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Causes of Your Fleet Vehicle Leaking Brake Fluid

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A leak is one of the worst things you can see on your vehicle. Leaks, particularly brake fluid leaks, often indicate internal problems that need immediate attention. Although it can be frustrating to take your vehicle out of commission to address the problem, it is pertinent that you do so. The best way to prepare for this problem is with knowledge. Why is your brake fluid leaking? What can you do to avoid this problem in the future? Let’s explore more about leaking brake fluid and how brake fluid is essential to your vehicle. 

What is Brake Fluid?

Brake fluid is a type of hydraulic fluid that is integral to your vehicle’s brake system. Whenever you press the brakes, brake fluid helps transmit pressure to each tire’s braking mechanism. Fluid is used because it is non-compressible, meaning that pressure will be equally distributed. So when a brake fluid leak occurs, it reduces the fluid in your brake lines. Furthermore, it introduces air into the system. This may cause problems stopping your vehicle. 

What are the Symptoms of a Leak?

So we know what brake fluid is; how do I know if my brake fluid is leaking? Here are some signs you should watch out for:

No. 1: Brake Warning Light

Whenever the brake warning light comes on, you know something is wrong with your brakes. There are four reasons that your brake warning light may come on. 

  • If you have low brake fluid levels
  • If the parking brake/emergency brake is activated
  • If you have a problem with the ABS module in your brakes’ anti-lock system
  • If you have defective sensors in the brake master cylinder or parking brake. 

No. 2: Fluid Under the Vehicle

Just like the brake warning light, you may see fluid underneath your vehicle for many reasons. Look at the color to determine what kind of leak you have. 

  • Green-Tinted: coolant leak
  • Pink/Red: transmission fluid or power steering fluid
  • Brown/Black: engine oil
  • Clear/Yellow/Dark Brown: Brake fluid

Whenever you see a puddle under your vehicle, you should take it in for service. 

No. 3: How the Brake Pedal Feels

You know how your brake is supposed to feel when you’ve been driving a vehicle every day. If it suddenly feels less resistant or “mushy,” you know you may have a problem. You’ll notice that braking feels different when you have an issue with the master cylinder, brake booster, or brake fluid levels. If air enters your brake line, it can also cause this feeling. If you pump your brakes several times and you don’t feel hydraulic pressure buildup, you likely have a brake fluid leak.

No. 4: Brake Pedal Dropping 

You’ll also know something is wrong if you step on your brake pedal and it drops all the way to the floor. If this happens before you hit the road, you shouldn’t drive. However, if you’re already driving and experience brake issues, use gear braking. This is when you downshift your gears to slow the car down; when you’re going slow enough, pull the parking brake. Find a safe place to get off the road as soon as possible. 

What Causes Brake Fluid Leaks?

No. 1: Brake Master Cylinder Reservoir

This reservoir is made of plastic. Exposure can cause the plastic to become brittle and eventually crack. Brake fluid will flow down the back of the engine in this case. 

No. 2: Worn Out Brake System

Your brake system includes brake pads, rotors, brake shoes, and drums, all of which can wear down as you use your vehicle. When these parts wear out, your caliper piston or wheel cylinder piston may become hyperextended, breaking them and causing a leak. 

No. 3: Bleeder Valve

Bleeder valves are a part of your brake calipers and brake drums. They allow air to be expelled from steel brake lines. If this valve is damaged or loose, brake fluid may leak out. 

No. 4: Piston Seal

Pistons are an integral part of your brake system. These are moving parts powered by brake fluid. If the seals on the piston that help contain the brake fluid become damaged, it can cause a leak. 

No. 5: Brake Lines or Brake Hose

These are resilient parts of your brake system, but that doesn’t mean they can't suffer from rust, pitting, or tears. If these parts break, you may see brake fluid leaks. 

No. 6: ABS Module

We mentioned the ABS module earlier. This pump holds high-pressure brake fluid, and the seals may wear down over time. This will end up causing a brake fluid leak. 

Take Control of Maintenance with Azuga

All of these parts can be checked regularly as part of a preventative maintenance program. Azuga’s fleet management system helps you implement preventative maintenance in a simple and streamlined way. Learn more about how Azuga’s maintenance alerts work by speaking with an expert for a demo.