How to Troubleshoot a Brake Vacuum Booster

How to Troubleshoot a Brake Vacuum Booster


The brake booster is a power braking system provided by a vacuum and hose mechanism attached to the system. This should, in theory, assist braking; however, if it is not working properly then you may find it actually makes pressing on the brake pedal to slow or stop the car much more difficult. Naturally, it is absolutely vital to remedy this potentially dangerous issue. There are steps you can take to diagnose and fix the problems.

Instructions
Pump the brake several times and hold the pedal down while attempting to start the engine. If the power brake is working, it will pull the pedal down further. If the pedal does not move, you have a problem. This confirms that you need to carry out a basic troubleshooting process.

Start the engine and check for vacuum in the hose. The engine should smooth out if you plug the hose end. If you don't feel the vacuum suction, the problem is a restricted vacuum port and this must be cleaned.

Attach the valve and hose to the brake booster and listen for any air leakage. This indicates a cracked booster, which you must have replaced for the mechanism to work properly.

Replace the booster if the brake still has no power assist and you have exhausted the previous steps.

How to Check a Brake Power Booster

How to Check a Brake Power Booster

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.

Things You'll Need
Vacuum gauge


Instructions
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.