Note: The thermostat is an integral part of the casing.
Functionality check
1. Before deciding whether the thermostat fails, check the coolant level and drive belt tension (see chapter 1) and sensor performance (or indicator) temperature.
2. If the engine takes too long to warm up (which can be determined by the cold air coming out of the heater or by the temperature indicator readings), then the thermostat may be stuck open. Make a replacement.
3. If the engine is warm, touch the lower radiator hose with your hand. If the hose does not heat up, then the thermostat is probably stuck in the closed position and is not allowing coolant to pass from the cooling jacket into the radiator - replace it.
Caution: It is prohibited to operate the vehicle without a thermostat. The engine control system will constantly record the open state of the thermostat, which will reduce the effectiveness of exhaust gas toxicity control and lead to increased fuel consumption.
4. A hot lower radiator hose indicates coolant circulation in the system, which is only possible when the thermostat is open. To determine the cause of engine overheating, refer to the subsection "Determining the causes of malfunctions" at the beginning of this manual.
Replacement
Warning: You must wait until the engine has completely cooled before performing this procedure.
5. Disconnect the negative battery cable.
Partially drain the coolant from the cooling system. If the condition allows, the drained liquid may be reused for its intended purpose. If you intend to change the fluid, read the safety requirements for handling antifreeze given in subsection 2.
6. Remove the generator (see chapter 5).
7. Locate the thermostat housing, which is located in the upper radiator hose, on the left of the cylinder block (see illustration).
3.7. The thermostat housing is located on the left of the cylinder block (for clarity, shown with the generator removed); It should be noted that the thermostat is not separated from the casing
8. Loosen the clamp and disconnect the radiator hose from the thermostat housing. If necessary, grab the hose near the fitting with a pipe wrench and twist it to disconnect it. It may be necessary to cut the old hose during removal in order to replace it during subsequent assembly.
9. If the outer surface of the thermostat adjacent to the hose is subject to corrosion, has pits or other defects, then further damage may occur when the hose is removed. In this case, it is necessary to replace the thermostat housing.
10. Unscrew the bolts and disconnect the thermostat housing. If necessary, use a soft-faced hammer to remove the casing. After depressurization of the casing, a spill of coolant may occur.
11. Clean the mating surfaces of the cylinder block and thermostat housing. Install a new O-ring into the housing groove (see illustration).
3.11. After cleaning the housing or when replacing the thermostat, a new O-ring must be installed
12. Connect the thermostat housing to the intake manifold and tighten the mounting bolts to the required torque.
13. The rest of the assembly is carried out in the reverse order of removal. At the same time, you should not miss a convenient opportunity to inspect and replace the cooling system hoses as necessary (see chapter 1).
14. Charge the cooling system as described in Chapter 1. Start the engine and check for coolant leaks.
15. Repeat the operations described in paragraphs. 1-4 to make sure that the reasons that led to it were eliminated during the replacement.