PeachParts Mercedes-Benz Forum - View Single Post - Why should I flush my brake fluid every year, you ask?

Richard Eldridge · #25 10-31-2002, 02:23 PM

My old 1977 Toyota Celica once got a seized wheel cylinder. When I replaced it, I noticed that there was a rust spot, nearly round, on the inside of the cylinder, just as you would assume would be made by a drop of water trapped inside. In addition, the fluid was nearly black.

I assume that this stuff was black because it had slowly been dissolving rubber from the seals and other rubber parts, since dust would have a hard time finding its way into the master cylinder.

I had heard of silicone brake fluid and replaced the system with silicone fluid, using a Mity-Vac.

The car seemed to have a harder pedal, and stopped as well as any car with disc/drum brakes. I never had another wheel cylinder or caliper go bad after that, over 75,000 miles and 7 years.

I also replaced the fluid in my wife's 1980 Toyota Corona. Again, I never had another brake problem, other than usual wear.

Before that, the procedure was to replace both wheel cylinders and all the shoes everytime the damned thing seized, roughly every 3 years on every other car I owned. When I as younger and more foolish, I would take the brakes to Midas and they would change all sorts of stuff, but leave the fluid as dark as it was, unless changing the Master Cylinder. I assume that this was in hopes of zapping me again with their greatly overpriced, not necessarily needed and not all that competent work.

Then a neighbor showed me how to do brakes myself.

The silicone fluid did not change in color in 7 years on the Celica and 6 on the Corona.

On my Mercedes, I used DOT 5.1, being as they don't recommend silicone DOT 5.0.

The question is Being as silicone is so obviously better than hygroscopic fluid that has alcohol in it (which is why it attracts H20, why does MB not use silicone fluid? Is this related to the Automatic Brake Pumper gizmo?