What color is brake fluid when it leaks?

In this article, we will give you the correct answer to the question, “What colour is brake fluid when it leaks.” In addition, we will also give six causes that can cause the brake fluid to leak from the vehicle.

What colour is the brake fluid?

The brake fluid is Yellow. 

Modern vehicles use hydraulic fluids to enhance the braking efficiency of the vehicle. When the driver depresses the brake pedal, the pedal is connected to the master cylinder, which pushes the piston present in the master cylinder. The fluid present in the master cylinder is compressed and applies pressure on the piston present in the brake. In this way, the car brakes work.

However, in some situations, the brake fluid can leak from the system due to damage caused to the body. Below are the six causes of brake fluid leakage.

Damaged Brake Master Cylinder Reservoir

The brake master cylinder reservoir is generally made of plastic and can become brittle due to constant exposure to heat. Thus, once it becomes brittle, it can easily break even with the slightest impact of foreign material. Therefore a formation of a crack on the brake master cylinder can cause the brake fluid to flow out of the braking system.

The piston seal has failed.

The hydraulic braking system has pistons that are responsible for the application of pressure during braking. The piston is present in the brake calliper and the master cylinder. When the brake pedal is pressed, the piston compresses the fluid present in the master cylinder. 

There are seals present in the piston which restrict the fluid from flowing out, and if these seals are damaged, the oil can leak from the braking system. In such a case, the oil leak will be visible near the disc of the brake because the pressure generated by the master cylinder is transferred to the piston present in the calliper of the car.

Worn out brake pads, shoes, rotors, and drums

Braking involves a high amount of friction. Thus with continuous braking, the components such as brake pads and shoes can get worn out. Once the brake pads and the shoes are worn out, the piston present in the brake needs to extend more for applying the brakes. Therefore, the hyperextension of the piston can cause the seals present in the cylinder to break and cause brake fluid leaks.

Damaged brake lines and brake hoses

The hydraulic fluid from the master cylinder is transported to the brake calliper with the help of tubes and hoses. These hoses and tubes are generally made of rubber or metal. However, when the vehicle is used regularly, the continuous exposure to water and other foreign elements makes the brake line and hoses brittle. Hence, with time elapsed, these hoses and brake lines break, leading to brake oil leakage.

Damaged or Loose Bleeder valve

Each brake has a bleeder present on it. The function of a bleeder valve is to remove the excess oil from the brakes. When the new brake fluid is filled into the brake fluid tank, then during filling, some amount of air also enters into the system. Once the air enters the system, the braking efficiency decreases because the optimum brake fluid doesn’t reach the calliper. 

Hence, to avoid the situation of decrement in brake efficiency, the brake manufacturers install a bleeder valve used to remove air from the brakes. However, if the bleeder valve is broken, the brake fluid starts to leak from the braking system. Thus in such a case, getting the bleeder valve replaced is the best idea.

Faulty ABS module

ABS or anti-lock braking systems have become mandatory across the world. The ABS works on sensors that decide how much pressure must be applied to the brakes to prevent getting locked. 

Some parts of the ABS pump in your brakes contain high-pressure brake fluid. But due to constant usage, the seals in the ABS brake reservoir can get broken, and thus the brake fluid can start to leak from there.


In this article, we have answered, “What colour is brake fluid when it leaks.” Moreover, to provide more information behind the leakage of yellow brake fluid, we have also explained the different causes behind the brake fluid leakage.

Frequently Asked Questions (FAQs); What colour is brake fluid when it leaks?

Can you drive with a brake fluid leak?

The brake systems today are operated with the help of fluids. Hence if the fluid starts to leak from the brakes, then driving your car won’t be a good idea because the car’s braking will be significantly affected.

How much does a brake fluid leak cost to fix?

In total, you can expect to pay around $100 to $300 for a brake fluid leak repair job. However, if there is a leak in the brake master cylinder, you can expect to pay around $100 to $200.

What is the colour of brake fluid?

The brake fluid is yellow tint in colour. The colour is pretty close to the original colour before pouring it.

How long does the brake fluid last?

The brake fluid lasts for a maximum of two years. Hence, even if you are not driving your vehicle, you still get the brake fluid changed after two years.


  1. https://www.repairsmith.com/i/blog/brake-fluid-leak/#brake-fluid-leak-causes