Hey guys, I recently changed my rear brake pads and caliper on audi a6 2003 3.0 quattro and also bled the brake lines so its bubble free.
My problem is when I turn on the ignition, and press on the brake its deflates like a balloon with no resistance. Its fine when I turn the ignition off.
Is there a step that I need to take with the vag tool?

regards,
kevin

 

Either something is leaking or you have air in the system.
I use the two man method. I always have someone I can rope in. After the brakes pads are in I pump them ten or so times to push out the caliper then bleed them. If your spongy maybe the resevoir got low on you and you let some air in. Make sure your partner was holding the pedal to the floor while you tighten the nut or place your hose in a container below the liquid level so if it sucks up it will only suck fluid back in. That's a trick I learned when I am forced to work with my wife.

 

thanks Ill try to rebleed. wasnt sure if it was a car computer issue since it seemed to lose all pressure once engine was on.

 

you need to bleed with the car on...otherwise the brake pump isn't working.

 

Interesting --
I've never do it with the car on and haven't had any problems.

 

I always bleed with the car off and then on just to make sure, always works for me.

 

THanks everyone for your response... seems like i got some major problems
ok i attempted to rebleed assuming there was still air in the system. And noticed no fluid came out when I opened the front left bleed screw. After pumping and opening screw and seeing slow weak stream.. i noticed brake fluid leaking from under the car.. to the driver side of the transmission oil pan. It appeared to be leaking from above. I checked the brake fluid resevoir and there was no signs of leak with the hood open.. so its further down the system.

Im guessing I have some major damage here... anyone have any clue whats leaking? I might have damaged the system when I floored the brakes when I initally bled the brakes. I know your only supposed to go half way. Any help would be appreciated. Thank you

regards,
Kevin

 

It probably is a pierced line somewhere. If the car is old, or originated from an area with much salt on the roads, it is possible that one line corroded or developed a rust spot.
I know it is unlikely to see much rust under a newer Audi than mine (1995), but you never know.
If you don't have any leak by the master cylinder/reservoir, then you should get under the car and have someone pump the brakes and look for leaks. When a brake line leaks (sprays) under the car, is not hard to spot it.

 

So if it is a leak in a lining.. is it a big job? if anyone knows how much this could run me.. do you need to take alot of parts out to get to the brake lining?

 

I think it depends on what you find.
Some years back I remember mending a brake line on a Pontiac Le Mans (which it was pretty much the N. American version of the German Opel Kadet). I bought a line section, two adapter fittings, and a line cutter. Took out the pierced segment (was due to rust) and replaced it with the new one via adapter fittings.

I don't know what type of brake line (brass or else) these Audis have, since I'm yet to inspect anything brake-related.
Some other guys may tell you better what you need to do if you have a leaky line.