How To Bleed Cooling System In A Car

Bleeding a car’s cooling system is a challenging task and if not done correctly, it can lead to engine damage. The coolant system can start overheating due to the accumulation of air pockets. To learn how to bleed a car’s cooling system, keep reading!

how to bleed cooling system

Well, in this article, we’ll be discussing the answers to the following questions:

  • What is the function of a cooling system in a car?
  • Why do you need to bleed your car’s cooling system?
  • What will happen if you incorrectly bleed your car’s cooling system?
  • How to properly bleed the cooling system in a car?

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OK, let’s dive in!


What is the function of a cooling system in a car?

Three vital functions are served by the cooling system. The engine is first cleared of excess heat, then kept at the operating temperature where it operates most effectively, and finally, the engine is brought up to the proper operating temperature as rapidly as possible.

Why do you need to bleed your car’s cooling system?

To make sure there is no trapped air in the cooling system, it is crucial to bleed the system. Air pockets might accumulate in the cooling system during coolant replacement or other repairs that need draining the cooling system, which will prevent the coolant from flowing properly. These air bubbles can result in hot spots, which can damage engines and cause overheating. It’s crucial to bleed the cooling system by removing the air pockets in order to avoid this.

This entails opening the bleed valve, allowing the air to leave, and maintaining a coolant level in the system until all of the air has been released. Bleeding your car’s cooling system is an easy procedure that keeps your engine operating well and guards against any harm. When the radiator or engine block has lost coolant or has a fluid level below normal due to something failing or the necessity to drain the system to repair a part, you need to bleed the cooling system.

Air pockets may develop in the engine block, radiator hoses, radiator, and heater core when adding fresh coolant or antifreeze to the cooling system. By removing any air bubbles, the cooling system can function properly. Because there will be less hot coolant releasing heat for the blower motor to drive into the cabin if there is too much air in the heater core, the heat may not be as warm or not operate at all.

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What will happen if you incorrectly bleed your car’s cooling system?

If you incorrectly bleed your car’s cooling system, several problems can occur, including:

  • Overheating: Trapped air in the cooling system can prevent the proper circulation of coolant, leading to engine overheating. Overheating can cause significant damage to your engine, including warping of the cylinder head, blown head gasket, and cracked engine block.
  • Coolant leaks: If the cooling system is not bled correctly, it can cause leaks in the system. Leaks can lead to a loss of coolant, which can cause the engine to overheat and lead to serious engine damage.
  • Reduced performance: When the cooling system isn’t working correctly, your engine may not perform as well as it should. You may notice a decrease in power and acceleration, reduced fuel efficiency, and other performance issues.
  • Corrosion: Trapped air in the cooling system can cause corrosion in the system’s metal components. This corrosion can cause leaks and blockages in the cooling system and other engine components.

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How to properly bleed the cooling system in a car?

  • Prepare the coolant.
  • Lift up the car’s front end with a jack.
  • Fill the coolant to the MAXIMUM.
  • Start the engine.
  • Turn the temperature control all the way up.
  • Boost the engine’s revs to 3000–4000.
  • Carefully open the bleed valves.
  • If needed, refill the coolant.
  • Take a test drive.
  • Add coolant once more.

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Prepare the coolant

Prepare the coolant

Make sure your coolant is prepared. You should always use the precise coolant that your manufacturer specifies. Your engine could suffer from the improper kind of coolant! Check your service manual or get in touch with your authorized dealer if you’re unsure of the coolant you should use.

If the coolant is a concentrated anti-freeze coolant, mix it with 50% water and 50% coolant. For the correct directions, always read the coolant description. Make sure the coolant mix is appropriate if you reside in a chilly country. Your engine will be ruined if your coolant freezes inside of it.

Read more: How To Put Coolant In A Car

Lift up the car’s front end with a jack

Lift up the car's front end with a jack

This technique makes it much simpler to remove the air from the car, especially if your radiator is where your filling cap is located. This may not be necessary if your car already has an external expansion tank mounted in the back of the engine.
You may either use a floor jack or park the vehicle with its front facing upwards on a steep hill to raise it.
Always utilize Jack Stands along with a floor jack to raise your automobile to avoid any mishaps.

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Fill the coolant to the MAXIMUM

How to put coolant in a Car

It’s time to fill your coolant as fully as possible once the front of the automobile has been raised. Open the air bleed valves on your engine if it has them when you add the coolant. When coolant is dripping from them, close them. Since anti-freeze is poisonous, you should always make sure that none of the coolants is dripping into any floor or road wells.

You should bring back all coolants to your neighborhood environmental assessment. Bear in mind that if any animals consume the coolant, they could become fatally ill. Take caution when using antifreeze. Go to the next step once you’ve filled your coolant as much as you can.

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Start the engine

Start the engine

Now is the time to start your engine. Getting assistance from a friend is the best approach to complete this. If there is air in the system, the water pump may push some coolant from the radiator when you turn on the engine.

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Turn the temperature control all the way up

Turn the temperature control all the way up

You should now switch the climate control heat to MAX after starting the engine. Depending on the vehicle, many cars include a valve that, if the temperature control is set too cold, prevents coolant from flowing within the thermal pack.
This method will have no effect on other autos because they divert the airflow rather than the coolant flow. No matter what model you have, turning up your temperature control to the MAX heat is a simple process.

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Boost the engine’s revs to 3000–4000

Boost the engine's revs to 3000–4000

Have your pal get into the car and increase the engine’s RPMs to about 3000–4000. Using the spill tool will prevent the coolant from spilling out of the radiator as a result of this. While working on the system, keep the RPMs constant. While working on it, watch out that the coolant doesn’t become too hot.

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Carefully open the bleed valves

Carefully open the bleed valves

You can now loosen the air-leaking valves while your friend gently revs the engine. Make sure the coolant temperature is not too high because doing maintenance on your car at that point would be detrimental. At this point, keep an eye out for any coolant temperature peaks and leaks. Carefully open the bleed valves until water begins to flow from them, then close them. Repeat this several times until you can only get coolant out of them when you open them.

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If needed, refill the coolant

How to Add Antifreeze To Your Car

Keep the air-leaking valves closed. Restart your engine, check and top off the coolant level, and lower your car’s front end. Until the car is heated and the coolant temperature reaches and remains at 90C, you should still keep going through these steps. Reinstall the radiator cap. The air should no longer be present in the car if the coolant temperature has reached 90 C (work temperature) and your interior is heated. If you don’t utilize hot coolant carefully, it could hurt you.

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Take a test drive

Take a test drive

After your repair, you should check to see whether there are any leaks. Take your car for a long test drive if it seems good. During the test drive, pay close attention to the coolant’s temperature to make sure the car doesn’t begin to overheat. You really do not want your head gasket to blow as a result of overheating. Check the climate control’s temperature and all of its settings.

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Add coolant once more

How to Add Antifreeze To Your Car

Open your hood and double-check your coolant level if your test drive went smoothly with no temperature peaks or other odd behaviors. Do a coolant leak inspection. Then, after letting your car sit for a few hours, you can take it for another test drive, follow the same steps, and check for leaks and the coolant level. Your repair ought to be successful after completing all of these steps. Repeat this method if any odd behaviors persist, or carry on with your troubleshooting.

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How do I bleed the air out of my cooling system?

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How long does it take to bleed air out of the cooling system?

Depending on the model and approach you use, it typically takes 15 to 30 minutes. However, heating the engine and draining the coolant both take about 15-20 minutes.

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How do I know if I have air trapped in my cooling system?

Radiator airlock symptoms and signs include overheating while driving as usual. The heater isn’t working properly. decrease in performance.

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What happens if there is air in the cooling system?

Air bubbles can be a serious problem in the cooling system. They may result in hot spots in the engine, which may overheat and result in a variety of expensive internal engine problems. The first thing to remember is that you should have your cooling system evaluated at least once a year.

How do you fix an airlock in a cooling system?

An airlock develops when there is a leak in the cooling system, which enables air into the system. The airlock may lead to the car overheating since it prevents the coolant from flowing through the system.

Should air come out when you bleed a radiator?

Reopen the cooling system as usual and add distilled water to it. To open the thermostat and circulate the water throughout the entire system, let the car run for a few minutes, even until it reaches operating temperature. Drain it after allowing it to cool.

Can an airlock cause overheating?

Turn the valve on the radiator’s top using your radiator key. As illustrated in the diagram, secure the key in the square groove at the center of the valve and turn it slowly counterclockwise. There should be a hissing noise. The trapped air is now exiting.

Can you bleed the cooling system with water?

You can check if your radiators need bleeding through a few different methods. For instance, they might be heating up more slowly than usual or you might be hearing gurgling sounds. See if your radiators have chilly patches at the top but are warm at the bottom to determine if your heating system needs bleeding.

That is all for this article, where we discussed the answers to the following questions:

  • What is the function of a cooling system in a car?
  • Why do you need to bleed your car’s cooling system?
  • What will happen if you incorrectly bleed your car’s cooling system?
  • How to properly bleed the cooling system in a car?

We hope it was helpful. If so, kindly share it with others. Thanks for reading; see you around!