Safety Glasses
Nitrile Gloves
Wheel Chocks
Brake Line Flare Wrenches
Crescent Wrenches
Ratchet & Sockets
Brake Booster
Brake Fluid
Siphon Tool
Drain Pan
Shop Towels
Brake Cleaner
Step 1: Prepare Your Vehicle
Chock your wheels and set the parking brake. Pop the hood and disconnect the negative battery terminal. Set it aside someplace where it isn’t touching metal.
You’ll need to relieve the vacuum pressure that exists in the system so you can disconnect the vacuum line and separate the master cylinder from the booster. To do this, pump your brake pedal a few times with the engine off. Once the pedal firms up, you’re good to go.
Step 2: Locate the Brake Booster and Remove the Master Cylinder
Locate your power brake booster, which should be right against the back wall of your engine compartment on the driver’s side.
Remove the electrical connector leading to the brake fluid reservoir. This can be done by hand.
Before removing the booster, you’ll have to remove the master cylinder, which is directly in front of it. In some vehicles, you can just move the master cylinder to the side.
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Do It Right: If you are able to move the master cylinder to the side, there’s no need to unhook the brake hydraulic lines. If you don’t need to remove the hydraulic brake lines, the job won’t take as long because you won’t have to bleed the brake system. |
If you do need to remove the brake lines, leave the master cylinder cap on and remove the master cylinder from the booster. There’s no need to remove the fluid.
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Do It Right: Hold your fingers over the holes as you remove the master cylinder from the vehicle to make sure no brake fluid drips on anything. |
Next, remove the electrical cable leading to the brake fluid reservoir. This can be done by hand. Remove the clip that secures the connector and push the tab to release it.
Use the proper brake line flare wrench to disconnect the brake fluid lines and unscrew the mounting nuts with your ratchet and socket.
Once you’ve removed the master cylinder, tip it over your drain pan to allow any remaining fluid to drain. Keep in mind that brake fluid spills will damage painted surfaces, so if this happens, flush it with water immediately.
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Do It Right: If your vehicle has antilock brakes, you’ll also want to disconnect the brake line from the hydraulic control unit, or HCU, and remove this component so it’s out of the way. |
Inspect the seal at the end of the master cylinder... there should be no signs of brake fluid seepage. If you see fluid, there is a leak. If this is not corrected, the new booster will be damaged by allowing brake fluid inside the vacuum chamber and deteriorating the vacuum diaphragm. So, if the master cylinder seal does show signs of seepage, the master cylinder needs to be replaced.
Step 3: Remove the Old Power Brake Booster
With the master cylinder out of the way, you can turn your attention to the brake booster. Inside the vehicle, tilt your steering wheel up and remove the knee blocker to give you easier access. Your brake pedal attaches to a push rod that leads directly to the booster. Detach the retaining clip that connects the two components.
Next, use your socket to loosen the four nuts attaching the booster to the engine compartment wall.
Back in the engine compartment, disconnect the vacuum hose leading to the booster. Then slide the four studs out.
Tilt the booster up and carefully remove it.
Step 4: Install the New Power Brake Booster Cylinder
Now, you’re ready to do everything in reverse. Start by reading the documentation that came with the booster to be aware of all warnings. Then slide your new booster into position, and use the four studs to secure it to the wall.
Back under your dashboard, tighten the nuts, and reattach the brake pedal to the push rod.
Back under your dashboard, tighten the nuts, and reattach the brake pedal to the push rod.
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Do It Right: Lubricate the pin with the lubricant recommended by the manufacturer, and ensure the retainer safety clip is secure. |
Replace the knee blocker panel.
Clean the mounting surface on the booster thoroughly with a shop towel and brake cleaner before attaching the cylinder.
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Do It Right: Again, be sure not to get brake cleaner on any painted surfaces. |
Once everything is clean, use the nuts to reattach the master cylinder to the booster.
Reconnect the vacuum hose, HCU, and brake lines.
Reinstall the electrical wire leading to the fluid reservoir.
Reconnect your negative battery terminal.
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Do It Right: If you had to disconnect your brake lines, you’ll need to bleed the brake system. |
How to Bleed Brakes
It’s possible for air to get into brake lines, and the result is spongy braking. Brake bleeding is necessary to remove the air from brake lines.
How to Replace Master Cylinder
The brake master cylinder is what forces hydraulic fluid out to your calipers and wheel cylinders. If you’re noticing a brake pedal that slowly goes all the way to the floor, you could be dealing with a failing master cylinder.
How to Change Rear Differential Fluid
Changing your rear differential fluid is fairly straightforward on most vehicles and is an important maintenance item. It’s recommended you change your rear differential fluid every thirty thousand to sixty thousand miles.
The automotive repair work depicted in this series is performed under the direction of the manufacturer of the product featured. Prior to undertaking any of the demonstrated repairs on your vehicle, we suggest you consult with a certified mechanic or another professional who can adequately advise you of the proper repair or remedy required. O’Reilly Automotive Stores, Inc. and its affiliates (“O’Reilly”) disclaims any responsibility for injury or damage resulting from a viewer’s attempt to recreate the repairs shown in this series.