Sequence of execution
1. Prepare the car for work ("Preparing the car for maintenance and repair").
Warning: The coolant level should be checked when the engine is cold. A slight increase or decrease in the coolant level when the engine heats up and cools down is not a malfunction. This is due to the thermal change in the volume of the liquid.
2. Check the coolant level in the expansion tank, which should be 25-30 mm above the MIN mark on the expansion tank body. If the fluid level is at the MIN mark or below, add coolant to the tank ("Coolant - Replacement").
Recommendation. If you have to top up the coolant regularly, you should check the cooling system for leaks.
3. Check for fluid leaks from the radiator drain holes and engine block, the temperature sensor installation location, the connections of the rubber hoses of the cooling system and their integrity.
Recommendation. You can try to eliminate coolant leaks from under the hoses by replacing the spring clamps with screw ones. However, do not overtighten the clamps, as they may cut the hoses.
4. Check the integrity of the expansion tank housing, engine radiator and heater.
5. Make sure that the thermostat housing and the connection between the coolant pump and the cylinder block are tight.
6. Check for leaks from the pump drain hole (is located at the bottom of the pump), indicating wear of its seal.
7. To check the thermostat, start a cold engine. We control the temperature and circulation of the coolant in the small and large circles by touch, by changing the temperature of the hoses and pipes of the cooling system (in the photo the air filter is removed for clarity).
Article based on information from the website LADAman
Note: If the engine cooling system is in good condition, 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 electric fan starts to operate. When the coolant temperature rises to a certain value, the electric fan should turn on, and after the temperature drops, it should automatically turn off.
Recommendation. If the electric fan does not turn on in time, the liquid has boiled, it is necessary to check the serviceability of the fan electric motor or the serviceability of the engine control system. Checking the coolant temperature sensor is shown in the section "Coolant Temperature Sensor - Checking and Replacing".