When you push the brake pedal, hydraulic fluid travels through the brake line to multiply the force of your push. This gives the brake cylinders the power they need to slow or stop your vehicle. When you have a brake line issue, there's several things that will alert you to the fact.
Low Brake Fluid Warning Light
Many vehicles have a warning light that will turn on when the brake fluid drops below a certain level. If this light comes on, it can mean that you have a leaking brake line.
Gradual or Sudden Brake Loss
A damaged brake line will cause a drop in hydraulic pressure. That loss of pressure will translate either to a gradual loss of braking power or an outright inability to brake. When it happens suddenly, it can mean the brake line ruptured or broke. If it happens gradually, it can mean the brake line has a leak.
Leaking Brake Fluid
If you move your car and see fluid on the ground, you may have a leaking brake line. Many fluids can leak from the car. Brake fluid starts out almost clear, but develops a yellow hue. It feels more slippery to the touch than oil. If the brake fluid is incredibly old, then it can darken to an almost-black color.
If you're unsure, try placing some paper towel or newspaper around where you think the brake fluid leak is happening. Pump the brakes a few times. If you have a leak, then brake fluid will come out onto the material.
You can also give your brake line a visual inspection if you happen to have access to a lift. Note that if you have any of the aforementioned signs, then you should take your vehicle to a mechanic as soon as possible.
Each wheel has a brake line connection. Jack the car up and place it on jack stands. Remove the wheels, and you will have access to the brake hose. You can see how much hydraulic fluid each cylinder has. You can also see if there's rust or other physical damage to the brake line itself.
If you're comfortable with doing so, you can purchase quality hydraulic hoses and replace the damaged lines. Or, you can purchase the hoses yourself and let a mechanic do it for you.
Just know that a damaged or leaky brake line is not something you should let slide for any amount of time. Pay attention to the warning signs, and seek to remedy the situation the moment you notice anything going on with your brakes. Click here to investigate more.