Engine Cooling System Parts and Their Functions

The engine is among the most active part of the vehicle. One of the major parts of the engine is the combustion chamber, where fuel and air mixture is ignited to produce energy in the form of heat. The regular explosions in the internal combustion chamber generate a lot of heat. That is where the cooling system comes in. The cooling system parts work together to regulate the temperature in the engine.

The heat formed during the combustion process can damage the engine components in minutes. The cooling system maintains the engine cool enough for it to perform its functions efficiently. The cooling circulation is one factor that determines how long the engine will serve.

With the technology change, so much has changed in vehicles, but the cooling system has not changed much. Modern vehicles feature more effective and reliable cooling systems, which keep the engine at a constant temperature. Read the article to understand cooling system parts and functions.

cooling system parts and function

Cooling System Parts and Functions:

The temperature of combustion gases in the engine ranges from 1500 to 2000 degrees centigrade. This temperature is beyond the melting point of the material, and it can cause serious failure of the engine. The major function of the cooling system is to regulate the temperature in the engine.

This system reduces the engine lubricating oil temperatures and cools its moving parts. Excess temperatures cause the oxidation of lubricating oil, resulting in carbon deposits. Removing excess heat from the engine will lower its thermal efficiency. Therefore, the cooling system is designed to remove approximately 30% of the heat produced by the combustion chamber.

The cooling system comprises components that enable the coolant to pass in the engine block and absorb heat produced during combustion. After absorbing the heat, coolant fluid flows via a rubber hose to the radiator for cooling. The airstream cools the fluid as it moves to the radiator.

The internal combustion engines of modern vehicles are cooled by both air and water. However, some engines use either liquid or air to get rid of the excess heat coming from the engine. Small or special purpose engines are cooled with air coming from the atmosphere. Their systems are less complex and lightweight.

In high-power engines, the heat flows from a closed loop of water moving to the radiator for cooling. Water moves the heat quicker and has a higher ability to remove heat than air. This cooling system is therefore complex and heavy. Here are the various cooling system parts and functions.

1. Radiator

A radiator is a major component of the cooling system. Its main function is to reduce the coolant’s temperature after it passes through the water jacket. The radiator has several components which enable it to achieve its cooling purpose. It has five sections: a drain, lower tank, radiator core, reservoir core, and upper tank.

The upper tank is situated at the top of the radiator. It is the entrance of the float cooling water as it gets in the radiator. It has two parts, namely the reservoir channel and radiator cap.

The radiator cover controls the water temperature. You can also use the cap to put water in the radiator. The Reservoir channel allows the flow of the radiator water in the reservoir in excess cooling pressure.

The radiator center has several elongated and flat pipes. The flat design enables a quicker heat release process. The pipes connect the lower tank and upper tank. The radiator cools the water from the upper tank through the pipes and channels it via the lower radiator tank.

Hot water got in the radiator through the upper tank and cooled with the help of radiator fans. It releases the heat through wind fins in radiator fins, and the cold water passes to the lower tank.

2. Cooling Fan

A cooling fan is a major part of the car cooling system parts. This part gets rid of the heat absorbed from the car’s engine using a coolant. The cooling fan is situated on the front side of the vehicle. In most vehicles today, the cooling fan is either activated by either an electric or thermostat system.

After the coolant absorbs excess heat from the engine, it moves to the radiator, and the cooling fans blow the heat away. Cooling fans function when the engine is stationary. However, electric cooling fans are automatic and turn on and off depending on the engine’s temperature.

Another function of the cooling fan is to provide external airflow when it is moving too slow. The main part of the mechanical cooling fan is the cooling fin. The fin is fixed on the engine and gets power from the engine crankshaft.

The cooling fan of an electric radiator is stand-alone and gets its power from the engine’s electrical system. It comprises a cooling fan, motor, and a cooling fan shroud. The cooling fan shroud is mounted to the engine radiator. It then carries the fan and motor.

3. Reserve Tank and Pressure Cap

Cavitation of engine coolant happens when the engine RPM is higher than normal, especially in sports driving. Cavitation makes the cooling system unstable, thus causing overheating and other damages to the cooling system components.

The reservoir cap prevents the occurrence of cavitation. It controls the pressure in the cooling system and maintains optimum radiator efficiency. The pressure cap in the radiator is made for maintaining pressure in the vehicle’s cooling system.

The pressure cap features a spring valve with the right PSI. In case the pressure goes beyond the set pressure, the spring valve opens and allows some coolant to bleed off. The reservoir tank collects coolant bled from the pressurized cap. Most reservoir tanks are made with plastic and can indicate the coolant’s temperature.

4. Water Pump

The water pump is one of the main water cooling system parts. Its function is to circulate the coolant for it to move in the cooling channel. The water tank is situated in the water jacket. The thermostat closes, causing water to flow in the water jacket. This helps in flattening heat in the engine.

When the thermostat opens, the coolant flows from the water jacket to the radiator to minimize its temperature. There are two versions of a water pump. One of them is the electric water pump, and it gets its power from electric currents. The second type is the conventional water pump driven by engine power.

Water pumps work more like an agitator. It resembles a disk and is made with a combination of aluminum and steel. Its design enables it to minimize friction and maximize the coolant flow. In most cases, it is located in front of the engine. It connects with the radiator using a hose.

5. Water Jacket

A water jacket on the vehicle cooling system is also known as a water shell. It is among the important components of the water cooling system in the engine. It helps in the even absorption of heat in the engine. It acts as a water channel around the vehicle’s engine.

The water jacket has a shape of a jacket in the cylinder block. When the vehicle’s engine runs, it generates heat, thus increasing temperature in the cylinder head and engine block. The water jacket cooling system also cools exhaust valves, cylinder covers, and cylinder liners in the engine.

6. Bypass System

The system bypass prevents pumps from deadheading when the internal unit valves close. It also allows differential pressure and temperature sensors to sense active flow.

This component works when the temperature in the coolant is so high to open the thermostat.

The bypass system allows the coolant get direct to return directly to the engine without going through the radiator for the temperature to balance. Most bypass systems are rubber hoses or fixed steel tubes.

7. Radiator Hoses

Radiator hoses are rubber devices that manage the flow of coolant from the water pump to the heater. Radiator hoses are of two types. There is the lower radiator hose and upper radiator hose. They transport engine coolant to and from the engine.

The upper radiator hose is also known as an inlet hose. It takes hot coolant from the engine to the radiator. The upper radiator hose is also called an outlet hose. It moves the engine coolant from the radiator to the engine.

These hoses are made with synthetic and durable rubber to withstand pressure, heat, and vibration in the system. The designs are molded based on the requirements of their application. The hose has a spring that prevents it from getting adjoined by the pump’s force.

It is always crucial to check if the hoses are working properly for effective cooling in the system. Some signs that show something is wrong with the radiator hose are steam coming from the engine compartment, AC not working, and coolant leaks.

8. Heater Core

A heater core transmits heat from the hot coolant in the engine and produces warm air in the vehicle interior. Its purpose is to heat the car’s cabin. After absorbing heat from the engine, the coolant passes through a winding tube of the heater core.

The heater core has various components, which are an HVAC blend door, blower, heater hoses or tubing, or bower motor. These parts work simultaneously to ensure the vehicle’s interior is warm as it cools the engine.

9. Thermostat

The thermostat works like a valve in a vehicle and motorcycle cooling system. It opens or closes the valve between the high-temperature radiator hose and water jacket. It speeds up the vehicle engine to get the required working temperature.

The thermostat closes or opens depending on the temperature of the engine. When the temperature in the engine is low, the thermostat is closed. This allows a closed coolant circulation in the water jacket.

The process fastens the increase in engine temperature since the heat from the combustion chamber circulates in the engine through the coolant. When the temperature goes beyond 180 degrees, the thermostat opens slowly.

The coolant starts circulating outside the radiator automatically. The thermostat has a special wax that reacts to the amount of temperature in the engine. Some thermostat, however, has an electric motor that controls its opening and closing.

10. Freeze Plugs

Freeze plugs are also known as welch plugs or core plugs. They are small plugs with a cylindrical shape. They fill passages in the engine made as a result of sand cores. Their main purpose is to protect the automotive engines from damages caused by cold.

Manufacturers make some passages for removing casting sand during production. They then fill these passages with freeze plugs to prevent coolant leaks. Initially, combustion engines were cooled using plain water. Plain water is prone to freezing.

When the coolant in the engine freezes, the freeze plugs push it out. Most of the vehicle these days does not use plain water but a combination of antifreeze and water. Freeze plugs serve you for thousands of miles, but they are not prone to damage.

Keep checking them regularly for damage in freeze plugs can result in a difficult and costly repair. Freezing is the main factor that causes the plugs to fail. Prolong the life of the freeze plug by using the right coolant.

11. Intake Manifold Gasket

The intake manifold is another major component in the cooling system parts list. It acts as a seal of various channels which connect the car’s engine. It is located on top of the engine’s cylinder head. It seals the areas around the air channels and coolant to prevent leakage.

The intake manifold gasket is more prone to failure. Most of the leaks in the engine area due to the failure of the intake manifold. Some signs of a damaged intake manifold are engine misfires, rough idling, and coolant leaks, among others.

12. Cylinder Head Gaskets

The head gasket is situated between the cylinder head and engine block. This component of the cooling system acts as a seal between the cylinder head and engine block.

The head gasket should be able to maintain its seal to prevent leakage between the two engine parts. It separates the passage between water and oil that flow through the cylinder head and engine block.

Head gaskets are designed to withstand the stress between the two engine components. However, excess heat in the engine can lead to a blown head gasket. Some signs that may indicate that your car is suffering from a blown head gasket are a milky white color in the oil, unexplained coolant loss, the bubbling of the coolant reservoir and radiator, and white smoke from the exhaust pipe.


The thermometer is among the old BMW cooling system parts. Its main purpose is to measure the coolant temperature. The results of the measurements are shown on the vehicle’s dashboard. However, newer vehicle models use ECT sensors instead of thermometers.

Engine Heat Indicator

The engine heat indicator is incorporated into the thermometer. It shows the temperature of the coolant in the engine. The thermometer and engine heat indicator work together to protect the car’s engine from overheating.

It shows the real-time temperature of the coolant in the engine on the display panel of the vehicle. This helps the driver to know when the vehicle cooling system is malfunctioning.

Frequently Asked Questions (FAQs):

What are the Different Types of Cooling Systems?

Cooling systems control the temperature of the engine. The two types of cooling systems are water cooling systems and air cooling systems. In air cooling systems, the heat conducted to the engine’s outer parts is radiated away by air from the atmosphere.

Most air cooling systems have fins around the cylinder heads and engine cylinders to increase their surface area. This makes the process more efficient. This cooling system is mostly for small cars, scooters, motorcycles, and small aircraft engines.

A water cooling system has two functions in a vehicle. It prevents the engine from overheating by removing excess heat that is produced in the engine. It also keeps the vehicle’s engine at a suitable working temperature for economic and efficient performance.

Is Liquid Cooling Worth It?

Liquid cooling is much worth it since water transfers heat more efficiently than air. This type of cooling provides you with better thermal performance. However, it is more expensive compared to air cooling.

Is Liquid Cooling Quieter Than Air Cooling?

Liquid cooling is quieter than air cooling. This is because you will not have fans running at high RPM constantly to cool the system. Therefore, if you prefer to have a quiet cooling system and are not on a budget, you should consider liquid cooling.

Which Cooling System Is Best?

The best cooling system will depend on the make of your vehicle. The two types of vehicle cooling systems are water cooling systems and air cooling systems. The two of them have their advantages and disadvantages.

Air cooling systems are lightweight, less complex, and work well on small automobiles. They are, however, noisier, and the cooling process is slow. Water cooling systems are ideal for trucks and large automobiles.

Water cooling systems are heavy and complex, but they are more efficient. Therefore the best system will depend on your needs and car type. However, I would recommend a water-cooling system since it is more efficient.

Final Words:

The cooling system is an important part of the vehicle’s engine. The cooling system parts work together to regulate the temperature in the engine. This system is exposed to too much heat, thus making it quite prone to damage. It is advisable to do regular checkups on the cooling system since any failure in the system affects the engine performance.

Some of the major signs of a failed cooling system are engine misfires, low coolant levels, white exhaust smoke, coolant leak and raising temperature gauge. Refill the right engine coolant periodically, and it will increase the system’s durability. The coolants have additives that prevent the cooling system components from corrosion.


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