The high pressure fuel pump cannot be repaired or overhauled. If there is any disruption to the normal functioning of the pump, it must be replaced. Roto-Diesel (Lucas-CAV) or Bosch high-pressure fuel pumps are installed.
Adjustment, as well as removal and installation of the high-pressure fuel pump, require special tools and should not be attempted without such tools. Below is a description of the work that can only be performed with a special tool.
Diesel engines operate either with direct injection or with fuel injection into the intake manifold or pre-chamber. In the D9B diesel engine, fuel is injected into a pre-chamber in the cylinder head, connected to the main combustion chamber. Fuel combustion begins in pre-chamber 1 under the influence of increasing pressure; burning fuel particles enter the main combustion chamber, where they are completely burned.
With the development of diesel engines, there have been some innovations that deserve a brief mention.
Fuel filter and fuel heater: Fuel filtration and heating are functions of the engine. The fuel is heated by the coolant flowing through the channels in the cooling system fitting. The thermostatic element shown in Figure 284 regulates the amount of fuel heated. The degree of heating depends on the ambient temperature. At temperatures below 15°C, the thermostatic element moves from its position "a." Fuel can then enter through port "c," flow through port "d," be heated by the water nipple, and then flow to the filter through ports "e" and "b." As the temperature rises to between 15°C and 35°C, the thermostat valve is not fully open. In this case, only part of the fuel enters the filter through the described path. The remaining fuel is fed directly into the filter through "c" and "b".
Figure 284. Sectional view of fuel filter and fuel heating device. References to letter designations are given in the text. 1. Thermostatic element; 2. Air bleed valve; 3. Fuel filter
The power circuit has an automatic air removal device. For this purpose, an air bleed valve is installed.