The most common causes of soft, spongy brakes are:
Air in the brake lines - A leak somewhere in the brake system can allow air into the system. Because air compresses, it applies less pressure to the brakes than hydraulic fluid normally does. The result: you need to press your brake pedal further down toward the floor. The solution? One or more Brake Fluid Services may be needed to remediate the issues.
Brake adjustment problem - Brakes should automatically adjust as they wear down, but this self-adjusting function can fail. The solution? Brake shoe service.
Either way, a Brake Inspection is the first step to making your mushy pedal feel normal again.
While most spongy brakes are caused by some kind of brake fluid problem, there are several parts of your brake system where that leak or pressure disruption could originate.
Spongy brake causes that can be fixed with routine maintenance include:
Low brake fluid - A common cause of spongy brakes. Brake fluid levels fall over time (even without leaks), and air enters your brake lines to fill the void. If there’s no leak involved, bleeding the brake lines (draining enough fluid to evacuate the air) and topping off the fluid will restore proper hydraulic pressure.
Moisture in the system - When there is too much moisture in the system, the brake fluid can get too hot and cause what is known as a brake pedal fade. The solution? Test the brake fluid and replace if needed.
Spongy brake causes that need diagnosis and repair include:
Leaking brake fluid
Master cylinder failure - this part must be working perfectly to deliver correct pressure from the pedal to the brakes.
ABS hydraulic assembly problems
Leaking calipers (on disc brakes)
Brake shoe adjustment problems (on drum brakes)
From the master cylinder to the calipers and brake shoes, Midas technicians know all the places where spongy brakes start. We’ll tell you what needs work now (and what can wait), and provide a written estimate before making any repairs.
Air compresses (unlike hydraulic brake fluid), causing the brake pedal to feel spongy. But air in the brake lines is also a symptom of several other brake problems, from worn braking system parts to brake fluid leaks. Some of these problems can lead to brake failure, so early diagnosis of any change in brake response is a very important road safety measure.
The first thing you’ll feel with air in your brake lines is a soft, spongy, or mushy sensation in your brake pedal. If your brake pressure keeps dropping, you’ll need to press your brake pedal further and further toward the floor of your vehicle. If the air in your brake lines is due to a brake fluid leak, your brakes could eventually fail. That’s why you should have your brakes checked as soon as you feel any difference in your brake pedal or brake response.
Spongy brakes are one of several symptoms of a bad master cylinder -- when the cylinder’s seals are too worn to maintain pressure from the brake pedal to the brake lines.
Let’s quickly review how brakes work. Pressing the brake pedal pushes the fluid in your master cylinder through the brake lines to exert hydraulic pressure on the brakes. This pressure brings the brake pads or shoes into contact with the rotors and/or drums, creating friction that slows down and stops your vehicle.
Have your brakes checked as soon as you notice any of these symptoms that may point to a bad master cylinder (as well as other serious car problems):
Soft or spongy brakes
Hard of stiff brakes
Leaking brake fluid
Brake pedal falls to the floor when applying pressure