Your toilet isn't the only thing that needs a good flush to work properly. Some automotive systems do, too—notably, your brakes.
While most motorists know they should seek a professional opinion if their brakes grind or squeal, that may be the extent of their brake system maintenance. Many people take the condition of their brake fluid for granted. It's out of sight, out of mind.
When you step on your brake pedal, brake fluid is used to transmit that force equally throughout the brake system. The fluid's pressure then activates a friction device—a brake pad, brake shoe or both—against the wheels' rotors or drums. The more pressure applied, the greater the friction and the quicker the vehicle stops. For this to happen safely all system components must be in good working order, and it all starts with the brake fluid.
Brake fluid does not last indefinitely. It is hygroscopic, meaning that it absorbs water from the air. Over time, this increasing water content will dilute the brake fluid and allow it to boil at a lower temperature than the system was designed for. How does this affect you? When the brake fluid boils, vapor is produced. Then, when you apply your brakes, much of the pressure is wasted on compressing this vapor instead of getting to the friction devices. With enough water buildup, brakes can fail completely-perhaps with catastrophic results.
Brake fluid also contains corrosion inhibitors to protect system components such as the brake calipers, wheel cylinders, brake lines and master cylinder from moisture, acids and sludge. When the brake fluid is old and the inhibitors wear out, corrosion can become a major concern. One of the biggest and most expensive concerns is the damage it can do to the anti-lock braking system (ABS) components, such as the modulator and internal valves. If an older car needs to have its ABS unit replaced, the replacement cost may exceed the value of the car!
Most repair facilities are cognizant of the problems caused by worn-out brake fluid and will have the necessary equipment on hand to check its condition. There are several devices a technician can use for this task. "Dip strips" check for moisture content or copper content in the fluid (if there's copper in the fluid, it shows that the copper brake lines have corroded). Other devices can measure the fluid's electrical resistance or its refractive index.
Is it time for a flush? If your brake fluid is very dark in color, or you cannot remember the last time your system was flushed, it might be time to seek the advice of a professional.
EnCompass