Cooling system includes: cooling jacket (in the cylinder block and in the cylinder head), radiator, coolant pump, thermostat, cooling fan, connecting hoses and other items.
The coolant, heated in the cooling jacket, is pumped into the radiator by a pump, where it is cooled by a fan and the oncoming air flow that occurs when the car is moving. The coolant then returns to the cooling jacket by means of a pump and cools the engine. The cooling jacket is a network of channels for the passage of fluid. These channels are formed by the spaces between the cylinder liners in the cylinder block and communicate with the channels in the block head. The movement of the liquid is organized in such a way as to provide the most efficient cooling of those elements of the engine that are most heated during its operation.
Schematic diagram of the cooling system,
1 - coolant pump,
2 - to the heater,
3 - to the radiator,
4 - from the heater,
5 - from the radiator,
6 - thermostat.
Radiator
The radiator is located in front of the car and is designed to cool the liquid coming from the cooling jacket. The radiator consists of the right and left tanks and the radiator core. In the right tank there is an inlet pipe through which coolant flows from the cooling jacket. It also has a drain cock through which coolant is removed. The core of the radiator has many finned tubes through which the coolant flows from the right tank to the left. Thus, the coolant, which is heated while passing through the cooling jacket, is cooled in the radiator by the air flow forced by the electric fan and the oncoming air flow that occurs when the vehicle is moving. Automatic transmission models have a dedicated automatic transmission fluid cooler located in the left radiator reservoir.
Radiator cap
Radiator cap - sealing type; it must seal the radiator and withstand the increased pressure resulting from the thermal expansion of the coolant. The increased pressure in the radiator prevents the coolant from boiling even at temperatures above 100°C. The radiator cap has steam ("dropping") valve and air valve ("vacuum valve"). At a coolant temperature of 110-120°C, the excess pressure inside the radiator, caused by the thermal expansion of the liquid, reaches 0.3-1.0 kg/cm2 or 30-100 kPa. If the specified limit is exceeded, the steam valve opens under the action of pressure, and the steam exits through the steam pipe to the atmosphere. The air valve opens under the action of vacuum, which is formed inside the radiator after the engine is stopped and the temperature of the coolant drops.
Expansion tank The expansion tank is intended for the excess volume of the coolant, which is obtained as a result of its volumetric expansion when heated. When the coolant temperature drops, it returns from the expansion tank to the radiator; thus, the radiator is always filled with coolant, and unnecessary loss of coolant is not allowed. To make sure you need to add coolant, check the level in the expansion tank.
Coolant pump
The coolant pump provides forced circulation of the coolant through the cooling system. It is mounted in front of the engine on the cover of the timing chain drive and is driven from the crankshaft using a V-belt drive.
Thermostat
The thermostat has a wax bypass valve and is installed on the inlet pipe of the cooling circuit. The thermostat has an automatic valve controlled by the temperature of the coolant. This valve closes when the coolant temperature drops and thereby prevents the circulation of fluid through the engine, speeding up the warm-up process. At the same time, since the bypass valve is open, the coolant circulates only inside the engine (on a small circuit of the cooling system). When the coolant temperature rises, the automatic thermostat valve opens and the bypass valve closes, allowing the coolant to circulate through the radiator. The wax filling inside the thermostat core expands when heated and cools when cooled. Heating the wax filler of the power element creates a force that overcomes the force of the spring, under the action of which the valve is held closed; thus opening the automatic valve. When the wax filler cools, it contracts and the automatic valve closes under the force of the spring. In these engine models, the thermostat ensures that the operating temperature of the coolant is maintained at about 82°C.