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I am working on a 2012 Audi Q5. I had to remove the rear calipers because someone engaged the parking brake while I was changing the pads and rotor, frustrating story there. When I was putting the calipers back on, did not know I needed a scanner to tell the computer to retract the Electronic Parking Brake (EPB). Bought the scanner to retract EPB. I asked my FIL if the EPB was engaged, and instead of looking he hit the switch. The electronic parking brake pushed the piston all the way out of the caliper. To assiste with getting the piston put back in, I pulled the caliper and put it my vice and put the piston back in the caliper. After I got everything back together, I bought a vacuum pump to assist with the bleed, and I think I have gotten just a out all the air out of the system. However, when the car is running and I push the brake pedal down and hold it, it will go to the floor. I does this slowly and with a pretty good amount of force from my right leg. The pedal feels nice and firm, but when held it will go to the floor. Does the ABS system need to be burped? Is there something else that I’m missing? Can a good independent do this, or does it have to go to the Audi dealer?
I have used the pump on all four wheels to no avail.
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An independent can bleed the ABS system.
You most likely ran the lines dry up to the ABS modulator when the piston popped out.
You need to belled the ABS modulator first before bleeding it downstream so if you don’t have the proper equipment, take it to any indy shop and have them bleed the brakes.
Based on your description there may still be air in the system. It may also need to be reset once all the air is out. In short, you may want to take it to an Audi specialist to have them look it over to determine the problem. Late model ABS systems on German vehicles are not for the faint at heart. Someone with experience and equipment would be a wise investment in my opinion.
Good luck and keep us posted.
I did a little google research last night. I’m going to give it one more go before I throw in the towel. I’m going to use the vacuum pump and at the same time do the traditional pump pump pump hold. I’m sure that will not work, but can’t say die yet. I have an appointment set up for first thing Tuesday with someone that knows what he’s doing, and has the tools to burp the ABS.
officially given up…. Re-bled with vacuum tool and pump method. No joy. Did the redneck activation of ABS module, no joy. Calling professional on Tuesday. Moving on to replacing the fuel filter in my Cruze Turbo Diesel. I hope I have better luck with that.
And BTW, not a fan of German cars. Domestic and Japanese much easier to work on.
Took it to a professional. It seems that I damaged the master cylinder while bleeding. New master cylinder will arrive tomorrow and will be installed. Lesson learned on bleeding brakes….
[quote=”jrbpit” post=169917]Took it to a professional. It seems that I damaged the master cylinder while bleeding. New master cylinder will arrive tomorrow and will be installed. Lesson learned on bleeding brakes….[/quote]
there is two things that could of happen…
1. the tech found a problem and found the problem in the master cyclder… which could of been air causing you the problem but the tech doesnt know for sure so he has to replace the part to gerinty that it is fixxed.. unless you saw him bleen the system with a pump system not the bottle system… he would of connected a big bottle to his air tank or hand pumped it…to get the air out. I will explain what that is in a little bit…
2. when you do the bottle at the bleader… you have the chance to suck air in and also can … when you push the master cylinder in normal operations you dont push it all the way to the ground… so lets say you push it like 75% all the way throgh in and out throw normal operation.. so 25% you dont do normaly.. so you will get dirt and grind at the walls of the 25% area… now mack to when you bleed the brakes… when the bleeder is open you will push the peddle down ferther then normal like all the way down.. in to that 25% area… now you could have thick greese like tar or rust caused by old brake fuild or anthing ruff or sticky in there… so what are the gaskets made of in the master cylinder rubber… so when you push it throw and for an example lets say rust started for form… that would act like sand paper on the rubber gasket and try to start and tare it… causing the pistin in the cylinder to start to leak… that is why techinally you shouldnt pump the brakes but use a pressure system to bleeed your brakes because then you dont get in to that bad 25% area…
so your all probably saying wasnt it starting going bad already… and that would be yes… it just happen to go bad when you pumped your brakes in that normal unused area..so if you think number 2 happen … then you did nothing wrong to it… it was already bad… just an FYI to maybe make you feel better and clear some confustion that prople have…
now to explain what the pressure bleading system is … is the take off the cap of the master and have a large bottle that will push brake fuild through the system and will keep positive pressure on the system to proven air bubbles -from coming back in the brake system… so you will like pressureize the contaner and go to each bleeder and open it up and when its clear close it and go on to the next one.. all you have to do is check to make sure that the pressure doesnt drop below a level… no pumping so no entering that 25% area… I hope that all makes sence to you guys
here is a guy showing you how to bleed the master cylinder and showing you the inside of it too
I could not find a Eric video of him doing one… might be a good video ideaalso sorry for you all telling like everyone here why you all are doing brake bleeding wrong… but I just wanted to inform you all
so don’t kill me.. 😛it has been a while but…. Father In Law got the car back from shop after installation of a genuine Audi master cylinder. No difference….
I’m beginning to think when the rear caliper pistons were extended all the way out, that somehow screwed up the calipers and is causing the pedal squish.
Did I mention how much I hate German cars…..
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