Brake Fluid Flush

[01Y87]

How important is changing the brake fluid? I don't see that anywhere in the maintenance schedule yet the dealer was trying to sell me on it for $90. He said my brake fluid has a lot of moisture in it.....but isn't it supposed to take up all the moisture from the lines? I've never heard of regularly flushing it.

bruce

[Joe 1320]

All you would have to do is observe what the old fluid looked like as it was coming out, then compare it to the fresh fluid going in and you'll be a believer as to why it's a good idea.

[e40]

A change of brake fluid is required every 2 years (regardless of miles) on my Audi. Not sure why, but it's not too complicated either. Just suck out all the old fluid from the MC with a baster, replace it with new fluid. Then bleed around to all 4 corners.

[Injuneer]

He said my brake fluid has a lot of moisture in it.....but isn't it supposed to take up all the moisture from the lines?
bruce

The purpose of the brake fluid is not to absorb the moisture in the lines. Purpose is to provide a non-compressible, non-corrosive fluid that will not boil at elevated brake temperatures. Problem is, brake fluid does absorb moisture very easilly. Then it becomes corrosive and has a reduced boiling point. Now its eating up your brake lines and calipers and can boil under hard braking, reducing braking effectiveness.

If you never brake hard, you may never see the problem with the reduced boiling point. But you will start to see pistons corroding and getting stuck in the bores, and leaking seals.

An interresting link:

http://www.phxsyss.com/Strip%20Dip%2...ers%20Position

[Warren Seale]

What about the fluid for the hydraulic clutch? Is it a good idea to change this? I looked for a bleeder valve on the slave cylinder but didn't find anything.

Warren

[MN6WS6]

That service sounds like they are using BG products, which makes a specific machine just for doing this job. The bottom line, it works. Not just because I sell it through my work, but because I've had one done.

My Astro is a testament to this fact. The van had 270,000 miles when I had this done, and the brake fluid had NEVER been changed. The flush takes about 30 minutes to do, and the difference is dramatic. It uses DOT 4 brake fluid with a cleansing agent, and the cleansing agent works as well. You can pour it on old brake fluid and watch is dissolve the black away. My brake pedal feel was increased dramatically, the pedal rose up off the floor, and the braking effectiveness was significantly improved. Now granted, most folks will never see that many miles on their vehicle, so the change won't be as noticeable, but it does make a difference. The one time you have to brake hard makes it worth the money.