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Stupid Brake Bleeding Mistake

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Old 06-16-2014, 08:50 AM   #1
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Default Stupid Brake Bleeding Mistake

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?
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Old 06-16-2014, 08:59 AM   #2
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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?
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Old 06-16-2014, 09:36 AM   #3
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All the way to the floor, but I've always done it that way...maybe I shouldn't huh?
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Old 06-16-2014, 10:59 AM   #4
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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.
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Old 06-16-2014, 12:27 PM   #5
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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.

Good Luck
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Old 06-16-2014, 05:54 PM   #6
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As long as there is clean fluid all the way from the m/c to the caliper. I hate to push dirty brake fluid uphill through the ABS, etc.

Last time I bled from the bottom up was on a Kawasaki 900 Z1 motorcycle. It just seemed to work better and I had installed a second front brake rotor and caliper and larger m/c.
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Old 06-17-2014, 05:39 AM   #7
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All the way to the floor, but I've always done it that way...maybe I shouldn't huh?

No, you should not. It pushes the piston into a region that it never travels and can score the walls. It might have developed an internal leak if you can't figure where the fluid is going.
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Old 06-17-2014, 08:12 AM   #8
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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.
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Old 06-17-2014, 04:43 PM   #9
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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.
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Old 06-17-2014, 05:04 PM   #10
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Is it possible air was admitted to the system when the reservoir ran low? If so, purging air can be difficult.

The correct way to bleed these cars is by using a MOTIVE pressure bleeder. Maybe somone near you could loan it to you before you undergo heroic measures....
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Old 06-18-2014, 04:46 PM   #11
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Is it possible air was admitted to the system when the reservoir ran low? If so, purging air can be difficult.

The correct way to bleed these cars is by using a MOTIVE pressure bleeder. Maybe somone near you could loan it to you before you undergo heroic measures....
The mity-vac pump I used wasn't a brake bleeder, it was a vacuum pump fluid extractor which is a large reservoir (maybe 2 gallons?) with a hose and a pump to create vacuum, and it can be reversed to create pressure also.

Does the motive bleeder force fluid from the reservoir out to the calipers? Or does it suck it to the caliper from the bleeder screw? If it forces it, I may go get a new cap for my reservoir anyway, and I will just drill a hole and put an adapter in the one I have so that I can hook a hose up to it and force it with the fluid extractor.
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Old 06-18-2014, 04:47 PM   #12
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Uberwgn - I also noticed you are in MA. I am on the Cape. How far are you? It is always good to know who is close by...
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Old 06-18-2014, 05:42 PM   #13
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Not too far from Norwood, Needham, etc.
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Old 06-21-2014, 03:19 PM   #14
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So, I could not find a motiv bleeder anywhere nearby and didn't want to order one on line and have to wait - so I followed some DIYs on here and built one from a garden sprayer. I couldn't find a master cylinder cap that fit, but I found that a gas cap to a small engine (like a lawnmower) from Napa fit ALMOST perfectly. It still leaked a bit once I pressurized it, but it worked. It took me about 4-5 hours to buy all the right parts and build the tool (multiple trips to the store when caps didn't work or I got the wrong hose size, etc.) and my brakes were bled in about 10 minutes after that. That is the way to bleed brakes.

Then I re-coded my ABS control module using the Ross-Tech instructions and the car is back up and running. I now just have to find a new wheel speed sensor and I think the car will be ready for inspection, haha.
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Old 06-22-2014, 04:34 AM   #15
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So, I could not find a motiv bleeder anywhere nearby and didn't want to order one on line and have to wait - so I followed some DIYs on here and built one from a garden sprayer. I couldn't find a master cylinder cap that fit, but I found that a gas cap to a small engine (like a lawnmower) from Napa fit ALMOST perfectly. It still leaked a bit once I pressurized it, but it worked. It took me about 4-5 hours to buy all the right parts and build the tool (multiple trips to the store when caps didn't work or I got the wrong hose size, etc.) and my brakes were bled in about 10 minutes after that. That is the way to bleed brakes.

Then I re-coded my ABS control module using the Ross-Tech instructions and the car is back up and running. I now just have to find a new wheel speed sensor and I think the car will be ready for inspection, haha.
LOL…4-5 hours and multiple trips to the store vs Amazon Prime and two day delivery….you must have really enjoyed McGyvering it.!!!
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Old 06-22-2014, 05:20 AM   #16
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The MOTIVE is a handy tool.

An alternate strategy is to get a 45mm cap and connect it to your regulated air compressor. The Ultimate Garage used to sell this part. Not sure where to source it today.

Click the image to open in full size.
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Old 06-22-2014, 09:56 AM   #17
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LOL…4-5 hours and multiple trips to the store vs Amazon Prime and two day delivery….you must have really enjoyed McGyvering it.!!!
lol - yes! I was getting really frustrated. But I thought about it again, I guess I started later than I thought and it really took me about 3 hours in the end and there was a lunch break in there. Honestly, if it weren't for that damned brake cylinder cap, I would have had everything in less than an hour and probably put it together in about 15 minutes. It was a mess.

Uberwgn - that sounds like another strategy, but I like the hand pump better, as you would have to work pretty hard to get it much over 20 psi, and an air compressor may blow out the seals....and I obviously do stupid things from time to time.
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Old 06-22-2014, 11:40 AM   #18
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The Motive pressure bleeders are possibly the only ones left on the market and they turn bleeding from a chore into a simple job. Since they push fluid in through the master reservoir, there's no chance of getting air in at the wheels.

Sometimes you can get one at Autozone and the other places that have "free tool rental" but if you have to mail order it...this is one of the tools that you will say "How come I didn't buy one of these 20 years ago?!"

I don't know how Audi has laid land mines, but in conventional dual-master systems, if you push the pedal all the way to the floor you may throw a small piston (in the master) all the way to one side, where it locks in to indicate one side has failed. That can be manually reset but IIRC not without a tear-down. (You'd want to get a more recent & better experience on that.)

If you are thinking of replacing the master in order to reset this--CHECK. It may be fairly simple to reset, and I can't help guess what a whole new master cylinder costs for this car.
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Old 06-22-2014, 05:07 PM   #19
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I prefer Bavarian Automotive's pressure bleeder. The quick disconnect at the master cylinder cap is much better than twisting the line. They are exceptional at warranty as well if you get a bad pump or thin casting on the ring that attaches the pump to the reservoir. That ring is plastic and broke on me…Bavauto just sent me a new assembly!!

http://www.bavauto.com/lview.asp?img...ib500/pb03.jpg
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Old 06-22-2014, 05:07 PM
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