Your car's brake system is a very delicate structure. It relies on a precise balance of brake fluid pressure in the lines, and that fluid must be clean and free of any contaminants. While most people know that dirty brake fluid is problematic, what some people don't realize is that moisture in your brake fluid can be just as dangerous, if not more so. Here's what you need to know about moisture and your car's brakes.
Brake Fluid Attracts Moisture
The composition of brake fluid makes it naturally attract moisture because of the glycol content in it. Because of this tendency, most brake fluid also contains an additive called TEG, which is designed to actually dehumidify your brake fluid. The TEG additive will help to keep the moisture levels down, which will help to protect your brakes.
Moisture Is a Serious Concern
While this moisture isn't a big deal in a very small concentration, if it starts to accumulate beyond about one or two percent, it will actually affect the boiling point of your brake fluid. If there's too much moisture in the fluid, it will reduce the boiling point, which means your brake fluid will boil at a much lower temperature than it's supposed to. Ultimately, this will cause your brakes to fail completely.
When brake fluid has the TEG additive, not only does it draw the moisture out of the fluid and reduce the risk of this problem, it also raises the boiling point of your brake fluid in general. TEG has a very high boiling point, so when it's added to brake fluid, it helps to control that boiling point effect from the moisture in the system.
You Can Test for Moisture in Your Brake Fluid
There are actually several ways that you can check your brake fluid for the accumulation of any moisture. One is through the use of a test strip that is similar to what you'd use to check the chemical balance of pool water. The test strip changes color based on the water concentration in your car's brake fluid, letting you know if it's reached a concerning level.
You can also test your brake fluid through the use of a digital, handheld refractometer. You simply place a couple of drops of brake fluid on the test spot of the refractometer, and it will analyze it and tell you what the water concentration is as well as what the boiling point is as a result.
Finally, you can take your car to a local mechanic to analyze the fluid if you don't have the test strips or the refractometer available to you. Your mechanic can test it and let you know if it's time to flush the system or if you just need additional TEG additive to control the problem.