Your car’s master cylinder is one of the most important parts of its braking system.” The master cylinder converts mechanical pressure into hydraulic pressure that engages the brake calipers in the car’s wheels.” Without a functional master cylinder, the car’s braking system performs below par and can easily put you at risk of vehicular accidents or increased car repair costs. That is why you need to be familiar with the symptoms of a bad brake master cylinder.
You must know these signs because driving with a bad master cylinder is a bad idea. Why, might you ask? “A brake master cylinder serves as a valve that pushes brake fluid through the brake lines. ” It does this by pushing a metal rod (which is connected to the brake pedal) through a cylinder, which forces brake fluid through brake circuits to the car wheels. It is one of the key components of the brake system that car owners should pay attention to.
Symptoms of a Bad Brake Master Cylinder
Interestingly, the symptoms of a bad brake booster are similar to those of a bad brake master cylinder. The same applies to symptoms of a bad clutch master cylinder. Heck, some uninitiated folks might even confuse one for the other until a diagnosis is done. That said, you want to look out for the following symptoms if you are looking to steer clear of the potential issues that come with a bad brake master cylinder
1. You Get Warning Lights
One of the more obvious bad brake master cylinder symptoms is the dashboard warning lights that come on. Although brake warning lights apply to both the bad master cylinder and brake booster, it’s a good idea to run a check on your master brake cylinder when they come on.
This warning light is often triggered by a brake fluid level sensor located within the brake fluid reservoir. Barring those instances when said sensors fail, a brake warning light indicates that the brake fluid level is too low. If the lights stay on after you have topped off the reservoir with brake fluid, the chances are that there is a problem with the car’s brake master cylinder.
2. Brake Fluid Leak
This is one symptom that most folks overlook because it is linked to other car issues. It would be best to be wary of brake fluid leaks, given its role in the braking system. The master cylinder uses brake fluid to move the car’s brake calipers or brake drums into engagement.
When there is a brake fluid leak along the brake lines, the brake master cylinder won’t function properly. You can find evidence of brake fluid leaks by looking for drops of fluid under the brake master cylinder. Check closely for leaks at the fittings connecting the reservoir to the brake master. Examine for any leaks around the brake sensor. Another indication of a leak is that you have to top off your brake fluid more often than not.
Read Also: No Brake Fluid Coming Out When Bleeding [Causes and Fixes]
3. Spongy Brake Pedals
One very obvious symptom of a bad brake cylinder is a spongy brake pedal when you depress it. Functional brake pedals are firm, even a tad bit hard sometimes, depending on the amount of force you apply when stepping on the pedal. You get a spongy brake pedal when the master cylinder cannot generate the hydraulic pressure required to activate the car’s brakes.
One reason for this situation is the wear and tear of the ‘ rubber seals’ in the brake master cylinder. These seals are designed to keep brake fluid within the cylinder. In the event that they get worn out, a leak occurs, and that’s when you get the spongy brake pedal.
In essence, spongy brake pedals can be caused by a bad master cylinder or air in the lines. The latter reason prevents the brake fluid from moving around more efficiently. Other reasons for a spongy brake pedal are damaged brake lines, rust, and leaks in the brake calipers.
Read Also: Brake Pedal Hard and Brakes Lock Up [Causes and How to Fix]
4. Contaminated Brake Fluid
Damaged rubber seals within the brake master cylinder can contaminate the brake fluid. Openings in the damaged rubber seal let in debris and dirt, contaminating the brake fluid and reducing hydraulic pressure.
Once hydraulic pressure is reduced, stopping your car becomes difficult because the braking system cannot generate enough hydraulic pressure to stop the wheels. Stopping the car takes longer, and the risk of an accident increases exponentially. Your best bet is to observe the fluid to check if the brake fluid color has changed.
5. Sinking Brake Pedal
Under normal circumstances, a depressed brake pedal returns to its standard position the moment it is released. That’s why a sinking brake pedal is a strong pointer to a bad brake master cylinder. A sinking brake pedal is one that does not return to its normal position after being released.
A bad brake master cylinder can cause a sinking brake pedal. The brake master cylinder creates hydraulic pressure by compressing brake fluid, which applies the brakes to the car’s wheels. When the brake master cylinder ceases to function optimally, the result is reduced braking power and a sinking brake pedal.
A sinking brake pedal means that the brakes no longer function, so your best bet in such a situation is to test your brake master cylinder. You might give it a try if you know how to test if the brake master cylinder is bad. If you don’t have that technical know-how, then you should get professional mechanics to give your brake master cylinder a look.
FAQs
What Causes A Master Cylinder To Fail?
So what causes a master cylinder to fail? The truth is, a range of things can be responsible for a bad brake master cylinder. It is a mechanical device, so it is prone to wear and tear. The rubber seals can wear out, while their springs could fail at some point. Then there’s how you treat your brake fluid. Brake fluid absorbs air over time; that is why it is recommended that you replace it at stipulated intervals. When this is not done regularly, the moisture absorbed by the brake fluid can cause rust within the brake master cylinder.
What Is Wrong When The Brake Pedal Goes To The Floor?
If you have experienced this recently, you might want to get your brake system checked. It is often caused by a brake fluid loss, a bad brake master cylinder, or a bad brake booster. In most cases, the brake pedal drops to the floor when hydraulic pressure is lost. Your car’s braking system uses compressed brake fluid that flows through the brake circuits, applying the brakes to the wheels. When this pressure is lost, you get a brake pedal that goes to the floor.
What Is The Cost To Replace A Master Cylinder?
Sometimes, replacing a master cylinder might be your only bet. Replacing a master cylinder is not an overly expensive affair. The bulk of this cost lies in labor costs, as well as several factors: the service, the make, the year, and the car model. The amount of repair work required also affects the cost of replacing a master cylinder. A host of websites can help you determine how much it costs to replace a master cylinder.
How Do You Fix A Sinking Brake Pedal?
Fixing a sinking brake pedal simply requires addressing the issues that caused it in the first place. One such issue is a faulty master cylinder. This mechanical device has two sets of internal seals, which often become damaged after repeated use. In such situations, air might enter the braking system; brake fluid might backflow into the brake master’s fluid reservoir; or fluid might leak. Sinking brake pedals occur when there is insufficient pressure or brake fluid in the braking system. The best way to address fluid leaks and low pressure is to replace the brake master cylinder.
How Do I Change A Master Cylinder?
There are two ways to go about this. You either get professional help or you go the DIY way. If you opt for the DIY route, you must have the right toolbox with high-quality mechanic tools. Here are the steps you need to take to change a master cylinder:
- Remove the Brake Master Cylinder
- Bench Bleed the Brake Master Cylinder
- Install the New Brake Master Cylinder
Final Words
The brake master cylinder ensures your car’s braking system operates smoothly. However, this mechanical device can go bad from time to time for a variety of reasons. When this happens, the brakes stop functioning optimally, and you risk an accident. Thankfully, there are signs that accompany a bad brake master cylinder. The trick is to identify the symptoms of a bad brake master cylinder. Once you can do that, you can easily fix the root cause and avoid the complications of an accident.
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