Every time you press the brake pedal, the calipers create friction around the rotors of your wheel, bringing your car to a safe stop. Almost all passenger car braking systems use hydraulic oil to transmit the force required to stop. An important component called the master cylinder converts the movement of the brake pedal into hydraulic pressure.
Over time, the master cylinder experiences a lot of pressure-related wear that eventually leads to failure. Unfortunately, many owners have difficulty recognizing the signs of a master cylinder problem. This article takes a closer look at three symptoms of poor braking that can stem from a faulty or faulty master cylinder.
1. Spongy or unresponsive brake pedal
Few braking problems can cause as much pressure as the brake pedal fails to produce the required braking force. Spongy or unresponsive pedals can reduce the effectiveness of your brakes. In extreme cases, your brake pedal might even sink all the way to the floor without any noticeable effect.
This nerve-racking problem usually stems from a leak in the brake fluid system. Leaks can occur in several places, including the master cylinder itself. Inside the master cylinder is a piston. When you press the brake pedal, the connecting rod pushes the piston, which increases the pressure on the hydraulic oil. This increase in pressure can cause your calipers to close.
Master cylinders with internal leaks have difficulty reaching the necessary hydraulic pressure. Instead of pushing the caliper, brake fluid leaks back around the rubber seal that protects the piston. Degraded seals are often at the heart of the problem.
2. Contaminated Fluids
As the seals inside the master cylinder wear, the rubber can chip and degrade, often resulting in visual contamination of the brake fluid. For example, you may notice small black specks inside the reservoir. You may also experience a spongy brake pedal if this contamination stems from the breakdown of the master cylinder seal.
The seal will naturally break down over time. That said, you can extend the life of your master cylinder seals by always using the manufacturer's recommended brake fluid. Likewise, change the brake fluid every 20,000 miles. Fresh brake fluid resists heat build-up better than old brake fluid, minimizing stress on seals and other components.
3. Braking resistance
Braking resistance occurs when your brake pads fail to release the rotor when you lift your foot off the brake pedal. Resistance can arise from mechanical or hydraulic problems. Mechanical problems include misaligned or corroded brake calipers, incorrectly installed wheel bearings or incorrectly sized pushrods.
On the hydraulic side, braking resistance can stem from overheating, hose failure, or master cylinder piston problems. Under normal conditions, when you release the brake pedal, the piston moves back to its resting position. This movement reduces the pressure on the fluid, allowing the calipers to reopen.
However, if the piston is damaged or deformed, it may not move smoothly within the cylinder. Therefore, your brake calipers may not release in sync with your brake pedal. In this case, the only solution is to replace the master cylinder.
Braking resistance can also arise from a master cylinder containing excess brake fluid. The master cylinder contains a special reservoir to hold the fluid that flows back when you release the brake pedal. However, if there is too much liquid in the cylinder, this reservoir will not have enough room to accommodate the inflow. As a result, the calipers are still under pressure and cannot be fully released.