Ford F150 F250: How to Replace the Brake Master Cylinder

If your brake pedal goes to the floor on your Ford F-150 or F-250 Super Duty, it might be a good idea to change your master cylinder.

November 7, 2014

This article applies to the Ford F-150 (2004-2014), and the F-250, F-350 Super Duty (2005-2014).

The master cylinder controls the brakes by activating them when you step on the pedal. The mechanical action is converted to hydraulic pressure that forces the disks in the calipers to press the brakes against the disk stopping the vehicle. A leaky master cylinder allows air into the system. Air does not compress like brake fluid so the pedal travels further. Replacing the master cylinder on your Ford F-series is easy. It involves unmounting and remounting the assembly as well as bleeding the system.

Materials and Tools Needed

  • Socket set
  • Dot 3 Brake fluid
  • 7/16 Wrench (tubing wrench)
  • Ratchet
  • Brake bleeding kit or clear line with a glass jar

Step 1 – Prepare your truck

• Set the parking brake on your truck.
• Lock the wheel to prevent the truck from rolling.
• Open the hood, and locate the master cylinder in the yellow case on the right side along the firewall.

Step 2 – Remove the old cylinder

• Unscrew the two bolts connecting the cylinder to the hydraulic booster.
• Pull the master cylinder from under the hood

Step 3 – Place the new cylinder

  • Bolt the new master cylinder in its place.
  • Connect the brake lines.
  • Reconnect any electrical connections.
  • Unscrew the reservoir's cap, and fill the reservoir with Dot 3 brake fluid until it's filled to the MAX line marked on the reservoir.
  • Screw the top back on.
  • Bolt the new master cylinder in its place.
  • Reconnect any electrical connections.
  • Unscrew the reservoir's cap, and fill the reservoir with Dot 3 brake fluid until it's filled to the MAX line marked on the reservoir.
  • Screw the top back on.

Step 4 – Bleed the brake system

  • Jack the truck up.
  • Secure the truck with the jack stands.
  • Remove the front wheel.

(Related Article: How to Remove a Tire - Ford-trucks.com)

  • Loosen the round shape valve on top of the caliper.
  • Ask a helper to pump the pedal ensuring there is no air in the system.
  • When fluid spurts out of the valve, tighten it back.
  • Repeat the procedure until no air is visible in the line.
  • Repeat the same steps for your other wheel.
  • Fill the cylinder to the fill line after bleeding it.

Step 5 – Reverse the above steps

  • Install the tires back on your truck and tighten the lug nuts. Lower the truck back to the ground, start it, and pump the brake pedal a few times before driving.

Pro Tips

  • Use tubing wrenches on the brake line fittings in order to avoid rounding them off.
  • A brake bleeding kit can make this a one person job. When bleeding the brakes, start with the wheel cylinder furthest from the master cylinder and work forward to the shortest line moving downward in line length.
  • This is a good time to replace the fluid in the system. Wait until the fluid runs clear in each bleeding to flush the lines fully.
  • ALWAYS test the brakes before driving off. Ensure that there are no obstructions when performing initial system testing. Using a car ramp or wheel chock as an added stopping measure is a good idea.
  • Wear safety glasses and gloves to protect your skin. Wipe up any fluid immediately as it will ruin paint.

How to Replace the Brake Master Cylinder

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