Galco

Update: Turns out, as others have suggested, no need to bleed the ABS. See explanation and video in thread below. Hope this helps others.
Link: https://www.audiworld.com/forums/sho...php?p=24500851

Looking for some help from the group! Could someone provide the instructions (repair manual)to bleed the ABS?

Trying to bleed the brakes and not getting too far. System has LOTS of air as I've pushed nearly a quart through just one line (right, rear) and still lots of bubbles. I'm using a pressure bleeder with a mild 10-12 pounds of pressure. Fluid is in the pressure bleeder and still way too many bubbles. Somehow, air must have gotten into the system and I suspect the ABS. Maybe the resivor went dry, despite my efforts.

Would anyone please be able to reference the repair manual to advise how to bleed the ABS? I need to resolve this today for the work week ahead. I've searched and tried the recommended version on other sites via the Vag Com however, it errors out and said its not available. This is the process I tried without success, this procedure must be for older models.

Procedure for Bleeding the ABS Brake Pump on VW Passat and Audi A4/S4, A6/S6, and A8/S8:
[Select]
[03 - ABS Brakes] 
[Basic Settings - 04]
Group 002
[Go!]
This will trigger the ABS pump to turn on for about 10 seconds. You should hear the fairly loud pump clicking during this time.
Click the [Done, Go Back] button and you're all set


BTW, 2006 A8L Sport

Thanks in advance!!!

Mister Bally

You do not need to fiddle with the ABS unit to bleed the brakes. Connect pressure bleeder to reservoir, pressurize, open farthest bleedr screw and wait for clear fluid. Tighten bleeder screw and bleed 3rd farthest brake line etc.

bmwm750

I haven't had to operate the ABS during a bleed on the Audi yet, but I've done it on several Porsches during major brake work.

Typically, the only time that you need to worry about the ABS pump is if the system went totally dry- i.e. during component replacement (typically the ABS unit itself).

In your case, I would just keep flushing fluid through, and go around the car in sequence until you get clear fluid.

Once done with the pressure bleeder, I'd get about 10 pumps of fluid through per caliper the "old fashioned way" with a helper.

Galco

Did that, sent 1 qt through single line and STILL lots of air? Suspect I've got air in the ABS as any air in the lines alone would have been bleed out by now.

Unless anyone else has a suggestion, it looks to me that I need to bleed the ABS. I have searched for our models (D3) but nothing...

thanks in advance.

Galco

Good thoughts, thanks! Just surpirsed that it would take a quart and the line is still full of air. I picked up more fluid and will push more through via the pressure bleeder and follow up with the old fashioned pedel method as you suggested, once all air is out.

If others have ideas, please share.

Thanks guys!

mishar

I had dry system when I had to fix my rear left caliper. Fixed it without problem old fashion way (my friend was pumping the pedal).

That VCDS procedure probably requires Access Code.

snapdragon

Unlike previous VAG models, the Audi ELSA instructions say there is no requirement to cycle the ABS on the D3. I think it is the pressure bleeder entraining air into the fluid. If brake fluid is agitated, the bubbles stay suspended in the fluid. If you put some in drinking glass and then pour a trickle of fluid in, see how the bubbles taken down by the fluid causes bubbles to get stuck?

bmwm750

Exactly. This is why I love pressure bleeders to FLUSH fluid through, but I still finish the job by BLEEDING the "old fashioned way" by pumping non-pressurized/ non-agitated fluid through using a helper on the brake master.

You'll also notice that the true professional grade pressure bleeders use a rubber diaphragm to separate the chamber that holds brake fluid from the pressurized air chamber (typically shop air on these units). This is to avoid pushing air into the fluid the way the Motive units do (there's just no way around this short of physically separating the chambers).

Galco

I was getting rather nervous as I just couldn't understand why after 1 full liter of fluid through a single line and still so many air bubbles. I suspected that I must have run the reservoir dry and introduced air into the ABS or potentially worse and very expensive to repair. After reading the comments of Mister Bally, bmwm750, mishar and later snapdragon, I calmly proceeded with the pressure bleeding process.

I began sending the next liter through my pressure bleeding while watching the line carefully. Still puzzled why so many bubbles, no less nor more than before. As a test, I pulled the drain tube out of the submerged fluid in my collection bottle, then back in and same results, lots-o-bubbles. Finally, I noticed if I raised the collection bottle off the ground and close to the same height or higher than the bleed screw, BINGO, no bubbles.

Check out this video and you will clearly see the difference.

http://www.youtube.com/watch?v=7TwyO...ature=youtu.be

Did the rest the same way, tested the brake pedal and felt very good. Went for a successful road test and the result was a firm brake pedal. :-)

So, for the physics majors out there, perhaps you can explain what happen and why the continuous flow of bubbles with the collection tube at the lower level and no bubbles at the higher level, relative to the bleeder?

For the rest of us, lesson learned.

Galco

Bump to get your thoughts on the video in message above