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Brake Fluid Flush: Why Should You Care?

American Government Special Collections Reference Desk

Brake Fluid Flush: Why Should You Care?

JD Durham (SubmitYOURArticle.com)
May 17, 2011


Copyright (c) 2011 JD Durham

How brake fluid flush or replacement ends up in the mind of motorists is usually a mechanic recommends it. When the mechanic tells you that it is going to cost you $60 to $100, you think "Hey, my car stops fine. Why should I care about that!?"

I could tell you that the National Traffic Safety and Highway Administration (NTSHA) found that over 20% of vehicles in a sampling had moisture content in their fluid that exceeded 5%. Or that a Car Care Council survey found brake failure was on the minds of over half of the motorists they surveyed.

Unfortunately it is hard to understand something like brake fluid needing replaced when you can't relate to it. Let's try to understand some simple things to unravel it, shall we?

The brake fluid is the hydraulic fluid that is used to apply pressure via the calipers or wheel cylinders on the brake pads and or shoes to stop the car. That fluid does a great job, but looses it's effectiveness as it absorbs moisture. The higher the moisture content, the lower the boiling point of the fluid and the more likely your brakes are to fade (not work) when you need them.. Now you can understand that moisture (water) in the fluid lowers the boiling point to possibly a very dangerous level.

To further place things into a perspective that you can relate to, a normal stop from 60 mph generates enough heat to move a 1 cubic foot block of ice through the stages from ice to steam in under 5 seconds. That is a lot of heat! In a panic stop from that same speed the heat is even greater.

If we have old fluid in the system that has been heated and cooled many times during the normal operations of braking, that fluid becomes contaminated with moisture, dirt, rust and other things which attacks all the hydraulic components including master cylinder, ABS pump, calipers, wheel cylinders, lines, etc. Most manufacturers have some suggested interval to perform a brake fluid flush. These intervals vary from 2 to 4 years and mileages from 24,000 to 60,000 miles. Experience has taught me this is too long between services.

Years ago when we performed brake services, it was a standard practice to "bleed" the brakes at each wheel when collapsing the caliper or cylinder to install new pads or shoes. Unfortunately two things have stopped this beneficial practice; the first is the manufacturers are no longer suggesting it be done; the second is as mechanics we have to work within the constraints of the shop owner and the customer. The shop owner wants it done faster and the customer doesn't want to pay for it.

These items have significantly increased the cost of brake service because we now have more hydraulic parts being replaced and more brake discs (rotors) being replaced when the hydraulic component seizes and destroys them.If you want to have a safer car and one that is less costly to repair the brakes, then opt to have your brake fluid replaced about every two years or at least have the old fluid bled off at the wheels once a year.

There are lots of tools to check for moisture from strips to electronic testers like the Wagner Brake Fluid tester. Where the problem arises in using this equipment is that the mechanic must drain some fluid from one of the wheels (preferably a front) to test otherwise the readings are going to be false. They typically don't want to do this as it takes their time and most car owners are under the false impression that "the mechanic is just trying to sell them something." So if they do anything at all it is usually to test at the master cylinder. I have personally tested this at a wheel and the master cylinder and found a large discrepancy in the boiling points indicated. Want to guess which one had a lower boiling point?

Now you know the mechanic was not "tryiing to sell you something", he was protecting your life, your family, your car and all the other motorists that you travel with each and every day.

JD Durham is a World Class Technician, an Automotive Hall of Fame honoree with 45 years experience in the automotive service and repair industry. He is a staff writer at http://straighttalkautomotive.com where you can find other articles tools and information to help you with maintaining your vehicle.

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