Did You Know that Brake Fluid Can Boil?
If you have even a passing interest in how your car works, you may know that the braking system relies on a special type of fluid. But did you know how much abuse the brake fluid comes under during everyday use and how it needs to deal with extremes of temperature while remaining intact? It pays to understand this so that you can always look after your brake fluid and, crucially, change it as and when needed. So, what do you need to know about brake fluid and car servicing?
Fluid at Work
Whenever you put your foot on the brake pedal, this activates a cylinder that pushes the brake fluid through different lines and hoses to each wheel. As this fluid cannot be compressed, it will, in turn, apply pressure to the pistons that sit within each calliper. Those pistons will push pads made from friction material against a brake disc attached to your road wheel, causing the vehicle to slow down. So, as you can see, good quality brake fluid is a very important part of the picture.
Extreme temperatures are generated during extended or heavy braking. This can cause the liquid to become so hot that it would boil if it were not pretreated and designed accordingly. If it were to boil, it would turn to vapour and would no longer be able to transmit the pressure from your foot to the road wheel. Clearly, that would be a disaster, as you wouldn't be able to stop!
When the brake fluid is new, it can easily deal with these extremes. However, it has "hygroscopic" properties, which means that it also has the capacity to absorb tiny particles of moisture. As time goes by, moisture can leak into the system through connections, joints, braided hoses and the fluid reservoir. This water may contaminate the brake fluid to such a degree that it can lower its boiling point. The lower the boiling point, the more likely the fluid is to degrade, which could significantly affect the car's braking ability.
What You Need to Do
Brake fluid is specially designed so that it has a very high boiling point and is also designed to take into account a certain amount of water infiltration. Yet it cannot last forever, and you certainly need to take the vehicle to a mechanic according to manufacturer-recommended guidelines. They will check the system's integrity and replace the brake fluid so it is ready for more abuse ahead.