To repair a brake line, you must remove the old brake line, install the new brake line, add brake fluid to the system and bleed the brakes. This can be done without professional help, but it requires brake fluid, new brake lines, open-end wrenches and clean rags. Safely support the car using jack stands before beginning repairs.
To start, remove the wheel and loosen the old brake line using two open-end wrenches. Although the brake line is rubber, it connects to stronger metal parts and usually connects two metal parts at a point that requires the flexibility of rubber. The connection is made up of two halves, with fittings shaped like hexes, that require two wrenches to pull apart. Place a wrench on each fitting and loosen the connection, but be sure to have a rag nearby to prevent the leaking brake fluid from making a mess.
The new brake line goes on just as the old one came off. Hand thread the connection together and use the same two wrenches to secure everything. After installing the new brake line, add brake fluid and bleed the brakes to remove any excess air that can adversely affect the quality of their performance.