Master Cylinder Priming - In-Vehicle or Bench

WARNING: This page is about a different car, the 2007 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: 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: Carefully read cautionary information on product label. For additional information, see product Material Safety Data Sheet (MSDS). For 24-hour MEDICAL EMERGENCY INFORMATION on Ford/Motorcraft products call: 1-800-959-3673 (FORD). 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 reservoir to run dry during the bleeding operation. Keep the brake master cylinder reservoir filled with clean 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 the brake master cylinder has been installed new or the system has been emptied or partially emptied, it must be primed to prevent air from entering the system.

Fig 1: Locating Brake Tube Fittings

Courtesy of FORD MOTOR CO.

For in-vehicle priming, disconnect the brake tube fittings from the brake master cylinder.

CAUTION: Use a soft cloth between the bench vise and the master cylinder to prevent damage to the master cylinder mounting surface.

For bench priming, mount the brake master cylinder in a vise.

Fig 2: Installing Short Brake Tubes With Ends Bent Into Brake Master Cylinder Reservoir

Courtesy of FORD MOTOR CO.

Install short brake tubes with the ends bent into the brake master cylinder reservoir.
- Fill the brake master cylinder reservoir with clean, specified brake fluid.
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.
If necessary, install the brake master cylinder into the vehicle. For additional information, refer to HYDRAULIC BRAKE ACTUATION .

NOTE: Refill the brake master cylinder reservoir as necessary.

Bleed the master cylinder at the outlet tubes.
- Have an assistant apply and hold the brake pedal.
- Loosen the brake outlet tube fittings at the master cylinder one at a time.
- Tighten the outlet tube fittings.
- Repeat the above 3 steps until no air bubbles are visible in the expelled brake fluid.
Remove the short brake tubes and install the master cylinder outlet tubes.
- Tighten to 18 Nm (13 lb-ft).

Fig 3: Loosening Brake Inlet Tube From 4WABS Hydraulic Control Unit (HCU)

Courtesy of FORD MOTOR CO.

Loosen a brake inlet tube at the 4WABS hydraulic control unit (HCU).

NOTE: Refill the brake master cylinder reservoir as necessary.

Have an assistant apply and hold the brake pedal.
Tighten the inlet tube fitting at the HCU.
- Tighten to 18 Nm (13 lb-ft).
Repeat Steps 8-10 until no air bubbles are seen in the expelled brake fluid.
Repeat Steps 8-11 for the remaining 4WABS hydraulic control unit inlet tube.
Bleed the brake system. For additional information, refer to Brake System Bleeding .