How to Repair a Leaking Brake Booster Vacuum Hose

If you think that your brakes don't have sufficient stopping power, there could be a problem with the brake booster vacuum hose. This hose is instrumental in making the connection between the master cylinder and the brakes themselves, and when there is a leak, your brake pedal will still feel firm, but the brakes will lack power behind them. Repairing a brake booster leak is a matter of replacing this hose.

Step 1 - Jack Up the Vehicle

Drive your vehicle onto a flat surface so you can use a good floor jack to lift the car. Place the tool under the frame and begin jacking up the vehicle. Set jack stands nearby so they can take the weight of the vehicle in case the jack slips by accident.

Step 2 - Take off the Tires and Brake Cover

Use an impact gun or a lug nut wrench to loosen the lug nuts on your tires. Set the lug nuts aside together in a safe place and remove the tires to gain access to the brake housing.

On some models of vehicles, you'll find a metal cover over the brakes, too. Remove this by prying it off with the flat side of the lug nut wrench.

Step 3 - Remove the Master Cylinder

You will find the brake master cylinder located at the top of the brake assembly. It will be held in place by two nuts on threaded posts. Remove these nuts with an adjustable or open-ended wrench, and then remove the cylinder. This will allow you to get to the brake booster vacuum hose.

Make sure you have a safe place, such as a plastic bag or a bowl, to put all of the nuts removed in this process so you don't lose them.

Step 4 - Remove the Vacuum Hose

The brake booster vacuum hose will be in behind the master cylinder, held in place with one nut. Remove this and slide the hose out from the rear of the brake housing. Disconnect it from the brake line, and take it to your local auto parts store to make sure you buy a properly fitting replacement.

Step 5 - Install a New Vacuum Hose

Once you have the old vacuum hose off of the brake line and brake assembly, position the new one in its proper place and begin securing it. Reconnect the brake line as well as the assembly itself. Then, replace the nut for the brake booster vacuum hose.

Step 6 - Replace the Brake Cylinder

Now that the new vacuum hose is installed, you can slide the master cylinder back onto the threaded post. Secure with the two nuts that you removed initially.

Step 7 - Bleed Brake Lines

Any time you work with the brake lines, you'll need to bleed them afterward in order to release any air trapped inside. Open the bleeding nut on the back of the brake assembly and let the brake fluid flow until pure liquid comes out. Close the bleeding nut and add brake fluid to the reservoir to replace any that was lost.

Step 8 - Replace Tires and Lower Car

Replace the brake cover and tires. Tighten the lug nuts onto the wheel and lower the car back to the ground.