Bleeding the braking system is the last step when changing brake pads.
1. Take the cap off of the brake master cylinder. Brake fluid becomes tainted with dirt and other airborne contaminants or due to the mechanics of your car. The fluid may also draw in moisture from the air, and this will lower the fluid’s boiling point. Prior to changing your brake pads and calipers, you need to bleed brake fluid from the car’s system. However, you need to ensure that your brake fluid is topped off prior to doing this. Inspect the fill line to determine if you need to top off the fluid. Make sure the cap is left off as you bleed the system.
It is necessary to add fluid because you are bleeding the fluid that is trapped in the line – the fluid from the calipers – so it is crucial to maintain a consistent supply in your car’s master cylinder.
2. Determine the bleeding sequence. In most cases, you should start out by bleeding the brakes that are farthest from your car’s master cylinder. Review your owner’s manual prior to doing so. Every car varies in the exact order that this should be done. If you do not have a copy of your car’s owner’s manual, contact a local auto parts store for assistance.
3. Connect a small plastic hose onto the car’s bleeder nipple. Inexpensive aquarium tubes are ideal for this step. Attach the other end of the plastic hose to a pan or small bottle, as this will safely catch the removed fluid. To prevent air from getting back into your car’s system, you should make sure the bottle is held or hung above the calipers. Make sure that gravity is assisting you.
Bleeding your brakes video:
4. Seek help from an assistant who will pump the brakes for you. When the engine is turned off, have this person repeatedly pump your brakes until they are resistant. They should make significant noise to show you that they are resistant. When you reach this point, you should slightly unscrew the bleeder screw. Then ask your assistant to hold down the brakes.
The fluid should start to be drawn out of the hose and into the pan or bottle. When your assistant’s foot reaches the floor, properly screw the bleeder screw back on. Continue repeating this process until you determine that there are no air bubbles left in the plastic tube.
5. Perform a second check to ensure the system is free of air bubbles. If you hear fluid gurgling in your car’s master cylinder while compressing brakes, this indicates that air bubbles are still present. Bleed them again prior to doing anything else.