Brake Servo: Malfunction Symptoms, Function, and Price

The braking system is one of the most critical systems in any vehicle, and the brake servo plays an essential role in its efficiency.

This often overlooked component is responsible for facilitating the application of braking force, increasing safety and driving comfort.

If the brake pedal feels harder than usual, or if you feel that the car takes longer to brake, this is a sign that there are problems. Ignoring these signs can compromise your braking ability and endanger safety on the road.

In this article, find out in a clear and straightforward way everything you need to know about how the brake servo works and what it is for, as well as the signs that indicate a fault in this component.

 

What Is A Brake Servo?

A brake servo is a component of the braking system that helps amplify the force applied to the brake pedal.

It works based on the difference in pressure between the vacuum in the engine and atmospheric pressure, making it easier for the driver to brake with less effort.

 

What Does A Brake Servo Do?

This component reduces the force required to apply the brakes, making braking more responsive and efficient. This allows the driver to stop the vehicle easily and in a controlled way, even in emergencies.

In addition, this component helps reduce wear on the brake system components (e.g., brake pads), extending their service life.

 

What Are The Components Of A Servo Brake?

This system consists of several essential parts, such as:

• Vacuum chamber: where the pressure difference occurs;
• Servo chamber: the external part that houses all the other internal components;
• Diaphragm: membrane that separates the two parts of the chamber;
• Connecting rod: transmits movement to the master cylinder;
• Control valve: regulates the intake of vacuum and air;
• Return springs: restore the original position after braking.

 

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How Does The Servo Brake Work?

When the driver presses the brake pedal, the control valve closes the vacuum inlet and allows air to enter one of the chambers.

The pressure difference generates additional force that pushes the connecting rod, multiplying the force sent to the master cylinder.

 

What Is The Difference Between A Brake Servo And A Master Cylinder?

The servo brake amplifies the force exerted by the driver on the brake pedal, making braking easier. In turn, the master cylinder is responsible for generating the hydraulic pressure that activates the brakes on the wheels.

Both play complementary roles in the braking system to ensure that the vehicle can stop effectively and safely.

 

What Care Should Be Taken With The Brake Servo?

To avoid damage to this or other components, it is essential to follow certain precautions, which include:

• Check the vacuum hoses regularly;
• Change the brake fluid as recommended by the manufacturer;
• Avoid air or fluid leaks in the connections;
• Watch for signs of wear such as a hard pedal or noise when braking.

 

 

What Are The Symptoms Of A Faulty Brake Servo? 

When this component begins to fail, obvious signs appear while driving.

Identifying these symptoms early is essential to prevent accidents and preserve the performance of the braking system.

Below are the main signs to look out for.

 

1. Hard Brake Pedal

When the brake servo stops working properly, the brake pedal becomes harder to press, even with the engine running.

This is one of the most common signs of a malfunction, as it indicates that the brake assist is compromised.

 

2. Air Noise When Pressing the Pedal

If you hear a sound similar to air blowing when pressing the pedal, this indicates that there is an air leak in the diaphragm or valve.

This noise is typical of an internal or external leak in the system.

 

3. Less Effective Braking

When this component is faulty, it reduces the force applied to the braking system. As a result, the response when pressing the pedal is slower and less effective, even when applying normal force.

 

4. Increased Stopping Distance

With a faulty brake servo, the driver needs to apply more force to brake. This can lead to a longer braking distance, especially in emergencies.

 

5. Dashboard Warning Light

Some modern vehicles emit a light on the instrument panel when the braking system fails. The brake light or other related indicator may signal problems with the brake servo.

 

Can You Drive A Car With A Faulty Brake Servo?

A faulty brake servo significantly increases braking effort and stopping distance, compromising the safety of the driver and passengers.

 

What Happens When A Power Brake Booster Has A Vacuum Leak? 

If you hear air blowing when you press the pedal, the problem may be with the valve or a leak in the diaphragm.

Test with the engine off: press the pedal several times, then start the engine. If the pedal does not go down, the brake servo is compromised.

 

Is It Possible To Repair A Faulty Brake Servo?

Yes, but only on some models with a removable structure. You need to assess whether repair is feasible or whether replacement is more cost-effective.

To ensure that everything is done safely, you should contact an auto repair shop.

 

What Tools Are Needed To Replace And Repair The Brake Servo?

To repair this component, you will need the following tools in your workshop:

• Set of wrenches;
• Screwdriver;
• Wrench or socket wrench;
• Brake diagnostic tools;
• Brake servo repair kit (seals, diaphragms, among others).

 

How Much Does It Cost To Replace A Brake Servo?

The price of a brake servo varies between tens and thousands of euros.

The brake servo is essential for effective and safe braking. Knowing the symptoms of a malfunction, performing preventive maintenance, and acting in a timely manner is essential to prevent accidents and ensure the proper functioning of the system.

Always consult a professional and check the compatibility of parts with your vehicle.

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