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What's that noise?

Discussion in 'A4/S4 forum(B5 Chassis)' started by audinary, Jul 5, 2010.

  1. audinary
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    audinary Member

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    [Jul 5, 2010]
    'Evening chaps.

    For a couple of weeks now my A4 has been issuing a strange noise. I've taken various people out to try and determine the cause, including our "trained techicians" but they drew a blank. I'll do my best to describe.

    It starts (abruptly) when you hit about 35mph and then continues, but disappears (abruptly) when you slow to below 28mph. It remains at the same pitch and volume all the while, regardless of speed. Steering lock makes no difference.

    It's a wowowowowowowow sort of sound, the closest I've ever heard before was on the centre propshaft bearing of my Dad's old Sierra.

    I think it's eminating from the n/s Front, but it isn't the bearing. It isn't something daft like a stone caught in a disc or anything like that.

    The car is mechanically sound apart from needing the rear brakes replaced pretty damn quick.

    Any ideas? Common noise? Ignore it and hope it doesn't fall apart on me?

    I'm foxed.

    Cheers guys.
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  3. audinary
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    audinary Member

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    [Jul 6, 2010]
    It's still doing it...

    Anyone?
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 6, 2010]
    Does it do it with the clutch in? Just eliminate whether it is running gear or engine related, and is it gear dependent?
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  5. audinary
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    audinary Member

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    [Jul 6, 2010]
    Cheers for responding Andy

    Yep, clutch in or out. No change.

    Same pitch whatever speed, I described it as a WOWOWOW, when the noise starts it begins at a higher pitch momentarily, then reverts to the usual. So it's like a WEOWOWOWOW. Apologies for the crappo description.

    Had new front disks and pads 2000 miles ago, new n/s bearing 2500 ago.

    It's a wierd'un, ain't it?
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  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 6, 2010]
    Could it be the o/s bearing? If one was worn the other won't be far behind
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  7. audinary
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    audinary Member

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    [Jul 6, 2010]
    That was my initial thought, and I'll end up changing it anyway soon, but it isn't making anything like the same noise the n/s bearing was making, and the sound is louder through the n/s front window. Also it doesn't change pitch or volume with steering movements.

    When I did the n/s bearing it was virtually silent on left lock, but graunchy as hell on right lock. So, I think it might be something else.

    Hmm.
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  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 6, 2010]
    Girlfriend in passenger seat moaning about you driving too fast?
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  9. audinary
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    audinary Member

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    [Jul 7, 2010]
    Hadn't thought of that! I'll eject her at 35mph see if it makes any odds!
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  10. jcb
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    jcb Active Member VCDS Map User

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    [Jul 7, 2010]
    if it is speed dependant but doesn't increase in pitch or vloume whith braking, steering, accelerating then it could be something vibrating once it gets enough wind over it. increase in speed may not speed up the vibration
    have you checked your undertray or arch liners?
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  11. calvin
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    calvin parked up

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    [Jul 7, 2010]
    Assuming you dont have a bulge in the tyres and all other visible checks have been made you can try this:

    I know you shouldnt do it really (sorry Mr Health and Safety!), but, assuming your car is a FWD and not a Quattro (for obvious reasons!) - Jack the front up and chock the other wheels, then try running the car in gear VERY VERY carefully, going through the gears until you get to the 28mph - it will at least eliminate the vibration / road noise / wheelbearing load route at least, AND any issue with the undertray etc. flapping. and might give you the exposure to what is causing the noise.

    Just take it really really gently and ensure the car is securely jacked up and no people around to mow down in the event of a collapse...
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  12. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 7, 2010]
    I wouldn't try that with someone elses car let alone my own. Apart from the really serious H&S issues I doubt most cars would like any amount of drive through the wheels while they are dangling in mid air.
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  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jul 7, 2010]
    Try steering from side to side when its making the noise. If its a bearing then loading it up (by steering) will often change the pitch of the noise.

    Does it go away if you drive faster?
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  14. audinary
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    audinary Member

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    [Jul 8, 2010]
    Cheers JCB, Andy and Aragorn,

    Sorry I was unable to respond to my own thread, flipping work internet access has just been restricted.

    JCB, No undertray fitted. I did think about a possible wind / vibration but couldn't imagine anything making quite this sort of noise. Sorry about the ridiculous impersonations I'm doing, but the wowowow sound is about half a second between the w's, if you get what I mean. Like wowowow at regular talking pace, but by the time I it about 40mph it's drowned out by road and engine noise.

    Calvin, health, safety, and everything else apart, I can see myself doing this. Might get it up on a two-poster at work, or see if I can run it on the rolling road. Honestly hadn't thought of that.

    Aragorn, I know what you mean about teh pitch / volume changing when you load it up into a corner, before I changed my n/s bearing it was much louder turning right, and it actually quietened if you turned left. That was a totally different sound, though, and this one is completely unaffected by steering.

    Cars are weird.
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  15. gav
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    gav S6 vvv

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    [Aug 21, 2010]
    Calvins right, i tried this no problem and it worked fine..( mines was a drive shaft)
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