The brake system on cars and trucks uses a high-pressure rubber hose with specially crimped-on fittings at each end. One end attaches to a metal brake line connected to the master cylinder. The other end attaches to the front brake caliper. The rubber hose allows for the turning of the front tires. Due to the high pressure involved and the special fittings, a faulty rubber brake line must be replaced as a unit. You can do the job yourself with an assistant.
Park the vehicle on a level paved surface. Set the parking brake.
Loosen the lug nuts on the wheel where the bad line is. Raise the vehicle with a jack and support that side with a jack stand. Remove the lug nuts and wheel. Place a drain pan under the brake hose
Unfasten the metal brake line from the metal fitting on the rubber line. You will need to use a wrench to hold the fitting and a wrench to undo the metal line. Place a rubber hose cap on the end of the metal brake line to minimize brake fluid leakage (the cap can be purchased at an auto parts store).
There will be a "U" shaped metal clip that slides into a groove on the the metal fitting of the rubber line and holds the line onto a bracket. Use a flat screwdriver to pry out the clip. Remove the metal end of the rubber hose from the bracket.
Use a wrench to unfasten the other end of the rubber hose's metal fitting from the brake caliper. There are two types of fittings you may encounter. One is just a metal line, like the metal brake line you disconnected from the other end of the rubber line. The other is a "Banjo Fitting." With a Banjo fitting, the end of the hose that attaches to the caliper has a square block with a bolt that goes through it. Either unscrew the line or unscrew and remove the bolt. Note that the Banjo fitting bolt has a thin washer that goes with it. Remove the old brake line.
Install the new hose on the caliper first. Either screw the line into the caliper or place the block on the Banjo fitting on the caliper and install the washer and bolt. Tighten down.
Slide the other end of the hose through the bracket and push the clip into the groove in the metal fitting. Its a tight fit, so push hard. Thread the metal brake line into the new hose by hand. When it is threaded onto the new hose, finish by holding the metal fitting on the hose with a wrench. Tighten the metal line with another wrench.
Open the brake master cylinder reservoir and top it off with fresh brake fluid. Locate the bleeder screw on the caliper where you replaced the hose. Break loose the bleeder screw but do not leave it open. Hook up a bleeder kit to the caliper. The kit has a clear plastic hose and a clear plastic bottle. Fill the bottle about one-third full of brake fluid. Make sure the end of the hose that goes into the bottle is in the fluid. Attach the other end of the plastic hose to the bleeder screw.
Instruct your assistant to pump the brake pedal several times. Have her push down on the pedal until you tell her to let up. Open the bleeder screw. Fluid and air will be pushed into the bottle. Close the bleeder screw and tell your assistant to let up on the pedal.
Check the level of fluid in the master cylinder. Top it off if necessary. Repeat this procedure until no air is seen escaping from the caliper. Close and tighten the bleeder screw. Remove the bleeder hose from the caliper.
Replace the wheel and lug nuts. Snug down the lug nuts. Raise the vehicle and remove the jack stand. Lower it to the ground and tighten the lug nuts.
