How Does Brake Fluid Become Contaminated And How Do You Know If It's Happened To Your Car?

You may not think about the brake fluid in your car very often, but it's one of the most important components of your braking system. When you step on the brakes, the master cylinder underneath your brake pedal compresses the fluid in your brake lines. The fluid fills the brake calipers in your wheels, causing them to press against the brake pads and bring your car to a stop. In other words, the brake fluid is what transmits the force of you pressing on the brake pedal to your car's brakes. If you didn't have any brake fluid in your car, you wouldn't be able to brake at all.

Unfortunately, your car's brake fluid can become contaminated and cause poor braking performance. Your car's braking system isn't perfectly airtight, which allows moisture to collect in the brake fluid. Flakes of rust and rubber from corroded braking components and seals can also build up in your brake fluid, contaminating it. To learn more about how brake fluid becomes contaminated and how you can tell if your car's brake fluid needs to be changed, read on.

How Does Brake Fluid Become Contaminated?

Brake fluid is hygroscopic, which means that it absorbs water vapor from the air. It's similar to the packets that you sometimes find in packaged food items to keep them dry. Your car's brake fluid will slowly absorb moisture from the air as air enters the brake fluid reservoir, and water will start to build up in your brake fluid.

The water in your brake fluid can cause the seals and metal components in your car's braking system to corrode, and some of this corrosion will flake off into the brake fluid as you use your car's brakes and cause the fluid to shift around. Your car's brake fluid becomes highly pressurized when you step hard on the brakes, and this will cause any deteriorating components in your braking system to break off into the fluid.

How Do You Know If Your Brake Fluid Is Contaminated?

The most common sign of contaminated brake fluid is a loose-feeling brake pedal. This is caused by air building up in your brake hoses. When water builds up in your brake fluid, it may turn into steam when you're braking — the friction generated between your wheels and your brake pads generates a large amount of heat, which heats up the brake fluid in the calipers. When the water turns into steam, air will build up in your brake lines.

Air will become compressed when you step down on the brake pedal instead of smoothly transmitting force to your brake calipers, which causes your brake pedal to feel loose and unresponsive. You won't be able to slow down as quickly by stepping down forcefully on the brake pedal, as you can't transmit force as efficiently. This is a major safety hazard since it prevents you from coming to a quick stop if you need to brake in order to avoid hitting a pedestrian or another vehicle.

In addition to causing loose-feeling brakes, contaminated brake fluid can lead to your brakes seizing up. Rust and rubber in your brake fluid can build up in your car's brake calipers, locking the pistons that press against the brake pads in position and preventing them from retracting. You won't be able to disengage your brakes, and you'll have to have your car towed to a brake repair shop in order to have the damaged calipers replaced.

If your car's brake pedal feels loose, take your car to a brake repair shop to have your brake fluid inspected. A trained mechanic can look at the condition of the brake fluid in the reservoir to determine how contaminated it is. If your brake fluid is contaminated, a mechanic will flush it out and replace all of the brake fluid in your car. This is an inexpensive service that prevents further damage to your car and makes you safer on the road by increasing your brake pedal's responsiveness.

Contact an auto shop like Greg's Japanese Auto Parts and Service to learn more.