Cold coolant from the bottom of the radiator is pumped by a pump into the water jacket channels of the block and cylinder head, where it absorbs heat from the combustion chambers and moving parts of the engine, then flows into the upper part of the radiator. As the liquid passes through the radiator, it is cooled by the air flow (arising from the movement of the machine and, when necessary, from the fan),.and the process starts again.
To speed up engine warm-up and maintain its correct operating temperature, a thermostat is installed on the outlet of the cooling system connecting the engine to the upper radiator hose. When the coolant is cold, the thermostat is closed and the coolant circulates through the engine's water jacket, returning back through the bypass channel. As the temperature of the fluid rises, the thermostat opens and fluid begins to flow into the radiator.
The system is under pressure, which helps to lower the boiling point of the coolant. This ensures optimal engine operating temperature and reduces the amount of liquid required for cooling.
Hot coolant enters the car's interior heater and also transfers heat to the carburetor and intake manifold, which facilitates the process of converting the fuel into a vaporous state.
The fan pulley has an electromagnetic drive that is activated only when the coolant temperature is high. This design ensures that the fan operates only when it is really needed, resulting in reduced noise levels and energy consumption.
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Cooling system on XU engines
1. The cooling system on XU engines differs from the cooling system used on XL and XR engines in three main ways:
- a. The system is closed (air from the radiator is released into the expansion tank, not into the atmosphere).
- b. The water pump is driven by the camshaft drive belt.
- c. The radiator cooling fan is driven by an electric motor.
2. There are also minor differences in the hose routing and thermostat location. The basic procedures for working with the cooling system remain unchanged.