What is the purpose of a brake master cylinder in a car?
The brake master cylinder contains brake fluid and is connected to the brakes through the brake pipes and hoses. When you step on the brake pedal, brake fluid flows from the master cylinder to the braking unit at each wheel, creating enough friction to slow down and/or stop the car. The brake master cylinder has internal and external seals that can wear out over time.
If the external seals have worn out, they will leak brake fluid, reducing the amount of fluid in the car and causing the brakes to malfunction. Worn external seals can also leak the fluid into the brake booster and destroy it. The brake booster is essential for the proper functioning of the brakes, so if brake fluid has leaked into it, replacement is required.
If the internal seals have worn out, the brake fluid will continue to circulate inside, instead of being directed to the brakes. This weakens brake performance. The brake pedal will feel soft. When you apply the brakes, the pedal will go all the way to the floor without significantly slowing down or stopping the car.
After replacing the brake master cylinder, the mechanic should flush the old brake fluid out and replace it with new brake fluid.
Considerations when replacing a master cylinder:
- A leaking brake master cylinder can sometimes result in a broken brake booster; in this case, both elements will need to be replaced.
- Brake systems are extremely sensitive to debris, so they need to be cleaned thoroughly before and during the replacement of a master cylinder.
- The air will need to be bled out of the system before the new master cylinder is installed.
How to replace a brake master cylinder:
- Inspect brake master cylinder for leaks.
- Inspect brake booster.
- Remove the brake master cylinder if faulty.
- Replace with new brake master cylinder if faulty.
- Change the brake fluid.
- Bleed entire brake system of air.
- Clean brake fluids from all the wheels.
- Perform brake safety inspection.
Your mechanic should check the amount of brake fluid every time the car is serviced. If you feel a change in the way your brake pedal feels (a softer pedal), you should have a mechanic inspect the master cylinder and brake hoses. In most cars, the brake warning light should come on when the amount of brake fluid is lower than the manufacturer’s recommended amount.
What common symptoms indicate you may need to replace the Brake Master Cylinder?
- Brake warning light is on.
- Brake fluid leak (clear fluid on the ground or under the brake pedal inside the car.)
- Soft brake pedal (pedal goes all the way to the floor when pushed).
Do you need to replace a brake master cylinder?
All services associated with proper function of your brakes are important. In addition to safety issues, ignoring small repairs can quickly lead to more serious (and more expensive) problems.