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.
This article originally appeared on YourMechanic.com as What Can Cause Brake Fluid to Leak From the Brake System? and was authored by Elan McAfee.