Understanding How Your Car’s Engine Cooling System Works

Did you know that while driving your car on the highway at about 80 kilometers per hour it produces several thousand explosions a minute? The combustion process uses fuel and air to create these controlled explosions in order to propel your car forward. Obviously, all of these explosions produce a huge amount of heat which needs to be controlled, otherwise, it would destroy your engine in a few minutes. And this is where the cooling system comes into play. The modern car engine cooling system remains relatively similar to the cooling systems found in the first cars that were introduced. While yes, modern cooling systems are far more efficient and reliable at doing their job, they’re still simplistic in what they do and how they do it.

Basically, cooling systems feature a liquid coolant that’s being circulated through the engine, then into the radiator to be cooled with the help of air stream coming from the vehicle’s grille. As a result of your car engine cooling system, the engine operates at constant temperatures no matter the temperature of the air outside. The reason why having a properly working cooling system is essential for the performance of your vehicle is that an engine whose temperature is too low will operate inefficiently in terms of fuel economy, and emissions will rise. On the other hand, if the engine’s temperature is too high, it will inevitably get damaged and it will eventually self-destruct.

Nowadays, you’ll find two types of cooling systems: air- and liquid-cooled. Air-cooled engines are found on older cars and many modern motorcycles, but other modern vehicles use liquid-cooled systems, which are the ones I’ll focus on. Liquid cooling systems are made up of a water pump that circulates the liquid coolant, passages inside the engine’s block and heads, a radiator, a thermostat which controls the temperature of the liquid coolant, a radiator cap that controls the pressure, and plumbing elements like interconnecting hoses which transfer the liquid coolant and are also connected to the vehicle’s heating system which has hot coolant to warm the car’s interior on colder days.

As briefly aforementioned, the car engine cooling system operates by sending the liquid coolant through the passages located in the engine block and heads. As the coolant passes through these passages, it collects the heat and takes it to the radiator through a rubber hose. The heat is then cooled off in the radiator with the help of air stream that enters from the grill. Once the hot liquid is cooled off, it returns to the engine to absorb heat again. The water pump is responsible for keeping the fluid flowing through the system of hidden passages and plumbing.

The thermostat is located between the radiator and the engine to ensure the coolant stays above a specific temperature level. If the temperature falls below, the thermostat will block the flow of coolant to the radiator, which forces fluid through a bypass right back to the engine. The liquid coolant will then keep circulating in this fashion until it reaches the specified temperature, at which point, a valve will be opened by the thermostat that will allow the liquid coolant back through the radiator.

The car engine cooling system is specifically designed to be pressurised in order to prevent the coolant from boiling. When under pressure, the coolant’s boiling point is raised significantly. However, too much pressure can have a negative impact on the other parts of the cooling system, so the radiator cap is in place to control the pressure levels. If the system reaches a high amount of pressure, the cap is designed to release some of it. In the past, the pressure would be released to the pavement, but modern systems capture the released fluid into a reserve tank, which is then returned into the system after the engine has cooled down. These cooling systems are known as closed cooling systems.

Now that you understand how cooling systems work, you also need to understand why it’s important to keep them working properly. If your cooling system is faulty, it will overheat the engine and eventually damage it. That being said, proper maintenance is important for prolonging your engine’s life and ensure your cooling system operates trouble-free. The most important part of cooling system maintenance if flushing and refilling your coolant. This is due to the fact that anti-freeze (the coolant) has additives in it which prevent corrosion inside the system. The corrosion will accelerate when different types of metal interact with each other through the coolant, and that will cause scale build-up that will start clogging the thin flat tubes found in the heater core and radiator, resulting in overheating of the engine.

Long-life or extended-life bottles of antifreeze last up to 5 years or 250.000 kilometres before needing replacement. However, chances are you are using a more generic bottle of anti-freeze, which should be replaced every 2 years or 50.000 kilometres. If you intend on replacing a generic coolant with a long-life one, make sure you flush the generic one completely, else you can’t expect to gain the benefits of using the long-life coolant. Flushing the cooling system requires equipment, so make sure you do it at a reputable shop, as you’ll also have to remove the thermostat to ensure the job is done properly. Flushing your coolant at a reputable shop is especially important if your liquid coolant has debris or scale floating around it, or starts looking brown-ish. When replacing the type of coolant you’re using, also replace it with a new thermostat of the appropriate temperature, as that’s just cheap insurance, so to speak.