Symptoms of a Bad or Failing Brake Master Cylinder

The brake master cylinder is one of the most important components found in modern car braking systems. It serves as the main valve that pushes brake fluid through the brake lines so the brake calipers can squeeze the pads against the rotors. It functions by pushing a metal rod through a cylinder to force fluid through the braking system to the wheels. One end of this rod is attached to the pedal and is actuated when the pedal is depressed. Usually, a faulty brake master cylinder will produce one of these 4 symptoms that alert the driver of required servicing.

1. Abnormal brake pedal behavior

One of the first symptoms commonly associated with a bad or failing brake master cylinder is abnormal brake pedal behavior. The master cylinder is the component that generates all of the pressure for the braking system, and if it develops any sort of problems sealing or distributing pressure, this may be felt in the pedal. With constant use over time, the seals inside of the cylinder can wear out and form internal leaks. A bad brake master cylinder may result in a pedal that feels mushy, spongy, or slowly sinks to the floor when depressed.

2. Contaminated brake fluid

Another symptom of a bad brake master cylinder is contaminated brake fluid. Brake master cylinders use rubber seals that can break down and wear out over time. When they do, they can contaminate the brake fluid and will turn it a dark brown or black color. Aside from contaminating the fluid, a brake master cylinder with worn seals will not be able to hold brake pressure as effectively and may result in a mushy pedal or one that slowly sinks to the floor.

3. Leaking brake fluid

Brake fluid leaks from the master cylinder or unsecured reservoirs on the cylinder holding the fluid lower critical brake fluid levels. The brake master cylinder needs adequate levels of fluid to exert the right amount of hydraulic pressure to slow down the car. You’ll need to have the brake master cylinder replaced in this situation. If left unresolved, your ability to slow down the car will be impaired.

4. Check Engine Light comes on

Another symptom commonly seen for newer vehicles is an illuminated Check Engine Light. The braking systems on newer vehicles may have brake fluid level and pressure sensors installed in the master cylinder. These sensors are meant to detect any problem with the vehicle’s brake fluid pressure, which is generated by the master cylinder. If they detect that the pressure has dropped, it is possibly due to a problem with the master cylinder. Such issues may also ignite a Brake Warning Light too.

The brake master cylinder is essentially the heart of the braking system and vital to reliable brake operation. It is an important component of the handling and safety characteristics of the vehicle. A vehicle with a bad brake master cylinder will have inoperable or compromised brakes, and therefore will be unsafe to drive. For this reason, if you suspect that your brake master cylinder is having a problem, have the brake system diagnosed by a professional technician to determine if it the car needs a brake master cylinder replacement.


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JOHNNY

33 years of experience
102 reviews
JOHNNY
33 years of experience
Ford Escape - Brake System Inspection - Sacramento, California
The convenience is worth the cost. I was also tired of the dealership not really caring about my old car. Last couple of times I had to wait well over an hour to get my car after the dealership said "It's ready!". They also wouldn't fix the things I asked saying they didn't have time and I need to come back.
Toyota Camry - Brake System Inspection - Carmichael, California
Johnny was early, friendly, and thorough! He explained things to me about my car that I had no idea about before! I booked him for a diagnostic appointment and I’m definitely requesting him for a follow-up!

Jay

37 years of experience
850 reviews
Jay
37 years of experience
Chevrolet C10 Pickup - Brake System Inspection - Moreno Valley, California
Knowledgeable, Professional, Friendly, and PATIENT! Sickeningly HONEST, as I tried to ply him with cash, alcohol, outside work, and wild dancing girls - although I wouldn't have "ratted him out" if he HAD accepted. A guy like this needs a "bigger cut" than what you are paying him ... because loyalty like his is hard to find these days! THANKS!
Volkswagen Jetta - Brake System Inspection - Moreno Valley, California
As usual, Mr. Jay provides efficient and professional quality of work. I would highly recommend him to any customer searching for a good mechanic.

Benji

22 years of experience
201 reviews
Benji
22 years of experience
Land Rover Range Rover Sport - Brake System Inspection - Phoenix, Arizona
Benji performed a detailed inspection on my 2007 Range Rover and completed the work very quickly. Highly recommend!!
Lincoln MKX - Brake System Inspection - Gilbert, Arizona
Very professional and knowledgeable. Very good business sense and cordial. Thank you for taking care of my car today! ☺

Robert

22 years of experience
185 reviews
Robert
22 years of experience
Toyota Prius - Brake System Inspection - Grapevine, Texas
Very pleasant, helpful demeanor. Answered questions willingly and helpfully. Today was just a diagnosis; he'll do the repair in a couple of days - very quick response.

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