How to Repair a Master Cylinder on a Ford Ranger

The master cylinder is the heart of your Ford Rangers brake system. When the driver pushes down on the brake pedal, a piston inside the master cylinder forces hydraulic fluid to each of the four wheels. On the front wheels a caliper forces brake pads against a steel disc, slowing the vehicle down. On the rear wheels a wheel cylinder forces brake shoes against a steel drum. When replacing the master cylinder you will introduce air into the hydraulic circuit. Therefor it is important to bench bleed the new master cylinder before installing it into the vehicle. Then you must bleed the entire brake system after the master cylinder is installed.

Instructions

Disconnect the ground cable from the negative battery terminal. Loosen the retaining bolt, using a wrench. Then pull the clamp off the terminal.

Unscrew the nut, bolt and spacers that secure the master cylinder pushrod to the brake pedal, using a socket.

Loosen and remove the hydraulic brake lines from the master cylinder, using a line wrench.

Unscrew the nuts that secure the master cylinder to the firewall.

Pull the master cylinder away from the firewall and remove it from the vehicle.

Disconnect the ground cable from the negative battery terminal. Loosen the retaining bolt, using a wrench. Then pull the clamp off the terminal.

Push the brake pedal down to expel the vacuum pressure from the power booster.

Loosen and remove the brake lines from the master cylinder. Rotate the fittings counterclockwise, using a line wrench. Pull the fittings away from the master cylinder.

Unscrew the nuts that connect the master cylinder to the power booster, using a socket. Remove the nuts and lock washers.

Pull the master cylinder away from the power booster and remove it from the vehicle.

Secure the new master cylinder into a bench vise, by positioning one of the retaining tabs into the vise and tightening it.

Plug all but one of the hydraulic line holes on the bottom of the master cylinder.

Fill the master cylinder with fresh brake fluid.

Insert a Phillips screwdriver in the rear of the master cylinder (the side that mates with the power booster). Position the screwdriver against the master cylinder piston in the center of the hole.

Push the screwdriver in and out until fluid comes out of the open line hole.

Move one of the plugs so that the open hole is plugged and a new hole is open.

Push the screwdriver in and out against the master cylinder piston until fluid comes out of the open line hole.

Move the plug so that the last hole is open and the other two are plugged.

Push the screwdriver in and out against the master cylinder piston until fluid comes out of the open line hole.

Set the new master cylinder into position on the firewall. Be sure to guide the pushrod through the hole in the firewall.

Screw the nuts and lock washers onto the studs that secure the master cylinder to the firewall.

Thread the retaining bolt through the brake pedal and brake pedal pushrod. Then screw on the nut, bolt and spacers.

Screw in the fittings that connect the hydraulic lines to the master cylinder.

Reconnect the ground cable to the negative battery terminal. Slide the clamp over the terminal and tighten the retaining bolt, using a wrench.

Set the master cylinder into position in front of the power booster.

Screw the nuts onto the studs that secure the master cylinder to the power booster, using a socket.

Screw the fittings on the hydraulic brake lines into the master cylinder, using a line wrench.

Reconnect the ground cable to the negative battery terminal. Slide the clamp over the terminal and tighten the retaining bolt, using a wrench.

Raise the vehicle's front and rear, using an automotive jack. Support with jack stands placed underneath the frame or axles.

Remove the wheels and tires, using a lug wrench.

Fill the master cylinder reservoir with fresh brake fluid. Be sure not to allow the reservoir to run dry at any point during this process.

Locate the bleeder screw on the front drivers-side brake caliper. Attach a length of clear plastic tubing to the bleeder screw. Immerse the other end of the tube in a jar half-filled with brake fluid.

Ask an assistant to pump the brake pedal a few times and then hold it against the floor.

Open the bleeder screw, using a wrench. Allow a little fluid to seep out--you will notice small air bubbles in the fluid. Close the bleeder screw before your assistant releases the brake pedal.

Repeat the two steps listed above until there are no more bubbles in the fluid.

Repeat the process listed above on the brake caliper on the passengers-side front wheel.

Repeat the process listed above on the wheel cylinder on the drivers-side rear wheel. The bleeder screw on this wheel will be located on the inboard side of the brake drum.

Repeat the process listed above on the wheel cylinder on the passengers-side rear wheel.

Reinstall the wheels and tires.

Lower the vehicle.