Your brakes are the most important safety system on your vehicle. Soft brakes, meaning a brake pedal that no longer offers the same reassuring pressure it normally does, can be an alarming thing to encounter while driving. This is especially true if your brakes go soft all at once, without any advance warning. Also known as spongy brakes, this brake pedal feel is almost always an indication of a problem with your vehicle’s hydraulic brake fluid system, and it has several potential causes. Brake problems are almost always a serious issue. Check out these three tips for dealing with a soft brake pedal as safely as possible.
1. Try to Pump the Pedal
Soft brakes arise because your vehicle’s brake master cylinder isn’t able to generate the full pressure required for maximum braking power. This can be due to a number of problems: a leak in a brake line, a loss of pressure within the master cylinder itself due to a failed seal, or air being introduced into the braking system. Your first reaction to encountering spongy brakes should be to rapidly pump the brake pedal with your foot. Even if there is a defect in your braking system, this can usually generate enough pressure to stop safely on the side of the road. Almost every vehicle on the road has a dual-circuit braking system. This means that the front and rear brakes are separate from each other in case of a problem. The chances of both braking circuits failing at the same time is low, so pumping the brakes lets the still working circuit help slow the vehicle.
A sudden loss of braking pressure likely means that a leak or a seal failure occurred quite recently. Brake fluid is usually clear or yellowish in color. If it’s going to leak, it almost always does so where a line meets another component, such as the calipers at each wheel, the cylinder in drum brakes, the brake proportioning valve, the master cylinder in the engine compartment, or even the ABS pump. Inspect the area behind each of your vehicle’s wheels for signs of leaking fluid, and also look under your hood to see if your master cylinder or ABS pump is leaking or damp. (It’s usually located on the firewall.)
For those who live in an area with road salt is common, slide under the vehicle and inspect the hard metal brake lines themselves. Note any areas that are corroded or wet with brake fluid. The braking system operates under pressure, so a small pin leak can lose a lot of thin brake fluid. While rarely the source check the flexible rubber brake lines themselves. They should be firm and dry. Next, check the master cylinder to see if it’s filled up to the indicator line on the side of the reservoir. If the fluid is low, try adding some and pumping the pedal to regain pressure in the system. It goes without saying that any leaking brake fluid represents a problem that should send you to your local NAPA AutoCare immediately for repair. There is no acceptable level of brake fluid loss, so routinely topping off brake fluid is never an option.
3. Bleed Your Brakes
If you happen to be in the driveway or close to home when you encounter soft brakes, you can try bleeding your brakes to remove excess air that might have entered into the system. You don’t have to have a leak for air to be present in your brake lines. If you have overheated your brakes during spirited driving or towing, the fluid can boil and create gas that will make your pedal feel spongy. This is because gas, unlike fluid, can be compressed. That gas needs to be removed. Luckily you have options and the procedure isn’t that difficult.
Each of your brake calipers or brake drum wheel cylinders will have a bleeding screw that will allow you to force air out of the lines using the brake pedal (or a brake bleeding kit) and the proper bleeding procedure for your vehicle. The goal is to flush the brake lines of old fluid and replace it with new fluid. Brake fluid attracts moisture and can corrode brake lines from the inside. Make sure to keep the master cylinder topped up with fresh fluid during the bleeding procedure so you don’t introduce air bubbles into the system.
Soft or spongy brakes can be frightening, but you can usually correct the problem without too much hassle. If the above tips don’t bring back the firm brake pedal feel you used to know, park the vehicle until it is fixed. You can pick up a service manual and work through the diagnostic process yourself, or have the vehicle towed to the experts at your local NAPA AutoCare Center for a thorough inspection.
Check out all the brake system products parts available on NAPAonline or trust one of our 17,000 NAPA Auto Care locations for routine maintenance and repairs. For more information on dealing with soft brakes, chat with a knowledgeable expert at your local NAPA Auto Parts store.
Photo courtesy of Wikimedia Commons.
Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.