We take a look at the main symptoms of a failed vacuum brake booster and discuss its function. We also evaluate the replacement cost of a vacuum brake booster and determine if it is safe to drive when this part fails. Let’s start with a quick look at the signals:

The most common Bad Brake Booster Symptoms is a stiff brake pedal in combination with a longer braking distance. Sometimes you also hear a hissing sound coming from the engine when idling. A warning light may also appear on the dashboard.

Here is a more detailed list of the most common symptoms of a failed brake booster:

Bad Brake Booster Symptoms

1. Hard brake pedal

When you try to brake your car, you don’t need to apply much pressure. This is true except when the vacuum brake booster fails.

When this vital part fails, you lose your brake assist. To make the vehicle stop, you must apply a lot of pressure to the brake pedal.

2. Longer braking distance

Most drivers are well aware of how long it takes to bring the vehicle to a stop. If this time seems to be dragging on, something may be wrong.

When the brake assist function is lost, much more force must be used to stop the car. This increase in braking distance can be sudden or subtle, depending on how quickly the part fails.

3. Hissing Sound

Brakes can make a variety of noises, from screeching to screeching, none of which are good. However, the distinctive hissing sound is associated with a faulty vacuum brake booster.

When the vacuum actuated brake booster begins to leak, air will escape from the diaphragm or housing. This gust produces a hissing sound that is most noticeable when braking.

4. Dashboard warning lights

Your modern vehicle is configured with a host of sensors that alert you when a problem occurs. The anti-lock braking system is no different.

If you get an ABS warning on your dashboard, it could be a sign that something is wrong with the vacuum brake booster. Not only will your braking ability be affected, but you could also have problems with the traction and stability control systems, which have their own warning lights.

Vacuum brake booster function

The brake booster assists the driver when braking a vehicle. Dramatically reduces the effort required by applying force to the master cylinder. The master cylinder is responsible for distributing fluid to the brakes for proper operation.

There are three brake booster designs, the vacuum actuated being the most popular. However, some vehicles have the Hydro-Boost model or an electronic assembly model.

In the vacuum brake booster, the internal diaphragm separates the two different sides. These compartments are called the working chamber and the vacuum chamber. As the brakes are released, you will find the same amount of vacuum on both sides. However, when you step on the brake pedal, a control valve creates more pressure in the working chamber. The result of this operation is the activation of a push rod that applies force to the master cylinder, allowing braking assistance to assist the driver.

Vacuum brake booster location

The vacuum brake booster is located between the firewall and the master cylinder. To replace the booster, you will also need to remove the master cylinder. That is why many people choose to replace both parts at the same time.

The brake booster check valve is located directly on the brake booster. If it’s not there, it could be in the vacuum hose. However, some of these check valves are built directly into the vacuum hose and therefore cannot be repaired. If the check valve is faulty, you may need to replace the vacuum hose.

Vacuum Brake Booster Replacement Cost

The average replacement cost of a vacuum brake booster is between $300 and $700, depending on the car model and labor costs. Labor costs between $100 and $200, while parts typically cost over $150.

However, there are several factors that affect how much you pay, including the type of vehicle you drive, how difficult the brake booster is to reach, and what other parts need to be replaced.

Most vacuum brake boosters will last 150,000 miles or more and will rarely go bad. However, vehicles driving in arid climates may experience increased dry rot, which can lead to premature deterioration of the vacuum brake booster diaphragm and cause failure.

If the vacuum brake booster fails, do not continue driving your vehicle. In fact, you should never drive with an indication that something is wrong with your braking system. If your brakes are more difficult to operate and you are having trouble stopping your vehicle, it’s time to have the system inspected by a qualified mechanic.