The system is filled with liquid (antifreeze) based on ethylene glycol, non-freezing at ambient temperatures down to -40°C. The circulation of fluid in the system creates a water pump. From the pump, liquid is supplied to the engine cooling jacket, washes the combustion chambers and then enters the thermostat. Depending on the position of the thermostat valve, the liquid enters the water pump (at low temperature) or radiator (at high temperature). The normal thermal regime of the engine is determined by the temperature of the coolant, which is maintained automatically by a thermostat in the range of 85-96°C.
Warnings: It is not recommended to fill the cooling system with water, since antifreeze contains anti-corrosion and anti-foaming additives, as well as additives that prevent scale deposits.
Coolant is toxic! Avoid inhalation of vapors and contact with skin. Timely eliminate the violation of the tightness of the cooling system in order to avoid the ingress of coolant vapor into the vehicle interior during its operation. Your health is more valuable than a new cooling system pipe or a tube of sealant!
Radiator with a horizontal liquid flow, with a tubular-tape aluminum core and plastic tanks. There is a drain cock at the bottom of the supply tank. In the tanks there are inlet and outlet pipes of hoses to the water jacket of the engine, pipes of hoses connecting the radiator with the expansion tank. If the car has an automatic transmission, a heat exchanger is installed on the left side of the radiator to cool the working fluid.
Expansion tank (pic. 5.15) serves to compensate for the changing volume of the coolant depending on its temperature. The tank is made of translucent plastic. To control the level of the coolant, marks of the maximum and minimum levels of the working fluid are applied to its walls. At the top there is a filler neck, hermetically sealed with a plastic stopper with two valves inside it (inlet and outlet), collected in a single block. Exhaust valve opens at 140 kPa (1.4 kgf/cm2), providing an increase in the temperature of the start of boiling of the coolant and preventing intense vaporization. When the liquid is cooled, its volume decreases and a vacuum is created in the system. The inlet valve in the plug opens at a vacuum of about 3 kPa (0.03 kgf/cm2) and lets air into the expansion tank.
Note: The plug valves are very important for the normal operation of the cooling system, but often when problems occur (boiling of coolant, etc.) motorists pay attention only to the operation of the thermostat, forgetting to check the valves. Leakage of the exhaust valve leads to a decrease in the boiling point of the coolant, and its jamming in the closed state leads to an emergency increase in pressure in the system, which can cause damage to the radiator and hoses.
Water pump centrifugal type provides forced circulation of fluid in the cooling system, is installed on the front plane of the cylinder block and is driven by a toothed timing belt. The axis of rotation of the pump pulley is eccentric to the axis of its housing, which allows adjusting the belt tension by turning the housing around the axis. The pump has sealed bearings that do not require relubrication. The pump is not subject to repair, in case of failure (fluid leakage or bearing damage) it is replaced as an assembly.
Thermostat with a solid temperature-sensitive filler maintains the normal operating temperature of the coolant and reduces the warm-up time of the engine.
It is mounted on the cylinder head in its front part on the right in an aluminum collapsible housing. At a coolant temperature of up to 82°C, the thermostat is completely closed and the liquid circulates through a small circuit, bypassing the radiator, which accelerates engine warm-up. At a temperature of 82°C, the thermostat begins to open, and at 96°C it comes off completely, providing fluid circulation through the radiator.
electric fan with a plastic seven-bladed asymmetric impeller, it ensures the radiator is blown with air at low vehicle speeds, mainly in urban areas or on mountain roads, when the oncoming air flow is insufficient to cool the radiator.
To increase the efficiency of work, the fan is installed in the casing and attached to it at three points through rubber cushions. The casing, in turn, is attached to the radiator at four points.
The electric fan is controlled by the engine control unit, which receives information about the coolant temperature from the coolant temperature sensor located in the water jacket of the cylinder head. When the coolant reaches a temperature of 95°C, the fan turns on at a low speed. At a liquid temperature of 96°C, the control unit turns on a high fan speed via a thermal relay. When the coolant temperature drops to 82°C, the electric fan turns off.
On vehicles with air conditioning, an additional electric fan can be installed as an option, designed to blow through the air conditioning heat exchanger. In this case, the engine control unit additionally uses information from the air conditioner pressure sensor to turn on the electric fans. When the air conditioner is turned on, the additional electric fan of the radiator of the cooling system starts to rotate at a low speed until the liquid reaches a temperature of 96°C or until a certain pressure is reached at the outlet of the air conditioning compressor. After the specified conditions are reached, the control unit turns on the high speed of the electric fan.
The radiator for the interior heater is also included in the cooling system with hoses.