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Discussion Starter #1
mechanic replaced the vacuum pump to 'fix' a problem. $600 later and the prob still isn't fixed! he showed me the pump with the car at idle and it was pulling about 5". anyone know how much the vacuum the pump should be pulling?

now i believe the pump was good and we just blew $600. i would like to address it with him but need to know what a functioning pump operates at.

thx so much for anyone's help.

cheers, jason
 

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Discussion Starter #3
yes, brake issues.

brake pedal was going all the way to the floor. first he said it was a master cyl, sounds about right, replaced it. pedal still bottomed out. took it back then he said it was the vacuum pump. replaced it, $600+. all was good for a few days, then the pedal went to the floor. took it back, now he says it's some bypass valve.

up until now we were happy with his work. depending on how this is handled will dictate if he keeps us as a customer.

i'm going to ask him if it's possible that the master and vacuum pump were incorrectly diagnosed. plus, as far as the vacuum pump goes, wouldn't a pump with low or no pressure going to the booster cause a hard pedal vs a bottoming out pedal. if so, why did you look at the vacuum pump?

when the pedal was bottomed out the car would not stop, so there is a leak in the system somewhere. the car would slow down so some pressure was getting to the brakes. i don't know what this bypass valve is.

thx for the info. any other ideas or thoughts are welcomed and appreciated.

cheers, jason
 

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Pedal to the floor would be the master cylinder assuming there are no leaks. The bypass valve I think is part of the anti-lock system. I have not had to learn all the details of the A4 breaking system. My last car was a '96 Passat that did not have anti-lock breaks.


Good luck, keep us informed on your progress.
 

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Discussion Starter #5
update, and hopefully we're done with this. so far so good.

from the beginning:
brake pedal was getting soft, hence the need to replace the master cyl, which we did. when the m/c was pulled off found fluid in the booster, so the booster was replaced. after a little driving the pedal is now bottoming out. at least that's what i thought. i never drove it so this was being passed on to me by my wife who knows nothing about cars/mechanical stuff/etc, but no worries, not her thing. the pedal wasn't 'bottoming out' as to the firewall, it was going almost all the way to the floor, but not quite. there was still psi in the hyd side of the system, but since it was going soooo far down then getting hard it felt like the bottom. when this happened the car would slow, so again, there was still psi on the fluid side, just not enough to stop quickly.

so the first time back the mech drives the car and sees that the pedal is going down far, but not bottoming out so he believes there is still psi on the fluid side so he starts looking at vacuum. the pump was pulling 5", and fortunately the dude working on the car showed me first hand so no question there. mech was lead to believe that the you could step on the brake and stop fine but because of the low psi the booster wasn't recovering. so that's how he got to replacing the vacuum pump. drive off the lot, works fine for a while, then same issue.

back for the second time, he finds a hairline crack in the plastic bypass line. when stepping on the brakes, depending how fast and frequent the line would sometimes flex and lose vacuum psi. boom, pedal goes to the floor.

he replaced the line with no charge. apologized, saying they prob cracked it replacing the booster and was very patient and helpful answering my questions when we picked the car up. i'm sure he knew i was starting to question what was going on. i asked questions, listened to his answer, if i wanted more detail on how or why something was going on he answered it. and again, apologized a couple of times. i'm extremely pleased with how it worked out.

one other thing: i don't know that the vacuum pump needed to be replaced just yet, even though it was only pulling 5" it seemed to be enough to operate the sys, but i feel it was going to need to be replaced eventualy so i looked at this as a little preventative maintenance.

if anyone is in the phoenix area and needs a great mechanic lemme know.

thanks for your input a/t.
cheers, jason
 

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back for the second time, he finds a hairline crack in the plastic bypass line
DING DING! (not a bypass line, it is the line that supplies vacuum to the booster)

That was the problem from the very start. VERY VERY common problem on these cars and it is the very first thing that should be checked when having the symptoms you had. The vacuum pumps on these cars are very simple in operation and are very durable, simply put, they don't fail. I would bet that the master cylinder and brake booster were just fine as well. Either your mechanic didn't know any better, or he was taking you for a ride from the start.

Sorry to hear of your troubles and bad experience. I would not recommend that mechanic to anyone. Its too bad you didn't get the old parts back, they are easy to bench-test.
 

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Discussion Starter #7
hey dzl.

i don't think that line was the prob from the beginning. like i said, a soft pedal was the first issue. it was creeping toward the floor, hence a slow leak on the hyd side. not bottoming out first go 'round. then i saw the booster with the fluid in it so i know that was true.

after the booster was replaced is when the pedal was 'bottoming' out. again that's why he went down the vacuum road, and the reason for my question that started this thread. i saw the 5" so i know that's what it was pulling. the acct troll said it should be pulling 30, i thought our mech said 20, either way both are a long way from 5. so did it need to be replaced right then? i don't know, it seemed to be ok when we took it in, but i do believe that with it only pulling 5 it was going to have to be replaced sooner or later. i don't mind preventative maintenance and taking care of it while it's apart rather than have it go out on the highway.

trust me, i was not happy when we went back the first time. after the second time i was pretty much livid, but i'll always listen and see what the other side of a story is. all his reviews online were very good, that's why i was so confused with what was going on. he took time to answer everything i asked, if i wanted more detail he broke it down more and neither of us ever got upset. i've seen guys get pissed if you question them or their work, big red flag there.

i still stand by this guy's work and honesty. thanks though for the questions and input, never hurts to have ideas for the next prob that will come up.

cheers, jason
 
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