Have you ever wondered how the engine cooling system of your car works? It may not look like important, but it’s an essential part of the car ensuring the perfect functioning of the engine.
The car engine cooling system is a mix of devices working to cool the engine temperature holding it at the best operating level.
History tells that the German engineer Karl Benz, considered the inventor of the car, was the first one equipping cars with the first cooling system. Wilhelm Maybach, instead, designed the first honeycomb radiator put on the Mercedes 35 HP, which has been the first successful vehicle with an integrated cooling system.
From the very first models with a liquid cooling system distilled water has been used, that transports and dissipates heat inside the cooling circuit. However freezing was still a problem, because water turns into ice when temperature goes below 0°C, freezing the radiator as well; hence antifreeze solutions have been invented made with ETHYLENE GLYCOL, used for the first time during the WWI.
In this video we’ll see how the car cooling system works, its components and how they operate together.
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The cooling system of a spark-ignition engine consists of various components, let’s now see them in detail:
- The main part is the water pump, ensuring the liquid to flow through all components. It consists of an IMPELLER and gets activated by the transmission belt through a PULLEY;
- Let’s now talk about the RADIATOR, which works as a heat exchanger; it consists of an inlet port, a pressurised cap helping to raise the boiling point of the coolant and an outlet port;
- The THERMOSTAT is a valve that regulates the coolant flow and helps to maintain a proper operating temperature for the engine. The thermostatic valve is made by a frame and a spring that activates the charge cylinder;
- The cooling FAN helps in cooling the engine when the the cooling system is off and the liquid is not flowing, or when more ventilation is required;
- The water TEMPERATURE SENSOR is connected with the control unit managing the pump, keeps also the driver updated of increasing temperature of water thanks to a specific warning light on the driver console;
- The THERMOSTAT SWITCH activates the cooling fan.
We’ve seen all the parts of the cooling system, now let’s see it in action. As we’ve already said, the cooling system’s main task is to hold the engine at the proper temperature.
The coolant is in an easily accessible container in order to refill it when necessary. The fuel tank cap has to be pressurised because by holding the pressurisation in the whole system the boiling point of the liquid will considerably increase.
The water pump spreads the liquid through the whole system by a radial impeller. This piece is activated by the timing belt connected to the pump with a pulley and the liquid starts to flow in the engine and cooling it.
It’s now time for the thermostat: it is a valve that regulates the flow of the coolant. The valve is always immersed in the liquid in order to detect the temperature. When the liquid starts to absorb the heat from running engine and its temperature is between 158° and 194° F (70°-90° C), the thermostatic valve opens allowing the liquid to reach the radiator inlet port.
The radiator is indeed a heat exchanger; through a small-pipes grid where the liquid flows and a series of metal fins it dissipates the heat outside, if necessary helping with the cooling fan.
The fan is activated when there is no natural ventilation and consequently sufficient heat exchange, for example when the vehicle is stationary with engine on, on a hill or in very hot days.
Once the liquid has cooled, it’s put back in the system cooling the engine.
The liquid cooling system is advantageous because it maintains a better control over the engine temperature and thanks to the presence of the liquid ducts, which soundproof the cylinder, this system results less noisy.
On the other hand, it also has disadvantages: it requires more maintenance so it is certainly more expensive than an air cooling system; in addition, having multiple components like hoses, pumps and radiators, it is heavier.
Now let’s talk about the problems related to a possible failure of the cooling system.
The most common is the thermostat failure and 2 types of malfunctions can occur:
- In the first case, the thermostatic valve does not open, therefore the coolant flow will be blocked and will not reach the radiator, causing overheating and a lot of damage to the engine;
- In the second case, the thermostatic valve remains always open, this will lead to a steady flow of the coolant not allowing the engine to reach the optimum operating temperature, straining the cylinders in their motion and wearing out the sensitive parts of the engine.
In this video we have explained how the cooling system works, its components and failures. If you know any other disadvantages or advantages of this system let us know and don’t forget to follow our automotive world playlist.