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Nasty noise at idle, which goes away when moving. Cam belt change fix?

pengjn Mar 3, 2011

  1. pengjn

    pengjn Member

    Hi everyone,

    I dropped my car at Audi this morning because for about a week it's been making a nasty noise at idle, which goes away once I start moving. They have just come back to me and told me that they want to change the cam belt and that will 'probably' fix the problem. Can a dodgy cam belt cause a noise at idle that would go away once moving?

    They want £399 + ~£100 for the water pump, which i've read it's worth changing at the same time.


  2. ashaudia3

    ashaudia3 Member

    I had a 05 a3 2.0 140 dsg last year and had same thing. got my dad to have a look and noise only happened in park or nutreal. I had audi have a look and they suggested to service box so i spent 180 with them and the noise went away for couple days. so off that ad say gearbox troubles mate. car did it for 6month of owning it. I began to get the turbo playing up with limp mode so i got shut.

    Hope this helps
  3. pengjn

    pengjn Member

    THanks for the reply. Audi phoned back a while ago to say they now think that it's a problem with the alternator. Is there a mechanism that engages the alternator only when the car is moving? I thought it was linked to the engine so that it was running when the engine is running? I suppose my question is - could a problem with the alternator make a noise whilst at idle but not whilst moving for some reason?? Odd.
  4. Geraldy212

    Geraldy212 Sportback owner

    Penjn, the alternator is engaged all of the time, unlike the aircon compressor which has a clutch. The alternator at engine idle is probably not providing much electrical current, and is therefore not loaded very much. At running speeds it is generating more current and so that makes more resistance to its rotation. Could change the noise characteristics, although I have never heard it happen this way. As the alternator is so accessible, let Audi play with it. They will very quickly find out if the alternator is the problem. Good luck mate.
  5. Lewis583

    Lewis583 Active Member VCDS Map User

    The alternator will have a free-wheeling pulley which has a one way clutch inside of it. they are known to make a noise when the pulley gets some age on it.
  6. pengjn

    pengjn Member

    Very interesting. Changing the alternator pulley fixed the problem. Audi charged £240.00 for the investigation of where the noise was coming from. Doesn't this seem a bit much if the alternator isn't buried deep in the bowels of the engine compartment?
  7. NHN

    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

    You got of litely mate, quick run before they find the real bill dropped under the printer tray, £240 is nothing.
  8. navnayyar

    navnayyar Member

    Most local garages could have told you it was pulley. Think they are £40-50 brand new. Audi dealership are full of sh*t. They charge for plugging in diagnostics even when they know there wont be a fault code and last time i checked this was 110+vat. If you dont know much about cars trust me dealership have a great field day with you

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