Xoutpost.com - Any GOTCHAs with Brake Fluid Flush on the E70?

Xoutpost.com (https://xoutpost.com/forums.php)

- X5 (E70) Forum (https://xoutpost.com/bmw-sav-forums/x5-e70-forum/)

- - Any GOTCHAs with Brake Fluid Flush on the E70? (https://xoutpost.com/bmw-sav-forums/x5-e70-forum/110259-any-gotchas-brake-fluid-flush-e70.html)

Quote:

Originally Posted by PeterQ (Post 1165210)

I have a MityVac vacuum pump with the brake bleed attachment that I've used previously with success on various Mercedes from 1970s to 2000s. Anybody used on of these on an X5?

I have. It works. Slowly, but works. I stopped using it though and just went back to the helper on the pedal method. :dunno: YMMV

And more recently... I've just gone to have the dealer do the brake fluid for my last 2 X5's that needed flushing. Guess I'm getting lazier in my old age.

With the motive power bleeder, I've done it with the wheels on when I first got the x5. Just tuck my head under the back for the rears and turn the steering wheel for access to the fronts. It's that easy.

Quote:

Originally Posted by robnitro (Post 1165223)

I bled mine while doing a brake job but felt like there would be enough room to do with the wheels on. Good to know! Next bleed is due in ~6 months so I'll probably go that route.

Quote:

Originally Posted by robnitro (Post 1162663)

The thing about flushing brake fluid is to remove water in the system.
Let's say a bad system has 10% water by volume.
If you change 90% of the fluid, now you have an average of 1% by volume water in the system.
Since brake fluid is hygroscopic, water in the abs system fluid amount will migrate to balance out in the rest of the fluid in short time leading to 1% water all over. That's why in older cars I never had issues with just changing the fluid in the reservoir more often. Water in more saturated sections migrates over to drier sections. Of course in the bmw, I do flushes to change more of the fluid but not everyone has access to ista and my point is that changing a majority of the fluid is the key to preventing water buildup and corrosion.

In cases where water doesn't mix with fluid, like silicone dot 5, the water builds up in the low points as the fluid doesn't "hold" the water like our brake fluid does.

I have one of those brake fluid testers that tells you the % that is water when you dip it in the brake fluid reservoir. Are these useless if it's only testing the portion I can actually reach? It's been almost 4 years since I last did the brake fluid and it's still registering as 0% or < 1% water (OK).

From what I understand, water gets evenly distributed in the system as brake fluid is hygroscopic. The dryer fluid will take moisture from the wetter fluid.

The dirt however will stay by the caliper due to rubber, but then it's the water that kills brakes.

A yearly turkey baster drain and fill of the reservoir is good. But with the motive power bleeder, it's so easy why bother with that method?