The fuel pump sucks fuel from the tank through the coarse fuel filter. In this case, diesel fuel flows directly in front of the fuel pump of the fuel thermostat, which, depending on the fuel temperature, determines the degree of pre-heating of the fuel.
2.0L engine
2.0L engine (low pressure side)
1. Injector pump; 3. Fuel pump; 15. Bypass valve; 30. Nozzles; 43. Coarse fuel filter; 50. Oil drain hose; 63. Fuel tank; 73A. Throttling hole in the upper part of the fuel filter; 86. Fuel thermostat. Thermostat closed, fuel not heated. 89. Central mount device; 148. Fuel heat exchanger; A – Tank inlet; B – Pipeline to the fuel pump; C – Feed line to heat exchanger; D – Inflow from heat exchanger; E – Coolant supply; F – Coolant flow side
For preheating, diesel fuel flows from the thermostat through the diesel fuel supply line (C) to the heat exchanger (148) to the fuel supply line (E), through the diesel fuel drain (D) back to the thermostat and from there via the fuel pump to the fuel filter.
If the fuel temperature is below 18°C, the thermostat is fully open and the entire amount of fuel flows through the heat exchanger. At temperatures between 18 and 30°C, the mixed mode prevails, i.e. the fuel partially flows through the heat exchanger and partially directly to the fuel supply pump. At temperatures above 30°C, the fuel supply to the heat exchanger from the thermostat is stopped.
The thermostat is mounted on the outside of the heat exchanger. A - fuel supply from the fuel tank, B - inlet pipe to the fuel pump, E - coolant inlet, F - coolant outlet.
Engines with a capacity of 2.2/2.5 l
The fuel flows in front of the fuel filter through a heat exchanger, which is screwed into the side of the cylinder head. A thermocouple is mounted on top of the heat exchanger, which, depending on the fuel temperature, directs its flow completely or partially through the heat exchanger: from 18°C to 30°C mixed mode, above 30°C – without preheating.