Check For Air Trapped In System

1. Check the brake master cylinder fluid level.
2. Place the brake master cylinder filler cap loosely on the brake master cylinder reservoir.
3. With one technician acting as an observer at the brake master cylinder, and another technician applying the brakes, pump the brakes rapidly 20 times.
4. On the final application) hold the brake pedal in the depressed position.
5. Remove the brake master cylinder filler cap, and observe the fluid in the brake master cylinder reservoir. Quickly release the brake pedal. A geyser will spout in the brake master cylinder reservoir if the system has air in it.

NOTE: Pumping the brake pedal compresses trapped air. When the brake pedal is released, the compressed air expands, forcing brake fluid back into the brake master cylinder with sufficient force to form a geyser.

6. If necessary, bleed the system.