Do I get a brake line flush...

[Flycaster]

Going in for my 2-year annual maintanence. Only have 9.5K miles. Will the stealership flush my brake lines as part of the maintanence program when they change my oil/filter?

[Craig in Alabama]

Hi Flycaster,
I just had mine done, although it was at the three year mark for me.
I believe BMW will just suck the old fluid out of the reservoir and refill. That has been the approved method for lots of cars lately. I questioned Honda about it and they do the same thing. I wait on my car when they do the service at the BMW dealer and it only took them about an hour.

Craig

[pbdm4k]

Originally Posted by Craig in Alabama

Hi Flycaster,
I just had mine done, although it was at the three year mark for me.
I believe BMW will just suck the old fluid out of the reservoir and refill. That has been the approved method for lots of cars lately. I questioned Honda about it and they do the same thing. I wait on my car when they do the service at the BMW dealer and it only took them about an hour.

Craig

Replacing the fluid in the reservoir is hardly the best way of doing it, this doesn't replace the old fluid in the lines. You're better off flushing the lines yourself, or if you're not the home mechanic type, perhaps bring it to a private garage. Every 2 years should be about the right time to flush the brake fluid.

[20Ducks]

I just flushed mine. Took 30 minutes with my assistant (wife) pushing the brake pedal. Reason: I cooked the DOT4 fluid at a recent HPDE. It was fun!

[Rey]

Three is a school of thought that says brake fluid circulates slowly throughout the brake system - that explains how the fluid in your reservoir becomes dirty. If it didn't circulate it would remain clear. This school says just change out the reservoir from time-to-time.

[20Ducks]

Originally Posted by Rey

Three is a school of thought that says brake fluid circulates slowly throughout the brake system - that explains how the fluid in your reservoir becomes dirty. If it didn't circulate it would remain clear. This school says just change out the reservoir from time-to-time.

Agreed, esp when flycaster has less than 10k miles on the clock!

[Flycaster]

Originally Posted by 20Ducks

Agreed, esp when flycaster has less than 10k miles on the clock!

Great, save me som $. Let's hear more support of simply changing out the reservoir. And if so, about how many times a year?

[ward]

they should change it with no issues,

be sure to mention it so they don't forget though...

why do it yourself when the dealer will do it for free?

[pbdm4k]

Originally Posted by Rey

There is a school of thought that says brake fluid circulates slowly throughout the brake system - that explains how the fluid in your reservoir becomes dirty. If it didn't circulate it would remain clear. This school says just change out the reservoir from time-to-time.

I'll agree with you that it does slowly circulate, afterall, when you press on the pedal, the fluid from the reservoir is being pushed into the lines. Release and it flows back.

But for any hard driving, I'd prefer the more thorough brake line flush. I'd also recommend a full flush ESPECIALLY if you track your car.

[Rey]

Agree that if you track your car, then a complete flush is the way to go, simply because the track heats your brakes like no other place.
I usually change my oil at about 5000 mi., no matter what a mfg recommends. At each oil change it is simple for me to check the color of my brake fluid. If it is less than clear, I just suck the reservoir dry with a turkey baster and refill. Takes all of 3 minutes. BUT, BUT I am starting with a new car. When I buy a used car, one of the first things I do is change every fluid - brakes, coolant, differntial, transmission. Then I have a good baseline.

[Craig in Alabama]

The reason that I got from Honda that they only change the fluid in the reservoir (and this was a long time ago on an Acura) was that if you bleed the lines in a conventional manner, the pedal goes all the way to the floor, forcing the master cylinder seals into previously "uncharted territory". Their argument was that this led to leaking master cylinders. Nothing I could do would make them bleed the lines like I wanted. I had always bled my cars that way, but I had also rebuilt a few master cylinders...
I have since used both methods and I prefer it when I know that fresh fluid is all through the lines.
That said, if BMW is doing it for me, they can do it however they want. When it's my turn to do it, I'll probably do it the old way. As long as you change it out every couple of years it probably doesn't make any difference on a road car, anyway.
Of course, I only have 18,000 miles on my '04, so it's no big deal.
Craig

[ward]

actually if you use a vacuum bleeder like most new shops do, and make sure the reservoir doesn't go dry the pedal won't move at all

[Flycaster]

Originally Posted by ward

actually if you use a vacuum bleeder like most new shops do, and make sure the reservoir doesn't go dry the pedal won't move at all

What's a vacuum bleeder, how much? How does it work, where is it attached?

[Craig in Alabama]

Hi Flycaster,
Mity-Vac makes the best one that I know of. You attach a hose to the bleed nipple on the wheel cylinder, pump up the MV to build vacuum, open the bleed nipple and release the vacuum. It sucks the fluid right out of the master cylinder. Of course, check the MC after each suck (!) to make sure the level doesn't go down too low. If you start with the wheel furthest from the MC, the other three wheels don't take but a couple pumps until you have clean fluid throughout.
A very handy tool. $20 -$40 depending on whether you get plastic or metal.
Craig