What Does A Brake Vacuum Pump Do?

A brake booster helps to increase the braking capacity of your car. But what does a brake vacuum pump do? Why is it needed only in diesel engines? What happens if it does not work properly? Answers to many such questions coming up!

Brakes are a vital component of your car. But do you know how brakes work? The brake booster helps to increase hydraulic pressure in the braking system. 

This in turn puts pressure on the brake pads, the brake rotors, and finally the wheels, bringing the car to a stop.

Brake boosters are an important part of the modern-day braking system, they help to stop your car comfortably on the road. But the brake booster cannot work without a supply of vacuum pressure.

If I talk about a petrol engine, then the engine can provide the vacuum required for the brake booster to operate efficiently. But unfortunately, diesel engines don’t have a throttle valve in the intake manifold. So, it cannot produce enough vacuum required for a vacuum booster. That is why there is a need for a special brake vacuum pump in diesel engine cars.


What Does A Brake Vacuum Pump Do


So what does a brake vacuum pump do? The vacuum pump helps increase the hydraulic pressure of the brake fluid, which brings your car to a stop. It helps in supplying the required vacuum to the brake booster so that your vehicle’s brakes will operate efficiently. The brake vacuum pump is like a safety device in your car. 

If it is damaged because of overheating, then the brake booster will not work properly. In turn, the brakes will not work properly and therefore the car may not stop on time. So, you need to take special care of the brake vacuum pump and replace it at the first sign of any faults. In this article, I will discuss brake vacuum pumps, how they function, how to diagnose a damaged brake vacuum pump and other such questions. So, keep reading for more information.


You might like to read: No Brake Fluid To Rear Brakes When Bleeding: 6 Reasons Why This Happens


Where Is A Brake Vacuum Pump?

The brake vacuum pump is usually mounted directly on the head of the cylinder and is driven by a camshaft.

The vacuum pump is used in such vehicles, which cannot produce sufficient vacuum in the intake manifold required by the brake booster to run efficiently. The cars include compression ignition engines (diesel engines), turbo engines, or those with variable valve timing.

What Does a Brake Vacuum Pump Do?

To understand this, you need to first understand how a brake booster works.

The Working of a Brake Booster

You will find brake boosters in all conventional vehicles. There will be one brake booster on the driver’s side, mounted on the engine’s firewall. 

The brake booster consists of two chambers which are separated by a diaphragm. Both the sides of the chamber are maintained under vacuum when you don’t press the brake pedal. 

But as soon as you press the brake pedal, the atmospheric valve opens on one side of the chamber, and the air is allowed to enter. But the other side is still under vacuum. This pressure differential helps in increasing the braking power of your car.


What Does A Brake Vacuum Pump Do


Why Diesel Engines Need a Brake Vacuum Pump?

Petrol engines utilize the engine vacuum to increase the force you apply on the brake pedal. But in diesel engines and turbocharged cars, the engine cannot create enough vacuum required for amplifying the force applied on the brake pedal. 

So a brake vacuum pump is used to draw extra air to create the proper vacuum effect in a brake booster like a petrol engine.

A brake booster vacuum pump is also necessary for high altitudes to create enough vacuum in the brake booster and thus helps in stopping your car smoothly and comfortably. The vacuum pumps can be driven either mechanically or by an electric motor.


You might like to read: My Car Dies When Brakes Are Applied, What Should I Do?


What Are The Common Signs Of Damaged Brake Vacuum Pump?

The vacuum pump may get damaged or have wear and tear with time. You will notice various possible signs when the brake vacuum pump is damaged. I am listing some of them.

#1. Hard Brake Pedal

If the brake vacuum pump gets damaged, you will notice that you need to push the brake pedal quite hard while applying brakes. You will require much effort to stop your vehicle.

#2. Intermittently Working Power Brakes

The diesel vehicles are equipped with an electric brake vacuum pump that continuously provides vacuum to the brake booster so that power brakes will work all the time. 

But if your power brakes only work sometimes, you will understand that there is a problem with the vacuum pump.

The vacuum pump may have a wiring problem, or the vital components inside the pump get damaged with time. Consequently, your power brakes will not work efficiently.


What Does A Brake Vacuum Pump Do


#3. You May Hear Hissing Sound

If you hear a hissing sound while applying power brakes, there may be some problem with the vacuum brake pump.

#4. Spongy Brake Pedal

If you notice your brake pedal has become spongy or goes down to the floor while the engine is running, there may be a problem with the vacuum pump.


You might like to read: 6 Reasons Your Car’s RPM Goes Up When Pressing Brake


Frequently Answered Questions

#1. What happens if the brake vacuum pump fails?

If the brake vacuum pump fails, the brake pedal will be stiff, requiring much effort to apply brakes.

#2. What are the symptoms of a faulty brake booster?

I am listing below some of the signs and symptoms of a faulty brake booster.

  • Stiff brake pedal
  • Spongy brake pedal
  • The engine will not function properly.
  • The stopping distance will increase
  • You will hear a hissing noise
  • Warning lights come on
  • Leaking power steering fluid


What Does A Brake Vacuum Pump Do


#3. Can a vacuum leak cause brake problems?

Yes, if there is a vacuum leak, it can cause brake problems. The vacuum leak will cause a lower vacuum in the brake booster, leading to the failure of the brakes. 

The RPM of the engine starts to decrease. It will even increase the temperature inside the engine, which consequently damages the piston, valves, and other vital parts of the engine.


You might like to read: 7 Reasons Why The Brake Pedal Goes To Floor When Engine Starts


A Few Final Words

The brake vacuum pump is an essential component of your vehicle’s braking system. It helps in stopping your car comfortably at your desired location. 

It is designed to last almost the lifetime of your car. But overheating or continuous use damages the brake vacuum pump. 

You may experience a spongy brake pedal or find it difficult that time in applying brakes. I will suggest not to drive your car in such a condition. Better take your car to the nearest mechanic. He will inspect your car and may install a new brake vacuum pump.

Thank you for reading this article, we hope that we have covered all your questions. If you have more doubts about brake vacuum pumps, brake boosters or any other queries, please feel free to drop us a comment below.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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