My Brake Pedal Sinks to the Floor, What Could Be the Problem?

Technical  ·  February 17, 2022

My Brake Pedal Sinks to the Floor, What Could Be the Problem?

No matter how many pedals your car has, there’s one thing you must know about them. Each pedal shouldn’t be too easy or challenging to push down with your foot. So, if you find that your car’s brake pedal sinks to the floor far too quickly, that means you’ve got a problem.

A brake pedal that sinks to the floor, aka spongy or soft brake pedal, is a tell-tale sign of a brake system problem, like inadequate brake fluid or a failing master cylinder. Air in the brake lines and brake fade can also cause the same issue. Get to your mechanic immediately!

Any issue that affects your car’s brake system should not be taken lightly. So, keep reading this guide to understand what’s causing the problem and how to fix it.

Is It Bad If the Brake Pedal Goes to the Floor?

Yes, it isn't good if your brake pedal goes all the way down. You should immediately take your car to the mechanic when you notice it happening. That is not the kind of thing you'll want to put off until later.

If your brake pedal suddenly sinks to the floor, that means you’ve got what they call a soft brake pedal, or your mechanic might refer to it as a ‘spongy’ brake.

No matter what term anyone uses to describe it, your brake isn’t supposed to go all the way down like that.

Ideally, your brake should be moderately challenging to press down with your foot – not too hard or too easy to push to the floor.

Your brake pedal connects directly to your car’s brake system, so when it doesn’t respond properly, it means that the system has a problem that needs your immediate attention.

4 Possible Causes of a Soft Brake Pedal

When you’re in a situation where your brake pedal sinks to the floor, that means that your brake system has one or more significant problems.

For example, the problem could be a leak, a bad master cylinder, air in the brake lines, or brake fade.

Let’s take a closer look at each of those possibilities.

#1 Brake Fluid Leak

What that means: Your car’s brakes use a hydraulic system with brake fluid to function correctly. When you press the brake pedal, that will compress the fluid and cause it to apply the brake pads that slow down your wheels.

When the brake pedal goes all the way to the floor without any resistance, it’s likely because there’s not enough brake fluid in the system for the brake pedal to push back.

The only way brake fluid could disappear from the system is if it leaks out.

How it happens: Brake fluid leaks happen when parts of the system experience wear, pitting, rusting, or other forms of damage. For example, a hole might form in the brake lines causing fluid to leak out onto the road underneath.

How to fix it: You can resolve this issue by fixing the leak and topping up your brake fluid. The first challenge is to locate the source of the leak and repair or replace the part that’s causing it.

Once that’s done, you or your mechanic can then pour new brake oil into the system.

#2 Bad Master Cylinder

What that means: The master cylinder is responsible for pumping brake fluid into the brake lines. So, when your brake pedal doesn’t offer any resistance and falls to the floor too quickly, that means the brake lines have no pressure, i.e., the master cylinder isn’t pumping any brake fluid into them.

How it happens: Master cylinders will typically fail due to excess wear. That’s especially true if your vehicle has used the same master cylinder for many years without any replacements.

How to fix it: The solution here can be either a repair or a replacement. Your mechanic might be able to fix the master cylinder.

Depending on your car’s age and the cylinder’s condition, you might be better off replacing the part with a new one.

#3 Air in the Brake Lines

What that means: Your brake lines are only meant to carry brake fluid, which produces enough force to activate the brakes when you press down on the pedal.

However, a spongy brake pedal could mean that your brake lines have air in them instead of brake fluid.

How it happens: Your brake system is sealed, so nothing gets in or out. However, air can get in during repairs, when new fluid is added, or because of a leak somewhere.

How to fix it: The only way to get the air out of your brake system is to bleed the brake lines. This process removes any air that the system might be trapping in the lines.

#4 Brake Fade

What that means: Lastly, spongy pedals can also be the result of brake fade. Brake fade happens when the system loses its ability to stop your car because the brakes are overheated.

How it happens: It’s normal for brakes to become hot when you use them to stop your car. However, brake fade and the loss of stopping power will happen if there’s too much heat for the brakes to handle.

For example, if you’re going down a long hill and brake continuously, your brakes will overheat and cause brake fade.

How to fix it: When you notice brake fade starts to happen, you’ll have to bring your car to a complete stop and let your brakes cool down. 

That might not be possible while you’re still going downhill. So, switch to a lower gear to reduce your speed without having to press on your brakes too hard.

Then, find a safe place to bring your car to a stop.

What to Do If Your Brake Pedal Suddenly Sinks to the Floor

If your brake pedal suddenly sinks to the floor, you must immediately bring your car to a mechanic. Explain the situation to your mechanic and have them troubleshoot your car's brake system.

Even if you only briefly experience a spongy pedal, you don’t want to take any chances. Your brake system is critical for your safety, that of your passengers, and everyone else on the road. 

Don’t wait for your brake pedal to turn spongy before giving it your attention. Here’s how to check on the health of your brakes.

To learn more about brake pedals and your car, check out CarpartAU for new posts every day. You can find replacement parts in the Marketplace or through the Parts Finder


By Ray Hasbollah

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