Can a Bad Master Cylinder Cause Brakes to Lock Up?

The master cylinder is a crucial part of your car’s brake system. Brake fluid pushes through this cylinder valve to make the caliper press brake pads on the rotors. Therefore, can a bad master cylinder cause brakes to lock up? The answer is a resounding yes, and you should pay more attention to its maintenance. You might get into an accident while on the road if there’s any problem with this part.

To understand this better, let us examine your car’s braking system and how the master cylinder plays an important role.

What Is a Brake?

Your car’s braking system slows down and halts the motion of your vehicle. Multiple components work together to convert your car’s moving energy into heat. Friction plays part in this conversion of energy.What Is a Brake

Two forms of friction control your vehicle. The first is kinetic, or moving friction. The second is static or stationary friction. The amount of friction depends on several factors including: The types of materials in contact, the smoothness of the rubbing materials, and the amount of pressure holding these materials together.

To summarize, your car’s brakes work when a static surface rubs with the moving surface of your vehicle. This rubbing action converts kinetic energy into heat. When there is less kinetic energy in your car, it slows down. When your car’s kinetic energy is zero, it stops.

For your car to move again, brakes are released. When you step in your accelerator pedal, the heat in the combustion engine turns to kinetic energy via the transmission and drivetrain, and your car starts to move.

What Causes Brakes to Lock Up?

Faulty brake pads and bad calipers on your disc brakes will cause your brakes to lock up. Faulty cylinders on your drum brakes can also cause your vehicle problems.What Causes Brakes to Lock Up

It would be best if you looked out for warning signs that your car’s safety system is breaking down. For example, if your car veers sharply to one side when you apply brakes, you should have your vehicle immediately diagnosed by a mechanic.

Typically, cars with anti-lock brakes shouldn’t lock up unless your vehicle has the above mentioned problems. There are also other factors that can affect your braking system. These include overheated braking systems, use of the wrong brake fluid, and damaged calipers, rotors, or drum brake backing plates. Another potential factor that can affect your braking system is when your caliper pistons or brake wheel cylinders are worn out.

Take note that if your car has no anti-lock features, your vehicle will lock up if you apply hard and steady pressure. This lock-up occurs when you slam on your pedal, and if your tires squeal, your brakes will probably lock up afterward.

Some modern cars have safety features that include a secondary braking system. These back-ups are the ABS (Anti-lock Braking System) and the emergency brake.

Let’s know: How to Fix Brake Fluid Leak?

What Is a Master Cylinder?

The master cylinder drives the pressure generated by the brake pedal to the braking mechanism attached to your car’s wheels. When you press down on your brakes, that force pushes a piston through the brake cylinder, and this force converts into hydraulic pressure.What Is a Master Cylinder

In turn, this pressure pushes hydraulic fluid into your brake lines, and this force transmits more pressure to your secondary cylinder attached to each wheel. This secondary cylinder pushes your caliper pistons to drive the brake calipers in your disc brakes, which slows down and stops the wheel from turning.

Where Is the Master Cylinder Found?

In power-assisted braking systems, the master cylinder attaches to the brake booster component. This component, attached to the firewall in the engine compartment, supplies more power to the braking system.

The master cylinder is attached directly to this firewall in manual braking systems, and it is also linked directly to the brake pedal.

Can a Bad Master Cylinder Cause Your Brakes to Lock Up?

Based on the mechanics of your car’s braking system, the answer is yes. The master cylinder drives your entire braking system, and if this component gets damaged, your brake will most likely lock up.

How to Spot Problems in Your Brake Master Cylinder?

Knowing the importance of the master cylinder, you should have your vehicle’s brake system checked regularly. This maintenance procedure should diagnose how effective your braking system’s operation is.How to Spot Problems in Your Brake Master Cylinder

It would be best to watch for tell-tale signs that your braking system is failing. Here are a few common red flags that will help you spot a bad or failing master cylinder:

1. Your Brake Pedals Feel Wrong, Displaying Unusual Behavior

For example, if you step on your brake pedal and it feels lacking resistance (it sinks slowly to the floor), then your brake fluid pressure may be too low. This behavior is a sign that your brake master cylinder is damaged.

Whenever you feel something is off in your brake pedals, take your car to a mechanic as soon as you can.

2. Leaking Brake Fluid

If there’s a leak in your brake’s hydraulic system, your car’s brake fluid level will drop. Your master cylinder has several seals to keep brake pressure contained. However, if the seals wear out, internal leaks will occur. Your brake fluid pressure will drop and cause your brakes to fail.

3. Contaminated Brake Fluid

Remember that brake fluid should have a clear, golden yellow, or brown color. Get a sample of your brake fluid. If it is black or dark brown, your fluid is most likely contaminated. Contaminants may damage the internal parts of your brake system, and they will most likely cause failures in your brake’s performance in the future.

4. Brake Warning Light Comes On

If your car has those modern brake fluid levels and pressure sensors, then you should pay attention to what it is saying. These sensors will detect unusual or massive drops in pressure and alert you.

Read Also: How to Replace Wheel Studs on Disc and Drum Brakes?

How to Take Care of Your Brakes?

Here are some tips on how to take care of your brakes:

Check Your Brake Pads and Rotors

Brake pads and rotors are the main contact between your braking system and your tires. Since they are constantly rubbing together, they deteriorate fast. Wear and tear happen due to friction and heat, and you should schedule frequent maintenance for these components.Check Your Brake Pads and Rotors

At home, you can inspect your brake pads to see if there are cracks and if the depth is still sufficient. When using your car, pay attention to any burning smell. Does the distance it takes to stop increase significantly if you apply brakes? If yes, maybe it is time to replace your brake pads and rotors.

Periodically Flush Your Braking Fluid

Brake fluid is vital because it transmits pressure from your pedals to your tires. Unfortunately, brake fluid attracts moisture.

This moisture damages brake systems and causes corrosion on the metal parts of your brakes. This damage reduces the boiling point of your hydraulic fluid, affecting the effectiveness of your brakes. Take your vehicle to regular maintenance and have these parts checked for failures when this happens.

Bleed Your Vehicle’s Brake Lines

You should bleed your brake lines to remove excess air. When the air becomes trapped inside your car’s brake lines, it drastically reduces your braking system’s efficiency.

It is safer to assign this task to a certified professional as this procedure requires various tools and equipment not regularly found in average homes. However, if you think you can do it, the main idea is this: depress the brake pedal while adjusting the bleeder valve.

You should bleed your brake lines every two to three years.

Upgrade Your Brake Parts

You may find it necessary to replace some parts in your braking system. Try to take this opportunity to upgrade your components to higher-performance parts. Slotted disc brakes are more heat resistant, and ceramic pads are quieter and produce less brake dust. These replacements and upgrades will improve the longevity and performance of your car’s braking system.

Also Know: 5 Best Brake Pads for Chevy Silverado 1500


Your car’s master cylinder plays a crucial part in your vehicle’s brake system. Although it includes various mechanical components, how it works is very straightforward.

Your braking mechanism depends on your master cylinder, so your brakes will most likely lock up if it is damaged. Fortunately, there are many ways to detect early warning signs. Look out for unusual behavior in your brake pedals and fluid leaks under your car. Pay attention to burning smells, and feel if your car is swerving when you brake.

Most importantly, you should take your car to an ASE-certified mechanic for preventive maintenance. Don’t wait for problems to pile up. Your brakes are essential to road safety, and you should take care of them.