Thermostat — checking without removal (VAZ-2112)

We start a cold engine and monitor the coolant temperature using the temperature gauge on the instrument panel. The temperature at which the main thermostat valve begins to open is 85+2°C (it is indicated on the thermostat cover). While the engine temperature is below the specified value, the main thermostat valve should be closed. In this case, the liquid will circulate in a small circle. This can be determined by touch - the lower radiator hose and the radiator itself should be noticeably colder than the thermostat housing, through which the hot coolant circulates.

When the coolant temperature reaches 85°C, the main thermostat valve begins to open and a gradually increasing flow of hot liquid enters the radiator. At the same time, first the radiator itself, and then the lower radiator hose will begin to heat up.

At 102°C, the main thermostat valve is fully open and the main flow of fluid passes through the radiator. In this case, the radiator should be hot in the upper zone and slightly cooler in the lower zone.