What is Engine Cooling System? | How Engine Cooling System Works?

An engine is a device that transforms the fuel chemical energy into useful mechanical work. As the engine runs, it generates extreme heat. This heat may cause engine failure. Therefore, for the proper cooling of the engine, the car uses an engine cooling system. Generally, the cooling system continuously maintains the engine temperature. This article mainly explains the engine cooling system working, types, parts, and applications.

What is an Engine Cooling System?

An engine cooling system is a set of various parts that allow liquid coolant to flow through the engine block and cylinder head passages to absorb the heat of combustion.

As the coolant absorbs heat, its temperature increases. This hot coolant is returned to the radiator through a rubber hose for cooling. When the heated coolant flows into the radiator through a thin tube, it is cooled by the air flow.

It is a key component of an internal combustion engine that prevents engine overheating. The cooling system cools the engine as well as stabilizes the temperature to meet the engine’s operating requirements.

The main function of the engine cooling system is to maintain the engine temperature as normal and prevent it from overheating.

The engine cooling system cools the engine by circulating coolant (a mixture of water and antifreeze) through the engine vents. Some vehicles use the air-circulation method to cool the engine. In this method, the air flows through the finned cylinder casing.

The engine overheating may damage or completely fail the engine. This heat generates due to the combustion of the air-fuel mixture inside the combustion chamber. As the combustion process completes, the engine temperature becomes very high. The cooling system extracts this engine through the heat transfer method.

The cooling system works effectively by eliminating extra heat from the internal combustion engine and helping to maintain the engine at the normal operating temperature.

Working of Engine Cooling System

When the engine runs, it generates extreme heat. This heat generates due to the air-fuel mixture combustion inside the combustion chamber of the IC engine. A cooling system is used to control the heat of the engine.

There are multiple water vents in the engine block along with the engine cylinder. These vents circulate coolant through the engine head, dissipating engine heat and allowing coolant to flow optimally out of the engine. The rubber hoses connect the inlet and outlet of the water pump to the engine.

engine cooling system working

A cooling system works in the following way:

  1. As the engine heats up, the cooling system starts working. A water pump pumps coolant into the engine water vents.
  2. As the coolant starts circulating through the water vents, it absorbs engine heat and reduces its temperature up to the normal operating temperature.
  3. When the temperature of the coolant reaches up to 160 to 190 Fahrenheit, it expands the thermostat paraffin wax and opens it. The thermostat acts as a valve that opens and closes for the coolant.
  4. When the thermostat paraffin wax opens, the coolant passes through the hoses and enters the radiator. The radiator acts as a heat exchanger.  
  5. When the coolant comes into the radiator, the radiator fan blows cold air through the radiator fins, which helps to reduce the coolant temperature quickly.
  6. As the coolant cools, it transfers back to the water pump. The water pump pumps it again into the water vents, and the whole process repeats.
  7. The cooling system heat-absorbing capability varies according to the type of engine.

Read More: Working of Fuel System

Parts of Engine Cooling System 

The engine cooling system has the following major parts:

  1. Water pump
  2. Radiator
  3. Radiator overflow tank
  4. Thermostat
  5. Hoses
  6. Coolant temperature sensor
  7. Radiator cooling fan
  8. Freeze plugs
  9. Manifold gasket and head gasket
  10. Heater core

cooling system components

1) Water Pump

The water pump is known as the heart of the engine cooling system. The proper operation of the water pump is very important for the proper working of the cooling system. In case of a damaged water pump, the cooling system can’t properly extract heat from the engine, which may lead to engine failure.

This pump has a radial impeller inside the housing. The engine drives to the pump impeller. A serpentine belt uses to connect the engine pump pulley to the pump pulley. It transfers the rotary motion of the engine to the pump pulley and rotates the pump impeller.  

Read More: Types of Water Pumps

2) Radiator

The radiator works as a heat exchanger between the engine and the cooling system. Aluminum is used for the construction of the radiator. It has many small diameter tubes and fins. It also contains a pressure cap, drain plug, outlet port, and inlet port.

The radiator transfers the heat of the hot coolant coming from the engine to the ambient air. This hot air is expelled to the environment or inside the car through heater cores.

3) Radiator overflow tank

The radiator overflow tank is a plastic water tank. It has an inlet port that connects to the radiator and an overflow outlet port. It installs near the radiator.

It’s the same tank where you add water before driving. Therefore, you must add the appropriate amount of water into your radiator tank before driving so that your cooling system can work efficiently.

4) Thermostat

It is a valve that opens and shuts for the coolant. It also helps to isolate the radiator from the engine until the minimum temperature is reached.

As the engine temperature reaches up to a specific temperature, the thermostat opens and allows the coolant to flow through the radiator. It contains paraffin wax that opens and expands at a certain temperature.

If the thermostat is missing in your car, the engine will give off heat directly to the radiator and take a long time to warm up.

5) Hoses

In an engine cooling system, the rubber hoses are used to connect the engine, radiator, and water pump to allow water or coolant to flow through them. These hoses complete the circuit.  

6) Coolant Temperature Sensor

As the name represents, the coolant temperature sensor is a device that observes the temperature of the engine. It delivers the necessary data to control the working speed of the cooling fan.

The coolant temperature sensor delivers data to the engine temperature gauge, which displays the engine temperature on the vehicle dashboard. The ECU system of your car uses this data to control the fuel injection rate and engine ignition timing to improve vehicle performance.

7) Radiator Cooling Fan

Your car may have more than radiator cooling fans. These fans are installed inside the radiator, behind the radiator closest to the engine. This fan has a casing for safety reasons and to regulate the air properly.

The main purpose of the radiator fans is to keep air flowing by the radiator when your car is slowing down or stopping. As the car stops with the running engine, the radiator cooling fan reduces the engine temperature.

8) Freeze Plugs

In the manufacture of an engine block, a special sand molds into the shape of the coolant channels in the engine block. This sand statue is installed in the mold. Aluminum or liquid (molten) iron pours into this mold to make the engine block.

As the casting cools, the sand is removed. After this, the casting also removes from the engine block holes. Then the coolant can easily flow through these holes. Then plug the holes to prevent coolant from leaking out.

9) Manifold Gasket and Head Gasket

An internal combustion engine consists of an engine block and one- or two-cylinder heads. The surface where the block meets the head is flat for a perfect fit. However, this fit cannot be fully waterproof to stop combustion gases from escaping. A head gasket uses to seal the block to the head.

Read More: Types and working of Head Gasket

10) Heater Core

The hot coolant also delivers the engine heat to the heater core that further transfers heat to the interior of the car. Two rubber hoses are used to connect the heater core to the cooling system.

The first hose carries hot coolant from the water pump to the heater cores. The 2nd hose returns the coolant to the engine top.

Types of Engine Cooling Systems

The engine cooling system has the following major types:

  1. Air-cooling system
  2. Liquid-cooling system

1) Air Cooling System

In the air-cooled engine, the cooling system blows cold air instead of coolant to cool the engine. These types of cooling systems are usually found in conventional motorcycles and cars.

Air-Cooled Engine, air cooling system

In the air-cooled engine, the aluminum fins use to cover the engine block. These fins also extract heat from the engine cylinder. A powerful fan pumps air into these fins, moving engine heat to the circulating air to cool the engine.

The cylinders of these engines are more efficient than the water-cooled engine cylinders. They have the capacity to bear more temperature than the water-cooled cylinders.

The air-cooled system provides the significant benefit of preventing corrosion damage to the cooling system and preventing coolant freezing and boiling at extreme temperatures.

However, the air-cooled engine temperature control is highly complicated, and high temperature resistant ceramic components are needed when the fixed working temperature increases significantly.

In the air-cooling system, the amount of heat extracted by the engine varies according to the temperature of cooling air, the temperature of the fins, the speed/amount of the cooling air, and the total surface area of ​​the fins.

These types of engine cooling systems are mainly used in low power engines such as small air car engines, small cars, scooters, and motorcycles where the machine’s onward motion provides enough speed to cool the engine. They also use in compact industrial engines.

Read More: Working of Air-cooled Engine

Advantages and Disadvantages of Air-Cooling System

Advantages Of Air-Cooling System
  1. The air-cooling system has lightweight.
  2. They don’t need antifreeze.
  3. These are best suitable for the water shortage applications
  4. They have a simple design.
  5. They are small in size.
  6. The air-cooling systems require less installation area.
  7. It prevents the engine parts from corrosion and overheating.
  8. It increases engine performance.
Disadvantages Of Air-Cooling System
  1. It generates extreme noise.
  2. These cooling systems are not as efficient as water-cooling systems.
  3. They can’t supply a uniform cooling.
  4. These are not best for large and high-power engines.
  5. They are best for applications where ambient temperatures are lower.
  6. The air-cooling system requires very large fans to cool the engine.

2) Liquid Cooling System

The liquid cooling system is also known as an indirect cooling system. This system cools the engine through a liquid coolant instead of air.

liquid cooled engine

In this cooling system, the actual cooling material (i.e., air) does not directly cool the system. The air cools the water, and the water cools the engine.

This system uses water jackets to surround the engine. A water pump uses to circulate the water in these jackets.  

As the water flows through the water jackets, it extracts engine heat through the heat transfer process. As the engine heat transfers to the water, it heats up. This hot water moves into the radiator. The radiator has a fan that blows cold air and cools the water. This cold water again pumps into the water jackets, and the whole cycle repeats.

These cooling systems are commonly used in large engines such as trucks, buses, tractors, and cars.

Read More: Working of Liquid-cooled Engine

Advantages and Disadvantages of Liquid-Cooling System

Advantages of Water-Cooling System
  1. It has a compact design of engines
  2. The water-cooling system delivers uniform cooling.
  3. You can install the water-cooled engine anywhere in the vehicle.
  4. These are best suitable for both small and large engines.
Disadvantages of Water-Cooling System
  1. The water-cooled engines are heavier than air-cooled engines because they have a circulating pump, radiator, and jackets.
  2. These systems consume more power and reduce engine efficiency.
  3. The presence of water may corrode the engine parts.
  4. These systems require regular and more maintenance than the air-cooling system.

Why is Engine Cooling System Important?

An engine cooling system is a most important of the vehicle. It prevents the engine from damage. You must use an engine cooling system because of the following reasons:

  1. While the engine is running, the temperature inside the engine can reach 2,500oC, which is higher than the melting point of the engine parts. This high temperature may melt or damage the parts of the engine. Therefore, it is necessary to use a cooling system to remove the maximum heat of the engine.
  2. Thermal stresses can develop in the engine due to a large amount of heat. Therefore, a cooling system requires to lower the engine temperature, which reduces thermal stresses.
  3. The moving parts of the engine require proper lubrication. The lubrication system reduces the friction of the moving parts and ensures the proper working of the engine. However, the engine’s high temperature can change the properties of the lubrication. The change in lubrication properties may affect the engine’s moving parts. Therefore, to stop this, you must use an engine cooling system.
  4. The higher the temperature, the lower the engine’s volumetric efficiency.
  5. Under some specific conditions, the cooling fins may vibrate and increase the noise level.
  6. At high temperatures, the engine output reduces.

FAQ Section

What is a Cooling System?

A system that extracts additional heat by the engine and prevents it from overheating is known as a cooling system. The cooling system consists of a coolant, thermostat, hoses, water pump, radiator, and freeze plug. It uses air or liquid (i.e., water or coolant) to extract heat from the engine.

What are the functions of cooling system?

The engine cooling system performs the following major functions:

  1. The main function of the cooling system is to eliminate additional heat from the engine and prevent the engine from overheating
  2. It ensures the normal operating temperature of the engine.
  3. It increases the temperature of the cold engine when needed.
  4. It extracts heat by the engine and delivers this heat to the heater to heat up the car cabin.

What are the components of Cooling System?

The engine cooling system has the following components:

  1. Heater Core
  2. Water Pump
  3. Manifold Gasket and Head Gasket
  4. Radiator
  5. Freeze Plug
  6. Radiator overflow tank
  7. Radiator Cooling Fan
  8. Thermostat
  9. Coolant Temperature Sensor
  10. Hoses

What are the types of Engine Cooling Systems?

The engine cooling systems have the following major types:

  1. Water-cooling system
  2. Air-cooling system
Read More
  1. Types and working of Fuel Delivery System
  2. Different types of Engines
  3. Working of Fuel Regulator
  4. Signs of a bad Cooling System
  5. Signs of Coolant Leak

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