What Does Pumping the Brakes Mean?

Chances are that you’ve pumped the brakes in the past, especially if you’re a longtime driver or own an older vehicle built before the introduction of the anti-lock braking system (ABS). It’s natural to respond to the brake pedal acting up by releasing and stepping on it until the brakes finally respond.

However, pumping the brakes isn’t good for your vehicle in the long run. Furthermore, it doesn’t always solve the underlying problem behind the brake. If you pump the brakes over and over again, it’s better to bring your vehicle so that its brakes can be examined for possible issues.

What Does Pumping the Brakes Mean?

Pumping brakes refers to applying the brakes in quick succession. You step on the brake pedal, let up, and then press your foot down again multiple times.

Why Do You Have to Pump the Brakes to Stop?

Fluid pressure makes it possible for the brakes to stop your vehicle. Without enough pressure, the brake system can’t run at peak efficiency, if it can operate at all.

If the brakes can’t build up sufficient fluid pressure, the brake pedal will behave differently. The pedal might feel soft and spongy. It might even give way to your foot and drop to the floor.

Pressing the brake pedal signals the master cylinder to move brake fluid through the brake lines. The ensuing flow of brake fluid generates fluid pressure required by the brakes for operation.

While insufficient fluid pressure is a common reason for the brake pedal going to the floor, moisture in the brakes is another possible culprit.

Water boils at a lower temperature than brake fluid. It will vaporize upon encountering the heat and pressure in the brake system. Vaporization creates bubbles of air in the brake fluid.

Air bubbles pose a problem because they alter the brake fluid’s compressibility. Hydraulic fluid resists compression, hence the feeling you get when you put your foot on the brake pedal.

Unlike unyielding brake fluid or liquid water, air is compressible. The presence of air bubbles in the brake lines makes hydraulic fluid more compressible. The brake pedal will drop lower and feel spongy instead of firm. Worse, the air will reduce the brakes’ performance.

Pumping the brakes can partially compensate for the issues of insufficient brake fluid and air bubbles in the brake line. By stepping on and releasing the brake pedal multiple times, you might get some improvement out of the brakes.

Issues That Lead to Pumping Brakes

Here are some of the most common problems that force you to pump the brakes:

Insufficient Brake Fluid

Most cases of low brake fluid stem from a leak. Inspect the area around the brake caliper, the brake lines, and the master cylinder for any signs of hydraulic fluid leaking out of a damaged part.  If you find any leaks, replace the affected parts immediately.

Air Bubbles in the Brake Lines

As mentioned earlier, air bubbles in the brake lines are one of the most common underlying reasons that force you to pump the brakes. But how do air and moisture enter the brake system in the first place?

There are many ways for moisture to get inside the brakes. Water can seep into the gaps of improperly sealed parts and joints, especially if the seal has worn out. Or it can filter through the tiny pores in brake hoses that are invisible to the naked eye and require a microscope. Also, whenever you open the brake fluid reservoir for checking, there’s a chance that moisture and air can pass through the opening.

Brake bleeding gets rid of air in the brake system. However, improper bleeding can leave some air inside the brake lines.

Moisture in Brake Fluid

Brake fluid naturally absorbs moisture, which can create air bubbles upon vaporization. Preventing water buildup is one of the reasons why you must replace fluid regularly. Too much moisture can make the brakes less responsive, forcing you to pump the brake pedal.

Master Cylinder Issues

The master cylinder is the heart of your brakes. It takes the pressure produced by the brake pedal, multiplies it, and drives the force through the rest of the brakes.

While a long-lived part, the master cylinder can develop issues and even fail prematurely. A bad cylinder can reduce the brakes’ performance, leading to pumping the brakes to compensate for the loss. If you feel the brake pedal rise as you pump it, you have a malfunctioning master cylinder on your hands.

If the pedal starts to rise while you’re pumping it, then the master cylinder is a big problem.

–Anthony Harlin, ASE Certified Master Automobile Technician

Bleeder Valve Issues

Brake fluid bleeder valves play a critical role in the brake bleeding process that eliminates air bubbles in the brakes. The wheel’s respective bleeder valve is on the line near the hub.

A worn-out or broken bleeder valve will leak brake fluid and serve as an entry point for air to enter its attached brake line. Between insufficient fluid and an influx of air bubbles, you’ll end up pumping the brakes.

How To Fix the Issue

Pumping the brakes is a temporary stopgap that won’t fix the underlying issue. It might stop working, and it increases the wear and tear of the overworked pedal.

If you pump the brakes often, check your brake system thoroughly. Identify what’s causing issues like a sinking brake pedal and malfunctioning brakes. If it’s low brake fluid, replenish the reservoir and eliminate leaks. If it’s air bubbles or moisture, put your vehicle through careful and thorough brake bleeding.

For those who lack the time or the DIY repair knowledge to track down the issue, the next best thing is to bring your vehicle to a trusted auto repair shop.