The Difference Between Power Brake Booster & Vacuum Brake Booster

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If you own a vehicle made after 1968, it’s likely that you have a power brake system. While there are several evolutions of this vital vehicle operating system, the basic premise of applying leverage, forcing hydraulic pressure, and friction still remains the fundamental process for slowing and stopping a vehicle. One of the most commonly misunderstood issues is understanding the difference between a power brake booster and a vacuum brake booster.

In all truth — a power brake booster and vacuum brake booster are the same part. Each utilizes vacuum pressure to assist in the application of hydraulic fluid and utilizing friction between the brake rotor and pads. Where confusion exists is calling a Hydro-Boost Power Brake Assist System a power brake booster. A Hydro-Boost system bypasses the need for vacuum and uses direct hydraulic pressure to accomplish the same task.

In order to simplify things, let’s break down how a vacuum-based brake booster works as opposed to a hydraulic-based brake booster, along with a few tests for diagnosing potential problems with both.

How Does the Vacuum Brake Booster Work?

A vacuum-based brake booster receives its power via a vacuum system attached to the engine’s intake manifold. Vacuum is circulated through the brake booster, which applies pressure to the hydraulic brake lines when the brake pedal is pressed. This system is used in a vacuum booster or power brake booster. The vacuum supplied by the engine operates an internal bladder, which supplies the force to the hydraulic brake lines.

There are generally three sources of a vacuum brake booster failure:

  1. No vacuum pressure from the engine.

  2. Inability of the brake booster to absorb or create a vacuum internally.

  3. Broken internal parts, such as the check valve and vacuum hose, inside the brake booster that fail to supply power to the hydraulic lines.

What is a Hydro-Boost Power Assist Service?

The hydro-boost power system works nearly identically to the vacuum-based system, but instead of relying on vacuum pressure, it uses direct hydraulic pressure. It is powered by the power steering pump and will typically fail at the same time as power steering. In fact, that’s typically the first indicator of a hydro-boost power brake failure. However, this system utilizes a series of back-ups to keep the power brakes working for a short period of time in the event of a ruptured power steering hose or broken power steering belt.

Why is a Power Brake Booster Called a Vacuum Brake Booster?

A brake booster is designed to provide power-added assistance to help apply the brakes. It’s mainly due to the job of a brake booster that a vacuum-assisted system is called a power brake booster. It’s also common for a hydraulic-powered brake booster to also be associated with the term power brake booster. The key to knowing which type of brake booster is used on your vehicle is to consult your vehicle owner’s manual.

Most of the time, this question is asked when a problem with your brake system has popped up. A professional mechanic can be quite helpful in diagnosing a problem with your brake system. During a brake system inspection, they’ll complete several diagnostic checks to determine the root source. This includes the power brake booster. If you have a vacuum-based system, or hydraulic, they’ll be able to identify the issue and recommend the best replacement parts and repairs needed to get your car back on the road.


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Michael

15 years of experience
518 reviews
Michael
15 years of experience
Mercedes-Benz GL450 - Brake Pads Replacement (Rear) - Atlanta, Georgia
Micheal was punctual and friendly. Work was completed within promised time. Will definitely use again.
Volvo S80 - Brake Pads Replacement (Front) - Roswell, Georgia
Michael was SUPER QUICK with doing my brake and rotors. Great communication throughout the whole process. Will always recommend

Kenneth

19 years of experience
509 reviews
Kenneth
19 years of experience
Toyota Sequoia - Brake Pads Replacement (Front) - Newport Beach, California
Kenneth did a great job and very knowledgeable. He has a great attitude and I will for sure be using him again.

Chuy

13 years of experience
129 reviews
Chuy
13 years of experience
Honda Civic - Brake Pads Replacement (Front, Rear) - Cicero, Illinois
Excellent work on doing the breaks for my car and the break and steering system flush I’ll definitely recommend and take into consideration for chuy’s work whenever I need a fix on my car

Richard

16 years of experience
72 reviews
Richard
16 years of experience
BMW 328i - Brake Pads Replacement (Rear) - Dublin, California
Richard was an outstanding mechanic. After he arrived, the first thing he did after taking the initial pictures of the car is an assessment into what work was asked. He quickly verified that I did not need brake fluid and my front brakes even-though it affects his personal commitments and time, which I think is highly appreciate and thorough professional. He was detailed oriented - took time to make sure that all the issue are fixed. He paid attention to detail in overall car assessment- he goes above and beyond. He was also teaching me through the process which I found highly educational and appreciate him providing the information ensuring and making me comfortable what he was doing and explaining patiently all the questions that was thrown at him. When he works - you know he's highly skilled and experienced and knows his stuff. He is highly experienced. He is a "Master" mechanic in true sense :)

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