Brake Pedal Goes to Floor When Engine Running [How to Fix]

If you have to press the brake pedal all the way to the floor to stop your car, it needs to be fixed right away. When the brake pedal goes to floor while the engine is running, what are the likely causes and solutions?

When the engine is running, the most typical cause of the brake pedal going to the floor is a lack of brake fluid. This fluid maintains the needed pressure or force to supply braking power to the wheels’ brake pads.

Brake fluid may escape through holes or cracks in the brake fluid line, resulting in no pressure being delivered when the brake pedal is pressed.

To stop your car, you don’t need to slam on the brakes. There is a problem if you can only stop your car by slamming on the brake pedal all the way to the floor. It might be the master cylinder or a faulty brake power booster. You should also be aware of other causes for this problem.

In this article, we’ll look at six potential causes of this brake issue:

  1. Leaking Brake Line or Brake Caliper
  2. A Malfunctioning Master Cylinder
  3. Air in Brake Lines
  4. Brake Booster Is Not Working
  5. Driving Style
  6. Brake Fluid Is Not Enough

We’ll also look at 4 possible solutions for this brake problem:

  1. Check the Brake Fluid Level
  2. Inspect the Brake Lines
  3. Inspect the Brake Calipers
  4. Inspect the Brake Master Cylinder

Read on to know the reason why the brake pedal goes to the floor when the engine is running, including how to fix this problem.

brake pedal goes to floor

Brake Pedal Goes to Floor – What Causes It?

When the engine is running, the most typical cause of the brake pedal dropping to the floor is a lack of brake fluid. So, any holes or cracks in the brake fluid line must be sealed in order to fix this problem.

If your vehicle‘s braking system is in good working order, your car should slow down slightly as soon as you lightly push the brake pedal. The car’s speed will be substantially reduced if you put more pressure on the pedal. However, if you apply maximum pressure to the brake pedal, the car should come to a complete stop right away.

So, if you’ve applied full force to the brake pedal and the car still won’t stop, there’s most likely an issue with the braking system in your vehicle. Because braking problems might have a variety of causes, it could be one or several.

Your car will lose a portion of the required braking pressure if there are leaks in the brake fluid line or any other braking system components. Sometimes, if there is no leaking and the brake pedal goes to the floor, there could be a vacuum leak in the master cylinder or brake booster.

Other factors may be contributing to the issue. Problems or issues with a car’s braking system, fortunately, are not difficult to identify. Because the braking system of a car has few parts, you or a mechanic can easily fix it if any issues emerge.

Brake Pedal Going to the Floor – Possible Causes

When your brake pedal goes to floor, there are only two possible causes: brake fluid leaks or a faulty master cylinder. However, you should be aware of other causes in case the two main causes aren’t the problem. Let’s take a look at them one by one.

1. Leaking Brake Line or Brake Caliper

The most common cause of brake power loss is brake fluid leaks from the brake fluid line or from the brake calipers. There should be enough brake fluid in the system to allow the braking system to generate sufficient braking power when needed.

The brake cylinder piston is compressed when your foot presses on the brake pedal. The brake lines will be under more pressure as a result of the compression. Moreover, the brake fluid will move to the brake caliper due to this action. The brake pads will move and squeeze into the brake rotor because of the brake fluid’s high pressure.

The car will stop due to the friction between these components. There will be no pressure available in the brake pedal if the brake line has a leak. As a result, if you step on the pedal, it will just hit the floor without you feeling anything.

Because you use your brakes every time you drive your car, you should have enough brake fluid in your system to deliver the necessary braking pressure.

2. A Malfunctioning Master Cylinder

The process of increasing brake fluid pressure takes place in the master cylinder. Braking pressure is weakened or worsened if the master cylinder is not functioning properly. The brake pedal may go all the way to the floor but still stop, or it may never work. Internally, a faulty master cylinder allows brake fluid to bypass seals.

If your braking system has no problem, the brake pedal will be firm when you step on it due to the pushrod’s connection to the master cylinder. The brakes on the wheels are activated by the hydraulic pressure produced by this cylinder. It’s the one in charge of pushing brake fluid to all four wheels.

To maintain the correct braking power or pressure, this cylinder should be entirely sealed. Rubber seals in the master cylinder keep the brake fluid from leaking out. These seals will allow brake fluid to escape or leak if they are worn out, broken, or already old. When this happens, your brake pedal will become spongy, and your car’s braking power will be weakened.

brake pedal goes to floor when engine running

3. Air in Brake Lines

After replacing the master cylinders, some drivers have reported that the brake pedal goes to floor sometimes. This frequently happens when a new master cylinder is installed and no air bleeding is performed. If the air in the cylinder is not bled out, some air will still be present.

Air will obstruct the passage of brake fluid inside the brake line, causing the brake pedal to feel spongy rather than firm. The brake line may be damaged as a result of this issue.

4. Brake Booster Is Not Working

A spongy brake pedal can be caused by a brake booster that isn’t working properly. As you press the brake pedal, this brake booster assists in the delivery of braking power.

To stop your car, you don’t need to apply too much foot pressure to the brake pedal if it’s in good condition. This component of the braking system is usually found between the brake pedal and the master cylinder and is ultimately connected to the engine.

It has a vacuum line that it uses to overcome the braking system’s fluid pressure. If you’ve noticed that your stopping distance has increased, it’s possible that a defective brake booster is to blame. The brake booster does not provide enough power to allow your vehicle to stop normally.

5. Driving Style

One of the reasons your brake pedal goes to the floor when you stop your car could be your driving style. The brake fluid becomes hotter as you use your brakes more. When the brake fluid is always heated, it loses its designed density.

So, in other words, it will get thinner. The less efficient a brake fluid is at delivering the needed braking pressure, the thinner it is. To supply the required braking power to the brake pads, more force or pressure will be required.

As a result, your car’s braking system will be unable to deliver the required braking power. Therefore, even if you slam on the brakes, the braking power will be insufficient. This condition is caused by riding on the brakes. Another common mistake is failing to release the parking brake.

6. Brake Fluid Is Not Enough

The brake fluid level on the brake fluid plastic can or canister is one of the things you should check in your vehicle. Every driver of a motor vehicle must perform this task on a regular basis. Lack of brake fluid in the container might also result in a loss of braking power.

So far, we have discussed why the brake pedal goes to floor when the engine is running, as well as why the brake pedal goes to the floor but the car still stops. Next, we’ll look at how to diagnose and repair a spongy or soft brake pedal while your car is running.

Brake Pedal Going to the Floor – Possible Solutions

Fortunately, fixing the problem of the brake pedal going to the floor sometimes (or all of the time) is not that difficult. The reason behind this is that there aren’t many variables and many car parts involved. The key to solving a problem is correctly identifying it.

1. Check the Brake Fluid Level

Because leaky brake lines are the most common cause of this problem, this should be the first thing that you check. Examine the level of brake fluid in the plastic container. Is it significantly lower than it should be? If that’s the case, the leak is somewhere else.

2. Inspect the Brake Lines

After checking the brake fluid level, the brake lines and brake calipers should be examined next. Check each of the car’s four wheels for any oil residues. To do so, you may need to remove the tires. Then follow the brake fluid lines to see if they have any holes or cuts.

A leak occurs when there are traces of oil or oil residues in a line. Replace it or have a certified car mechanic replace a damaged brake fluid line with fresh brake fluid present.

how to fix brake pedal goes to floor

3. Inspect the Brake Calipers

Examine each wheel’s brake calipers. The brake calipers must be exposed by removing the wheels. Examine the calipers, as well as the bleeder screws, for fresh brake fluid or fluid residues.

If you are not a skilled mechanic, you may need to hire a professional to inspect, repair, or replace parts.

4. Inspect the Brake Master Cylinder

The brake master cylinder should be checked next. This is a job for a skilled technician, but you must understand how it’s done to avoid being duped.

Oil seals in this cylinder keep brake fluid from escaping. These seals will eventually wear down, causing brake fluid to leak. A new cylinder unit must be installed in its place. Because it is a crucial component of your car’s braking system, replacing it with a rebuilt unit is not recommended.

You should not drive your car if you notice any signs of a brake system leak since it is unsafe. Resolve the problem first. If you’re unable to make the required repairs, seek the assistance of a certified mechanic. He possesses all of the required tools, expertise, and skills to complete the task successfully.

How Much Does It Cost to Repair a Brake System?

A master cylinder repair typically costs between $200 and $300. The cost of the repair will be determined by the scope of the issue and how simple or difficult it will be to fix. If both cylinders are broken, the cost can easily double.

Repair expenses for a complete brake job, which includes cylinders, pads, drums, calipers, and rotors, might reach $750 or even more. To avoid such costly repairs, it’s a good idea to check your car’s brake system on a regular basis.

The filling up of the brake fluid level in the plastic can is the least expensive and easiest task you can perform. Make sure the master cylinder isn’t devoid of brake fluid while topping up the container, or you’ll introduce air into the system, causing braking issues.

Conclusion – Brake Pedal Goes to Floor – Causes and Solutions

When the engine is running, a brake pedal that goes all the way to the floor is most commonly caused by a lack of brake fluid.

To bring a moving vehicle to a full stop, sufficient braking force must be applied to the wheels’ braking pads.

Brake fluid aids in the maintenance of the needed braking pressure. But brake fluid will be able to escape if the brake fluid line has holes or cracks. This results in no pressure or force applied when you compress the brake pedal.

We’ve looked at the six possible causes of a brake problem in this article:

  1. Leaking Brake Line or Brake Caliper
  2. A Malfunctioning Master Cylinder
  3. Air in Brake Lines
  4. Brake Booster Is Not Working
  5. Driving Style
  6. Brake Fluid Is Not Enough

We’ve also looked at four potential solutions for fixing a brake problem:

  1. Check the Brake Fluid Level
  2. Inspect the Brake Lines
  3. Inspect the Brake Calipers
  4. Inspect the Brake Master Cylinder

The problem of the brake pedal going to the floor while the engine is running should be solved by one of these possible solutions. If you are unable to resolve the problem yourself, take your vehicle to a reputable mechanic as soon as possible to get the brakes fixed.