How to Bleed Brakes
You may not be aware of it, but your car may be in need of a brake fluid change, right now. Commonly known as "bleeding the brakes", this procedure should be done every 2 to 3 years as well as every time new brakes are installed.
Here we will explore the least-complicated way of bleeding the brakes on your car. After reading this article you will be able understand how to bleed your car's brakes with the least amount of fuss.
Brake fluid doesn’t actually wear out, but it does get contaminated with metal particles, air, water and other debris.
It must be changed more frequently than most people realize, especially if it’s equipped with ABS (Antilock Brake System); tolerances are much closer with ABS, than on non-ABS brakes, and even very small metal flakes can cause a malfunction.
If air gets into the brake lines, the brake pedal will feel soft and spongy instead of the usual solid feel. The air in the brake lines will compresses, act like a spring, and not allow the brakes to be applied with the proper force.
Air also carries moisture that contaminates the fluid and will turn into steam in a high speed, high temperature, braking situation.
The night before you bleed the brakes, spray the bleeder screws threads with Liquid Wrench, or some other penetrating oil. This will make them much easier to remove, especially if you live in snow country.
The next day, if you want to save yourself aggravation, remove the bleeder screws and clean the two small holes with a paper clip or small drill bit. Use a wire brush on the threads and wrap them with a couple of inches of Teflon tape and re-install.
These are some items you'll need to bleed the brakes:
- A box wrench for the bleeder screws. Don't try to use pliers or vice-grips, they will only mess-up the bleeder.
- Two small cans of brake fluid.
- Two feet of see through aquarium tubing.
- A glass mayo jar with 1-2 inches of brake fluid in it.
- A willing helper that can follow "up" and "down" instructions.
- Teflon tape.
- A foot long piece of 1x3 or 2x4 lumber.
- Drill bits or paper clips, for cleaning the bleeders.
- A wire brush for cleaning bleeder threads.
- Access to the brake bleeders. Depending on your car, you may have to jack-up the car (always use jack stands), and remove the wheels to get access to the bleeder screws. If so, you'll need a floor jack and jack stands.
- Speed-bleeders, if you want to save yourself a lot of time and aggravation.
- Cleaning rags or shop towels to keep things neat and clean.
This is what you'll typically need to do:
- Remove the master cylinder lid and suck out all of the old brake fluid, it will provably look dark and dirty. Use a syringe or turkey baster and finish cleaning the reservoir with a lint free rag.
- Fill the master cylinder with new brake fluid to 1/4" of the top (depending on your car). Place the lid back on but don't tighten it. If you don't replace the lid, the fluid will squirt all over the place when the pedal is depressed.
- Place a piece of wood under the brake pedal to prevent it from traveling farther than it normally does. This will save the master cylinder piston seals from being damaged. A piece of 1x4 or 2x4 board will do fine.
- Start bleeding the wheel that is farthest from the master cylinder, usually the rear passenger side wheel.
- Place the box wrench on the bleeder screw and make sure you can turn it.
- Slip one end of the clear tubing on the bleeder screw and place the other end in the brake fluid inside the glass jar.
- Tell your helper "down" so she will start to press on the brake pedal. Ask her to echo your commands so you know that she heard you.
- Open the bleeder screw a quarter turn until all the air bubbles, and eventually clear fluid, come out.
- Close the bleeder screw.
- Tell your helper "up" so she will release the brake pedal.
- Check the brake fluid in the master cylinder after 3-4 times of doing this. If you allow the master cylinder to go empty, you will have to start the bleeding all over again.
- Now bleed the other wheels in succession, the rear driver side wheel, front passenger side wheel, and lastly, the front driver side wheel. Now make sure all the bleeders are tight and the master cylinder is full, and you are done.
The easiest way, by far, to bleed the brakes is to invest in speed-bleeders. These are replacement bleeder screws that have a tiny check-valve in them; they allow the air and old fluid out, but no air back into the system. The seven-dollar investment is well worth your time.
If you use speed-bleeders, you can bleed the brakes by yourself. Simply open a speed-bleeder, put a rag over it to catch the fluid, then press the pedal a few times. Close the speed-bleeder and go on to the next wheel.
No matter how you do it, bleeding the brakes is an important and much-neglected procedure that is not hard to do once you learn the details.
