How to Bleed Air Out of a Car Brake Line

Anytime you disconnect a brake line fluid or if the master cylinder, where you pour in the brake fluid, runs too low and air is able to get into the lines you must bleed the air out of the lines.Air in the brake lines will be the cause for a mushy brake pedal or when you hit the brakes the pedal may skip and push down low to the floor which is a very dangerous situation.Bleeding the air out of the lines is not that difficult and will take very little of your time to do it!

Difficulty: Moderate

Instructions

Things You'll Need:

• Proper size crescent wrench, with open and closed end to fit bleeder valve
• Rubber hose to fit over bleeder fitting, about 12 inches long
• Plastic bottle or container
• Extra can of your specific type brake fluid
• Old Rags
• A Helper
• Eye Goggles
• Rubber Gloves

1. Locate the bleeder valve for the brakes, there is one behind each wheel. The valve will be located on a part that has a rubber brake line hose connected to it. In some cases you will need to remove the wheel for proper access to the valve. See picture in step #3 to view valve.

2. Start at the rear wheels first for bleeding and work your way to the front wheels, however if you have only disconnected one brake line for instance, you should be able to just bleed that one wheel, but if you changed your master cylinder which feeds all 4 lines then you must bleed all wheels.

3. 
   Bleeder valve with wrench attached

   Loosen the bleeder valve nut just enough to be sure you won’t have any issues with it and that it isn’t froze stuck and then re tighten right away without allowing any fluid to escape. If you have a frozen nut, spray some rust buster penetrating oil on the nut and wait a little while and try again. It is important to use the correct size wrench so that you do not strip the nut by slipping on it with a pliers or vice grips or even worse, break off the nut.

4. 
   Master cylinder

   Remove the cover for the master cylinder and be sure the brake fluid is up to the top.

5. 

   Get your rubber hose and bottle ready at the wheel you will be working on and obtain the right position for the hose and container. The object here is for the brake fluid, when it is under pressure through pumping the brake pedal, to run through the hose from the bleeder valve and into the bottle, which fluid can be reused as long as the container is clean.

6. Your helper should get in the car now and with the engine running, if you have power brakes, while you are at the wheel with your rubber gloves and eye goggles on, loosen the bleeder nut just enough so that fluid begins to come out. Have your helper in the car pump on the brakes a few times and be sure you have your hose in place for the fluid will begin to shoot out. Then have the brakes pumped one last time, but this time, have your helper “hold” the pedal down as far as possible, while you quickly tighten the bleeder nut back. This wheel is done!

7. 
   Typical brake fluid

   Go back to the master cylinder and fill again to the top with more fluid. You may use the fluid you caught in your bottle or put in new fluid. During this process you never want your master cylinder to run dry or too low because you will only get more air in the lines and have to bleed all the wheels.

8. Wipe dry the bleeder nut area and any fluid that may have spilled over at the wheel so you can check for any possible leaks later after a test drive.

Tips & Warnings

• * Make sure the fluid level in your master cylinder doesn’t run too low during the bleeding. You may even have a second helper pouring new fluid into the cylinder while you are bleeding the air out at the wheels.
• * Always test drive the car locally and out of traffic and then re check to be sure there are no leaks at the valve.
• * If the brakes feel soft or miss and then catch there is a possibility that all the air was not removed or there may be other issues causing the problem, in which case you may need a mechanic to trouble shoot.
• * With the engine running during the bleeding process be constantly aware of the moving engine parts, such as the fan blades and moving belts, to stay away from those dangerous areas.

[hatednation]

on 5/14/2009 Thanks for your help, It wasnt as bad as I thought it would be!!