Sometimes car owners are faced with such a problem that the engine overheats (this can be seen from the coolant temperature sensor on the dashboard) or, conversely, in winter it is cold in the car for a long time, since the air in the heating stove does not heat up. Such a breakdown often lies in the operation of the thermostat, which is responsible for the circulation of coolant in the engine cooling system.
To exclude other variants of malfunctions in the cooling system, you must check the thermostat yourself. To do this, you need to remember the principle of its operation and the functions assigned to it. The thermostat works to ensure rapid engine warm-up at subzero temperatures, as well as to protect the engine from overheating in the summer. The principle of operation of the thermostat is to open or close a valve in a pipeline with a coolant. When starting the engine, the thermostat valve must be in the closed position for the coolant to circulate in the small circuit. If after 2-3 minutes you try the hose connecting the thermostat and the radiator with your hand, and it is cold, then the thermostat is in the closed position. If it turns out to be warm, this means that the valve is not tightly closed and the engine will warm up for a long time, which entails increased fuel consumption, because the motor does not reach the operating temperature. When the temperature sensor reaches the level of 85-90 degrees, the branch pipe from the thermostat to the radiator should be just as hot, since the valve should open when this temperature is reached, and the coolant should pass through the radiator along a large circuit. If this does not happen, this indicates that the thermostat is stuck in the closed position, the coolant is not able to circulate and cool down and the engine may overheat. If these symptoms occur, the thermostat is defective. In order to check the thermostat yourself and make sure it is broken, you need to remove it. This should be done on a cold car so as not to burn yourself. First you need to drain the coolant, and then remove the thermostat itself. We remove all scale and dirt from it and start checking its performance at home. Of the instruments, only a thermometer with a scale of more than 100 degrees is required. We take an old saucepan, fill it with clean water, lower the thermostat into it and put the saucepan on the stove. The check is as follows: when heated to 81-85 degrees, the valve should open, and when it cools below 80 degrees, it should close. In clear water, these moments will be visible. If the thermostat is found to be faulty, it must be replaced, since it cannot be repaired.
