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2.7tt v6 noise

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by BillyV6, Jun 5, 2013.

  1. BillyV6
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    BillyV6 New Member

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    [Jun 5, 2013]
    Hi all, have a petrol v6 and on idle it makes like a rattle noise, have had a couple mechanics look under bonnet but nobody seems to know wht it could be. When revs go over 2k it stops the noise completely. Happens in park, neutral and driver and reverse make no difference. Wondering if anybody had any idea. Does not affect performance at all, no flat spots or lack of power or hesitation. Under hard acceleration from a standstill it goes almost instantly, but when poodling round town sitting at 1500 rpm the noise is apparent.

    Any ideas ppl? Cheers
    #1
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  3. BillyV6
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    BillyV6 New Member

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    [Jun 5, 2013]
    Oh and if u look under bonnet sound seems to originate from the near side in between front light and engine...
    #2
  4. gen.heinz guderian
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    gen.heinz guderian Well-Known Member Regional Rep VCDS Map User

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    [Jun 5, 2013]
    Belt tensioners?
    #3
  5. BillyV6
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    BillyV6 New Member

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    [Jun 5, 2013]
    How would I check that? Big job?
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  6. BillyV6
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    BillyV6 New Member

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  7. Shargo
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    Shargo New Member

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    [Jun 23, 2013]
    I would suspect one of the chains, AFAIK there are three and they are tensioned by hydralic operated from the engine oil thus higher rpm gives higher pressure.
    Two of the chains are driven by the inlet camshafts and drive the adjustable exhaust cams. The chain for the right side is located at the rear of the engine, I'm unsure about the left bank.
    The third chain drives the oilpump if I've understood it correctly.
    I have no idea how difficult / expensive it is to verify this but a failure will very likely be a major.
    #6
  8. JJREED§
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    JJREED§ New Member

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    [Jul 29, 2013]
    I have the same problem. It sounds like it coming from the back right of the engine. Ive stuck a tuning stick down to try identify the noise but cant pin point it. also the same as billyv6 if i slightly pick the revs up it clears, also when the car gets up to temp the noise clears. Can anyone confirm if it is the tensioners doing this as i had new belts and tensioners fitted a few months ago and there was no noise.
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  9. audi-a6
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    audi-a6 Member

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    [Jul 29, 2013]
    I had a similar noise, turned out to be a pulley, to test get a can of wd40 and spray all the pulleys that you can access and see if the noise goes right away, if it does.... time for new pulleys
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  10. Shargo
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    Shargo New Member

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    [Jul 30, 2013]
    One simple test first: When the car is cold and with AC turned OFF so the electric fans aren't running does the sound stop?
    If so turn the AC back on and check if the noise starts. If it did, then go back and turn off AC again to verify that it really is one/both electric fan(s) that causes the sound.

    Otherwise: If it's a big/difficult job depends on your skills, tools and place to work at. My best advice is to buy a good service manual, I like the one Bentley published - it's reasonable for DIY jobs. Do note that it is written for US spec. cars, how much is different for RHD (moved or mirrored) I have no idea.

    Hunting down noises on an engine can be tricky, it takes experience to be good at it (which I don't have). What you also need is understanding of how things in the car works (thus how they should sound), a huge load of patience and methodically work.

    Some noises can go for a long time before the component fails others not. And in some occasions the sound gets worse before failing other times that isn't noticeable. So when you have unusual noise be prepared something can fail and in our engine a fail might result in an engine rebuild. I don't write this to say you shouldn't try to fix it yourself but so you are aware of the consequences of not fixing it correctly and in time.

    While I have worked at a garage I'm not a trained mechanic, I might be able to locate the fault but there is no way that I'm able to write a guide on how to troubleshoot it nor would I take it on as a job on anyone else car.

    Another method trial and error, replace thing on a whim (oh someone said it's probably that part lets change it). Nope wasn't that, NEXT! It's an expensive and inefficient method but there are a surprisingly large amount of people using it, including not so skilled mechanics. Sometimes even the most experienced guy is forced to do this since troubleshooting just gets to expensive so replacing a common cause makes sense.

    What a good mechanic will do is to spend up to an agreed amount of time troubleshooting and see what he can find / exclude. Lets say something like two to three hours if he gets to work undisturbed. And you want a skilled mechanic (authorized or not doesn't matter in my book) , avoid the cheapest garages - that would likely be wasted money.
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  11. JJREED§
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    JJREED§ New Member

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    [Jul 30, 2013]
    Cheers Shargo. Ive spent several hours playing with engine trying different ways to identify the noise. Im certain its coming from the r/h/s bank. So im gunna go with the tensioner.

    Can any one confirm that the tensioner from the 2.7t audi is the same as the 2.8 4motion vw?
    #10

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