Symptoms Of a Bad Master Cylinder In Your Truck

The master cylinder in your truck is an essential component for safe driving since all the operations of your brakes solely rely on the master cylinder. Like other parts of your truck, it can also fail, and understanding the signs it shows when it becomes faulty can help you rescue it before it stops working completely. In this guide, we will go through some of the symptoms of a bad master cylinder to help you know when to replace it.

What is a Truck Master Cylinder? 

The master cylinder is a hydraulic device of the braking system that pushes the brake fluid through the brake lines whenever you engage and disengage the brakes. It has two chambers, each with a piston connected to the brake pedal. 

When you press the brake pedal, the pistons push the fluid from the reservoir to the brake calipers or wheel cylinders through the brake lines. It is this action that creates the friction which stops your truck. But things might not go as planned when you have a bad master cylinder.

Signs of A Bad Master Cylinder

The brake cylinder coordinates all the braking operations within your truck. Safe driving solely depends on its condition. If you have a bad master cylinder, you will experience a number of signs you should watch out for. Here are the common signs.

Low Brake Fluid Levels

The master cylinder supplies the hydraulic pressure to the parts of the brakes at the wheels. If the fluid leaks, air will get into the system, and the pressure will reduce. Low pressure implies that the entire braking system will not work effectively from the brake pedal to the pads or shoes. If such happens, you will note that the brake fluid level is low or empty, topping up is not a solution. Instead, check the condition of the master cylinder.

The Brake Pedal Feels Super Soft or Spongy

A leak in the braking system can result in a spongy brake pedal and lead to brake failure. Whenever your brake pedal sinks freely is an indication that the brake fluid is being pushed out of the system and the presence of air in the brake line. Either way, the way the performance of your brakes will be interfered with. 

Dirty brake Fluid

Brake fluid impurities could point to a bad master cylinder. When your brake fluid is dirty is an indication of a problem with the master cylinder. The fluid should either be clear or golden, but when it is colored, it indicates the presence of impurities. The impurity that makes the brake fluid dirty comes from the master cylinder, which allows moisture into the system or metal particles from the cylinder is falling into the system.

Grinding Noise

When you press the brake pedals and hear a grinding noise is an indication that the master cylinder is becoming faulty. The noise usually results from the warn-out brake components but not the master cylinder. It indicates that too much pressure is exerted on the front or rear brakes, resulting in premature wear and grinding noise. 


The master cylinder of your truck is part of the braking system that facilitates how the brakes’ internal and external parts work. Just like other parts of your truck, it wears out with time. Before it fails, you should be able to know when you have a bad master cylinder by following this guide.