A brake booster is a critical component of many braking systems. It magnifies the slowing or stopping force of the existing system, making it more powerful and more effective. To have a brake booster go out basically equates to having the entire mechanism go out, as the remainder of the system is designed to have the booster in place. Replacing the booster isn't a difficult matter; if you can change your brake pads and bleed your brakes, you can change the booster. It isn't usually an expensive part either, typically around 100 dollars. Here, you will find the information needed on how to replace this part.
Step 1 - Find the Brake Booster
This part is located adjacent to the master cylinder. There will be four mounting screws protruding through it to secure it in place. The booster is also attached to the brake pedal in the interior of the car. This is where you will start.
Step 2 - Remove the Brake Booster
The booster will be attached to the brake pedal with a piece called a booster rod. This goes through the firewall and is typically secured to the pedal with a cotter pin. There may also be nuts. Remove the fasteners, regardless of what they are, and set them aside in a plastic bag. Your new brake booster will not come with replacement fasteners, so it's important that you keep these.
Slide the rod off the brake pedal. Then, disconnect the vacuum brake line that connects to the booster. In the engine compartment, four bolts will secure the booster to the master cylinder and firewall. Loosen and remove these. There are usually two more in addition to these four that will secure the brake booster to the master cylinder; these should also be removed. Wiggle the brake booster away from the master cylinder once it's free. There will be a seal between the two that you need to keep as well, as the new part does not generally come with another one. Finally, remove the brake booster completely.
Step 3 - Install the New Brake Booster
Set the new brake booster on the four mounting screws, and tighten the nuts on the bolts to the master cylinder. Start these by hand so that the threads are not ruined. Then, insert the push rod through the firewall, and reattach the vacuum hose. Secure the nuts to the four mounting screws, and then finally reattach the push rod to the brake pedal by whatever means it was originally secured with, whether by cotter pin or by bolts.
Step 4 - Bleed the Brakes
You will need to bleed the brakes after replacing the brake booster. Once this is finished, your brake system should be fixed and ready to go!