How to Replace a Power Brake Booster

The brake booster provides power assistance during braking. Inside there is a disc-like diaphragm that separates the booster’s two halves. When the engine is running, vacuum is applied to both sides of the booster. When the driver steps on the brakes, the pedal operates a valve which allows outside air to enter. This allows atmospheric pressure to enter the booster, creating a pressure differential that forces the booster power forward into the master cylinder for power assist. When the brakes are released, vacuum returns to both sides of the booster and a spring returns the diaphragm to its original position.

If the power brake booster is not functioning properly, you will notice problems such as the brake pedal being very hard to press, and the vehicle taking longer than normal to come to a stop. It may be time to replace the power brake booster.

Materials Needed

  • Pliers
  • Protective gloves
  • Ratchet, sockets and extension
  • Repair manuals (optional)
  • Replacement brake booster
  • Safety glasses
  • Screwdriver and/or small pick

Part 1 of 2: Remove the faulty brake booster

How to Replace a Power Brake Booster 2

Step 1: Locate the brake booster. The brake booster will be mounted to the firewall on the driver’s side.

How to Replace a Power Brake Booster 3

Step 2: Remove the master cylinder from the brake booster. Remove the master cylinder fasteners using a ratchet or wrench. Then pull the master cylinder away from the booster. Typically, the brake lines are long enough that this can be done without disconnecting the lines.

How to Replace a Power Brake Booster 4

Step 3: Disconnect the booster vacuum supply line. Remove the hose clamp by squeezing it with a pair of pliers and sliding it away from the booster. Then gently remove the hose by pulling it away from the booster.

How to Replace a Power Brake Booster 5

Step 4: Disconnect the booster pushrod from the brake pedal. Using a small screwdriver or pick, remove the retaining clip from the booster pushrod. Then remove the pushrod from the brake pedal.

How to Replace a Power Brake Booster 6

Step 5: Remove the brake booster fasteners. Remove the fasteners securing the booster to the bulkhead. These are typically located under the dashboard. The best way to reach them is by using a ratchet with an extension.

How to Replace a Power Brake Booster 7

Step 6: Remove the brake booster. Pull the booster away from the firewall and remove it from the vehicle.

Part 2 of 2: Install the new brake booster

How to Replace a Power Brake Booster 8

Step 1: Position the new brake booster unit. Place the new brake booster in the same location that the old one was removed from.

How to Replace a Power Brake Booster 9

Step 2: Reinstall the fasteners. Reinstall the brake booster fasteners and tighten them down using a ratchet and extension.

How to Replace a Power Brake Booster 10

Step 3: Reconnect the pushrod to the brake pedal. Reinstall the pushrod onto the brake pedal and put the clip back on.

How to Replace a Power Brake Booster 11

Step 4: Reconnect the booster vacuum hose. Slide the vacuum hose back onto the booster. Then reinstall the hose clamp by squeezing it with a pair of pliers and sliding it onto the booster.

How to Replace a Power Brake Booster 12

Step 5: Reinstall the master cylinder. Reinstall the master cylinder and tighten down the mounting bolts using a ratchet or wrench.

Replacing a brake booster can be tough. If this seems like something you’d rather leave to the professionals, YourMechanic offers expert brake booster replacement conveniently done at the time and place of your choice.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace a Shock Absorber
Replacing a shock absorber can take some work, as it requires lifting your vehicle and ensuring you are aligning the new shock correctly.
How to Replace an Electronic Brake Control Module (EBCM)
ABS systems is controlled by electronic brake control modules (EBCM) which monitors sensors and relays data for smooth and safe braking.
What is Brake Fade?
Brake fade is the temporary loss or reduction of full brake power. Learn how to reduce the chances of it happening to you.

Related questions

The car pulls to the left after it gets warmed up
Hello! I believe the problem you are having may be to do with the electric steering system. I would suggest having that checked out by a capable technician. Also you mentioned that the alignment has been done. Compare the readings...
what happens if your wheel sounds like you're dragging something while driving
Hey there, thanks for writing in about your 2000 Ford Mustang. It sounds like you have a brake shoe (https://www.yourmechanic.com/services/brake-system-inspection) that has come apart and is dragging on the brake drum. Have the rear and front brakes checked (https://www.yourmechanic.com/services/brake-system-inspection) to...
Vacuum hose unhooked brake - 1990 Dodge D150
Hello. The vacuum hose (https://www.yourmechanic.com/services/brake-booster-vacuum-pump-replacement) from the brake booster goes into a tube on the intake. This tube is going to be about the same diameter as the hose and may need a clamp to secure it properly. The small...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com