How to Check a Brake Power Booster

by K.K. Lowell

A brake power booster is a vacuum operated device which reduces the effort needed to press the brake pedal and apply the brakes. In most cases the vacuum is created by the running engine and air is drawn from the booster through a rubber hose connected to the intake manifold. Diesel engines do not produce much vacuum and may employ a vacuum pump. High pedal effort and poor braking action indicate a problem with the booster or the vacuum system.

Depress the brake pedal repeatedly with the engine off.

Continue to hold the brake pedal down and start the engine. The brake pedal should be pulled down slightly after the engine starts. A problem with the brake booster or the vehicle vacuum system is indicated if the pedal does not pull down slightly.

Connect a vacuum gauge to the hose from the engine to the brake booster and start the engine. A reading of 16 inches or more of vacuum rules out a problem with the vacuum system and indicates the need to replace the brake booster.

Items you will need

About the Author

K.K. Lowell is a freelance writer who has been writing professionally since June 2008, with articles appearing on various websites. A mechanic and truck driver for more than 40 years, Lowell is able to write knowledgeably on many automotive and mechanical subjects. He is currently pursuing a degree in English.