Unlike some other fluids, brake fluid does not get consumed during normal vehicle operation. If your car’s brake fluid is significantly low, that means there’s a problem somewhere in the brake system. The issue could be anything from worn-out pads (causing the caliper pistons to move outward) to a leak somewhere.
In other words, low brake fluid is typically the result rather than the cause of brake system problems. Regardless of what’s causing the low fluid level, you’ll want to address the concern right away to ensure your vehicle remains safe to drive.
Pressurized brake fluid acts as the medium to activate your car’s brakes. In a disc brake system, when the driver presses the brake pedal, the fluid acts on a caliper behind each wheel. Each caliper squeezes a pair of brake pads against a disc-shaped rotor, creating the friction needed to slow the vehicle.
In a drum brake system, when the driver presses the brake pedal, the fluid acts on a wheel cylinder behind each wheel. Each wheel cylinder pushes a set of brake shoes outward against a brake drum, creating the friction needed to slow the vehicle.
The brake fluid is pressurized by a device called the master cylinder. A reservoir, which typically mounts to the top of the master cylinder, houses the brake fluid. The master cylinder is activated by the brake pedal.
Brake fluid quality is regulated by the Department of Transportation (DOT). There are four primary types of brake fluid: DOT 3, DOT 4, DOT 5, and DOT 5.1. Most production vehicles use DOT 3 fluid, though some high-end models use DOT 4. DOT 5 and DOT 5.1 brake fluids are typically found in high-performance applications and race cars.
While it’s okay to mix DOT 3 and DOT 4 brake fluid, you should not mix DOT 5 or DOT 5.1 with any other type of brake fluid. Consult your owner’s manual to determine the correct type of brake fluid for your car.
Proper braking performance depends on an adequate brake fluid level. If your car’s brake fluid is significantly low, you’ll notice one or more of the following symptoms:
One of the most obvious signs of low brake fluid is a low fluid level in the reservoir. You’ll want to check your car’s brake fluid regularly to ensure there aren’t any leaks or other related problems with the brake system.
Most cars have a brake fluid level sensor, which is typically located in the fluid reservoir. When the brake fluid drops below a certain level, the sensor triggers the red brake warning light on the dashboard.
There’s also a pressure differential valve and switch designed to alert the driver of a loss of pressure (from a leak) in one of the brake fluid circuits. When the switch closes, the red brake warning light turns on.
A low brake fluid level can indicate that your car’s brake pads are worn out. As the pads begin to wear, the caliper pistons must move out farther to apply the brakes, potentially resulting in a low fluid level. The worn-out pads or shoes can lead to an increased stopping distance and other braking performance issues.
You may also hear a grinding noise from the brakes. The noise results from the brake pads being worn down to the point that their backing plates or wear indicators make contact with the rotors.
A brake fluid level that’s significantly low can potentially lead to a low or soft brake pedal. This is a serious problem, as it typically indicates there’s a leak somewhere that could seriously hinder your vehicle’s braking ability.
Some vehicle manufactures recommend a periodic brake fluid service while others do not. But because brake fluid easily absorbs moisture, it can end up containing as much as 3% water in less than two years. An increase in moisture can decrease the fluid’s boiling temperature, which can reduce braking performance. The moisture can also wear away at critical brake system components. For these reasons, it’s a good idea to replace your car’s brake fluid periodically.
Most experts recommend replacing brake fluid every two years or 30,000 miles. It’s a good idea, however, to check your owner’s manual to determine whether the vehicle manufacturer recommends a different schedule for your application. You want to avoid driving around with dirty brake fluid or fluid that’s moisture-contaminated.
Driving your vehicle when it’s low on brake fluid puts your safety at risk and can even damage other braking system components. So make sure to keep a bottle of brake fluid in your trunk in case of emergencies.
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Don’t miss out on road trips because your brakes aren’t doing their job. Shop for top-notch brake fluid right here at CarParts.com today.
Watch these videos for tips on how to check your fluid levels:
If you want to prevent low brake fluid levels, you must identify the part that’s causing this issue. Replace the faulty brake part as soon as possible and refrain from driving your vehicle to avoid creating additional costly problems. Luckily, you can get high-quality replacement parts like brake calipers, caliper pistons, and pad sets here at CarParts.com.
CarParts.com is your one-stop shop for world-class brake parts and accessories at competitive prices. Our extensive catalog of products includes brake pad sets, brake calipers, and brake caliper pistons for various makes and models. We also make it easy to find a compatible part that fits your budget. Just plug your vehicle’s details in our website’s built-in vehicle selector and browse the results. Do you have any questions about our products, such as their price tag or fitment? Our helpful customer service team is on hand 24/7.
Why leave your home to purchase replacement brake parts when CarParts.com delivers straight to your doorstep? Order today and enjoy fast delivery of replacement brake calipers, brake caliper pistons, and brake pad sets.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.