Engine cooling system
All models of the vehicles considered in this Manual are equipped with a positive pressure engine cooling system with thermostatic control of the working fluid circulation. The water pump is fixed to the engine block and pumps the coolant through the cooling tract of the latter. The flow of liquid washes the areas of each cylinder in the block, after which it is directed to the rear of the engine. Cooling channels laid in the block and cylinder head castings provide intensive cooling of the intake and exhaust ports, spark plug installation areas and exhaust valve guides.
General diagram of the cooling system operation
1 - Expansion tank; 2 - Lid; 3 - Built-in silica gel tank; 4 - Intake pipe; 5 - Radiator; 6 - Thermostat; 7 - Ventilation tube; 8 - Flow from engine to radiator; 9 - Flow from radiator to engine; 10 - Cooling system pump; 11 - Oil radiator; 12 - Cylinder block; 13 - Cylinder head; 14 - Heater delivery pipe; 15 - Windscreen washer heater; 16 - Heater radiator; 17 - Double pulsation valve; 18 - Circulation pump; 19 - Heater return pipe
From the moment the engine is started, the cooling system goes through three operating modes: at the first stage, until the coolant temperature rises above a certain value, it circulates in a small circle from the working circuit of which the radiator is excluded. As the liquid heats up further, the plate valve of the wax-filled thermostat entering the system tract opens and the radiator is connected to the circulation circuit. Then, when the coolant temperature reaches the next control value, a temperature-sensitive switch is triggered, activating the cooling system fan, the additional air flow pumped by it significantly increases the efficiency of the radiator heat exchanger.
The cooling system has a sealed design and is tightly closed with a radiator cap capable of withstanding a certain excess pressure, which increases the boiling point of the coolant and, accordingly, the efficiency of heat removal through the radiator. When the internal pressure in the system exceeds a certain value, excess coolant flows through the connecting (overflow) tube into the expansion tank. As the system cools, the liquid automatically returns from the tank to the radiator.
Adding coolant to the system is done through the neck of the expansion tank (see Chapter Routine maintenance) which simultaneously also acts as a receiver, accumulating the excess liquid displaced from the radiator.
Due to the listed design features, such a cooling system is called closed, since it excludes any functional losses of the working fluid.
Heating and ventilation system
The heating system consists of fans and heat exchangers located in the front and rear passenger compartment units. Hot coolant passes through the heat exchangers. When you move the heater control knob located on the control panel (for more details, see. Comfort Chapters User manual) the valves open and hot air begins to flow into the car's interior. If you turn on the heater fan, air will be forced into the interior.
Outside air passes through a filter before entering the passenger compartment (refer to Chapter Routine maintenance). The bulk of dust particles will settle in the filter. It is necessary to observe the frequency of filter replacement. A filter blocked by dust will limit the air supply to the cabin, which will lead to stagnation of air inside the cabin.
Distribution of air flows of the ventilation system is carried out using dampers. An air circulation mode is provided. The dampers are controlled using servo drives.
Independent heater
The standard equipment of some models may include an independent heater, which provides the ability to autonomously warm up the engine and the car interior using a timer signal or a remote control. The operating principle of the independent heater is discussed in Section Independent heater Chapters User manual.