The braking system in your vehicle is designed to bring the car to a stop when you apply pressure to a pedal in the passenger cab. When you signal the brakes to engage, the pressure you put on the pedal has to be transferred to the wheels. This is where the brake lines come in. Most vehicles rely on hydraulic pressure, which these hoses are designed to deliver to the brakes.
The hydraulic pressure is built up in the brake fluid, which is sent from the master cylinder to the brake calipers through the hoses. If these do not work properly, it can cause the brakes to fail. A good rule of thumb to follow is to inspect the brake lines whenever routine maintenance is done.
A number of issues can arise, from leaks and air in the lines to damaged or torn lines. If you notice that the brakes on your car are acting up, the first thing you should always check is the brake fluid level. Low levels could indicate a leak somewhere in the system, so check back soon after refilling the reservoir. If the level has dropped significantly, chances are that a leak is the culprit. Inspect the brake lines and other components of the system for signs of wear or evidence of brake fluid on the outside of braking components.
If the brake lines are leaking, but they are otherwise undamaged, the ends of the lines can be flared. This way, the connection can be placed deeper into the hose and prevent further leakage. Most brake lines come pre-flared, but if they need to be shortened, they will also need to be flared again. The appropriate diameter that a line can be expanded to can be found in the owner's manual.
When inspecting brake lines for damage, you will notice that they are bent. This is the way it should be, as mobility is key to allowing the lines to move and adjust as the car does. The bends are also ideal for keeping the lines out of the way of other parts, where they may otherwise be susceptible to damage.