Cooling system thermostat — testing and repair (VAZ-2108)

The thermostat is checked for the temperature at which the main valve begins to open and for the stroke of the main valve. The thermostat is installed on the BS-106-000 stand and lowered into a tank with technical glycerin. From below into the main valve 9 (see figure 9) rest the bracket of the indicator leg. The initial temperature of the glycerin in the tank should be 78-80°C. The temperature of the glycerin is gradually increased by approximately 1°C per minute with constant stirring so that it is the same throughout the volume. The temperature at which the main valve stroke is 0.1 mm is taken as the temperature at which the valve begins to open.

The thermostat must be replaced if the valve opening temperature differs from (87±0.2)°C and the valve stroke when the temperature rises to 102°C is less than 8 mm.

The simplest check of the thermostat operation can be carried out by touch directly on the car. After starting a cold engine with a working thermostat, the radiator outlet pipe should heat up when the coolant temperature reaches 87-92°C.