Skip the auto shop - Our mechanics make house calls

Q: How does brake fluid get dirty?

asked by on

How does brake fluid get dirty?

A: One way that brake fluid becomes contaminat...

One way that brake fluid becomes contaminated is when moisture is absorbed by the brake fluid through rubber brake lines. This moisture will break down the brake fluid and cause rust in the brake system. Excess moisture in brake fluid will increase its temperature because the boiling point of water is lower than that of brake fluid. When this happens air gets into the brake lines and the brakes may become less effective. Brake fluid that has been contaminated by water or moisture can also weaken the master cylinder and caliper rubber seals and lead to brake leaks and an overall failure of the brake system. This type of contamination most commonly occurs in an environment that is particularly humid and in conditions of heavy braking. Another way that brake fluid becomes contaminated is when grime and debris from the brake system accumulates in the brake fluid. Over time, the heat that is generated from braking causes the brake fluid to break down and become contaminated. Brake fluid should normally be changed every two years but this is something that may already be included in the maintenance schedule for your vehicle. Pay close attention to the color of your brake fluid. Normal brake fluid should be a light yellow color and look almost clear, while contaminated brake fluid looks dark brown or black in color.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: My car needs to have its brake pads changed and has a crank sensor problem

Hi there. Before we assume the root cause of the problem, there needs to be a proper diagnosis performed. There is nothing more costly than replacing parts that are not needed or a misdiagnosis resulting in unnecessary parts being replaced....

Q: Vehicle is shaking when braking from above 35 mph

Hi there. From what you're describing, the squeaking noise is common with a brake pad on the front of the vehicle that is wearing down to the wear indicator mark that is making contact with the rotor. This could be...

Q: Leaking Steering Fluid

If the rack is leaking, it has to either be rebuilt or a properly re-manufactured rack from a name brand vendor has to be installed. In either case, the rack will have to be removed from the vehicle. In case...

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.