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How-to » Brakes » Hydraulic System » How to Replace a Brake Master Cylinder
 Note: This is a general guide for all vehicles.

How to Replace a Brake Master Cylinder

PARTS
  • Brake Fluid
  • Brake Master Cylinder
STEPS
Edit
Moderate
Safety Tip:
Always wear safety glasses when working on your vehicle. Wear other personal protective equipment (PPE) when necessary, for example latex gloves or closed toe shoes.



1
Open hood and locate your brake master cylinder.
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2
Inspect brake fluid level.
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3
Using a turkey baster, withdraw the brake fluid from the master cylinder.
4
Remove the brake lines from brake master cylinder using flare nut wrenches.
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5
Disconnect any electrical connectors from the brake master cylinder.
6
Unbolt the brake master cylinder from the brake booster or from the firewall.
7
Mount new brake master cylinder in a vice.
8
Fill both chambers of the brake master cylinder reservoir with clean (new) brake fluid.
9
Using a bench bleeding kit thread the adaptors into the brake master cylinder.
10
Route the tubing back into the brake master cylinder reservoir.
11
With a Phillips screwdriver, slowly pump the piston using full strokes.
12
Keep pumping the brake master cylinder until all the air is removed. Keep the master cylinder reservoirs filled during this step.
13
Install the new brake master cylinder to the brake booster.
14
Remove bench bleeding fitting and install brake lines. Some brake fluid may leak out but the brake master cylinder should stop any major leak.
15
Fill the master cylinder reservoir with clean (new) brake fluid of the correct type.
16
Secure your vehicle on a level surface, making sure your car will not roll or lean too much when jacked up.
17
Lift up your vehicle with a floor jack.
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18
Secure the vehicle with jack stands on both sides for safety before starting any work. The pinch welds and the frame are the two best locations. Do not rely on the jack to hold the vehicle up while working.
19
Remove the wheels by removing the lugs nuts that are holding them on. To do this you will need to find the correct size socket and large ratchet or tire iron and turn them counter clockwise. If your vehicle is equipped with hub caps (plastic covers over the wheels), these will need to be removed to access the lug nuts.
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20
Place a 1 x 4 block of wood under the brake pedal to prevent the pedal from traveling to far.
21
Locate the brake bleeder valve on your passenger side rear brake caliper or wheel cylinder.
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22
Install a piece of clear plastic tubing over the brake bleeder valve screw and place the other end into a container half full of brake fluid.
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23
Have your assistant slowly depress and hold the brake pedal down.
24
Crack the bleeder valve open. Old fluid and air bubbles will travel down the clear tubing and into the container. Tighten the bleeder valve.
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25
Repeat this process until clean fluid comes out of the bleeder valve and there are no more air bubbles. Check and refill the master cylinder with clean (new) brake fluid of the correct type. Do not allow the master cylinder to drain completely.
26
Repeat steps 22 through 25 in the following order: Left rear wheel, right front wheel, left front wheel.
27
Reinstall wheels, lower the vehicle to the ground and verify the repairs with a road test.
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