Brake Line Repair: How to Remove Air from Your Brake Lines

Automobile brakes can often become soft and spongy, a sign that your car may need a brake line repair. These repairs often involve bleeding your brakes to remove built-up air in the brake lines. Air in brake lines is usually there because it gets pumped into brake lines and becomes depressed when you apply your brake pedal. The process for removing this air can be slightly different for an ABS brake system, but the difference is mostly in the tool needed. Generally, you will need only a few tools and a helper to bleed your car's brakes. Just follow the four steps below.

Step 1 – Raise your Car

You'll need your car off the ground to do this project. Then, use your car jack to raise the car enough to slip a jack stand under the car's frame. You'll need four of these jack stands under the car, each one at a corner of your car. This will make your car more secure and safe.

Step 2 – Loosen the Car's Bleeder Valve

The bolt that secures this valve may be quite tight, could even be a bit rusty or corroded. If necessary apply a few drops of penetrating oil to the bolt the night before you begin your project. If the bolt is still stubborn after applying the penetrating oil, try tapping the bolt with a hammer to break it loose from the corrosion. Don't remove these bolts, just loosen them.

Step 3 – Remove Some Brake Fluid

Slide a drip pan under the master cylinder. Brake fluid can be rather caustic and will remove paint from any surface, so you should collect the fluid in the drip pan, rather than allowing it to drip on the floor of your garage or driveway. Remove the master cylinder reservoir top and use your baster to remove some of the brake fluid. To keep air from being drawn back into the master cylinder, attach one end of your plastic tubing over the bleeder bolt, and place the other end of the tube in a small bottle that has one or two inches of clean brake fluid in it. Finally, pour fresh brake fluid in the master cylinder and replace the cover.

Step 4 – Bleed the Brakes

Have your helper sit in the drivers seat. When you give the signal he should depress the brake pedal. Then, turn the bleeder bolt just enough to release air that will be forced out of the line by the pressure on the brake pedal. When you see brake fluid begin to trickle out of the bleeder hole, close the bolt. Repeat this process until when your helper applies pressure to the brake pedal, only fresh brake fluid from the master cylinder leaks out through the bleeder hole. Tighten bleeder bolt. Repeat at all 4 wheels. Then fill the master cylinder to the top with fresh brake fluid and replace the master cylinder cap.