Brake Boosters: Vacuum Vs Hydroboost Systems

The hydro-boost system is a power-assisted braking system. It uses hydraulic pressure from the engine’s power steering system, rather than engine vacuum, to supply even more power to the brake pads. This gives you much greater braking power than if you just had manual brakes.

With a hydro-boost system, you can apply up to 1000 pounds of pressure to the brake pads, ensuring your vehicle stops quickly and easily. The benefits of this system include less wear and tear on your braking components due to increased braking pressure and improved stopping performance.

Additionally, with a hydro-boost system, you don’t have to worry about your brakes failing due to a lack of engine power or extreme temperatures. The hydraulic fluid does not boil away like a vacuum booster. This makes it ideal for high-performance applications such as off-roading or drifting, where extreme conditions are common.

On top of all this, some vehicles saw their fuel economy improve when switched from a vacuum booster setup to a hydro boost setup due to decreased weight thanks to the slightly shorter hoses used. Overall, the hydro-boost system has many advantages over relying on simple vacuum boost technology for improved vehicle safety and handling.

What Is Hydroboost?

Hydroboost is an innovative technology that has revolutionized the braking systems of 4×4 trucks. It relies on power steering pump pressure instead of engine vacuum to pressurize the brake system, drastically improving vehicle braking performance. This improved level of consistent pedal response is because the power steering pump is always pressurized, eliminating the need for manual pumping for stiffer brakes.

The most evident benefit of hydro boost is the unparalleled level of confidence it instills in drivers when negotiating steep downhill grades while off-throttle with cammed-up engines, which can struggle to deliver reliable vacuum at lower RPMs.

In addition, a ‘firmer’ pedal feel and more dynamic stopping capability are also notable hallmarks associated with hydro boost installation. Upgrading your 4×4 vehicle with hydro boost technology can improve your overall driving experience without compromising safety or reliability.

What is Vacuum Brake?

The vacuum brake booster is crucial to an automobile’s braking system. It connects to the engine’s intake manifold to receive power. When the driver hits the brake pedal, the booster creates a vacuum that pressures the hydraulic brake lines. This pressure leads to greater friction, and the car stops.

Vacuum brakes can also fail due to insufficient vacuum pressure from the engine or if a leak in one of the internal bladders supplies the force to the hydraulic lines. For a vehicle’s brakes to remain reliable and properly functioning, regular maintenance must be done, including checking for any leaks in those parts that make up part of this system. By doing so, serious issues with your braking system can be avoided.

How Can I Test the Vacuum and Hydroboost Brake?

Putting on a new brake isn’t enough. You need to test it to know if it’s working fine or not. You can run the below tests to see if the brakes are working fine or not.

Test for Vacuum Brakes

Supply Test

Carrying out a vacuum supply test on a vehicle’s booster is important in ensuring its optimal performance. Before starting the engine, it’s essential to pump the brake pedal to deplete the booster reserve. The next step involves disconnecting the vacuum supply hose from the booster and connecting a vacuum gauge with a cone-shaped adapter.

Allowing the engine to idle while reading the gauge makes it easier to measure accurately. On most vehicles, between 15” and 20” Hg (50 and 70 kph) should be displayed idle.

However, if this reading is low, you should check that there are no blockages in the vacuum hose or other mechanical faults, such as leaky valves or worn rings. An intake manifold vacuum leak or improper cam timing could also be possible causes for this reduction in source vacuum.

Valve Test

Testing the vacuum inlet check valve is essential to ensure its proper operation. The check valve functions as a one-way street, allowing only the vacuum to pass into the booster, which is necessary for proper brake performance. To test it, firstly, take the vacuum supply hose from the intake manifold or vacuum pump and blow it into the hose. If air passes through the valve and into the booster, the check valve might malfunction and should be replaced.

Inspecting and replacing any defective parts when needed is important to keep your car running smoothly. Replacing a faulty check valve can ensure that the optimal performance of your brake system will return.

When testing this part, it’s important to consider potential risks from working around utilities such as fuel lines or electric current. Additional steps may also be necessary depending on your car’s model, so consult with a certified professional if you are uncertain how to proceed with inspecting and servicing your vehicle.

Test for Hydroboost Brake

Power Assist Test

The hydro-boost power assist system uses hydraulic pressure instead of a vacuum to provide assistance with braking. This means greater assistance than a vacuum system is available, resulting in higher performance and control.

The hydro boost has an accumulator which helps provide several power-assisted stops if the system experiences a disruption such as a belt breakage or hose rupture.

To ensure that the hydro-boost power assist system is functioning properly, it is important to inspect key components such as hoses, pumps, and drive belts for leaks, any lower power steering fluid levels, and test operation and accumulator performance.

Control over fluids running in or out of the hydro-boost is handled by spool valves, cylinders filled with machined rings inside them. These spool valves can also be found in other hydraulic components, such as valve bodies included in automatic transmissions.

Function Test

Performing the hydro-boost function test is an important step in ensuring the safety of your vehicle. The test checks to see if the hydro-boost system, which multiplies available braking power when activated, works properly.

To begin the test, switch off the engine and apply medium force on the brake pedal five or more times, which will discharge any power stored in the accumulator. Afterward, you should notice a hardening of the brake pedal. 

Next, start up your engine and repeat this process with medium force – if everything is functioning as it should be, then you’ll find that the brake pedal moves downward slightly toward the floor before pushing back upward.

However, if there’s no change in its position or feel, something’s not working correctly, and you must investigate further. If all goes well during this process and it passes this basic test, proceed to do an accumulator test.

Which One Should I Choose?

When choosing between a vacuum brake booster or a hydro-boost system, there are several factors to consider. Both brake boosters use power assist to make braking easier but they have different advantages and drawbacks.

Vacuum boosters are the more common choice for cars and light trucks. They use engine vacuum from the intake manifold to help apply force on the master cylinder piston, increasing brake pedal pressure. Vacuum boosters are relatively inexpensive and easy to install. However, they do not provide as much power assistance as a hydro-boost system.

On the other hand, hydro-boost systems offer more power assist than vacuum boosters, making them ideal for heavier vehicles such as SUVs and trucks. They use hydraulic pressure from the power steering pump to amplify the braking power. Hydroboost systems are more expensive and difficult to install, but they can provide smoother braking with less brake pedal effort.

Ultimately, the type of system you choose should depend on your vehicle’s size, weight, and performance needs. If you’re unsure which one is right for you, it’s best to consult a certified professional for advice.

Frequently Asked Questions [FAQs]

1. Are There 2 Types Of Vacuum Boosters?

Yes, there are two vacuum boosters: vacuum assist and hydro-boost. Vacuum assist boosters use engine vacuum to create the extra force needed to power the master cylinder and increase brake pedal pressure. This type of booster is found on most cars, trucks, and SUVs. Hydroboost systems use fluid pressure rather than a vacuum to provide additional braking force. These systems are typically used in vehicles with larger engines and more weight.

2. How Often Should I Check My Hydro-Boost System?

You should check your hydro-boost system regularly, as any issues can increase the risk of an accident or injury. You should also inspect the key components such as hoses, pumps, and drive belts for leaks, low power steering fluid levels, and test operation and accumulator performance. If you notice any problems, have the system inspected and repaired immediately.

3. What Is The Difference Between A Brake Booster And A Vacuum Pump?

A brake booster and a vacuum pump are two different components that work together to provide a hydraulic braking system for a vehicle. The brake booster is a device that increases the line pressure in the hydraulic braking system by using pressure from the engine vacuum or an externally-applied pressure source, such as a hydro-boost system. A vacuum pump is a device that draws air out of the atmosphere and creates a vacuum to move air through the brake booster and activate the system.

4. What Is The Advantage Of Hydro Boost Brakes?

The main advantage of hydro boost brakes is the increased braking power. The hydro-boost system uses hydraulic pressure from the power steering pump to increase brake force and reduce pedal effort. This allows for more effective stopping power without increasing pedal effort, which can be beneficial when a driver needs to make a quick stop or when more braking force is required when carrying heavier loads. Additionally, the hydro-boost system is more resistant to wear and tear than a vacuum booster.

5. Will A Brake Booster Work Without A Vacuum?

No, a brake booster will not work without a vacuum. A brake booster is an air-assisted device that uses either a vacuum or a hydro-boost system to increase the force the driver’s foot applies on the brake pedal. Vacuum-assisted boosters use engine vacuum to create suction in the booster, amplifying the pressure applied to the brakes.


Understanding the differences between vacuum and hydro boost systems can help you choose the right system for your vehicle. Vacuum boosters are less expensive and easier to install but may not provide as much power assistance as a hydro-boost system. Hydroboost systems are more expensive and difficult to install, but they can provide smoother braking with less brake pedal effort.

John D. Archer