If You Have a Spongy Brake Pedal, Could It Be Your Master Cylinder?
The typical braking system on a modern-day automobile has many individual parts. Above all else, however, it relies on hydraulic fluid, which must be pumped with consistency to all four corners of the vehicle. Inside the braking system is a specific part known as a master cylinder that controls how much brake fluid is sent at any one particular moment. What should you know about its operation, and what can happen when it goes wrong?
During Normal Operation
When a driver puts their foot on the pedal, they should meet a certain amount of resistance. If so, this means that the master cylinder is doing its job and pushing the hydraulic fluid (which is not compressible) through to each caliper.
Signs of a Problem
If there is something wrong with the cylinder, the driver is likely to encounter a pedal that is "spongy." In other words, it feels as if there is more give than there should be, but in the worst-case scenario, the pedal could go all the way to the floor without any reaction.
How the System Works
Inside the master cylinder is a pushrod with a pair of pistons and springs. The pushrod extends further into the master cylinder when you activate the pedal and presses against the pistons. As it does so, this will allow adjacent ports to open, flooding the cylinder with hydraulic fluid. This fluid will then be forced through the brake lines to each individual caliper so that the braking process can begin.
When you take your foot off the brake pedal, the pushrod will retract, and the springs will return to their original position. This will close the ports and stop the brake fluid from flowing out of the adjacent reservoir.
Looking for Problems
You may be able to tell if you have a problem with your cylinder if the reservoir is unusually low. Sometimes, the rubber parts that seal the various ports can begin to perish, and if they do so, fluid may leak out. It's very unusual for the "hard" parts within the cylinder to fail (such as the pistons and springs), and if they do so, you'll probably need to replace the entire cylinder.
Service Time
In the meantime, always ensure that your master cylinder is serviced whenever you present the vehicle for a major check. The mechanic will take a close look at those rubber seals and replace them as needed before flushing the system out and restoring everything to normal. Look into car servicing near you.