Mustang Master Cylinder Removal

The brake master cylinder on your Ford Mustang works as a hydraulic pressure pump to actuate the brakes every time you depress the pedal. Worn out pistons, valves or damage to the unit may cause the master cylinder to lose pressure and fail. Removing the brake master for service or replacement is an easy but involved process. You will need to bench bleed the rebuilt or new unit before installation and possibly bleed the entire brake system once the master cylinder is in place.

Removing the Master Cylinder

The master cylinder on your Mustang is easy to access through the engine compartment. It mounts on the brake booster (a cylinder-shaped component) on the firewall, right in front of the steering wheel. To start removing the cylinder, unplug the fluid level sensor at the base of the brake fluid reservoir on top of the unit.

When disconnecting the brake lines at the master cylinder, place a shop rag under the unit to catch any fluid spills and use a flare wrench to avoid damaging the fittings. After that, plug or cover the line openings to prevent contamination of the system. Now you can unscrew the mounting nuts and bolts, if your Mustang model is equipped with hydro boost, and remove the cylinder from the engine compartment.

Once you finish servicing the master cylinder or have the new unit ready, bench bleed the cylinder to get rid of any air trapped inside. You can do this by placing the master cylinder on a vise. Connect clear rubber hoses to the unit fittings and insert the other end of the lines into the reservoir. Fill the reservoir with DOT 3 brake fluid and pump the cylinder piston in and out, until you see no bubbles going through the hoses.

Reinstalling the Master Cylinder

Now you can reinstall the unit on the brake booster. When connecting the lines, start the retaining nuts by hand to avoid damaging the threads. Then tighten the lines with the flare wrench and plug the level sensor electrical connector.

Test the brakes by pumping the brake pedal several times and make sure it feels firm. If the pedal feels spongy, you will need to bleed the brake system. You can do this by following the instructions on your car owner's manual or vehicle service manual.