Car Fix DIY Videos

http://ford-trucks.com/how-tos is the leading Ford F-150 and Super Duty truck resource for technical DIY guides. Changing your brake master cylinder can save you money. For the full article, visit http://www.ford-trucks.com/how-tos/a/ford-f150-f250-how-to-replace-the-brake-master-cylinder-356122.

The brake system in your Ford F-150 or F-250 is pretty simple. As you step on the brake pedal, the master cylinder converts this force into hydraulic pressure, pushing brake fluid through the brake lines and into the calipers. In turn, the calipers press the brake pads against the rotors to stop your truck.

If your truck’s brake pedal touches the floor, a leaky master cylinder might be causing air to enter the brake system. And since air does not compress like brake fluid, the pedal will feel soft and spongy, and braking efficiency will be reduced due to a loss of pressure.

As you will be required to bleed the brakes along with replacing the master cylinder, this job is moderately difficult. It should take between one and two and a half hours to complete. The cost of a new brake master cylinder will cost you around $45, but if you take your truck to the mechanic, expect to pay upwards of $200 for the cost of labor.

For this project you will need a torque wrench and socket set, DOT 3 brake fluid, 7/16th tube wrench, 10 mm box wrench, a brake bleeding kit or an airline tube with a drain container, and a friend to assist you when bleeding the breaks.

Step 1 – Remove the master cylinder

First make sure the engine is off and the parking brake is engaged. Also chock the wheels to prevent your truck from rolling. Once you open the hood, you will see the master cylinder located underneath the yellow reservoir on the driver’s side corner of the engine bay.

Disconnect the brake fluid level switch and vacuum sensor wire electrical connector. They are located on opposite sides of the master cylinder.

Then, using a 7/16th tube wrench, loosen and disconnect the primary and secondary tube fittings on the left side of the master cylinder.

Use a ratchet and socket to remove the master cylinder mounting nuts and slide the master cylinder off of the brake booster studs.

Step 2 – Install the new master cylinder

To install the new master cylinder, simply follow the removal process in reverse order.

Mount the new master cylinder and torque the nuts to 20 foot-pounds. Connect the brake tube fittings and torque them to 14 foot-pounds. Then connect the brake fluid level switch and vacuum sensor connector.

Lastly, remove the filler cap of the new master cylinder reservoir and pour in DOT 3 brake fluid until it reaches the MAX fill line.

Step 3 – Bleed the brake system

Make sure your truck is parked on a flat, level surface and place it on jack stands. You will need to bleed the brakes one by one, starting from the rear brakes. First remove the passenger’s side, rear wheel.

Remove the bleeder valve cap on the caliper and attach a 10 mm box wrench to the valve. Then attach an airline tube to the valve and submerge the other end of the tube in a drain container partially filled with brake fluid.

Have your friend pump the brake pedal a few times and then hold it down to the floor. Open the bleeder valve by turning it counter-clockwise, and allow the old brake fluid to flow out into the container.

Tighten the bleeder valve immediately when you see clean, bubble-free brake fluid flowing out. Make sure the brake pedal is still depressed before closing the valve, and torque the bleeder valve to 18 foot-pounds.

Repeat the bleeding process starting from the other rear brakes to the passenger and driver’s side brake assemblies. Make sure to check the master cylinder before moving on to the next wheel and top off with brake fluid as necessary. Lastly, start the engine and depress the brake pedal to make sure there is no air in the brake lines.

Now it’s time to enjoy the new feel of your truck’s braking system.