The thermostat cannot be repaired and must be replaced if damaged. A simple check is carried out in the manner described in the section for gasoline engines. The thermostat opening temperature is between 83 and 89°.
When installing, the thermostat is installed with a new gasket. To ensure good sealing, a sealing compound is applied to the contact surfaces. Before securing the clamps, they should be checked. Replace if necessary. Fill the system with coolant. After installing a new thermostat, you should drive a short distance and check how the thermostat opens.
Figure 282 shows the thermostat housing and thermostat parts before installation. Figure 283 shows a housing with elements screwed into it.
Figure 282. Thermostat housing and thermostat.
Figure 283. Installed thermostat housing with the location of individual temperature switches. 1. Temperature switch, 15 nm; 2. Signal switch (overheating), 15 nm; 3. Expansion element (cold engine and high-pressure fuel pump starting); 4. Bolts, 12 nm