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Whine from serpentine belt

HibiscusS4 Aug 27, 2012

  1. HibiscusS4

    HibiscusS4 Member

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    Right, my S4 has developed a super charger type whine. I was very concerned it was terminal but have today removed the drive belt and its gone away. This leads me to beleive its one of 3 things and I'm looking for advice from anyone who has had any of these fail.

    I replaced the drive belt tensioner when I did the cam belt as the old one spun very freeley and felt like it had a bit of play. so its not this.

    The Air con pump, this feels a little graunchy but this is with the clutch dissengaged. The noise does not change at all when the AC is switched on and off except that the revs change slightly so the noise changes pitch. The AC is functioning correctly.

    The PAS pump, this feels fine and although I do get a slight singing noise when I dry steer its only when you turn extreamly hard without moving forwards/backwards. The whine does not change when the steering is used.

    The viscouse fan or its bearing, again both feel good and I get no overheating. The fan has good resistance and the bearing feels smooth. Are these available as replacement parts?
     
  2. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    alternator?

    Dont assume your new tensioner is still good either, it could have failed prematurely.
     
  3. HibiscusS4

    HibiscusS4 Member

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    Sorry, should have said that I changed the belts because of the noise and it didnt go away so I would imagine its not the new tensioner since the noise would certainly be different if the new tensioner was supplied faulty as opposed to a worn one.

    I didnt think of the alternator but since I last posted I have now refitted the belt and the noise is coming from the passenger side more prominently although this could be the PAS pump. I am leaning towards the AC pump but I dont understand why its no different with it running or not. As I understand when the AC is off the clutch dissengages meaning a totally different bearing is taking the load to when its engaged.

    On the plus side its not worn cams.
     
  4. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    PAS pump sits in the vee.

    Get a length of hose, put it to your ear, and put the other end near each suspect component.
     

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