I've got my Audi 100, 1989 model since ~4 years now and never bothered
about the brake fluid. There is a very good chance that the previous
owner never bothered either. I did consider to have the system
flushed, but at two independent garages they are hesitant to touch it.
One of them recommended to not bother, the other one recommended to go
to the Audi agent.
Both of them mentioned that the brake master cylinder could collapse
or something like this. IIRC, one of them said this could happen with
"all the brake pumping with no resistance". I almost decided to have
Audi dealer do it once my finances allow some long-term maintenance
expenses. However, I now had a clutch problem and a friend helped me
to bleed the clutch with his little pressure bleeder (the one you
connect to an inflated tyre and it pushes the fluid through). I am
wondering whether the complete brake fluid flushing can be that
difficult and risky.
I did a google search but could not find anywhere on this group that
anyone mentions a brake fluid flush as a risky procedure (nor on
www.audifans.com ). The closest I came was the following statement
(I'm not sure whether that's what they are worried about):
"DOT4 or above will do the job personaly i prefer the 2 man job
pumping the pedal but on the first few pumps take it real easy as
depending on the mileage i have had vehicles flick the master cylinder
seals inside out usually on nissans never had it happen on an audi but
u never know" (whole thread at:
Can I assume that there is no such risk, if I use the pressure
Is there any link to someone going through the procedure step by step?
As far as I understand, the propper procedure seems to be:
2) Brakes one by one starting with the longest line
Is there anything else I need to do?
I heard that it might make sense to push out the old fluid with air
first before putting in the new one. Would that make sense? Should I
get the old fluid out of the clutch and all lines and then do the new
one everywhere, or is this stupid?
If the pressure method, do I need to do something to get the old fluid
out of the master cylinder (maybe pump once or twice in the process)?
Thanks a lot for your help,