Bleed Car Cooling System

How to Bleed Your Car’s Cooling System

In Coolant by 4 Comments

Getting all the air out from your cooling system after a water pump or thermostat replacement can be really difficult.

Your engine could easily overheat and you may damage your engine if you have not got the air out from the cooling system completely.

I work as a mechanic and I have found a really good way to get the air out of the cooling system fast and effectively. This method can differ a bit between different car brands but the principle is the same.

Follow this step by step guide and get all the air out quickly and safely.

Different Methods of Bleeding the Car’s Cooling System

There are actually two different methods of getting the air out from your cooling system.

Old Manual Method

The manual method is the old style variant of bleeding the coolant system. Some cars have an air bleed valve to get the air out from the system, and some cars don’t have this air bleed valve which makes it a lot more difficult. However, the method for both of them is the same. Check out the step by step guide below to bleed your car’s cooling system efficiency.

Vacuum Method

Cooling Vacuum Bleeder

The new method, which I use myself, is the vacuum method. To use this method, you need a vacuum tool for this and compressed air (depending on the tool). However, this method creates a vacuum and sucks out all the air from the coolant system within seconds and then fills all the vacuum space with the coolant system instead. This is a really efficient method if you have the tools and you never have to worry about car bleeding anymore. You will get a perfect result every time and the process takes under a minute.

If you are interested in one of these tools, you can find one here on Amazon: UView Economy Cooling System RefillerIr?t=Askamastermec 20&l=Am2&o=1&a=B000Ihk1Vi

Manual Coolant System Bleeding

If you do not have access to compressed air and a vacuum cooling bleeder, it’s also okay to do it the manual way. This is the way I do it when I do not have access to a vacuum bleeder.

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1. Get your coolant/anti-freeze ready and fill up

The first step in this guide is to make sure your anti-freeze is ready. You should always use the correct coolant that is required by your manufacturer. The wrong type of coolant could damage your engine! If you are not sure which coolant you should use, check your repair manual or contact your authorized dealer.

Generally, mix the coolant with 50% water and 50% coolant (if concentrated anti-freeze). Always read the description of your coolant for the correct instructions. If you are living in a cold country, you have to make sure that the coolant mix is correct. If your coolant freezes in your engine, you will destroy your engine. To check your coolant freeze level, you can use a REED Glycol Refactometer with ATC (C°) Link to Amazon. If you have your coolant ready, we can continue to the next step.

2. Jack up the front of the car

A step that not many people do but which will get you a much better result, is to raise up the front of your vehicle first. With this method, you will get the air out of the car a lot easier. Especially if your filling cap is at your radiator. If you have a car with an external expansion tank, this may not be necessary.

To raise the front of the car, you could either use a jack or put the car on a steep hill with the front upwards. If you are going to raise your car with a jack, check your repair manual for the right jacking points so as not to damage anything under your car. If you are going to use a jack, use a good jack and not the jack that you gets included with your car. These jacks are dangerous and have caused a lot of injuries. If you do not have a good jack at home and are interested in buying one, you can check out our review of the best floor jacks. When raising up your car with a jack, always also use Jack Stands to prevent any accidents.

3. Fill up your coolant

Now when the car front raised, it’s time to fill your coolant as much as possible. If your engine has air bleed valves, open them at the same time as you are adding the coolant. Close them when coolant is flowing out from them. Anti-freeze is toxic and you should always check that your coolant is not flowing down in any wells on your floor or on the road. All coolant should be returned to your local environmental assessment. Keep in mind that if any animals drink the coolant, they can get very sick and it could lead to a death. Use anti-freeze with care! When you have filled your coolant as much as possible, open the radiator cap and go to the next step

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4. Start the engine

You should now start your engine. The best way to do this is to get help from a friend. When you are starting your engine, the water pump could push out some coolant from the radiator if there is air inside. To prevent this, the EPAuto Spill Proof Radiator Coolant Filling Funnel Kit Link to Amazon is really useful to prevent any spill.

5. Turn the climate control heat to max

After you have started your engine, you should now turn the climate control heat to MAX. It depends on the car, but many cars use a valve that will restrict the coolant from flowing inside the thermal pack in the car if the climate control is set to cold. Other cars redirect the airflow and not the coolant flow, so with these cars, this step will not make a difference. No matter which model you have, it’s an easy step to put your climate control to the MAX heat.

6. Rev the engine to 3000-4000 rpm

You should now rev up your engine a bit. This could cause the coolant to flow out of the radiator if you are not using the spill tool and I recommend to have a friend with you for this task. If you have a friend with you, you can loosen your air bleeding valves at the same time as your friend is revving the engine. Be attentive to any coolant temperature peaks and coolant leaks at this point.

7. Refill coolant if necessary

Close your air bleeding valves. Let your engine idle again and recheck the coolant level and lower the front of your car. At this point, you should repeat these steps until you get heat inside the car and your coolant temperature reaches 90c. Rev up the engine again and loosen the air bleeding valves until there is only flowing coolant from them. Put your radiator cap back. If your coolant temperature is now at 90c (work temperature) and you have heat inside your car, the air should now be gone from your vehicle. Warning: Hot coolant can cause damage to you if it’s not used with care.

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8. Go for a test drive

You should now make sure that you can’t find any leaks from after your reparation. If it seems good, take your car out for a long test drive. Be very attentive about your coolant temperature during the test drive and make sure the car does not start to overheat. Overheating can cause your head gasket to blow and you really do not want that to happen. Check all the functions and the temperature of the climate control.

9. Fill coolant again

If your test drive went well without any temperature peaks or other strange behaviours, open your hood and check your coolant level again. Check for any coolant leaks.

After this, you can let your vehicle stand for a couple of hours, then take another test drive and do the same procedure and check for leaks and the coolant level.

After all these steps, your reparation should now be successful. If there are any strange behaviours, repeat this guide or continue your troubleshooting. Check that guide out for any troubleshooting to your car. Many people replace parts without any troubleshooting at all. Don’t do that! Read our troubleshooting articles and learn how to troubleshoot in a proper way. Stop wasting money on replacing parts that were not damaged in the first place.


  • Raising up the front of the vehicle is the best way to get all the air locks out of the cooling system
  • Anti-freeze is toxic and should be used with care
  • You can use tools to make all this a lot easier

I hope you liked this guide and your reparation went successfully. If you have any questions about this guide, you can comment below. If you have any other questions about your car that you want answers for, you can ask us to our homepage.

4 thoughts on “ How to Bleed Your Car’s Cooling System ”

    1. Can you bleed your cooling system if there is no a/con gas in a/con system.

      1. On step 9 after your test drive, DO NOT! check your coolant level ! Wait for the cars cooling system to cool down then be cautious opening the radiator cap use a towel slowing turning it, this is after cool down period.

  1. I have an Hyaundi i40 and have just changed the radiator. I am experiencing an unusual thing air seems to be getting into my expansion bottle and bubbling up the water inside and the temperature goes sky high can you help? Thanks

  2. If you need answers to your car questions, it is much more likely that you will get answers in our car community. You can find our community here.

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