Brake Fluid replacement?

[abcxyz]

Hi, I think the manual says to change the brake fluid every 2-3 years. Is this really necessary since it's a closed system? Would it be sufficient to just top it off, or are there any adverse effects from not changing it every 2-3 years. I checked mine out and it still appears clear and nearly full. Please let me know. Thanks a lot!

[Yurick]

Well,
It is not nearly as critical to stick to the schedule with brake fluid replacement as oil changes. However, if moisture comes into the brake system, you are risking rusty brake lines and brake calipers. My personal belief is that it should be sufficient enough draining, refilling and bleeding the brake system each time you replace brake pads. Hmmm; come to think of it, it comes out to be every 2 to 3 years.

[coolbear1]

The system is not realy closed, the cap has to vent to the atmosphere to prevent building a vacuum. Changing the fluid (Bleeding) isn't as important when the brake system calls for dot 3 fluid, because plain dot 3 is mineral based fluid. But with dot 4 fluid,(Synthetic) the nature of the compounds absorb moisture much faster than mineral oil fluids, thus the more frequent changes. When the system is not maintained properly, moisture will eventualy get into the brake sytem, rust the steel lines, get peices of rust into the system and cause premature falure of the rubber o rings in all the brake components.

[Dave at Pelican Parts]

Even when the brake system is maintained properly, water will still wind up in the fluid. The fluid is hygroscopic--it absorbs water out of the air. And it must, as coolbear said, be open to the air to prevent creating a vacuum. So it will get water in it over time.

Wet fluid not only boils easier than fresh "dry" fluid, but the water in it can attack any steel parts of the system.

Change the fluid every 2-3 years, or more often if you really use the brakes hard. (E.g., if you track the car, or drive on steep mountain roads every day.)

--DD

[Jeron]

I changed the fluid in my grandfathers truck after 16 years with the first brake change. No towing and light use, obviously.

My wifes car 330i gets new fluid at each brake change because its easy for me.

My M3 gets new fluid every 6 months. Monthly track use.

Every brake change is the a good rule. The danger of going longer is not so much safety as longevity of the system components. You will never boil the brakes with normal street driving.

[abcxyz]

Thanks for your responses and input...I had it bled and flushed about 2 years ago, and i don't do mountain or very hard driving, so I guess I'll just change it at the next brake job then.

[Giorgio]

I have a 1997 bmw328is and it has a traction control and abs and I was told that to bleed the b rake system you have to take it to the dealer because they have the right tools to do that. please help,giorgio

[Jeron]

That is what it says in the Bentley too.

That is completely false. You can bleed your brakes using any of the typical methods.

What you cant do is cycle the ABS pump but it is not necessary to get the majority of the fluid changed.

[Yurick]

Yuo just need one person to pump and hold the brake pedal, while the second person is bleeding the system.

[coolbear1]

A pressure bleeder works great.

It makes it a fast one person job.

I made my own for allmost nothing.

[Giorgio]

to jeron,yurickand coolbear1, thanks for your responses and input. giorgio