How does Radiator Work? | What are the signs of Cracked Radiator?

The radiator works as a heat exchanger used to shift heat from one medium to another medium for the purpose of heating and cooling. The car radiator is the most important part of the engine cooling system. It plays a big role in cooling engine coolant. It removes the heat from the hot coolant and helps to prevent your engine from overheating. This article deeply explains the radiator working, parts, and some other important aspects.

What is a Radiator?

A radiator is a part of the engine cooling system used to remove the heat of the engine. The radiator is a key component of the car that works as a heat exchanger, transferring heat from the engine coolant flowing through the radiator to the air blown by the fan.

The main function of the car radiator is to prevent the engine from overheating and properly cool the engine coolant. Engine overheating or incorrect valve timing can cause serious vehicle damage.


Radiators are used to heat the environment or cool incoming liquids (i.e., coolant) such as HVAC dry cooling towers and vehicle engine cooling. Maximum radiators transfer most of their heat by convection process rather than thermal radiation. They are a good source of heat for the environment.

Radiators are most commonly used in the automotive industry for cooling the IC engines of vehicles. They are also used in stationary power plants, motorcycles, locomotives, railways, piston-engine airplanes, and other applications where IC engines are employed.

Brass and copper are most commonly used for the construction of radiators due to their high thermal conductivity. The different parts of the radiator are almost entirely soldered.

Working of Radiator

A radiator is one of the most important components of the engine cooling system. It helps to maintain the engine temperature. It is connected to the engine through hoses. The coolant flows inside the hoses.

A thermostat is installed at the front of the radiator that acts as a valve. It closes and opens according to the engine temperature. It regulates the flow of the coolant.

working of radiator

The working of the radiator is very simple. It works in the following way:

As the engine temperature increases, the thermostat sends a signal to the water pump. The water pump activates and pumps coolant into the hoses from where coolant circulates throughout the engine and absorbs its heat.

When the coolant absorbs engine heat, it becomes hot. This hot coolant is sent to the radiator. This hot coolant enters the radiator through the inlet port. The radiator has a fan that blows cold air through the hot coolant. This air absorbs coolant temperature and cools it.

This cold coolant is sent back to the engine, and the whole process repeats.

During this process, the radiator uses thin metal fins. These fins allow quick removal of coolant heat to the air outside the vehicle.

Types of Radiators

The car radiator has the following types:

  1. Tubular Type Core
  2. Cellular Type Core

1) Tubular Type Core

This type of radiator has two tanks: the lower tank and the upper tank. These two tanks connect with each other through multiple tubes. The water or coolant flows through these tubes.

Tubular radiator

The tubular radiator contains multiple fins installed around the tubes to increase the heat transfer rate. The air flows in between the fins and tubes. This air absorbs the heat of the water flowing through the tubes.

If one of these tubes is clogged, the cooling effect of that tube will be completely lost. However, in a cellular radiator, the clogging of a single tube causes losses but only affects a small part of the total cooling surface.

2) Cellular Type Core

The cellular-type core is also known as a honeycomb radiator because of its design. In the cellular radiator, water flows outside the tubes while air flows inside the tubes.

cellular type radiator

The core consists of a series of individual air cells. These cells are enclosed by water.

In the cellular type core, the clogging of a single tube causes losses but only affects a small part of the total cooling surface.

Read More: Different Types of Engines

Parts of Radiator

The radiator has the following major parts:

  1. Core
  2. Pressure Cap
  3. Inlet and outlet tanks
  4. Radiator Hoses
  5. Thermostat
  6. Water Pump

radiator parts

1) Core

It is one of the largest parts of the radiator. This is a metal block with metal fins. These fins ensure easy discharge of hot air.

The core is the area where coolant or water transfers its heat and cools down. As the liquid cools, it is sent back, and the whole process repeats.

2) Pressure Cap

The pressure cap plays a big role in sealing the cooling system. The pressure cap is also known as the radiator cap. It maintains the internal pressure of the radiator. This pressure is used to pressurize the coolant in the radiator to stop the coolant from boiling. It also improves the efficiency of the system.

The pressure cap always remains under high pressure. Therefore, you should properly inspect and maintain it.

3) Inlet and outlet Tanks

The inlet and outlet tanks are located where the coolant enters and leaves the radiator. These tanks are located at the top of the radiator.

As the coolant absorbs engine heat, it becomes hot and moves from the engine through the intake tank to the outlet tank. As the coolant cools, it exits the radiator outlet tank and returns to the engine. These tanks are connected through hoses.

Read More: Types of Internal Combustion Engines

4) Radiator Hoses

The hoses connect the water pump to the engine and the engine to the radiator. They connect to different parts of the vehicle. The coolant flows inside the hoses. The coolant moves from the radiator to the engine through hoses.

5) Thermostat

A valve that regulates the coolant level in and out of the radiator.

6) Water Pump

The water pump is used to pump the coolant from the radiator to the engine. 

Read More: Different Types of Water Pumps

Symptoms of Bad Radiator

The following are the symptoms of a bad radiator:

  1. Engine Overheating
  2. Coolant Leaks
  3. Low coolant Level
  4. Discolored coolant or sludge
  5. Shifting issues
  6. Hot Coolant
  7. The passenger heater not functioning

1) Engine Overheating

The main function of the radiator is to properly remove engine heat and ensure its cooling. So, if the vehicle continues to overheat, you may have a radiator problem. It may be due to a faulty thermostat.

As the thermostat doesn’t open and close properly, it leads to engine overheating and causes engine failure.

Read More: Signs and Causes of Engine Overheating

2) Coolant Leaks

The coolant leak under the car is a symptom of the faulty radiator. The leaked fluid may have a green, yellow, or red color. Plastic doesn’t have as much durability as metal. With time, plastic brittles and radiators start cracking. These cracks lead to coolant leaks.

Read More: Causes of Coolant Leaks

3) Low Coolant Level

The quick reduction in the coolant level represents that you might have damaged radiators. With the passage of time, the radiator cracks due to that coolant leaks. This leakage leads to a quick reduction of the coolant.

4) Discolored Coolant or Sludge

The healthy engine coolant most commonly has a dark yellow or green color. Rust and dirt from a failed radiator may lead to fluid contamination due to that coolant color converts into rusty or dark. Due to the rust and dirt, the coolant becomes thicker and forms sludge, which can affect engine cooling.

5) Shifting Issues

If your car contains an integrated transmission cooler, you may face problems with shifting as the liquid becomes grimy with coolant. This issue occurs due to cracks or faults in the system.

6) Hot Coolant

One of the major functions of the radiators is to cool the hot coolant. If you observe that your radiator is not cooling the hot coolant, there are high chances that your radiator has been failed. In such conditions, inspect the system and replace the faulty parts.

7) Passenger heater not functioning

The function of the heater is to take the heat by the radiators and transfer it inside the vehicle. If your heater is not heating your vehicle, it is a sign that you have a faulty radiator.

Causes of Radiator Failure

The following are the causes of radiator failure:

  1. Damaged Fins on the Radiator
  2. Thermostat failure
  3. Damaged or Leaky Hoses
  4. Insufficient Coolant
  5. Insufficient Maintenance

1) Thermostat Failure

A thermostat works like a valve. It allows the coolant to flow in and out of the radiator. If it doesn’t work properly, it may lead to engine overheating. In the event of a damaged thermostat, the car will quickly begin to overheat because it has no control to regulate the coolant properly.

Solution: Properly replace and maintain the thermostat and replace it after a specific interval.

2) Damaged or Leaky Hoses

Leaky hoses are the most common cause of radiator failure. These hoses connect the radiators to the engines and ensure the proper flow of coolant between them.

As the hoses are damaged, they couldn’t properly transfer coolant from the radiator to the engine due to that engine overheats. This overheating leads to radiator failure.

Solution: With time, hoses wear out or damage, and you need to replace them after a reasonable time. As you see symptoms of wear, be sure to replace them to avoid leaks and other possible failures.

3) Insufficient Coolant

Insufficient coolant leads to radiator failure. As the coolant level becomes low, the engine overheats, which leads to radiator failure.

Solution: Check the coolant level before driving. Add more coolant if it is lower than the required level.

4) Insufficient Maintenance

You must ensure the proper maintenance of your system. The maintenance improves the performance and efficiency of the system. Insufficient maintenance or repair leads to system failure.

Solution: Ensure the proper maintenance of your radiator.

5) Damaged Fins on the Radiator

The damaged or bent fins block the airflow. These fins are extremely delicate and a piece of tiny gravel hitting them while driving can cause damage.

How to replace a Radiator?

Follow the below-given steps to replace your radiator:

  1. First of all, park your car in a safe area.
  2. Don’t touch the radiator in hot engine conditions. Wait for 10 to 15 minutes until your engine fully cools.
  3. Lift the hood and find your radiator.
  4. Disconnect the electrical wiring and battery.
  5. Place a bucket underneath the radiator. Now unscrew the drain plug or remove the hose clamps near the radiator base and discharge the radiator coolant into the bucket.
  6. After discharging the radiator coolant, remove all the parts connected to the radiator.
  7. Some types of radiators contain a blower far. Disconnect this fan.
  8. Disconnect the old thermostat. 
  9. Now locate the bracketry that fixes the blown radiator in its place and remove the bottom bolts and nuts.
  10. Now eliminate the top nut and bolt that hold the top part of the radiator in its place.
  11. Disconnect the fan bracketry from the old radiator. 
  12. Buy a new radiator and install the fan bracketry on it. 
  13. Now install a new radiator in its place. Reinstall all other parts (such as fan, and hoses) in their original place.
  14. Remove the old thermostat. Buy a new thermostat and install it in its place.
  15. After connecting all the parts back to their place, add new coolant to the radiator.
  16. Now reconnect the electrical wiring and battery.
  17. Now Turn on the car engine and run it with the radiator cap still off. As the car circulates new fluid through the engine and radiator, it may be necessary to pinch and release the hose to eliminate air bubbles stuck in the hose.
  18. When the bubbles formation stops, now inspect for leaks and make a test drive of your vehicle.
  19. Congratulations if everything looks good and the car temperature stays normal.

Advantages and Disadvantages of Radiator

Advantages of Radiator

  • The radiator is very important to cool the engine properly.
  • It prevents the engine from overheating.
  • The radiators are highly efficient.
  • They generate very low pollution. These are environmentally friendly.
  • Good performance of oxidation corrosion resistance
  • The molding of the radiators is very easy. Therefore, they are available in multiple designs.
  • The installation of the radiator is very easy.

Disadvantages of Radiator

  • The radiator has high operation noise.
  • The insufficient maintenance of the car radiator may lead to engine overheating. They need proper maintenance and care for efficient working.
  • It requires a sufficient amount of air and coolant to work efficiently.
  • The heat of the device implies sits around it, reducing living comfort and creating drafts and cold spots.
  • It can become very hot during operation. Keep babies or pets away from heaters that are in use.

Applications of Radiator

  • The radiators are most commonly used in the vehicle cooling system to cool the engines.
  • They use in the HVAC systems.
  • They use to cool automatic transmission fluid.

Replacement Cost of Radiator

The radiator replacement cost varies according to the model of your vehicle, type of radiator brand, and the area where you live.

The average replacement costs of the radiator are from $990 to $1,150. The costs of the parts are from $762 to $850, while labor cost is from $228 to $300.

Labor Cost$228 to $300
Parts Cost$762 to $850
Total Cost$228 to $300

FAQ Section

What are radiators used for?

Radiators are used for applications where heat engines are employed, such as stationary generating plants, motorcycles, cars, hybrid cars, railway locomotives, and piston-engined aircraft.

What are the symptoms of bad radiator?

  • Shifting issues
  • Passenger heater not functioning
  • Discolored coolant or sludge
  • Engine overheating
  • Coolant leaks
  • Blown head gasket
  • Hot coolant
  • Low coolant level

What is the function of the radiator?

The main function of the car radiator is to monitor the engine temperature and ensures its proper cooling. It prevents the engine from overheating.

Where is the radiator located?

The car radiator is located in front of the engine under the hood. The radiator has the responsibility to maintain the engine’s normal temperature.

Can I drive with a bad radiator?

No, you shouldn’t drive your vehicle with a damaged radiator. In case of a damaged radiator, your car may generate various issues such as coolant leak, engine overheating, or engine damage. As the engine overheats, it may badly damage various parts of the vehicle.

What is the replacement cost of the Honda Civic radiator?

The average replacement cost of the Honda Civic Radiator is between $650 to $820. In this cost, the costs of the parts are between $450 to $550, while labor costs are between $200 to $270.

How often do radiators need to be replaced?

There is no specific time limit or distance when you have to replace your radiator. The service life of the radiator highly depends on its maintenance and repair. It also depends on the vehicle model and how much you drive your vehicle. It is recommended that you should replace your car radiator at approximately 79000 miles.

What are the signs of a cracked radiator?

You can identify a cracked radiator of your car by one of the below given signs:

  1. Passenger heater not functioning
  2. Engine overheating
  3. Coolant leaks
  4. Hot Coolant
  5. Low coolant level
  6. Shifting issues
  7. Discolored coolant or sludge
  8. Blown head gasket
Read More
  1. Types of External Combustion Engines
  2. Types of Pison Engines
  3. Working and types of Engine Cooling Systems
  4. How to add water to the radiator?
  5. Latest replacement cost of Coolant
  6. Signs of Bad Cooling System
  7. Working of HVAC System
  8. Signs of Bad Radiator Fan

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