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A Step-by-Step Guide to Bleeding your Brake Fluid

Published on: 27 October 2015

A Step-by-Step Guide to Bleeding your Brake Fluid

It is very important to bleed your brakes (also known as ‘flushing your brake fluid’) at least every two to three years, or when you feel that your brake pedal is not offering enough resistance underfoot. Remember, if you’re in doubt, rather consult a mechanic and ensure that your brakes actually need to be bled.

The fluid in your braking system is crucial to the transfer of force from the master cylinder to the corners of the car where braking is required. When your brake fluid is not in optimum condition, it will not retain a liquid state and won’t be as resistant to compression as it needs to be. This compression is crucial to the functioning of the brakes, and by bleeding the brakes, any air bubbles trapped in the brake fluid are released. If there is enough air in the lines, the air bubbles will be compressed when you press down on your brake pedal, rather than the necessary pressure being exerted on the actual brakes.  It is important to note that excess air in the lines can lead to dangerous brake failure.

Bleeding your brakes ensures that they do not fail and are as efficient as possible. It’s not an entirely easy task, but one that can be done with a bit of knack and know-how. Here is a step-by-step guide to bleeding your brakes.

Tools and Supplies:

You’ll need:

  • A small wrench set suitable for your car’s bleeder screws
  • Brake fluid suitable for your car (about 400 ml for simple bleeding or 1.4 l if you are replacing the braking fluid entirely)
  • Clear plastic tubing about 10 inches long, with an end that can fit comfortably over your car’s bleeder screws
  • A bottle or container for the bled-out brake fluid (this waste fluid must ALWAYS be disposed of properly and NEVER put back into the brake fluid reservoir)
  • A can of brake cleaner (available in most automotive shops)
  • Someone to help you with pumping the brake pedal when required

Prepare your vehicle:

  • Loosen all four of your vehicle’s wheel’s lug nuts.
  • Place the entire vehicle on jack stands, ensuring that the vehicle is completely secure and supported.
  • Remove all of the wheels from the car.
  • Install one lug nut (backwards) at each corner and tighten against the rotor surface. This helps to minimise caliper flex that may distort the feel of the pedal.
  • Now it’s time to open the hood and check the level of brake fluid. If it needs topping up, add in some more brake fluid. The reservoir should be full to its brim (to the maximum marking on the reservoir tank). Do not allow the reservoir to get completely empty at any point of the bleeding process.

How to flush your brake fluid:

  1. Bleed in the following sequence: left rear, right rear, left front, right front. Although this sequence is not mandatory, it is best for the process because it allows for minimal cross-contamination between the old fluid and the new fluid.
  2. Start on the first corner – locate the bleeder screw at the rear of the caliper body, remove its cap and set aside safely.
  3. Place an offset wrench over the bleeder screw, then place one end of the clear plastic tubing over the hole of the bleeder screw, feeding the other end of the tubing into your container for waste fluid.
  4. Ask the person who is helping you to ‘apply’ pressure to the brake pedal. Instruct them to first pump the brake pedal three times (all the way down to the floor) and then hold the pedal down firmly, responding with ‘applied;’ and ensure that they know not to release the pedal until told to do so.
  5. Loosen the bleeder screw only about ¼ of the way, which will release fluid into the tube and waste container. Although the brake pedal will release pressure and simply fall to the floor when you loosen the screw, ensure that your assistant does not take their foot off the pedal until you tell them to.
  6. 6.       Gently, but firmly, tighten the bleeder screw back into place. Once this is done, tell your assistant to take their foot off of the brake pedal. NB: Ensure that the bleeder screw is on properly before your helper releases the pedal – if they release too soon, you could suck air back into the brake system!
  7. Carefully check the tubing for air bubbles.
  8. Repeat this process for the other 3 wheels, moving systematically towards the driver-side wheel. NB: Don’t forget to check the brake reservoir after each bleed! Keep the brake fluid level topped up to its ‘full’ marking at all times!
  9. Once you have completed work on all four corners, spritz a bit of brake cleaner on each of the bleeder screws, or on whichever parts have come into contact with the brake fluid. Wipe clean and then dry with an old rag so that any leaks will be easily visible later when visually inspected.
  10. Do a thorough check to ensure that all bleeder screws are tight and there are no leaks.
  11. Re-install all four of the wheels
  12. When your vehicle is on the ground again, apply and release the brake pedal several times while the engine is OFF.
  13. Once you have completed step 12, road test your vehicle to ensure optimum functioning of the braking system. Drive slowly around your neighbourhood and avoid main roads and congested areas until you are certain that the braking system is working properly.

As you can see, bleeding a braking system is not an entirely easy process. If you have any doubt about your abilities to do this bit of car maintenance, it is best to seek the services of a professional mechanic.

For more car maintenance advice and tips to keep your car running in optimal condition, check out our blog page.