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How To Spot A Bad Or Failing Master Cylinder

How To Spot A Bad Or Failing Master Cylinder

A bad brake master cylinder can result in several issues. Here are some common red flags that indicate a faulty master cylinder:

1. Unusual Brake Pedal Behavior
Your brake pedal should reflect any major problems in the sealing or force distribution of your master cylinder. 
For example, you might notice a spongy brake pedal — where it’ll lack resistance and may sink slowly to the floor when pressed. The brake pedal may also not spring back smoothly into place after you remove your foot. This is usually due to an issue with your brake fluid pressure – which is likely caused by a bad brake master cylinder.
As a general rule, take your car to the mechanic whenever your brake pedal suddenly starts acting differently.

2. Brake Fluid Leaks 
Brake fluid leaking under your car is a clear sign that something is wrong. If this happens, make it a point to have your mechanic check your brake fluid reservoir. A leak will cause the brake fluid level to drop.
Luckily, the master cylinder has several seals inside it to keep the brake fluid and brake pressure contained. However, if any piston seal wears out, it’ll create internal leaks. 
A severe dip in your brake fluid level will compromise the performance of your brake system and your road safety.

3. Contaminated Brake Fluid
Brake fluid is supposed to have a clear, golden yellow to brown color.  
If you notice your brake fluid turning a dark brown or black, something’s wrong.
If your brakes aren’t performing up to par, there’s a chance that a rubber seal in the master cylinder has worn out and broken down. This introduces a contaminant into the brake fluid and darkens its color.

4. The Engine Light Or Brake Warning Light Comes On
Newer vehicles may have brake fluid level and pressure sensors installed in the master cylinder. These will detect unusual drops in hydraulic pressure and alert you.
That’s why, if your engine light or brake warning light turns on, don’t ignore it. It could be a sign of master cylinder failure, especially when accompanied by any of the previous symptoms.

5. Weaving When Braking

The brake master cylinder usually has two separate hydraulic circuits to transfer the brake fluid to two different pairs of wheels. Any failure in one circuit can cause the car to drift to one side when braking. 

6. Uneven Wear In Brake Pads
If one of the circuits in the master cylinder has a problem, it can translate to uneven brake pad wear. One set of brake pads will wear down more than the other —  which can again result in your car weaving whenever you brake. 

Post time: Feb-22-2023