The diesel engine fuel filter is installed on the front inner surface of the right wing in the engine compartment. When changing the filter, the filter housing must be disassembled. To remove water from the filter, unscrew the bolt (shown with a small arrow). Before unscrewing this bolt, put a hose on it so that the water to be removed can be collected in a container.
Pressing on the diaphragm pump (shown with a big arrow), You will be able to fill the pump with fuel and at the same time remove air from the filter housing and thereby prevent «dry» operation of the high pressure fuel pump (injection pump) when starting the engine after changing the filter.
Distribution injection pump (high pressure fuel pump) diesel engine is very susceptible to fuel contamination (dirt particles clog the holes in the hollow screw of the connection to the fuel line, and the pump heats up). It is especially sensitive to the presence of water in the fuel.
Water enters the fuel mainly due to condensation in the tank of a car or from an underground tank at a gas station. Liquid and solid impurities must be filtered out before fuel enters the high pressure fuel pump (injection pump). This happens in the fuel filter. Dirt particles are trapped in the filter element so as not to get into the pump. At the bottom of the filter, the water separates from the fuel as it is heavier.