel heating is controlled by a thermocouple (bimetal valve – clicking like expansion steel plate).
The function mode is similar to that of the M47.
Differing features compared to M47 (switching points)
At a fuel return temperature ≥ 73 oC (± 3 oC), 100 % of the fuel return flows back into the tank via the fuel cooler.
At a fuel return temperature ≤ 63 oC (± 3 oC), 60 % to 80 % of the fuel return flows directly to the filter and the rest flows into the tank via the fuel cooler.
Fuel cooling function
If the bimetal valve allows the fuel to return to the tank, the fuel flows through a cooler.
Cool external air enters the cooler through its own air guide, thereby removing some of the heat from the fuel.
