Auto Mechanics | Blog | Brake Pedal Goes To The Floor

Why Does My Brake Pedal Sink To The Floor?

If your brake pedal sinks to the floor, it indicates a serious problem with your vehicle's braking system. This is a critical issue that should be addressed immediately to ensure your safety on the road. There are several possible reasons for a sinking brake pedal:

• Brake Fluid Leak: One of the most common causes is a brake fluid leak. Brake fluid is essential for creating hydraulic pressure in the braking system. If there's a leak anywhere in the system, the fluid level drops, leading to a soft or sinking brake pedal.

• Air in the Brake Lines: Air can enter the brake lines if there's a leak or if the brake fluid level gets too low. Air is compressible, unlike brake fluid, so if there's air in the brake lines, you'll experience a soft brake pedal that sinks to the floor when you apply pressure.

• Worn Brake Pads or Shoes: Worn brake pads or shoes can also cause a low brake pedal. When the brake pads are too thin, the brake pedal may travel further before it engages the brakes.

• Master Cylinder Issues: The master cylinder is a vital component of the brake system that generates hydraulic pressure. If the master cylinder is faulty, it can result in a sinking brake pedal.

• Brake Caliper or Wheel Cylinder Issues: Problems with the brake calipers (in disc brake systems) or wheel cylinders (in drum brake systems) can lead to a sinking brake pedal.

• Brake Hose Problems: The brake hoses carry brake fluid between the brake lines and the calipers or wheel cylinders. If these hoses are damaged or deteriorated, they can collapse under pressure, leading to a sinking brake pedal.

• Faulty Brake Booster: The brake booster enhances the force applied to the brake pedal. If it's not functioning correctly, it can cause a soft or sinking brake pedal.

Regardless of the cause, a sinking brake pedal is a serious issue that requires immediate attention. Continuing to drive with a compromised brake system is extremely dangerous. It's essential to have your vehicle inspected by a qualified mechanic as soon as possible to diagnose and repair the brakes the problem.

Let's have a look at these problems causing your brake pedal goes to the floor. 

Air In The Brake Line

A low brake pedal could be caused by air in the brake lines. Air in the brake line prevents brake fluid flow which will be felt in a soft spongy pedal when you apply the brakes.

If this is the case have your brake lines inspected and perhaps a brake flush and / or bleed the air out of the system. Bleeding the brakes or flushing the brake fluid will get rid of the air inside the lines. Brake fluid has a boiling temperature and through the course of time may create moisture. The older the brake oil the higher the chance of boiling and moisture trapped in the system. You want all brake components to perform in peak condition and fresh brake fluid will lubricate your brake lines and components to spec.

Leak In The Brake Line

Another cause of a low brake pedal that goes to the floor is a loss in hydraulic pressure. Typically, brake lines are made of steel and prone to rust. This may lead to small holes in the brake lines and cause brake fluid to leak. If your brake pedal sinks to the floor and is low than have your brake lines and system inspected for a leak.

Brake Caliper Leak

Brake calipers are responsible for squeezing the brake pads against the rotors when you apply the brake pedal. If you run your brake pads too low and the piston inside the caliper is fully extended, this may cause a low brake pedal going to the floor. This can also lead to brake fluid leaking from the piston of the brake caliper. In either case, this should be looked after immediately to keep safe and prevent further damage. A faulty brake caliper may also cause the vehicle to pull to one side.

Master Cylinder Leak

The master cylinder, along with all other brake components performs a vital function. It is the main source of hydraulic pressure delivered to your brakes front and rear. A master cylinder that has grown old through use may leak through the seals internally and / or externally. You may not see a leak in the master cylinder as it can sometimes be internal only. Both leaks are critical to your brakes pressure and braking power which will be experienced by a low brake pedal to the floor.

Leaking Wheel Cylinders

Older vehicles still with brake drums in the rear have wheel cylinders. Just as a caliper squeezes the pads against the rotor in the from brakes, the wheel cylinders press outwards the brake shoes against the inner surface of the rear brake drums. A wheel cylinder that has developed a leak will lose brake pressure and cause a low, soft or spongy brake pedal.

Rear Brake Shoes Adjustment

If your brake pedal is low, try pumping the brakes a few times and see if it regains pressure. If so, your rear brake shoes might require an adjustment. Under constant brake shoe wear, the adjustment may become out of line. Also, if you have not used your emergency parking brake, try engaging the parking brake which may automatically re-adjust the brake shoes.

Low Brake Pad Wear

If your brake pedal is low and goes to the floor, you may have used up your brake pad life. If this happens, a low brake pedal might also be accompanied by a screech or squeal when you apply your brake pedal. You might even experience brake noise without applying the pedal. In either case, these are pretty clear indications to have your brake pads inspected and replaced.

Important: If you experience a spongy / soft or low brake pedal, or your brake pedal goes to the floor bring it into the garage for a checkup ASAP. Luckily these symptoms alert you to a potential problem in your braking system. Never delay a problem with your brakes.

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