5 Signs of a Bad Brake Master Cylinder

Bad Brake Master Cylinder

The brake master cylinder is at the heart of a modern car’s braking system. It sets off a chain reaction that leads to a series of different actions by different components of the braking system that work together to bring a car to a halt. 

When you have a bad brake master cylinder you will most likely have a variety of signs such as irregular brake pedal response, indicator light trigger, pedal won’t return, tainted, and out of line brake fluid. In this article, we will dive deeper and elaborate on each of these components.

In this article, we will discuss the various signs for a Bad Brake Master Cylinder like Irregular Brake Pedal Response, Indicator Light Trigger, Brake Pedal Won’t Return, Tainted Brake Fluid, Brake Fluid leaks out of the Line.

It houses the brake fluid and it is connected to the brake pedal by a connecting rod. When the pedal is depressed, the connecting rod is pushed into the brake master cylinder thereby creating pressure that pushes the brake fluids to the different parts of the braking system.

Several factors can cause the brake master cylinder to fail. This failure can cause the braking system to act abnormally. Several signs indicate a possible failure in the master brake cylinder.

1. Irregular Brake Pedal Response

Typically when the brake pedals are depressed and released, they should spring back to their original position. If they do not spring back to their original position, that might be an indication of a problem with the brake master cylinder. 

A loss of pressure inside the brake master cylinder will result in the brake pedals feeling spongy or mushy or cause it to slowly return to its original position or even not return at all. This loss in pressure could be a result of worn-out seals inside the cylinder resulting in leaks. This leak causes a reduction in pressure generated by the cylinder, hence the irregular brake responses.

2. Indicator Light Trigger

If your motorcycle is running on a bad brake master cylinder, one of the first signs it shows is a warning light. The light turns on and illuminates the dashboard when you step on the brake pedal. Typically, the pedal shakes and pushes the rod in the brake master cylinder. Once there is a decrease in the level of pressure of the brake fluid, this light will show. Keep in mind that the light will not be on only because the brake master cylinder is failing, but you need to check your brake master cylinder when you see this warning light on.

Newer model vehicles usually come fitted with a sensor at the base of the master brake cylinder. If for any reason the sensor detects a change in pressure in the brake cylinder, it will cause the ‘Check Engine’ light indicator or ‘Check Brake’ light indicator to flicker or remain permanently on.

3. Brake Pedal Won’t Return

Irregular brake response can also result from a sinking brake lever.  This way, the brake pedal fails to return to its normal position after you press and release your feet. Once this happens, you should inspect the brake master cylinder. The non-return of the brake pedal is a clear sign that your brake master cylinder is faulty.

4. Tainted Brake Fluid

The wearing down of the rubber seals causes brake fluid in the master cylinder to become discolored. Normal brake fluid should be clear in color or slightly golden yellow. If the brake fluid becomes dark or dirty brown, that is another indication that the master brake cylinder requires attention.

These signs should never be ignored as driving with bad or faulty brakes could have possible fatal consequences.

5. Brake Fluid leaks out of the Line

You will also notice that the brake fluid is leaking and wasting away once there is a failure of the brake master cylinder. The brake fluid is always found in the reservoir to make your wheels work smoothly. The brake master cylinder uses this fluid to also engage the brake calipers that house the brake pads. This way, the cylinder helps to activate diverse brake systems throughout the motorcycle wheels.

However, once the brake master cylinder, which often sits beneath the fluid reservoir, is failing, you will notice that the fluid starts to leak, unable to reach the wheels, brake circuits, and other components that need it for their own activation. What that means is that the brake fluid will leak out of the line as a result of the low level of the reservoir fluid which is also due to the wearing of the brake pads.

Failing Brake Master Cylinder: Frequently Asked Questions

Q: Can a brake master cylinder be repaired?

The most common repair work done on a brake master cylinder is to change its seals to stop leaks. These seals are made of plastic and over time they wear out. Once they do, a leak occurs and the easiest fix is to change the seals.

Q: How long does a brake master cylinder last?

Depending on the car model and type; the braking habits of the user, most master brake cylinders can go for 70,000-100,000 miles before they need repair. This can translate to once or twice during the life span of a car.

Q: How long does it take to replace a brake master cylinder?

The time it takes to fix a master brake cylinder varies. If the only repair work to be done is on the master cylinder itself, a change or repair should take about 45minutes to 1 hour.

However, if any other part of the braking system has been affected by the failure of the master brake cylinder such as the brake pads, the caliper, or rotors, then the repair work can take longer till all the parts of the faulty braking system are identified and fixed.

Final Thoughts

The brakes are a very vital part of the running of a car. Remember, the brakes can either make your ride safe or mar your experience on the road. Do not wait until the brake master cylinder completely stops working before you inspect your vehicle for any brake-related issues. So, it’s always a good idea to keep it running smoothly and in good condition. Once you notice any of the signs identified above, you should swing into action by having your mechanic inspect your braking system. You can find more tips and suggestions here on how to keep your car in great condition always or most of the time at least.