How to Bleed Radiator: 4 Easy Methods for Noobs

If you’ve ever repaired a leaky radiator, you might have been frustrated with the process of bleeding it. That’s because, for the vehicle to function properly, all air and moisture must be purged from the system. Trapped air in the radiator components obstructs coolant from entering the cooling system. Knowing how to bleed radiator can save you from wasting time and frustration.

That’s why we’ve put together this quick guide on how to bleed a radiator so that you are prepared next time it starts to act up again. We’ll cover everything from where on your car the radiator is located, what tools are necessary for the job, and how long an average job will take.

Where Is a Car Radiator Located?

The radiator is a part of the cooling system for your vehicle. Its main function is to keep the engine cool by dissipating heat from the engine and engine fluids. To do this, coolant flows through a series of tubes in and around the radiator, which is connected to the engine block.

You will find the radiator toward the front of the car after lifting up the hood. It should be near the engine. Some car models, such as Volkswagen Beetle, have the engine in the back. In that case, the radiator could be either in the front or the back of the car.

Bleeding the radiators can be tricky because it involves removing air from your cooling system so that it will again perform its job properly. The best way to do this is by using compressed air to help pull out those clogs and purge them from the system.

bleeding radiator
Radiator bleeding could be a tricky business. (Credit: Barrett-Jackson)

How to Bleed Radiator: Explaining the Methods

An overheated car means the radiator is not working properly. One major cause of a malfunctioning radiator is air bubbles in its system. You need to bleed it to get those bubbles out of the tubes and lines.

The process of bleeding radiator usually involves removing the radiator cap and using a little water to flush out any air bubbles inside the system. The task involves clearing out a clog or two. In some cases, it may need pulling out another part of your engine block. You need to call for an expert mechanic for that job.

Different Methods for How to Bleed Radiator System

For how to bleed radiator system, you could use any of these methods, depending on the design of your car radiator.
However, don’t start bleeding when the engine is still hot. Give it enough time to cool down completely. Otherwise, hot engine parts can cause burning or physical damage.

Take the radiator cap off

If you are looking for a simple method for how to get air out of radiators, apply this technique. Just remove the radiator cap and start the engine to keep it running for a while. The car will heat up gradually and push out the air bubbles trapped inside the cooling system. Fill up if the coolant level is lower than the correct level. You are done!

Use the bleeder valve or screw

This is another easy way regarding how to bleed radiator. In some car models, the radiator has a bleeder valve in the front or top side. This valve has been designed for releasing the trapped air bubbles in the upper part of a radiator.

Start the process by opening the radiator cap and filling it up with coolant. Secure the cap again and kick off the engine to keep it idle for 15 to 20 minutes. Touch the radiator hose and if it feels hot, open the bleeder valve or turn the bleed screw one or two notches.

Coolant will flow out and let it flow until there is no air bubble in the fluid. Then, close the valve or tighten the screw and wait until the engine cools down. Remember to put a pan underneath the car to catch that overflowing coolant.
Add some more coolant to make up for the amount lost during the bleeding process. Take the car to a test drive to see if it still overheats or not.


Bleed a radiator with no bleed screw

Take the radiator cap off. Make a mixture of coolant and distilled water and use that to fill the coolant tank up to the radiator neck’s bottom level. Pour pure coolant into the reservoir and keep adding until the fluid reaches the correct level.

Kick the engine off and wait 15 to 20 minutes until it reaches a certain temperature. The radiator cap should be off during this time. Once the engine heats up, the coolant will start flowing and eject the air in the system. Stop the engine and wait until it cools down. Add more coolant if needed and put the radiator cap back.

how to get air out of radiators
Take safety measures when bleeding a radiator. (Credit: Flashback502 / YouTube)

Elevate the car

If you are a noob and want to learn how to bleed radiator, follow this method. Collect a jack and jack stands because you will need to lift up the car. Elevate the front side of the car since the radiator is located there. Apply the parking brake and use tire chocks to block the wheels.

This elevation will raise the radiator to a point where its neck is above the engine and all other components in the cooling system. Remove the radiator cap and run the engine for a few minutes. This will purge the air bubbles from the system.

Fill the system with antifreeze after the engine cools down. Squeeze the radiator hose in case there is more air trapped inside. Add more coolant to the correct level and put the radiator cap back.

Do a test drive to see if the problems still persist. If these methods don’t work, you need to take the car to a repair shop for diagnosis by an expert mechanic.


These are some of the easiest methods regarding how to bleed radiator in a car. Even noobs can carry out these tasks in their garage. Just be careful and use safety equipment or you can injure yourself by touching the hot engine parts.