Like most other auto parts, brake lines can deteriorate in time, requiring you to do a brake line repair. If your car brakes are to function normally and keep you safe when you drive, you should inspect your brake lines and related equipment at least once each year and replace bad pipes or tubing. To repair your car's brake lines, follow these 6 steps.
Step 1 – Drain Fluid from Brake Lines
Loosening any connections on your brake lines will likely result in loss of brake fluid. To prevent this, remove fluid out of the master cylinder with a good siphon.
Step 2 – Prevent Excessive Air from Entering Brake Lines
Take steps to keep excessive air from entering your brake lines. To accomplish this, clamp the hose with hose clamps or self-locking pliers. You will also need to clean off loose dirt around your pipe openings that might enter the hoses when they're disconnected or reconnected.
Step 3 – Remove the Brake Lines
Generally, two union nuts are used to connect brake lines and brake line hoses. To remove a brake line, hold one of these nuts in place with a wrench while you use the second wrench to loosen the nut at the opposite end of the pipe. To keep from stripping the nuts' hex, use flare nut wrenches. When you have both nuts loose, pull the retaining clips that attach the fittings to the pipe.
Step 4 – Remove the Brake Line Hose
At one end of the hose you'll find a banjo bolt that connects the hose to the brake caliper. Disconnect this bolt and keep it where you'll find it later when you're ready to connect your new hose and sealing washers.
Step 5 – Replace Brake Line Pipe
When installing the new pipe, you may need to bend it. If so, be sure to make bends the same as those on the old pipe, using a pipe bender. Once you have attached the new pipe onto the retaining clips, tighten the nuts again. Check to be sure the pipes and hoses are not too close to any hot or moving car parts that they may be damaged.
Step 6 – Bleeding the Brake System
After working on the car's brake lines, they'll have air in them that could make your brakes mushy and less effective. To avoid this, bleed the air from the lines. Fill the master cylinder with brake fluid. Locate the bleeder valve on each brake caliper, and remove the cap that covers the valve. Turn the valve slightly open.
Attach a clear tube to the valve and place the other end into a container. Have your assistant depress the car's brake pedal, which will force air and fluid out of the brake line, past the valve, through the clear tube and into the container. When you see clean fluid flow through the clear tube, close the valve. Repeat this procedure with each of the other 3 wheels. When finished, refill the master cylinder with clean fluid.