What Are The Symptoms Of A Bad Brake Booster?

Brake boosters provide the power assist to the brake master cylinder during braking. 

So, bad brake boosters can cause problems with the engine vacuum and result in a costly repair of your braking system. It’s a good idea to be on the lookout for any symptoms of a faulty brake booster. 

Here’s what they look like:

1. Problems With The Brake Pedal

Faulty brake boosters will result in various issues with your brake pedals, including hard or stiff power brakes that are difficult to press down and increased stopping distance.  

This may be due to a failing vacuum pump or hydraulic pressure pump. 

You may also find that your brake pedal is positioned higher than usual. As a result, you may have to lift your foot higher to press on the brake pedal, apply more force, or press it more often to slow down the vehicle. 

2. Fluid Leaks

A fluid leak isn’t always physically visible unless you inspect your engine compartment. If your brake fluid levels remain consistently low, even after refilling them, you may want to check for internal leaks. 

One way to do that is by inserting a clean engine dipstick inside the booster vacuum check valve. If the dipstick comes out with any liquid residue, your car probably has a brake fluid leak.

Occasionally, you may notice other signs including a triggered check engine light or pooling of the fluid near the car wheels. 

3. Engine Noise And Stalling

A bad brake booster can result in engine stalling and reduced engine performance. If your brake system is vacuum operated, you may even notice hissing sounds when you depress the power brakes. 

This sound is caused by a vacuum leak within the vacuum booster.

 A brake booster problem such as a vacuum leak can also cause other problems like a cracked engine vacuum line, leading to a costly repair.

4. Warning Lights Are On 

Depending on your vehicle type and its built-in safety features, you may notice your warning light or brake light illuminated on the dashboard. 

Most commonly, your Anti-lock Braking System (ABS) light may turn on to indicate a faulty brake booster. Apart from the ABS light, your brake light, check engine light, or stability control lights may also show up on the dashboard.

How Much Does A Brake Booster Replacement Cost?

The average cost of your power brake booster replacement completely depends on the make and model of your vehicle. In total, getting a new brake booster can cost between $300-$1250.

You can expect to pay as low as $100 and as high as $900 for a new brake booster. To that, labor costs can amount to about $100-$300.

Note that other car repair services and replacement parts may be needed on top of the brake booster replacement, which can add to the final cost.

How Urgent Is A Brake Booster Replacement?

A faulty brake booster can be very dangerous and needs immediate attention.

Brake booster failure may lead to a loss of engine power and brake system efficiency. You’ll likely have to apply more braking pressure on the brake pedals or even have difficulty stopping the car.

In older cars, brake booster failure may cause the engine to run lean with insufficient vacuum pressure and fuel. A brake booster problem can also affect other components of the brake system like the brake pad or even tires. So it’s best to get your brake problem resolved ASAP.

4 Brake Booster Replacement FAQs

A brake booster replacement can seem an intimidating topic. So here are a few frequently asked queries and their answers to help you get to know this braking component better. 

1. What Is A Brake Booster?

A brake booster is a device that amplifies the force applied to the brake pedal and transfers that force to the brake master cylinder. 

In simple words, a brake booster ‘boosts’ the pressure on the brake pedal. This way, you don’t have to press as hard on your power brakes in order to slow down your car. 

Here’s how it works: 

• When you press on the brake pedals, a valve creates atmospheric pressure inside the vacuum boosters. The applied braking pressure goes through the brake booster (where it is amplified) and reaches the master cylinder.

• From there, the master cylinder converts the force to hydraulic pressure, and the hydraulic fluid carries it through the brake line.

• The hydraulic pressure then passes through the brake caliper and reaches the brake pad. In the brake pad, it generates friction and stops the wheels.

2. Can I Drive With A Broken Brake Booster? 

You can, but you really shouldn’t. 

If your brake boosters aren’t working well, chances are that you’ll have to press harder on the brake pedals to slow down the car. 

In some cases, a bad brake booster can lead to slower braking at the most. In this case, you can drive your car for a trip to the mechanic. But if you have a bad brake booster due to leaking fluid, for example, you absolutely should not drive your car.

Leaking brake fluid will not only lead to a hard brake pedal but can also result in brake failure. 

3. How Do I Test A Brake Booster?

Testing the vacuum brake booster is a fairly simple procedure for someone with decent mechanical knowledge. 

Here’s a general how-to: 

1. Start by turning off your engine compartment. Pump the brake pedal several times to ensure that there’s no vacuum in the power brake booster.

2. Press the brake pedal all the way down and simultaneously start the engine. Do not release the brake pedal.

3. If the brake pedal is working, you should feel slight resistance in the pedal as the engine compartment supplies pressure to the booster.

4. Now, keep the engine running and pump the brake again. Do this several times until the braking pressure becomes more firm, indicating that the brake booster is not leaking.

5. Next, you want to inspect the booster check valve to verify the vacuum pressure. Locate it on the power brake booster and disconnect the vacuum hose. If it’s working, air should not flow when vacuum pressure is applied. If not, you’ll need to replace your vacuum booster.

If you need any help during this process, it’s best to consult your mechanic and let them take over!

4. How Do I Replace A Brake Booster? 

Dealing with a brake booster failure can be a tricky process, and should therefore be left to your mechanic. 

However, if you do have a faulty or broken brake booster, here’s how your mechanic will replace it: 

1. The first step is to diagnose the brake booster problem based on your vehicle’s braking system. They’ll inspect the check valve.

2. They’ll take out the master cylinder by removing the mounting nuts and disconnecting the hydraulic brake line. Your mechanic may also need to take out the car battery and battery tray in some cases.

3. Next, they’ll remove the brake booster vacuum hose with a pair of pliers.

4. Now, your mechanic will disconnect the brake light and the booster pushrod from the brake pedal and remove the faulty brake booster. 

After that, they will replace the booster with a new one and reattach the other parts.