You should inspect the brake line pipes and hoses every six months for damage. Common problems on hoses include hardness, cracking, fraying or chafing. Pipes can suffer mainly from corrosion and dents. Any damaged components need to be replaced, though a little corrosion can simply be scraped off. Generally, hoses will need replacement more often than pipes.
Preparation
To prevent loss of fluid when removing the lines, siphon out the fluid from the master cylinder using a siphoning tool or clean, unused turkey baster. You can also remove the reservoir cap and seal the opening with cellophane to prevent air from getting in (this won't completely prevent fluid loss but will keep it to a minimum). Clamping the hoses shut will help so long as they are still attached; use a pair of self-locking pliers or brake hose clamps and place them as close to the pipe as you can. Clean away all dirt from the ends of the hoses to keep it from getting inside the hoses during removal.
Removing/Replacing the Lines
The brake lines are often connected to the hoses with two union nuts. Grab the nut at the hose's end with one wrench to hold it in place while you turn the nut at the pipe's end with another wrench. Use flare nut wrenches to avoid stripping the nuts at their corners; this isn't as important if the pipes are being replaced.
Once the nuts are loosened at both ends of the pipe, pull out the retaining clips attaching it to the fittings to remove the pipe.
If you are removing and replacing a hose, disconnect the banjo bolt attaching it to the caliper at the hose's other end. You will use the same bolt when connecting the new hose but with new sealing washers.
When replacing the brake line pipe, use prefabricated steel pipes (not copper) from an auto parts store. If the pipe needs to be bent before installation, use the old pipe as a guide and bend with a proper bending tool. Fit the pipe into the retaining clips at the fittings and tighten the nuts. Make sure the hoses are not twisted or kinked at all and both the pipes and hoses are clear of any moving or heated parts on the vehicle.
Bleeding
You must bleed the brake system of air after working on the lines. Make sure the master cylinder reservoir is filled first. There is a bleeder valve on each caliper. Remove the cap on one caliper's valve, turn the valve screw slightly and place a piece of clear tubing on the valve. Place the tubing's other end inside a clear container partially filled with brake fluid. While another person pushes down on the brake pedal, turn the bleeder screw more to allow air and fluid to flow through the tube. When you get a clear stream of fluid, close the valve.
Start this procedure with the right rear wheel and then move to left rear, right front and left front. Refill the master cylinder reservoir with fresh fluid after bleeding all four brakes and make sure the pedal feels firm and not spongy.
