One of the worst moments ever is when you press the brake pedal and find that the brake pedal goes to the floor when the engine is running at high speed.
This situation is not only bad but also very dangerous. People are discouraged from driving a car without the brakes working effectively.
If you ever realize that the brakes have started to weaken or have any strange sound, ensure the vehicle is checked as soon as possible.
In this article, we shall know why we can have a spongy brake pedal when the engine is running and how to fix it to have full-power brakes.
How Braking System Works?
Modern vehicles are equipped with hydraulic braking systems. When you press the brake pedal, it sends brake fluid through the master cylinder to the brake calipers or wheel cylinders, which then apply pressure to the brake pads or shoes, slowing the vehicle by creating friction with the brake rotors or drums.
Key components of the braking system include:
- Brake Pedal
- Master Cylinder
- Brake Lines
- Brake Fluid
- Brake Calipers or Wheel Cylinders
- Brake Pads or Shoes
- Brake Rotors or Drums
If the brake pedal goes to the floor, it usually indicates that one or more components in this hydraulic system is malfunctioning.
Brake Pedal Goes To The Floor – What Exactly Is Happening?
Your brake pedal might not feel as firm as usual when you press down on the pedal. You don’t feel the same level of pressure; instead, the pedal feels mushy or spongy.
The car still stops, but you might need to press down hard so that the brake pedal sinks to the floor. The pedal might sink slowly or fast. In other cases, the brake might not work at all.
This is called a “sinking” or “soft” brake and is especially problematic if it suddenly happens one day without any warning. Normally, even if you try to stomp on the brake pedal, it should not sink to the floor easily.
Symptoms of a Brake Pedal That Goes to the Floor
A brake pedal that sinks or feels unusually soft is one of the most alarming signs of brake system trouble. Recognizing these symptoms early can help you avoid complete brake failure:
- Spongy or Soft Pedal Feel: The pedal compresses too easily with little resistance. Often caused by air in the brake lines, moisture in the fluid, or failing master cylinder seals.
- Pedal Slowly Sinks Under Pressure: When you press and hold the brake pedal, it gradually drops toward the floor instead of holding steady. This is a strong indicator of an internal master cylinder leak.
- Increased Pedal Travel: The brake pedal moves much farther than usual before the brakes engage. Usually linked to worn brake pads, improperly adjusted drum brakes, or low brake fluid.
- Longer Stopping Distances: Even when pressing firmly, your vehicle takes more time to come to a stop. A clear sign that hydraulic pressure is not being delivered properly to the calipers or wheel cylinders.
- Brake Warning or ABS Light On: A low-fluid sensor or pressure imbalance can trigger dashboard alerts. Ignoring these warnings may lead to sudden loss of braking power.
- Burning Smell or Overheating Brakes: If brakes drag due to trapped pressure, pads remain in contact with rotors, generating heat and odors.
- Vehicle Pulls to One Side: Uneven hydraulic pressure between brake circuits can cause the car to veer when braking.
What Causes Brake Pedal Goes to Floor When Engine Running?
#1. Loss of the Brake Fluid.
Brake fluid is a very important factor in increasing or sustaining a high brake power. As the driver depresses the brake pedal, the pedal compresses the piston in the brake cylinder.
This compression increases pressure in the brake lines, making the brake fluid particles move to the brake caliper. Due to the brake fluid’s high pressure, the brake pads move and squeeze into the brake rotor.
This results in friction, which makes the car stop. So, what happens if there is a brake fluid leakage in the brake lines?
In this case, there won’t be any pressure on the brake pedal. Therefore, the brake pedal goes to the floor suddenly, and the car won’t stop or will make a very slight deceleration.
#2. Bad Brake Master Cylinder.
In normal circumstances, the brake pedal push should feel firm under your leg since it is connected to the master cylinder with a push rod. The master cylinder generates hydraulic pressure to activate brakes and pushes the brake fluid to the front and rear wheels.
The master cylinder must be sealed to keep pressure and power, which pushes the brake fluid to the calipers.
Therefore, if the rubber seals that keep the brake fluid inside are worn out or get torn, it will lead to internal leaking, which finally causes the spongy feel under your leg.
#3. Bad Brake Booster.
If the brake pedal goes to the floor but still stops, you could be having a failed brake power booster. The power booster’s role in the braking process is to give power assistance when the driver depresses the pedal.
This means that you don’t have to make a very high amount of power to stop the car. The brake booster is situated between the master cylinder and brake pedal and connected to the engine.
It uses a vacuum line to overcome fluid pressure in the braking system. When the brake booster is faulty, you will feel that the stopping distance is increased.
The pedal goes all the way to the floor to stop the car completely. This happens because you are not getting the sufficient power boost required to stop the car.
#4. Presence of Air in Brake Lines.
Many drivers have reported that the brake pedal goes to the floor after the new master cylinder replacement. This happens mainly if no air bleeding is done after installing a new master cylinder, and thus, there is air in the brake lines.
The air prevents brake fluid from efficiently flowing inside the brake lines, damaging the brake lines and giving the feeling of a spongy soft feel instead of the firm feel of the brake pedal when depressing.
#5. Style of Driving.
It sounds crazy, but there’s one more thing that causes the brake pedal to go to the floor: you, the driver. Your driving style will be the reason the brake pedal goes to the floor when you stop your car. But, how?
The more you use your brake, your brake fluid becomes hotter. Hot makes the brake fluid thinner. Thinner brake fluid delivers lesser efficiency for braking pressure. So, your braking system will not get the required power.
#6. Brake Fade.
Typically only an issue on hills or after repeated heavy braking, brake fade is a reduction in stopping power as the braking system takes on more heat than it is designed to handle.
If your pedal starts to sink after heavy braking, you may have boiled your brake fluid, or perhaps your brake pads are hotter than they were designed for.
When your brakes fade to the point where you can barely stop, you should replace your brake fluid. Once your brake fluid boils, it is never able to handle the same amount of heat as it once could.
Is It Safe To Drive Your Vehicle With a Sinking Pedal?
Driving with a sinking pedal isn’t safe. If your brake pedal goes to the floor but the vehicle still stops, you should have your vehicle checked immediately.
A sinking brake pedal can make braking difficult to gauge, which can cause you to brake too little and get into an accident. A sinking brake pedal can also mean that your vehicle could be nearing brake failure.
If you find that your pedal has sunk on a stoplight or intersection, check if your vehicle still has its brakes before accelerating. Sometimes, brake failure can occur at the same time the pedal sinks.
If the brake pedal falls to the floor, you shouldn’t drive at all. Lock the park brake and put the automatic transmission in park as soon as you can leave the road and get to a safe place.
How to Diagnose a Brake Pedal Going to the Floor?
If your brake pedal goes to the floor, follow these diagnostic steps to pinpoint the issue:
#1. Check the Brake Fluid Level.
Open the brake fluid reservoir and check the fluid level. If the level is low, there may be a leak, or the brake pads may be worn. Refill the reservoir to the recommended level.
#2. Inspect for Brake Fluid Leaks.
Look under the vehicle and inspect the brake lines, calipers, and wheel cylinders for signs of leaks. Puddles of brake fluid or wet spots near the brakes are clear indications of a problem.
#3. Test the Brake Pedal.
With the vehicle off, pump the brake pedal. A firm pedal that stays in place indicates good hydraulic pressure. If the pedal sinks to the floor or feels spongy, you may have air in the lines or a failing master cylinder.
#4. Bleed the Brake System.
If you suspect air in the brake lines, bleed the brake system at each wheel to remove any trapped air. This will help restore hydraulic pressure.
#5. Inspect Brake Components.
If there’s no visible leak, inspect the brake pads, calipers, and wheel cylinders for wear. Worn components can reduce the effectiveness of the braking system and contribute to a soft pedal.
How Do You Fix Brake Pedal Goes to Floor When Engine Running?
The good thing about noticing when the brake pedal goes down to the floor is that it’s usually very easy to diagnose, as there aren’t many possibilities as to why it’s happening.
Even better is that you can actually diagnose the issue yourself even with limited mechanical experience. In case the brake pedal goes to the floor, there are several actions to be taken in order to fix the issue.
#1. Check Brake Lines and Brake Calipers (or Wheel Cylinders).
The first action you can take is to check the level of the brake fluid. If the fluid is full, it means that there is no leak. If some fluid is missing or it is empty, it means that you have a leak somewhere.
In case there is a leak, you must check all brake lines from all four wheels, to see if the brake lines are leaking. In case the brake lines are dry, it means that the issue is not there. If you see that there is a leak on one of the four wheels, it means you found the issue.
In order to fix it, you need to remove the wheel, find the source of the leak, and replace the part if necessary. Often the culprit is a leaking caliper or wheel cylinder seal.
#2. Check the Brake Master Cylinder.
The second action you can take is to check the brake master cylinder, as it has two sets of seals which can wear in time and cause leaks. If this is indeed the issue, the brake master cylinder must be replaced with a new one.
Pay attention, it is recommended to be replaced with a brand new unit, not with a rebuilt one because they don’t last long or sometimes don’t even work from the beginning.
As with many other objects, when a second-hand unit is used, it is not as effective as a brand new one.
It is very important to mention that if you notice there are leaking signs, do not try to drive your vehicle, as the brake system will not work properly and is unsafe.
Instead, try to fix the issue and if you cannot manage it by yourself, have your vehicle transported to the nearest trusted service, where trusted professionals are able to solve your issue.
#3. Check Brake Rotors.
Brake rotors are usually visible without removing the wheels and may tell a story about what’s going on with the brakes.
Are there any gouges in the rotors? Do you see an uneven distribution of brake pad material along the surface of the rotor? Do you see any fluid leaks in the vicinity of the wheel?
#4. Bleed Brakes.
If you have soft brakes, you’ll want to try bleeding your brakes to see if this fixes the problem. Air in the lines can quickly lead to a squishy brake pedal. Take care not to get air into the ABS module. ABS lines can be tricky to bleed.
#5. Replace Your Brake Pads.
If you’ve just experienced brake fade after a large hill or a track day, consider replacing your brake pads. Brake pads that are designed to handle a higher temperature may be more appropriate for your use case.
Keep in mind there is no one brake pad that can do it all. Changing to a sport pad may reduce your stopping power on the street during a panic stop, when brakes tend to be much colder than they would be on a steep hill under heavy braking.
What to Do If Your Brake Pedal Goes to the Floor While Driving?
Few road situations are scarier than suddenly realizing your brake pedal has sunk completely to the floor as you try slowing your vehicle.
Resist panic in these crucial moments and follow these strategic steps to maintain control while bringing your car to a halt.
- Stay Calm: First, at all costs avoid abrupt steering changes and maintain your lane position. Jerky movements prompted by fear easily lead to fish-tailing or rollovers. Grip the wheel, take a deep breath, and steer as smoothly as possible.
- Pump the Brake: Next, try pumping the seemingly useless brake pedal in case a bubble in the line just needs purging. If the pedal briefly firms up, keep pumping until you regain braking capacity.
- Engine Braking: Downshift through your gear sequence, using engine resistance combined with intermittent brake pumping to cut speed. This one-two technique lets you harness your car’s mechanisms to decelerate forcefully but smoothly.
- Use the Emergency Brake: Finally, having scrubbed off all possible velocity, engage the emergency brake as a last resort if still moving too fast when nearing stopped cars or intersections. But only pull the lever gradually to prevent lock-up skidding.
- Check Brake Fluid Levels: With your vehicle secure, inspect for puddles or low fluid revealing dangerous system leaks requiring immediate repair. Crisis may have just been narrowly averted, but identified failure cannot be ignored. Only by pinpointing and addressing the root brake defect can future safe travel be restored.
Preventive Maintenance Tips
To help keep braking problems at bay, including severe ones like a spongy or sinking pedal, maintenance is key:
- Inspect the brakes regularly. At least once per year or 12,000 miles, perform a thorough check to make sure your brakes are functioning normally and repair any issues that come up.
- Keep the brake fluid clean and full. At every oil change, check the brake fluid condition and level. Flush the brake fluid every two years or when it’s dirty.
- Change your brakes on time. When the brake pads are at or below 1/4-inch of remaining thickness at the thinnest point, replace them.
How Much Does It Cost To Repair?
Honestly, the repair cost will depend on the problem and how simply or hardly it will be completed. On average, the repair cost of a brake master cylinder is from $200 to $300. It can take extra depending on the scope of the solution.
But, the most expensive thing occurs when your car needs a whole brake job. The total repair cost will go up to $750 or even more. So, regularly check your car’s braking system to prevent such kinds of repair costs.
Whenever you find any problems in your car’s braking system, you have to avoid driving because it’s unsafe. Primitively, detect the problem and then take action to solve it.
If you haven’t the ability to finish the repairs, just consult a certified mechanic. He has experience as well as all of the tools to do the task properly.
FAQs.
Q: Why Do I Lose Brake Pressure When I Start My Car?
You can lose brake pressure after starting your car if you have a leakage in any of the brake components. If the brake pedal goes to the floor but has no leaks, the problem might be related to the brake booster that has a vacuum leakage.
Q: How Do I Know If My Brake Booster or Master Cylinder Is Bad?
There are many ways to identify a bad master cylinder or brake booster. You can feel the brakes are so spongy or very soft under your leg, or there is a leakage in the master cylinder.
You can also feel that the brake pedal is hard to press or the engine is stalling and stop working while braking. All these are signs of a bad brake booster or master cylinder.
Q: Why Does My Brake Pedal Go To The Floor After Bleeding?
After bleeding the air out of the brake fluid, you must make some hard pressings on the brakes to retain the pressure back to the brake lines.
Q: What Causes a Hard Brake Pedal?
A hard brake pedal always means that the brake booster has a problem. The brake booster use vacuum air from the engine to assist in pressing by providing pressure to the brake master cylinder.
Final Words
The best approach for resolving this problem is to have a correct diagnosis. If you find yourself confused about the fault, take the vehicle to an expert for inspection.
Remember that any fault related to the brakes is related to the vehicle’s safety and the people who use it; thus, repairs must be done right. To maintain your vehicle’s brake system in good condition, change the brake fluid at certain intervals.