Thermostat check

At the thermostat, check the beginning of the opening and the stroke of the main valve. To do this, fix it on the stand BS-106-000 for testing thermostats and lower it into water, the temperature of which should be 73–75°C, i.e., lower than the opening temperature of the main valve by 5–7°C. Place the bracket of the indicator leg into the main valve.

Increase the water temperature gradually by about 1°C per minute with constant stirring. The temperature at which the main valve stroke is 0.1 mm is taken as the temperature at which the valve opens. If the main valve opening start temperature is not within 77-86°C or the valve stroke is less than 6 mm, replace the thermostat with a new one.

The serviceability of the thermostat can be checked directly on the car. With a working thermostat, the outlet pipe of the radiator after starting a cold engine should heat up when the fluid temperature reaches 80–85°C, while the arrow of the fluid temperature gauge should be approximately 3–4 mm from the red zone of the scale.