How to test the Power Brake Booster
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If your brakes are starting to feel spongy, the brake booster may be the root cause. Check the brake booster to see if it needs to be replaced.
In normal use, most car owners never think about the inner workings of the braking system. However, when you hit the brake pedal and notice that the car isn't slowing down, it grabs your attention pretty quickly. We all understand that a braking system is necessary for the safe operation of any vehicle, but few people know that the main cause of brake failure in older cars, trucks and SUVs is the brake booster.
The brake booster is used to supply brake fluid through the brake lines, which allows the system to work efficiently. If the brake booster fails, it can lead to a soft brake pedal or even complete failure of the brake system. In the next few paragraphs, we will explain how this important component works in the brake system and provide some tips to help you diagnose and determine if the brake booster is the root of your problem.
How does Power Brake Booster work?
To understand how a brake booster fits into a modern braking system, it is very important to explain how brakes work. To stop your vehicle safely, three scientific principles must be followed - leverage, hydraulic pressure, and friction. Each of these actions must work together in tandem to stop the vehicle. The brake booster helps provide the correct hydraulic pressure so that the brake calipers put pressure on the brake disc and create friction as the brake pads are applied to the rotor.
The Power Brake Booster also helps provide the amount of force needed for the right level of pressure to create an effective application of force. It works by drawing energy from the vacuum created by the engine during operation. This is why power brakes only work when the engine is running. The vacuum feeds an internal chamber that transfers force to the hydraulic brake lines. If the vacuum is leaking, damaged, or the internal components of the brake booster are damaged, it will not work properly.
3 Methods for Checking a Malfunctioning Power Brake Booster
The 1 method: Checking the brake booster is a fairly simple process. If you suspect that the brake booster is the root cause of your brake system failure, follow these three steps:
With the engine off, press the brake pedal several times. This ensures that no vacuum remains inside the brake booster.
Depress the brake pedal firmly one last time and leave your foot on the brake pedal when starting the engine. Do not release your foot from the brake pedal during this process.
If the brake booster is working properly, you will feel a slight pressure on the pedal when cranking the engine. This is because the vacuum in the engine pressurizes the brake booster.
The 2 method:If you have completed this step and the brake pedal does not move, this indicates that the brake booster is not receiving vacuum pressure. It is at this point that you should attempt to perform a secondary booster brake booster test.
Let the engine run for a few minutes.
Stop the engine, then depress the brake pedal slowly several times. When you pump it for the first time, the pedal should be very "low", which means there is little resistance to pressure. As you press down on the pedal, the pressure should get stronger, indicating that there is no leak in the brake booster.
The 3 method:If each of these tests pass, you can test two more components:
Inspect the booster check valve: The check valve is located on the brake booster itself. To find it, refer to your vehicle repair manual. You will need to disconnect the vacuum hose as it connects to the engine intake manifold. Be sure to disconnect it from the manifold, not from the brake booster. If it works correctly, the air should not pass under pressure. If air flows in both directions or you cannot blow air through, the valve is damaged and the brake booster needs to be replaced.
Check vacuum: The brake booster requires a minimum pressure to operate. You can check the vacuum and make sure the vacuum pressure is at least 18 inches and there are no vacuum leaks.
If you do not feel comfortable doing these tests, it may be a good idea to have a professional mechanic come to your place to complete the on-site brake inspection. It is not recommended to drive your car to a repair shop if you have problems with the brake system, so a mobile mechanic visit is a smart and safe idea.
