Master Cylinder Priming In Vehicle Or Bench
Master Cylinder Priming-In-Vehicle or BenchWARNING: Use of any other than approved DOT 3 brake fluid will cause permanent damage to brake components and will render the brakes inoperative. Failure to follow these instructions may result in personal injury.
WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes with running water for 15 minutes. Get medical attention if irritation persists. If taken internally, drink water and induce vomiting. Get medical attention immediately. Failure to follow these instructions may result in personal injury.
CAUTION: Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.
CAUTION: Do not allow the brake master cylinder to run dry during the bleeding operation. Keep the brake master cylinder reservoir filled with the specified brake fluid. Never reuse the brake fluid that has been drained from the hydraulic system.
NOTE: When any part of the hydraulic system has been disconnected for repair or installation, air can get into the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system after it has been correctly connected. The hydraulic system can be bled manually or with pressure bleeding equipment.
NOTE: When a new brake master cylinder has been installed or the system has been emptied or partially emptied, it must be primed to prevent air from entering the system.
1. For in-vehicle priming, disconnect the brake lines from the brake master cylinder.
2. For bench priming, mount the brake master cylinder in a vise and install short brake tubes with the ends bent into the brake master cylinder reservoir.
^ Fill the brake master cylinder reservoir with DOT 3 motor vehicle brake fluid.
3. Slowly press the primary piston or, for in-vehicle priming, have an assistant slowly pump the brake pedal until clear brake fluid flows from both brake tubes with no air bubbles.
4. If necessary, install the brake master cylinder into the vehicle.
5. Remove the short brake tubes and install the master cylinder outlet tubes.
6. NOTE: Refill the brake master cylinder reservoir as necessary.
Have an assistant apply and hold the brake pedal.
7. Loosen the brake outlet tubes at the master cylinder one at a time.
8. Tighten the outlet tubes.
9. Repeat the above 3 steps until no air bubbles are seen in the expelled brake fluid.
10. Bleed the brake system.