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Thread: Audi A4 Brake Failure Problem

  1. #1
    Join Date
    Feb 2007
    Posts
    1

    Exclamation Audi A4 Brake Failure Problem

    I have an Audi A4, 2003, while driving and without warning the brake pedal became very hard to press as if the servo had stopped working, exactly the same syptom as when he engine is not running. The fault is intermittent and very dangerous. Has anyone had this experience and if so how was it resolved.

  2. #2
    Join Date
    Mar 2007
    Posts
    1

    Default Audi A4 intermittent brake failure

    Hi there

    I am experiencing exactly the same problem at the moment, I drive an audi A4TDi sport, 2002. On several occassions now my brakes have done exactly the same thing - the pedal has gone hard with no response. It did it last week, and the brakes didn't come back, I had to get the car home using the gears and the emergency brake. But magically, in the morning, it is fine again. I had it in the garage most of last week, but they can't find anything wrong. I mentioned the servo but my garage said that if the servo fails, it fails outright, and they can't understand the intermittent problem. The mechanic has suggested it could be a problem with the master cylinder, so he is getting back to me today. But until I find out I am not driving the car.

    If you find anything more out I would really appreciate it if you would post your info, and I will do the same. Cheers.

  3. #3
    Join Date
    Oct 2006
    Location
    Sussex
    Posts
    1,824

    Default

    Hi

    Read this link-may be of some use Link

  4. #4
    Join Date
    Mar 2007
    Posts
    1

    Default A4 (2002) Brake Issue

    Just had the same issue,, the brake pedal locking whilst driving...very un nerving...Had car looked at and is apparently the servo and the pipe - cost 700 plus...

    not something I would expect from Audi - interested that there appear to be multiple insatnces of this, has anyone taken up with Audi?

  5. #5
    Join Date
    Mar 2007
    Posts
    5

    Default

    Hi my 2003 audi A4 brakes stopped working. after 3 visits to audi I checked all hoses and found the vacuum hose from the manifold had collapsed on itself and broken on the metal pipe that comes upwards from the manifold. The rupture was had to spot but it was on top of the rubber pipe above where the intake metal pipe was. I replaced the hose using proper vacuum rubber because the origial was so thin. The reason the brakes sometimes worked is because the system has an elecvtric backup motor which you can trace to the front right of the engine bay. Two brakes uses in a roww and the electric vacuum runs out. When refitting make sure the smaller id end of the pipe goes to the breather and the larger id goes to the intake pipe.
    Paul

  6. #6
    Join Date
    Apr 2007
    Posts
    10

    Default

    This is becoming a common problem on many VAG cars, it is usally the servo drawing in water through it's crimped seam and basically getting full of water so there is no room for the air to create assistance.
    The crimped seal always leaks air, but a negligible amount, but due to corrosion, blocked plenum drains or generally a lot of water in this area, it can suck water in over a period of time. Be wary that this is most common on the TDis, and if you're not careful, it can fail and dump the water into the engine via the vacuum pump.

  7. #7
    Join Date
    Apr 2007
    Posts
    1

    Default Audi A4 Avant 2002 Brake Failure

    This brake failure senario just happened to my wife.

    Pedal went hard, no breaks to speak of and she sailed through the intersection rather than turning left as she had planned...

    We have only had the car a month and the pedal going hard happened to me on the 2nd day similar to others describe - second press of the pedal was rock hard.

    At the time I thought it was just that I was not used to the car's braking yet.

    It is at the dealer now and the gent mentioned "vacuum hose" in that manner of "we have to check it all out throughly (but I have a reasonable idea where I will be looking").

    Having read this forum and the other link provided before I went, I nonchalantly replied "probably crimping or a split..." to which he nodded.

    It is all pretty disappointing I must say.
    We bought the Audi because it was my wife's "practical, super safe, dream car" as she is pregnant with our first baby and the 8 airbags plus the works safety-wise seemed fitting. Now when something as mandatory as the brakes fail she is frowning and looking at her new pride and joy in a whole different light.

    Meanwhile I am cursing myself for going back to a german car after years of trouble free motoring driving only cars built in Japan and swearing "never again" after owning a beautiful but ultimately reliability flawed Porsche.

    I am sure that they will fix the line no problems but really unless I can come home to the wife and point to an obviously upgraded hose that looks l belongs in the space program the damage is a bit already done.

  8. #8
    Join Date
    Mar 2007
    Posts
    5

    Default

    Hello there,

    Since I found the problem on my A4 the brakes have been fine. The reason you get one good use followed by no servo is because the electric backup servo provides enough vaccum for one use only. Audi should have a warning light on the dash for this. Since changing the vaccum hose which was so thin it was below spec the new hose has been fine. The original hose is a moulded piece of rubber with no reinforcing and collapses on itself. The cost of a foot of standard hose and three bends was less than ten pounds. I didnt check the audi replacement cost. Paul

  9. #9
    Join Date
    Oct 2007
    Posts
    2

    Angry Audi A4 Brake Failure

    Had the same problem.

    Brakes failed while driving at 60 mph with whole family on board. Luckily survived it.

    Took it to garage with your postings and spot on the pipes to the servo had collapsed. Asked them to replace all three to take no chances. Around 16 each plus an hours labour if that. The mechanic told me that the new pipes are made of stronger rubber, as though Audi where aware of the problem! There is no doubt in my mind that this was a design fault and should have been the subject of a recall- but can you imagine the negative publicity?

    M.

  10. #10
    Join Date
    Mar 2007
    Posts
    5

    Default

    Hi there,

    Glad to see the brake problem was fixed. I like the info about the new pipes being stronger and Audi most likely being aware of the problem. When I checked the original pipes they semed to have no reinforcing. My next problem is the CVT transmission hesitaing so much it is scary and last week it actually slipped on takeoff. My friend with an 04 A4 had her transmission replaced under warranty at 35,000 k ..... Time for a trade in. My 05 Subaru WRX is still going perfectly !!!

    Regards Paul

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