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Brake Pedal Goes To The Floor When The Engine Is Running – What You Need To Do

Table of Contents

When your brake pedal goes to the floor when the engine is running; there’s a couple of things you need to check immediately.

This is dangerous, not just for you, but also for the drivers around you as it can prevent your car from stopping, causing accidents.

Your brake pedal goes to the floor while your engine is running due to reasons such as a loss of brake fluid, a problem with your brake cylinder, or a faulty brake booster.

All of these problems can be identified quickly and need to be fixed timely.

Here, we will answer a common question: why does your brake pedal go to the floor when your engine is running?

We will talk about the possible causes, the likelihood of each, and the possibility of getting a brake job.

Brake Pedal Goes To The Floor When The Engine Is Running

What Causes My Brake Pedal To Sink?

Loss of brake fluid, brake cylinder problems, and a faulty brake booster are just some of the various factors that can cause the brake pedal to go to the floor while the engine is still running.

It is necessary to know about all of these causes so that you can identify why your brake pedal goes to the floor and solve the problem accordingly.

1. Loss of Brake Fluid

When your vehicle does not have any brake fluid, the brakes will simply stop working.

Brake fluid is a hydraulic fluid used in vehicles that help convert pressure into force, intensifying braking force.

The pressure exerted by the brake fluid enables the brake pads to move by sending brake power to the pads. 

The brake fluid is stored in the brake cylinder.

When the cylinder is cracked, the fluid leaks, removing all the pressure exerted on the brakes.

In such a case, the only way you will be able to stop your car is by sending your pedal to the floor. 

When your brake pedal goes to the floor, the first step you need to take is to check the level of brake fluid in your vehicle and see whether the fluid is leaking.

This may help diagnose your problem.

If it is leaking, don’t worry.

The problem of brake fluid can easily be fixed.

First, you need to check the level of fluid in the cylinder. If it is low, there is probably a leak somewhere in the cylinder.

The leak may be located in the brake lines, which monitor the brake performance of your vehicle.

If you find that the leak is in the brake lines, you will either need to repair them or change your wheel cylinder.

If the leak is not in the brake lines, you should check the brake master cylinder next.

If the oil seals on the cylinder are worn out, they could be causing the brake fluid to leak.

The cylinder will then need to be replaced. If the problem turns out to be in the cylinder, you should visit a mechanic and get the cylinder changed.

2. Faulty Brake Master Cylinder

If your master cylinder does not work, you will lose brake power, causing the brake pedal to go to the floor.

A master cylinder that does not work causes your pedal to feel soft or spongy, causing it to ultimately fall to the floor when pressed.

A brake master cylinder is the component of the car responsible for compressing fluid.

When this is not working, your vehicle’s brake lines do not get the brake fluid they need to function.

The brake master cylinder exerts pressure on the brake fluid to allow the brakes to function correctly.

So naturally, when the cylinder does not work, the brake pedal goes to the floor.

To maintain the pressure and power needed by the brakes, the brake master cylinder needs to be adequately sealed.

Therefore, if the seals are worn out, it can cause internal leaking of the brake fluid, causing the brake to go to the floor.

A working master cylinder ensures your brake pedal is firm when you step on it.

This is because it creates hydraulic pressure, which allows the brakes to function.

In the absence of this pressure, the pedal will not be firm, may fall to the ground, and in some cases, may stop working altogether.

After checking the master cylinder and finding it to be worn out or faulty, you should replace the cylinder with a new one.

The cylinder should not be rebuilt, or it will not last for long.

After replacing the master cylinder, it should be bled for air to prevent further braking problems. We’ll discuss these possible problems later.

In some cases, a mechanic might be able to repair the cylinder.

So, you should consult one immediately.

3. Bad Brake Booster

When a brake booster does not work correctly, its ability to increase the force applied to the master cylinder is compromised.

This requires you to apply additional pressure to the pedal, which can cause it to fall to the floor.

Applying pressure to the brake booster, a device that amplifies the force applied by the brake pedal, allows your vehicle to stop.

If the booster does not work, more pressure than usual needs to be applied to the pedal so that the car can stop. You may need to press it down as far as the floor.

The vacuum located in your car’s combustion section allows the combustion engine to function by exerting pressure.

This vacuum is also used by the brake booster.

Through the vacuum, the brake booster intensifies the pressure exerted on the pedal. 

In the absence of a properly functioning brake booster, there will be no force to pressurize the brake fluid, causing it to go to the ground.

The brake booster assists with the power when pressing down on the pedal, so you do not need to put in too much force.

If your brake pedal is going to the floor and you suspect that there is a problem with your brake booster, you should consult a mechanic immediately.

If the mechanic concludes that the problem with the pedal has been caused by a faulty brake booster, you will need to replace it.

4. Driving Style

A brake pedal going to the floor is not always caused by problems with car components or wear and tear.

Sometimes, your style of driving can cause it to go to the floor too. 

The brake fluid keeps getting hotter and consequently thinner the more you drive your vehicle.

When this happens, the fluid will need increased pressure from the cylinder to get the brakes to operate.

The car’s system may not have enough power to generate that much pressure, preventing your brakes from functioning correctly.

This problem may persist even when you take your brake pedal to the floor.

The reason behind this is the lack of brake power that results from the thin fluid.

Driving your vehicle too much is not the only driving style that can take a pedal to the floor.

This problem can also be caused by riding brakes and failing to release your parking brake.

Braking all of a sudden can cause your brakes to wear down quickly, so it is a good idea to monitor your braking style.

One way to prevent damage to your brakes and stop the pedal from going to the floor is to slow down your vehicle before a stop. 

If your brakes are spongy or are going to the floor, and nothing is wrong with your car’s components, you should look into your driving style.

You should also avoid riding the brake and should never forget to take off the parking brake before starting your car.

5. Air In The Brake Lines

Air in the brake lines will result in brake fluid compressing too easily.

This can cause the brakes to be soft or spongy, resulting in the brake pedal getting pressed too far and the brake going to the floor.

When a driver replaces their master brake cylinder, they may notice that their brake pedal goes to the floor later.

This happens when you haven’t bled out the air after replacing the cylinder.

When this step is skipped, air remains in the brake lines, causing the pedal to push to the floor.

Brake fluid, when moving inside the brake lines, provides a force that helps the brake stop.

The air in the brake lines interrupts the flow of brake fluid inside the brake line.

When there is air in the brake lines, it reduces the firmness of the brake pedal, making it soft, and causing it to fall to the floor.

The air in the brake lines may also damage the brake line.

You can solve this problem by getting your brake lines bled for air.

Brake bleeding should be done when the engine is turned off.

When your brake pedal goes to the floor, do not ignore the problem under any circumstance. Driving with a soft brake pedal is unsafe.

Either fix the relevant issues or take your vehicle to a mechanic and have the appropriate repairs done.

If the problem lies in your driving style, try to pinpoint the problem and fix it. 

What If Your Brake Pedal Goes to Floor But There Are No Leaks?

Brake Pedal Goes To The Floor When The Engine Running

If your brake pedal goes to the floor and there are no leaks, the problem most likely lies in your brake master cylinder or brake booster. 

These problems can include a vacuum leakage, which is a hole in the vehicle’s system that allows gas to enter and exit without being monitored.

The severity of the vacuum leakage depends on how big the hole is, the type of gas that enters or exits, and the difference in the pressure between the interior and the exterior of the system.

A brake pedal going to the floor without any leaks can be attributed to a vacuum leakage, worn-out cylinder, or a faulty brake booster.

Also, any reason for a soft brake pedal mentioned above can also cause the brake pedal to go to the floor when there are no leaks.

How Much Should A Brake Job Cost?

brake pedal goes to floor when engine running

A brake job can cost anywhere from $150 to $750, depending on what you need to get done.

The cost of a brake job depends on the problem with the pedals, the severity of the problem, and the time it will take the mechanic to fix it.

If you want your master cylinder repaired, it will cost around $200 to $300.

If the problem is with both of your cylinders, you may need to pay double this amount.

For a complete brake job, the cost can go up to $750.

This is inclusive of all components you will need, such as cylinders, pads, and rotors.

Luckily, you can avoid paying such a high cost if you check your car’s components daily.

This way, you can replace any faulty parts as soon as they stop working.

These minor repairs will cost much less than paying a high amount for a complete repair.

The costs for individual components are as follows:

  • Brake Pads – $150 to $250
  • Rotors – $350 to $550
  • Calipers – $150 to $250

The price of the brake job will also depend on where you get the job done.

Certain auto-repair shops will charge you much lower prices, while others will charge higher fees.

Paying a low price may seem appealing, but it can compromise the performance of your brake pedals.

A good idea is to find a trustworthy and reasonably priced mechanic and get your repairs done timely and regularly so that the cost does not build up.

Final Words

Your brake pedal going to the floor is a severe problem that needs to be addressed and fixed as soon as you observe it.

There are several causes of a brake pedal going to the floor, and luckily all of them have solutions.

These solutions are, at times, inexpensive and quick.

However, a complete repair or a replacement may be required in other instances, which is expensive and lengthy.

So, it’s important to keep an eye on your brake pedals so you can fix any problem before it gets out of hand.

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