Skip the auto shop - Our mechanics make house calls

What Can Cause Brake Fluid to Leak From the Brake System?

brake fluid leak

The braking system in a vehicle is designed to circulate brake fluid, using it create the pressure against the wheels when slowing or stopping is desired. It is a closed system, which means that the fluid doesn’t evaporate over time and require periodic topping off when it is operating optimally. If you have a brake fluid leak, it is anything but natural and is the result of another problem in your braking system. The only possible exception to this rule is if you’ve recently had parts of your brake system serviced and the brake fluid reservoir is low; this just means that the fluid has naturally settled throughout the system and required a little more to be completely full.

Since a brake leak can lead to brake failure, this is not an issue to take lightly and requires your immediate attention for your own well-being and the safety of others. Here are some of the most frequent reasons why a vehicle may leak brake fluid:

  • Damaged brake lines or fitting: This is a very serious issue that, although inexpensive to fix, can endanger lives if not tended to quickly. You will know if there is a hole in one of the lines or a failed fitting if there is little to no resistance when you press the brake pedal, even after pumping it several times to try and build up pressure.

  • Loose bleeder valves: Also known as bleeder bolts, these parts are situated on the brake calipers and serve to remove excess fluid when servicing other parts of the brake system. If you have recently had a brake fluid flush or other work, the mechanic may not have tightened one of the valves fully.

  • Faulty master cylinder: When brake fluid accumulates on the ground underneath the rear of the engine, the master cylinder is a likely culprit, although it could also indicate an issue with the slave cylinder. With other brake leak issues, the fluid tends to pool near the wheels.

  • Bad wheel cylinder: If you see brake fluid on one of your tire’s walls, then you probably have a bad wheel cylinder if you have drum-style brakes. Another symptom of a brake leak from a wheel cylinder is your car pulling to one side as you drive due to uneven fluid pressure.

If you have seen evidence of your car or truck leaking brake fluid or have checked the levels and found them low, seek help immediately. Our mechanics can come to you for a complete inspection to diagnose the cause of your brake fluid leak.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...
P0359 OBD-II Trouble Code: Ignition Coil I Primary/Secondary Circuit Malfunction
P0359 code definition The P0359 code indicates that a fault has been detected in one of the vehicle’s ignition coils, generally the number 9 coil. This code can also be associated...
P0608 OBD-II Trouble Code: Control Module VSS Output "A" Malfunction
P0608 means there is an malfunction in the vehicle speed sensor A control module often due too faulty speed sensor or shorted electrical wiring.


Related questions

Q: How Does Brake Fluid Work?

Brake fluid is a specialized type of hydraulic fluid whose properties are designed to provide pressure transfer to operate the brake while dissipating the heat developed during braking. Brake fluid is hygroscopic, which means it can absorb water, so it...

Q: Replacing Mopar ATF 4+ fluid with Valvoline ATF 4+ fluid

Sure you can. They all mix. Just make sure it's the 4+. It's the same design; they all mix perfectly fine. There is no problem in doing that at all. If you would like to have a technician perform this...

Q: Brakes grab and lock up occasionally - 1990 Chevrolet G30

Make sure the brake pushrod has some freeplay, how ever small. Also check the "check valves" on the hydroboost system to make sure they are releasing residual pressure appropriately.