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Jim Grant's Tech Tips
Brake Fluid Service
Q:
I recently saw an ad in the paper where a garage owner said that very
30k miles, one should drain the brake fluid and flush and replace it with
new fluid. What’s your opinion?
A:
Brake fluid is a hygroscopic fluid, which means it is designed to absorb
moisture, yes water. Why would you want brake fluid to absorb moisture?
A vehicle that is in motion has energy. To stop that vehicle you have
to remove that energy. To do that the energy is converted to heat. I know
it seems odd and you may think that the exhaust fumes have gotten to me.
I won’t argue that. But it is true that it is the creation of heat
that stops your vehicle. When you step on your brakes two pieces rub together.
The friction of this makes heat and lots of it. Brakes will easily get
hotter than 212 degrees. Guess what would happen if water wasn’t
absorbed by brake fluid? It would collect and when you really needed to
stop? The water would boil, change to a gas/air. Your vehicle wasn’t
designed to stop with air brakes. So to convert that energy you’d
have to hit something! Not a good idea. Brake fluid service/flush is a
needed service. Some manufacturers list brake fluid flushes as scheduled
maintenance, others do not. How does one know if their vehicle’s
brake fluid needs service? There are electronic testers and test strips
that can measure the moisture content in brake fluid. Regular service
of the brake fluid will prolong brake component life and allow anti-lock
brake systems to function correctly.
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