Anyone Changed Brake Fluid & Bled With VCDS
 

Pretty much as the title implies. The car is coming up for its MOT in a few weeks time, and in the process of doing other stuff, I was thinking of replacing the brake fluid, as it was last changed about four years ago.

Has anyone done this themselves, and if so, how? There is an option within VCDS to bleed the brakes, but I've never used it, so not sure what it involves.

Just wondering how much brake fluid I'll need to completely flush out the existing stuff.

I haven't done this myself. But as far as I can discover.

http://www.audipages.com/Tech_Articl...rakebleed.html seems to suggest 1 liter.

According to my workshop manual, see attached file

Yeah a litre should do it.

VCDS is only needed to cycle the ESP pump if the system has been opened in that area or drained. For a straight fluid change it doesn't need to be done. The sequence is different for cars with ESP though:

1 - rear left
2 - front right
3 - rear right
4 - front left

Thanks for that link. Just read it and it seems reasonably easy.

The link that Regulus gave mentions doing the front left first because it has the shortest run. If I just substitute the order you've given instead, that should be okay? From what it says, it just seems to be the quickest way to drain the reservoir to the lowest level.

In terms of draining the reservoir, the length of the pipe doesn't matter - you've got the same volume of fluid going through it whether its an inch long or ten feet :)

The shortest first logic to bleed the system makes sense because any air from the master cylinder or ABS module will come out sooner. Elsawin does give the two specific procedures though - with and without ESP.

Personally I think it makes no difference either way for a fluid change :D

Great. I shall delve into that as well for instructions.

Hi Sean, there's something in the back of my mind regarding performing output tests on the D3's ABS module that it logs an error that can't be erased. I remember Snapdragon posting something about it.

Here is what I have on the ESP procedure.

MJ is correct of course, as always :)

Ignore my comment, just now realised it's your D2. +++

You might also invest in one of these. Makes it all so easy.

www.toolstation.com/shop/p82378?r=googleshopping&rr=marin&utm_source=google shopping&utm_medium=feed&utm_campaign=googleshoppi ngfeed&gclid=CjwKCAjwwPfVBRBiEiwAdkM0HWaBrZq_vk_5z 6YnW5ItnP0DpUIJgGZjRYDDeoDnntJszSWd4YNLyRoC1J4QAvD _BwE

Beat you to it Mike. I've already ordered the bleeder +++

You'll need 2 bar pressure to push the fluid through the ABS unit.

Any insight into why this order? Diagonally opposites... kind of makes sense.
I've always been told to bleed furthest to closest to the reservoir (although with the location of the ABS pump, front left and rear left probably have shorter pipe runs than front right and rear right respectively)
The Audipages procedure uses a pressure bleeder and states using 10psi. Will the reservoir support 30psi (or 29.4 ;))?
Or does 2 bar mean absolute (so 1 bar above atmosphere)!

I bought a Mityvac vacuum bleeder (MV8000) to attack it from the caliper end. There are various versions of these pumps around, but Mityvac have a good trade reputation.
I paid about US$55 shipped from Amazon (click here). Just checked Amazon UK for the same item - £50, what a rip off!

Thats the order in Elsawin. The brake system is split in to two diagonally arranged circuits so its intended to bleed one circuit then the other.

Elsawin also states 2 bar pressure (relative) to push the fluid through the ABS unit. I do this routinely, topping up a spare tyre to just over 2 bar for each corner when using the Gunson tool. The D2 reservoir is just fine with the pressure. I do also routinely inspect the reservoir for cracks or damage though as I did once have an A4 blow it's top off due to UV damage to the plastic. On the A4 you can see the back of the reservoir looking in from the windscreen so it can catch the sun. The D2's is fully covered though so doesn't suffer in the same way.

I've never had much success with the vacuum tools as I've found they always pull air in from the bleed screw threads so you can't tell when the system is actually bled. I much prefer to push the fluid through :)

Just an update on this. Purchased the pressurised bleeder and finally got around to changing the brake fluid three days ago. Also made sure to have the instructions for the bleeder and the brake bleeding procedure to hand. All in, it took me about two hours to do. A long time you may think, but I wanted to ensure that I was doing everything exactly right and wasn't going to be rushed. Going by the old brake fluid I disposed of, I also bled the lines a little longer than necessary, just to be sure, to be sure, to be sure! So thanks to all who helped.

BTW This is what happens when you're brain is scrambled and you want to change the brake fluid by yourself! :Confused:

http://forum.a8parts.co.uk/attachmen...1&d=1523704142

Could have done it just one wheel at a time! :o