Execution sequence
1. We prepare the car for work («Preparing the car for maintenance and repair»).
Warning! The coolant level should be checked on a cold engine. A slight increase or decrease in the coolant level when the engine warms up and cools down is not a malfunction. This is due to the thermal change in the volume of the liquid.
2. We check the coolant level in the expansion tank, which should be 25-30 mm above the MIN·mark made on the expansion tank body. If the fluid level is at or below the MIN·mark, add coolant to the reservoir («Coolant - replacement»).
Recommendation. If you have to add coolant regularly, you should check the tightness of the cooling system.
3. We check the absence of fluid leaks from the drain holes of the radiator and the engine block, the installation location of the temperature sensor, the connections of the rubber hoses of the cooling system and their integrity.
Recommendation. You can try to eliminate the leakage of coolant from under the hoses by replacing the spring clamps with screw ones. Do not overtighten the clamps, as they may cut the hoses.
4. We check the integrity of the body of the expansion tank, engine radiator and heater.
5. We are convinced of the tightness of the thermostat housing and the connection of the coolant pump and the cylinder block.
6. Check for fluid leakage from the pump drain (located at the bottom of the pump), indicating the wear of its gland.
7. When checking the thermostat, we start a cold engine. We control the temperature and circulation of the coolant in a small and large circle by touch, by changing the temperature of the hoses and pipes of the cooling system (The air filter has been removed for clarity).
Comment. If the engine cooling system is in good order, then when the coolant temperature is less than 90°C, the thermostat valve should be closed, and the coolant should circulate in a small circle. As a result, the lower radiator hose and the radiator itself will be noticeably colder than the thermostat housing, through which hot coolant circulates. When the coolant temperature reaches about 90°C, the thermostat valve will open and a gradually increasing flow of hot liquid will begin to flow into the radiator. In this case, first the radiator, and then its lower hose, will begin to heat up.
8. Leave the engine running until the engine radiator fan is activated. When the coolant temperature rises to a certain value, the electric fan should turn on, and when the temperature drops, it should turn off automatically.
Recommendation. If the electric fan did not turn on in time, the liquid boiled, it is necessary to check the fan motor or the engine control system for proper operation. Checking the coolant temperature sensor is shown in the section «Coolant temperature sensor - check and replace».