How to Tell If Air Has Been Purged From a Master Cylinder Brake System

Vehicle Braking System

When brake systems are adjusted or replaced, they must be purged of air before use. So, if you aren't sure if your vehicle's master cylinder brake system has been purged, there are a few steps you must go through to check if the process has been completed. The process is quite simple and takes only a minimal amount of time.

Instructions

1. Climb into the driver's side of the vehicle and leave the door open. Do not start the vehicle. Lean out of the door and toward the tires. Press the brake pedal as far down as possible. Listen for any popping or uneven sounds.

2. With the vehicle still not running, slide back into the seat and close the vehicle door. Press the brake pedal down once again, this time feeling for any unevenness in the movement. If there are any sections in the movement where you feel jerking or a sudden bit of added pressure, you can be sure that the system has not been purged of air. You can feel the sudden changes in pressure due to the fact that the vehicle's power braking system is not running.

3. Start the vehicle and begin driving around slowly. Test the brakes just as if you were using them as usual. If you feel any unevenness or sudden pressure in the braking, you will again know that the system has not been purged.

4. Park the vehicle and leave it running. Press the brake pedal down hard once more. Listen to the power braking system, and if you hear any popping or other odd sounds, the system, once again, has not been purged.

Tips & Warnings

• Have another person listen outside of the vehicle as you press the brake pedal for an easier read.

• Always use caution when driving with possibly faulty brakes.