How Do You Test A Brake Master Cylinder?

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Brakes are one of the most important parts of driving a vehicle but the most important when it comes to safely driving a vehicle. Brakes are literally a life-or-death component of driving, so why not keep them in top condition? You can press down on your brakes and know something is wrong but what is the problem? We can’t tell you what everything means but we can tell you how to check for one specific issue. The brake master cylinder is an essential part of the braking system. It is crucial to know the condition of your brake master cylinder and how to test it.

What is A Brake Master Cylinder?

Raybestos MC391101 Professional Grade Brake Master Cylinder

The brake master cylinder is like a vein and the pedal is the heart. The pedal pushes a piston through the cylinder. This causes brake fluid to flow like blood through to all the slave cylinders. The slave cylinders cause friction on the wheel hub which slows the tires. Without a properly functioning brake master cylinder, the braking process could be delayed or not happening at all.

Signs You Should Check Your Brake Master Cylinder

The quickest and easiest way to know something is wrong is when your check engine light comes on. No, the light doesn’t automatically mean it’s the brakes but you know an extra thing to tell the mechanics when you take your vehicle in. They can confirm or deny your brake issues but also make sure the rest of the vehicle is in top condition.

Abnormal brake behavior may be harder to spot but if you know your car, you can tell when things are off. Because the master cylinder is controlling the pressure in the brakes, your brakes will begin to feel different when there’s an issue. Your brakes can feel weak or begin to sink. The lowering of tension is a sure sign you should inspect your brakes.

Contaminated brake fluid is the hardest to spot for a faulty brake master cylinder. You can’t see the brake fluid until you take apart the car. Brake fluid gets contaminated from the cylinder losing its sealing. Feeling your brakes sink or feel spongey are a sign to check your brake fluid. You have now double checked your brake master cylinder. Abnormal brake behavior and contaminated brake fluid are both confirmations of issues and also signs of the other issue.

How do You Test a Brake Master Cylinder?

First step first is to find it. To locate the master cylinder, you have to pop the top and look behind your engine. There you should see the brake fluid reservoir. It looks like a big plastic cylinder. If you have a manual, you’ll see two cylinders. The bigger one is for the brakes. Open up the cylinder and look inside at your brake fluid. If you see anything floating around or an off color, remove the object and replace the fluid.

If there is nothing in the fluid and no discoloration, have someone pump the brakes while you watch the fluid. After pumping the brakes a few times, look for bubbles or swirling in the fluid. Bubbles and swirling are indicators of a leak or air being introduced somewhere. This could also just mean that your cylinder is malfunctioning.

A brake fluid leak is hard to spot because it has no color. The only way to check would be to rub your hands across where your car is usually parked. Brake fluid has a consistency similar to vegetable oil. To check for leaks, you can run your finger along the sides of the cylinder or hoses and feel for any cracks or holes. If you don’t feel any thing, use the same method as you would for a hole in your tire. Run some soap water over the outside of the cylinder. If you start seeing bubbles forming over an area, that’s where the leak is. The leak could also not be spilling out fluid but could just be a faulty cylinder. You will still see bubbles and swirls in the fluid but it won’t be leaking anywhere.

To check for faults in your cylinder, have someone put the place the brake all the way down. While someone flattens the brake, you monitor the fluids. If you notice the brake fluid drops as the person rests on the brake, you will need your cylinder inspected. Unless you are a mechanic, this is best to take to a shop. Stay safe. Call a tow truck to transport your vehicle. It is NOT recommended to drive with faulty brakes. Even if it is a short distance, do not risk it.

If you own a vice, you can test your own brake master cylinder. Make sure your cylinder securely in the vice. Then use an impact screwdriver (or just a really big regular screwdriver) to put pressure on the plunger. If it moves, your cylinder is damaged and you should take your vehicle to a mechanic. If it doesn’t move, your cylinders are ok but still go get your vehicle inspected because something is causing that leak.

For more information on brake master cylinders or any other parts of your vehicle, be sure to browse the rest of our website. For immediate problems, contact us directly.

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