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Master Cylinder Problems

Madhurjya Bhattacharyya
Master cylinder problems are faced by most car owners, and are caused mainly due to wear and tear in the master cylinder. Here we give you the causes and symptoms of this condition.
An important part of the braking system of a vehicle, the master cylinder, is responsible for converting non-hydraulic pressure to hydraulic pressure, thereby helping other components in the braking system to stop the car. Without it, the pressure applied on the brakes would be of no use.
If it gets damaged due to some reason, it won't be able to perform effectively, which means that the vehicle would not have the power to stop. So, it's extremely important to determine the master cylinder problems and repair them fast enough so that you can have a smooth ride.


  • If there is a problem with the master cylinder or if it fails, you would notice a squishy or soft feeling while pressing the brake.
  • If constant pressure is applied on the brake pedal, say for example, if you are stopping at a stop light, the brake would sink to the floor. Moreover, the brake fluid would leak internally.
  • When the brake pedal moves further than its intended position, it's called 'extended travel'. If this happens, you will have to press the brake pedal over and over again so as to stop the car from moving forward. In addition to that, a red dash light would also be flashed, which indicates that the vehicle is low on brake fluid.
  • Many a time, people say that there would be leakage of brake fluid if the brake pedal is soft. However, this need not be the case always. There may be internal leakage, which can make the brake soft, thereby, requiring you to press the pedal a number of times.
  • Usually, this component has a plastic reservoir, which helps in holding the brake fluid. The plastic reservoir is attached to the metal part with the help of rubber grommets. These grommets move due to brake pedal and brake fluid pressure and over time, they wear and tear, thereby causing problems.
  • If the rubber grommets are damaged, a clear liquid, which is the brake fluid would come out, thereby, reducing the power of the brakes of your vehicle.
  • There are metal brake lines, which are attached to the cylinder, and when there is wear and tear of these brake lines, the brake fluid leaks.
  • Moreover, there may be leakage of brake fluid from behind the component due to damage to the O-rings. If this happens, the fluid would flow to the power brake booster.
  • The fluid also dissolves paint quickly, thereby leaving signs of bubbled paint and signs of blistering.


For repairing, you first need to identify the master cylinder and the reservoir, besides identifying the fluid lines and the other components. Remove the cap of the brake fluid reservoir, so as to get rid of the old brake fluid. Once you have removed the brake fluid, refill the cylinder and reinstall the cap. You also need to remove the electrical lines, which connect to the sensor of the fluid level. Moreover, you also need to remove the safety clips before you can remove the whole of the cylinder.
So, if you find any problems with your component, you need to immediately repair it. You can opt to do it yourself, which would save you a lot of money, or you can get it repaired from a mechanic shop. If you find that the brake is soft, check the levels of brake fluid and see if it is due to less brake fluid.