How Brake Bleeding Works


If the word “brake bleeding” makes you think of a clean, happy person stepping on the brake pedal while another grumpy, dirty, frustrated person yells, “Push down!” from under the car, you’re right. This is what happens. It’s a job that many people don’t like, but it has to be done at some point in the life of a car.

Every two or three years, most brakes should be bled. This will keep your brake system working at its best and keep your brakes safe. Small amounts of air can get stuck in the brake line, making the pedal feel spongy when you push it. If a lot of air gets into the brake line, your car won’t be able to brake at all.

That’s what I want to know. Air can get into your brake system when you have certain types of service done or if there is a leak. Because of things like worn pads, air can also get into the line (or an impatient driver who constantly slams on the brakes).

In this case, you are taking air out of the line. There are some tragic movie characters who drive off cliffs. This helps make sure that your brakes are in good shape and that you won’t drive off the edge of a cliff, like that. There are three ways to flush brakes:

  • Vacuum pumping
  • Pressure pumping
  • Pump and hold

To find out what’s wrong with your master cylinder if it’s low on fluid, you should look into it. It is very important that no fluid comes out of the braking system. To start, find and fix the leak.

In this article, we’ll look at each one.

Supplies for Bleeding Brakes

Before you begin bleeding your brakes, gather all of your necessary supplies and place them within easy reach. If you have to stop what you’re doing in order to look for a tool, the job is already difficult enough. Use this checklist as a guide to help you get started.

For disc brakes, use a 10 mm box wrench; for drum brakes, use an 8 mm box wrench (Double check to make sure these sizes fit your specific bleeder screws.)

If you’re just bleeding the lines, you’ll need one can of brake fluid; if you’re doing a complete replacement, you’ll need three. Use a fluid that is a different shade of color from the one already in the brake line. In this way, you’ll be able to tell when the old fluid is flushed out of the system and the new fluid is being brought into it.

  • Use a turkey baster to remove old fluid and debris from the master cylinder reservoir.
  • Clear tubing made of plastic
  • Brembo brake cleaner, one (1) can
  • Jack stands, a car lift, or a lift
  • As a one-time use bottle
  • Brake cleaner (for cleaning parts before reseating them)

You’ll need one or more of the following to bleed your brakes, depending on the method you choose:

  • Assistant who pays attention (two person method)
  • Brake bleeder with a vacuum (one person method)
  • Bleeder for brakes under pressure (one person method)
  • Screws with one-way bleeders (one person method)

Measure twice, cut once, as the saying goes. Read on to learn how to properly prepare for the task of bleeding brakes.

Preparations for Bleeding Brakes

Prepare for the actual bleed now that all of your supplies are in place. Regardless of which method you choose, you’ll need the same basic supplies. Consider using penetrating oil to loosen the bleeder valves the day before you intend to bleed the brakes. If you tap on these valves with a hammer, you run the risk of damaging them, as they are hollow. You’ll want to stock up on some old clothes. When brake fluid comes into contact with paint, it ruins it. Cleaning spills and drips as soon as they happen is the best way to avoid further damage.

Place the vehicle on jack stands or a lift the day before the bleed and make sure it is secure. A square of lumber should be placed under the brake pedal to keep it from falling to the floor when you begin bleeding the brakes. Remove all four wheels, then tighten one lug nut back against each rotor.

Before you begin bleeding, be sure to re-fill the reservoir with fresh fluid and continue to do so as necessary so that the fluid level stays above the seam at all times. When you refill the reservoir, remove the reservoir cover and replace it with a new one.

Connect a disposable bottle to the plastic tubing coming from the first bleeder valve. Use a long enough tube to reach the bottle without fear of it escaping the bottle as you are working. Be careful not to let air back up into your brake system the first time you perform this procedure, especially if this is your first time bleeding brakes.

Bleeding Brakes with One Person

There are a few products on the market that will make bleeding your brakes much simpler if you do it on your own. There are many options for purchasing these items, including at the local auto supply store or online.

Through the bleeders, vacuum pumps remove the brake fluid from the system. However, if the pump is not properly attached to the bleeder threads, there may be an issue. It is possible for air to enter the line if the bleeders aren’t thoroughly cleaned. Use brake cleaner to thoroughly clean the bleeder and bleeder hole before attaching the pump. Every vacuum pump is different. To make sure you’re using the pump correctly, consult your owner’s manual.

The bleeder valves are used to force the brake fluid out of the pressure pump. Using a fluid-filled pump, you open one valve at a time until the entire system is pressurized. As a result of the pump’s ability to store fluid, you don’t have to constantly refill the fluid reservoir.

Allowing the air and fluid to exit, the one-way check-valve bleeder screws snap shut before air can return. Assemble the bleeder with the check-valve on one end, and the clear tubing on the other. The check-valve works like a hiccup when you apply pressure to the brake pedal—no air will return.

You’ll need to bleed each line multiple times with the vacuum and pressure pump methods to ensure that no air has been moved through the system.

You’ve got a pal you’d like to prank on? The two-person pump-and-hold method is one of the most popular methods out there.

Bleeding Brakes with Two People

Brake bleeds require two people to operate the brake pedal and release air from the bleeders at the same time. If this technique is to work, the person pressing the brake pedal must pay attention to what the other person is saying or else they risk sucking air back into the lines.

With a friend, try this method for bleeding the breaks:

Step 1: Remove the rubber cap from each bleeder screw after the car has been raised on jacks and the wheels have been removed. Now is not the time to remove the bleeder valve with your box-end wrench. Fill up a bottle halfway with water and place the other end over the nipple of the bleeder valve.

Step 2: Hold the brake pedal as far as it will go and have your friend pump the brake three times. He or she must wait for your command before releasing the object.

Step 3: Turn the bleeder valve 1/4 turn after your friend has pressed the brake pedal all the way down. The brake fluid and air will be released in this manner. Close the valve by tightening the screw after it has been left open for a few seconds. Your friend will be able to feel the car’s accelerator pedal move toward the floor. Ask your companion to let go of the brake pedal once the screw is tightened. Using the clear, plastic tubing as a vessel, bleed the fluid until there are no more air bubbles.

Step 4: Following a thorough bleed of all of the brakes, check the brake pedal for firmness. Make sure it doesn’t feel spongy when you press down on it! Check for leaks by visually inspecting all of the bleeder screws.

Step 5: Make sure everything is in working order, then put your tires back on and go for a test drive. Test the brakes thoroughly before venturing out onto the highway. Keep an eye on your brakes until they’ve been checked out.

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