Brake fluid is hygroscopic, meaning that it tends to absorb moisture from the air. That is why air bubbles accumulate in your brake lines over time. Since air is more compressible than fluid, it causes your brakes to be spongy, or even worse, fail unexpectedly.

If you feel that something is quite unusual when hitting your breaks, then it’s time to check them and get the air bubbles out.

To get the air out of brake lines make sure the surface you are fixing your vehicle on is as flat as possible and that the car is parked. This will reduce the risk of your car rolling forward or backward when you try to fix your brake lines.

How To Get Air Out Of Brake Lines Without Bleeding

Step 1: Open The Master Cylinder Cap

Open the hood of your car and find the master cylinder cap. The cap usually has a round shape, but in some instances may also be octagonal. Try to see on which wheel the arrow on the cap is pointing at. After you fixated the direction of the arrow, open the cap by removing it clockwise until it is completely detached from your vehicle. 

Take a dry cloth and remove excess dirt from the cap and attach it back to the master cylinder. Ensure that the arrow of the cap is pointing in the same direction as the wheel that should be pumped first. Apply this step in the same order for all master cylinders. 

Step 2: Press and Depress The Brake Pedal

After making sure that you closed all reservoirs, get inside your vehicle and press on the brake pedals as many times as needed until all air gets pushed to one end.

You will recognize when this happens when your brakes start feeling firmer when you push them. In most cases, the air bubble gets pushed to one end within 20 times of stepping on each break.

Step 3: Open Cap Again

When you have pushed all the air to one end, open the cap of a master cylinder (doesn’t matter which master cylinder you choose).

You now want to pour new brake fluid into the reservoir until it gets filled to the brim. Fill the reservoir by tilting the bottle with fluid slowly to ensure that no air is getting in. Repeat this step with every master cylinder of your vehicle.

Step 4: Get Out any excess air

Close all caps and enter your vehicle again. Step on each break several times to let out all the excess air. This will be easier than the first time you did it because there are no more air bubbles stuck in your lines. 

Step 5: Test Drive

After you feel confident that your brakes are as firm as they used to be, take yourself out for a drive around the neighborhood and test the brakes safely. You can also make a quick stop at a mechanic to undergo a test.

Symptoms Of Air in brake lines

Accumulated air in your brake lines can be dangerous, and even life-threatening. Air bubbles are no joke, and you should spot them as soon as possible. The three main symptoms that signal the existence of air bubbles in your brake line are:

Spongy brake pedal

When brake pedals do not have that usual firmness you are used to when stepping on them they are described as being spongy or soft. Always be concerned when your brakes become too easy to step on. If this happens, it is because the air compresses more than brake fluid, giving you the signal that you most likely have air in your brake line. For a more detailed post about the symptoms of air in the brake system.

Loose brake pedal

Loose brake pedals are more easily spotted than spongy pedals and they have a drastic difference when being stepped on. Your brake lines most likely have air in them if your brake moves further than normally when stepping on it. There are even some cases where brakes become so loose that they touch the floor when being stepped on.

Ineffective brake

The most dangerous one of all three symptoms is when you have ineffective breaks. If you feel that your brakes are not working well when you step on them then it’s a clear sign your brakes might have air. 

Will air in brake lines go away

The short answer is no. The air stuck in brake lines will either stay stuck or more air bubbles will accumulate if the vehicle is not bled. 

If the air in the brake line is not removed as soon as it is spotted, the condition of your breaks will get worse. Your brakes will eventually end up failing as there will not be enough pressure from the brake fluid to ensure the proper function of the brakes. 

Another crucial thing to keep in mind about air stuck in brake lines is that the bubbles can eventually join together and form one big air bubble. If this happens, your brakes might fail unexpectedly and you might end up going as fast as you were going even after hitting the brakes. 

Getting Air Out By Bleeding

Bleeding is nothing more than the process of removing air bubbles in a brake line. When air is stuck in the brake line, the fluid is “bled” out of a bleeding valve, which is where it gets its name from. 

Bleeding is the recommended and most efficient way to get rid of the air bubbles stuck in the brake line by yourself. While getting air out by bleeding, make sure to keep a bucket full of water nearby in case of brake fluid spillage. 

The fluid is poisonous and toxic. It is so strong that it can even damage the paint of the car if you don’t wash it away. In case of fluid spills, use the bucket of water to wash the fluid off the car or your feet. 

How To Get The Air Out Of Brake Lines by Bleeding

Bleeding requires you to either crawl underneath the vehicle or find a way to jack it up. But unless you have a couple of professional tools hanging around your garage, you will probably do it the rough way. 

Before you start, you will need a wrench, a flexible hose, a jar, some newspapers or a blanket, and a good old friend. The ingredients might seem pretty odd, but they will surely get all that air out of your brake lines!

Step 1: Find The Bleed Screw

Place paper or blanket under the car to prevent getting dirty when crawling underneath. Make sure it is parked and that the emergency brakes are on. Then find the brake bleeder screw (shaped like a little nozzle) located behind your brakes. 

Step 2: Loosen The Screw

Choose the wrench that best fits the screw and loosen it up. If you know someone that has bleeder wrenches then that will make the process 10x easier. After loosening the screw, tighten it up again (not too tight).

CAUTION: Do not break the screw off. It will cost you a trip to the mechanic. If you have trouble loosening the screw then spray WD-40 or a similar penetrant over the screw. 

Step 3: Drain The Fluid

Take a flexible hose and put it over the screw you just tightened up. Place the other end of the hose in a big jar (preferably 2L).  You can also skip the hose and place the jar directly underneath the nozzle. 

Step 4: Pump The Brakes

Your friend will help by getting into the vehicle and stepping on the break a couple of times. To communicate clearly, have your friend say down when stepping on the brake pedal and up when releasing the pedal. 

Then tell your friend to keep holding the pedal down after and proceed to open the bleeder screw for the fluid to fill up the jar. 

Step 5: Close The Screw

After the fluid is released, close the screw and then proceed to tell your friend to let go of the brakes. You can repeat this process a couple of times until you are confident that all the air has gone out. 

Step 6: Open Reservoir

Open the reservoir cap of the master cylinder and slowly pour in brake fluid until you fill it to the brim. Tilt the bottle with fluid slowly to reduce the chances of air slipping in again.

How much does it cost to get the air out of brake lines?

If you think that repairing your car yourself is a bit too complicated, you can send it to a mechanic. It’s best to let a professional do it as the cost of repair is relatively cheap. 

It cost anywhere from $50 – $80 to get the air out of brake lines for basic cars and up to $175 for higher-end models. Investing in a repair might save you hours of trying to figure out how to fix it yourself, the foul smell of the fluid, and the risk of damaging your car even further. 

Driving with air in brake lines

Sure, you can drive one or two times with air stuck in brake lines and still make it home alive and well. But do it at your own risk, and preferably drive alone. 

Air bubbles need to be removed immediately after the brake pedals start to show the first signs of becoming spongy. 

Conclusion

The best solution to get rid of air bubbles in your brake line is to go to a professional. Sure it will cost some money. But in the end, what is money worth when your and your family’s life is in question?

If you have full confidence that you can repair this yourself, then it is recommended to go for the bleeding method as it has a higher accuracy rate than the non-bleeding method!