Q: What causes brake fluid leaks?

asked by on

What causes brake fluid leaks?

There are many factors that can lead to brake fluid leaks.

Let’s begin at the start of the system, with the master cylinder. This is a sealed unit with a reservoir to hold the brake fluid needed to operate the system. It may include a sensor that will illuminate a light to indicate a low level. The actual operational part of the master cylinder contains internal pistons with seals to build the pressure needed to squeeze the brake pads or shoes to stop your car. The brake booster rod pushes on these pistons, which have an external rear seal to keep the fluid trapped inside the cylinder. When the brake pedal is depressed, the pistons push the fluid and transfer the pressure through the brake system. Over time these seals can become worn and leak either internally or externally. A sign of an external leak is an area of missing or peeling paint on the brake booster just below the rear of the master cylinder. If the brake pad wear is excessive, it is possible for the caliper pistons to be overextended in their bores and pop out past the seal, causing fluid to leak past the piston. Flexible rubber brake lines can dry, rot, and crack or be damaged from abuse, road debris, or an accident. Metal brake lines can rust out, especially those subject to severe conditions where excessive salt is used in winter weather conditions. If the vehicle is near a salt water source, it can have the same effect on the lines over time. The seals in wheel cylinders will also wear over time and can leak fluid out onto the brake shoes. Even a loose brake bleeder screw can cause a leak.

Have your vehicle checked if you notice problems like a low brake pedal or a pedal that sinks down as you sit at a light with pressure applied to the brake pedal. No problem with your vehicle should be ignored, but certainly anything to do with the brakes, tires, steering, or fuel system leaks should be addressed as soon as you feel them occur. As with all concerns, regular maintenance checks will help to keep potential problems in check.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. What causes brake fluid leaks?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Will using the incorrect ATF on my car cause sensors to fail

With regard to the 2003 Acura TL Honda states in the Owner's Manual, "Always use Honda ATF-Z1 (Automatic Transmission Fluid). If it is not available, you may use a DEXRON III automatic transmission fluid as a temporary replacement. However, continued...

Q: My brother-in-law is fixing the car. First time yes it's been going on about two weeks finally the check engine light came on yesterday.

If the spark plugs are becoming coated with engine oil and there is excessive oil in the exhaust system, then there could be three symptoms to check. Symptoms PCV Valve could be plugged making the engine over pressurize and...

Q: Water in the break fluid.

Hello! The quick answer is yes we can get the water out. If you did not push on your brakes yet, then the water may not of made it past the brake master cylinder. The master cylinder would need to...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...