The engine cooling system uses special liquids based on a mixture of water and ethylene glycol. They have a low freezing point and a high boiling point. In addition, due to the complex of added additives, the coolant prevents corrosion of the channel walls, does not foam, and extends the service life of the coolant pump seal.
The volume of liquid in the engine cooling system is 7.8 l.
The circulation of liquid in the system is provided by a centrifugal pump installed in the cylinder block. The pump is driven by a toothed timing belt.
Depending on the engine temperature, the liquid in the cooling system can circulate in either a small or a large circle. The thermostat controls the direction of the liquid flow in the engine cooling system. It has two valves - the main and additional (bypass). The main valve controls the circulation of liquid in a large circle, and the bypass valve - in a small circle. The valves are interconnected - when one opens, the second closes and vice versa.
When the engine is cold, the thermostat bypass valve is open and the coolant circulates in a small circuit through the cylinder block, cylinder head, bypass valve and coolant pump, as well as through the throttle valve assembly and heater core. The heater core is built into the engine cooling system and is designed to heat the passenger compartment by circulating hot coolant through it.
![Cooling system [Shown on the example of a 16-valve engine, on an 8-valve the system is similar.]: 1…](https://www.vazbook.ru/img/vaz_2110/2291.jpg)
Cooling system [Shown on the example of a 16-valve engine, on an 8-valve the system is similar.]: 1 - heater radiator; 2 - coolant drain hose from the heater radiator; 3 - coolant supply hose to the heater radiator; 4 - coolant pump inlet pipe hose; 5 - expansion tank hose; 6 - heater radiator steam outlet hose; 7 - expansion tank; 8 - expansion tank fluid level sensor [Installed on some vehicles.]; 9 - thermostat; 10 - hose for draining liquid from the engine radiator; 11 - hose for supplying liquid to the throttle assembly; 12 - Engine radiator steam outlet hose; 13 - hose for supplying liquid to the engine radiator; 14 - engine radiator; 15 - radiator drain plug; 16 - Electric fan of the engine radiator; 17 - Coolant pump; 18 - Coolant pump inlet pipe; 19 - coolant drain hose from the throttle assembly
At a temperature of 85+2°C, the main thermostat valve begins to open, and the bypass valve closes, and for some time the liquid circulates in the small and large circles simultaneously. At a temperature of 102°C, the main thermostat valve is fully open, and the bypass valve is closed, and the main flow of liquid passes through the engine radiator, where it is cooled by the oncoming air flow. At the same time, the liquid continues to circulate through the throttle assembly and the heater radiator. When the air flow intensity is insufficient, an electric fan is turned on to cool the radiator. It is installed behind the engine radiator and turns on automatically by a signal from the electronic engine control unit.
To compensate for the thermal expansion of the liquid, an expansion tank is installed in the cooling system. The tank cap contains inlet and outlet valves, which allows maintaining optimal pressure in the system when the liquid is heated, as well as compensating for the vacuum when it cools down.