How To Check for a Brake Fluid Leak

If your car’s brake pads or brake shoes have worn out, you can normally expect your brake fluid level to drop. Such a scenario is easy to remedy: simply refill your car’s brake fluid. Suppose you have new brake pads and recently refilled your car’s brake fluid. A few days later, you discover that your brake fluid level is low again. What could be the most likely culprit?  There can only be one: a leak in the brake system, which is a more critical issue than just low brake fluid levels or worn out brake shoes. This article describes several tips in checking for brake fluid leaks.

Although a low level of brake fluid does not necessarily signal leakage (as in the case of worn brake shoes), the blinking red warning dash light would probably be the first indicator of leakage. If you are sure that your brake shoes are still okay, but you keep running low on brake fluid, it’s time to raise the warning flag.

The first thing to do when checking for leaks in the brake system is to locate the leaking point. You can do this by looking for wet spots on the wheels or tires, as well as on the driveway or road where your car is parked. If you do find them, check your brake fluid levels immediately. A puddle underneath the rear of the engine may often signal leakage in or near the master cylinder.

Sometimes, the leakage may not be in the form of drips that leave wet spots or puddles of brake fluid. The brake fluid may spray out of an unwanted opening in the brake hose or line whenever you step on the brake pedal to slow down your car. The airstream underneath the moving car can disperse this spray. Such a scenario will make it difficult to detect wet spots.

Inspect the drum of the wheel cylinder. If the wheel cylinder is leaking, the brake shoes and the inside of the drum will be soaked in brake fluid. For manual brakes, inspect the carpet inside the cab, or the area between the booster and master cylinder. If you notice wetness there, the most likely suspect is a leaking master cylinder seal.

You should also check for blisters in the paint of the booster, as they are tell-tale signs of brake fluid leakage. Brake fluid is corrosive and causes paint to blister. Check the brake lines attached to the master cylinder, as well. Brake fluid can also leak at the threaded connections of those lines.

Also check the rubber grommets used to mount the brake fluid reservoir to the master cylinder. Although these rubber grommets can withstand heavy shaking and movement, they can fail at some point. The leak can occur at the rubber grommets.

These are just some of the various ways to check for brake fluid leakage. If you suspect leakage and cannot find the leak yourself using any of these means, you should seek the help of an automotive mechanic. You would rather run out of gasoline than run out of brake fluid due to leakage.


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