How Does A Car’s Cooling System Work?

The modern cooling system of a car manages to keep the temperature regulated. But how does a car’s cooling system work? How can it maintain both warm and cool temperatures? What are the parts that make this possible? Read on to know more.


How Does A Car Engine Cooling System Work?

A car’s cooling system is a crucial component of the internal combustion engine. It maintains your car’s operating temperature by preventing overheating and regulating warm temperatures to the passenger compartment when required.

The heat inside a car engine’s combustion chamber can reach a temperature as high as 1600 degrees Fahrenheit. The ideal operating temperature of a car’s engine is around the 200 degrees range. The temperature generally depends on the coolant’s temperature. It is very easy for an engine to get damaged when the temperature reaches anywhere near 300 degrees.

The cooling system of an engine depends on the principle of heat transfer. This principle works on the movement of heat energy from one area to another. Heat energy seeks out colder areas to flow towards. For example, placing warm cans in an ice cooler can make the cans colder.

In a car’s cooling system, the water pump spreads coolant throughout the cooling system of the car. It uses spinning impellers to spread the coolant through the radiator, heater core, and the engine. This water pump is powered by accessory drive belts that operate the air conditioner compressor, alternator, and power steering pump. The belts are driven by a pulley placed on the front of the crankshaft.

The coolant flows through the engine with the help of water jackets. Water jackets are placed throughout the car’s engine but are mainly concentrated around the combustion chambers, as this is where the highest temperature is generated.

The flow of the coolant entirely depends on the thermostat. A thermostat uses a spring-operated poppet valve, which closes when the engine is cold, obstructing the coolant flow. It opens at a temperature of 185-190 degrees, depending on the thermostat’s rating.

The coolant’s flow through the radiator stops when the thermostat is closed. The coolant then flows through the engine by a bypass hose. This action permits the coolant to heat up without the cooling effect of the radiator. This allows the coolant and the engine to reach operating temperatures.

Once it is at operating temperature, the thermostat opens, permitting the coolant liquid to flow through the radiator. The thermostat uses a bimetal spring for this action. The spring has two different metals that expand and contract differently when exposed to change in the temperature. When the hot coolant heats the spring, both metals pull against each other, making the spring contract. This action opens the poppet valve and allows the coolant to flow.

When the coolant liquid passes through the car’s engine, the heat goes from the hot engine to the coolant. As the coolant passes through the radiator, this cycle of heating up and cooling down continues to maintain the required temperature. A cooling fan passes air through the radiator fins, making the radiator’s heat energy enter the atmosphere. Cooling fans are either powered by an electric motor or are belt-driven.

Belt-Driven Fans

Belt-driven fans generally function with a centrifugal clutch or a thermostatic clutch. The centrifugal clutch slows down the fan blades’ spinning as the engine speed increases. It allows the fan to freewheel, disconnected from the engine’s torque. It is based on the assumption that the vehicle must be moving down the road if the engine speed is high. When a vehicle is moving, air blows through the radiator, which requires lesser fan speed. Cutting down on the fan speed reduces the load on the engine, which improves fuel economy.

The thermostatic clutch has a built-in bi-metal spring that lessens torque to the fan blades when the engine is cold. As the spring heats up, it allows for the full operation of the fan blades. This reduces the fan speed as well, improving the fuel economy.

Electric Cooling Fans

Electric Cooling Fans are operated with the ECM (electronic control module), using input from the engine coolant temperature sensor. When the coolant reaches a set high temperature, the ECM turns the fan on and vice versa when the coolant reaches a set low temperature.

Electronic fans are ideal as they save fuel by not putting a load on the engine. The ECM electronically controls the temperature and maintains optimal coolant temperature. The ECM turns the cooling fan on when the air conditioning is on. The air conditioner condenser is placed in front of the radiator, making it vital that there is high-speed air blowing through the radiator and the condenser continually when the air conditioner is running.

Pressure Caps

All automotive cooling systems are sealed with a pressure cap. As heat increases pressure, the pressure starts building up in a cooling system when the temperature rises. The results can be damaging if you forget to check this pressure. Pressure caps vent the cooling system of a car at a preset pressure. Most pressure caps are set at 15 PSI (pounds per square inch) of pressure.

At 15 PSI, the pressure cap vents the pressure to the atmosphere. The pressure cap works the same as a thermostat with a bi-metal spring. This spring contracts and lifts the seal, allowing the air to escape.

A pressure cap can be placed on either the radiator or a plastic degas bottle (a reservoir). A degas bottle is placed in the engine compartment above the engine and radiator. Air rises when trapped in liquid; any air in the cooling system makes its way up to the degas bottle and is pushed out of the pressure cap. Air can be adverse to the car seat cooling system. Trapped air can inhibit the coolant’s flow and cause overheating false temperature readings, and lack of heat in the passenger compartment.

The car engine’s cooling systems that have the pressure cap on the radiator use an overflow tank. The overflow tank catches any coolant that escapes during pressure venting. If the radiator’s coolant level drops during the flow of the cooling system, the coolant is sucked out of the overflow tank and into the radiator.

Apart from keeping a car’s engine cool, a car engine’s cooling system can also keep you warm. The hot coolant is transferred to the heater core, and then to the air. This comes into the car with the help of a blower motor.

The heater core is a set of narrow tubes connected by thin layers of metal arranged in a honey-comb-like structure. The hot tubes heat the honey-comb, which transmits the heat energy to the air. This air is forced into the heater core by a blower motor.

Closing Thoughts

A car engine’s cooling system can keep the engine from self-destruction. The cooling system continuously keeps the temperature regulated according to what you want. Suffice it to say, the breakdown or failure of this system can be quite troublesome to deal with. Equipping yourself with an auto warranty can help you in such situations. Visit Consumera to know about the top auto warranty companies.