So, I replaced the rear brakes on my A6 and the flexible line to my front passenger side tire this weekend. When I went to bleed the brakes, I followed my usual procedure - my gf steps on the pedal, I open the screw, let out the fluid, close the screw and tell her to take her foot off the pedal and when to press again to start the entire thing over.
Well, I haven't bled my brakes in a long while and the fluid was coming out pretty greenish so I was trying to make sure I got it clear and it was taking a long time to flush it all out of the first wheel. I had a miscommunication with my gf and she pumped the pedal while I had the bleeder screw open (maybe 3-4 times!).
Now, I cannot seem to get any pressure to any of the wheels. Normally the fluid will spray out with force and if anything comes out, it kind of just dribbles out. I've bled like crazy and nothing. When she presses the pedal down, I can hear the piston making a noise I think.
What has me a little concerned is that I noticed that if I close all of the bleeder screws and fill the resevoir to the top, she can step on the peddle and it will suck the fluid down and the level never comes back up. I've dumped probably 16 oz. of fluid into the resvoir like this and it just keeps going down. I've looked for leaks and can't see any anywhere.
When I hooked up the Vag-Com to try to bleed the pump through the computer I followed the Ross-Tech instructions which said to go to group 001 or 002 and hit Go! but both groups show "error - Not Available". The only time I get anything in the vag com is if I go to group 101-105 I think. The output tests seem to work fine and I'm wondering if that is how you are supposed to do it on the A6, since the Ross-Tech instructions seem to be geared toward everything but the A4/A6.
Any thoughts on this? Should I just keep bleeding by hand?
I followed my usual procedure - my gf steps on the pedal, I open the screw, let out the fluid, close the screw and tell her to take her foot off the pedal and when to press again to start the entire thing over.
Did you put a stop behind the brake pedal or was she pushing it all the way to the floor board?
Just go to advance auto and get a mityvac or a pressure bleeder.
Worse case is pushing the pedal to the floor put the internals of the master cylinder into a corroded area rather than the operating area and damaged the seals, in which case the M/C has to be replaced. But I would pressure bleed the thing first. I haven't done the g/f on the pedal thing for 40 years…..it usually didn't work out anyway.
When I have problems like that I bleed it from the bottom up. Get a large syringe like 50 or 100cc from your drug store and clear tubing the right size to fit on the bleeder screw. Fill the syringe with brake fluid and slowly pump it in from the caliper.
Many years ago, I got into the habit of once in a while (Maybe monthly) pushing the brake peddle all the way to the floor.
Theory being is it keeps the little used portions of the cylinder wall clean.
I have yet to have any of those cars need a new Master Cylinder.
Some cars make this hard to do, but usually if you hold pressure on the brake peddle you can get it to the floor.
Thanks for all the responses guys. I had a chance to look at this some more tonight. I hooked up a mity-vac fluid extractor to the brake bleeder screw at each wheel with some hose that fit very tightly over the screw. When I did this I got LOADS of air coming out of the rear brake calipers/lines. It was so much I thought it HAD to be sucking it in from somewhere and would never stop. I went through all four tires about 3 times and by the time I got done the bake lines were pumping out clear fluid while under pressure/vacuum.
The front lines, however, seem to have a lot of fluid coming out, but it is only filling half the hose and the other half is air. It just doesn't seem right and I've bled them quite a bit. I've gone through over 32 oz. of fluid.
The peddle is firmer and has 'some' feedback when I press down on it, but it is still extremely soft. I had my gf hit the peddle only about 3/4 of the way while I opened a bleeder screw and it seems like the fluid just dribbles out, it doesn't squirt out like normal. It is as if I am not getting any pressure in the system.
I filled the brake reservoir and now, when you pump the peddle you can see the fluid level drop but when the peddle comes up it goes back exactly to where it was. I don't see any signs of leaks...
I won't have any more time for it until Thursday and half of me says to keep bleeding while the other half says to just go get a new master cylinder and stop messing around....it just seems to soft to be a bleeding issue at this point.
Oh, two more things - when I hit the pedal it sounds like a porpoise. And I had a flashing brake light on the dash and the vag com now, mysteriously, says that my abs module is incorrectly coded. So I'm looking into how to code that correctly, but I doubt that has anything to do with it.