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Fault Diagnosis time.... (We all love this)

Discussion in 'A3/S3 Forum (8L Chassis)' started by Welly, Jul 21, 2011.

  1. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    OK, so let me give you the basics...

    Loud humming, grindy sound which gets worse with speed. Definitely a rotational noise.

    Minorly affected by turning whilst driving. Not affected at all by dipping clutch, coming out of gear etc etc. If the wheels are doing over X speed, then she's humming.

    Naturally, you would think wheel bearing, as I did. But it's not. Just changed the bearing yesterday and refitted to find the noise worse than before....

    I know what I think it is, well, one of three possibilities. I just wanted other opinions....

    Discuss.
    #1
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  3. DaveA3
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    DaveA3 Audi A-Trizzle!

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    [Jul 21, 2011]
    CV joint perhaps? Driveshaft?
    #2
  4. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Interesting... Based on symptoms, which CV would you think, inner or outer?
    #3
  5. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jul 21, 2011]
    Have you checked the brake discs/pads for strang wear patterns?
    #4
  6. Dane
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    Dane Faster than a V12 Q7

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  7. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Yeah, but nothing unusual there. Brakes are old, and do need replacing however they shouldn't be causing the sort of din I can hear.

    Hmmmm, 50% chance = no chance. It's more likely to be the inner I think...

    If it is the inner CV though, I suspect it will fall apart upon removal, judging by the noise it's making.

    Failing that, it could be an out of shape tyre, or the box.
    #6
  8. Dane
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    Dane Faster than a V12 Q7

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    [Jul 21, 2011]
    Anything obvious on the propshaft? downpipe rubbing or anything?
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  9. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Not that I could see, that is however, a good point.

    I must admit it doesn't feel like it's coming from that area, but I shall have a look none the less...

    It would be sooooo easy to find on a ramp me thinks. All you would have to do is knock it into gear and drive it to like 40 mph in the air.
    #8
  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jul 21, 2011]
    Diff/haldex?
    #9
  11. Dane
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    Dane Faster than a V12 Q7

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  12. ScottD3
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    ScottD3 I want your faulty electronics

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    [Jul 21, 2011]
    get under it and wiggle some of that TT drive shaft, see if there is play.
    I'd go for CV joint and i'd opt for outer as well, since its happening when turning.

    Whats the 3 possibilities?
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  13. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Nope, deffo front.

    Messing about with the driveshaft to remove and refit the hub has made it worse which makes me think a CV joint is a possibility (as it's been disturbed).
    #12
  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jul 21, 2011]
    No visible splits in the CVs? grease caked everywhere?
    #13
  15. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    It's not just happening when turning dude, it's happening all the time. Turning, straight, simply all the time.

    I mean this noise/vibration is enough to make the dash rattle at 50 mph...
    #14
  16. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Over looked good. Inner did have a small amount of grease when I put my hand down there, but I didn't inspect as I was sure it was the bearing!! lol
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  17. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    I reckon that (in order of likelihood):

    1) Inner CV joint
    2) Gearbox
    3) Out of shape tyre
    #16
  18. ScottD3
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    ScottD3 I want your faulty electronics

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    [Jul 21, 2011]
    Sounds a bit like a tyre fault.
    jack one side up and check the tyre.
    when you're at it check for any other play or movement.
    I had a bad tyre on my A4 and it caused vibrations enough to make the satnav unreadable.
    #17
  19. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    OK, that's useful to know. I guess the easy test is to swap wheel front to back on the driver's side.

    Ten min test.
    #18
  20. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jul 21, 2011]
    Try your S3 wheels on the TT mate. Might be wheel balancing issue?
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  21. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    I don't think so mate, not with the level of noise it produces. Yes, vibration, but wheel balancing producing noise??

    Out of shape tyres make a right din though.
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  22. ScottD3
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    ScottD3 I want your faulty electronics

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    [Jul 21, 2011]
    I hate out of shape tyres.
    Bought a set for the pug just before the MOT, nasty little rumble/whine, MOT guy advised me of a out of shape tyre, went back to tyre place and 2 new tyres fitted and balance. car drove and sounded so much nice.

    and like you said, its only a 10min job and you can check other possible faults at the same time.
    #21
  23. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Whilst I agree, and out of shape tyres are a pain, the volume of the noise being created is mad. I would expect the tyre to be square.

    It is VERY loud.
    #22
  24. Lee172
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    Lee172 GT3071

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  25. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Yup, I think I will later on just so that everyone can hear it. It's easier than trying to describe it.
    #24
  26. DaveA3
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    DaveA3 Audi A-Trizzle!

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    [Jul 21, 2011]
    outer (wheel side) if its on steering slightly. Any splits or anything on inner or outer?
    Last edited: Jul 21, 2011
    #25
  27. Lee172
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    Lee172 GT3071

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    [Jul 21, 2011]
    I always thought outer cv's tend to make clicking noises when they're on the way out.
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  28. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    I guess I didn't explain very well. It's ALL the time, but the sound is altered very slightly by steering wheel adjustment. Only a slight change in the pitch.
    #27
  29. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Yeah, outers are easy to diagnose. Reverse in a tight circle and listen.
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  30. ScottD3
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    ScottD3 I want your faulty electronics

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    [Jul 21, 2011]
    Welly, I found a solution to your clunk and rumble

    [​IMG]

    I'll got back to the pub.
    #29
  31. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    lol, the amount of time I said that about the S3....
    #30
  32. Sandip
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    Sandip Well-Known Member

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    [Jul 21, 2011]
    I reckon it could be 2 things

    1. Dodgy tyre as mentioned

    2. Power steering fluid ok?? Possible that the steering rack is leaking on the seals??? (you won't have any visible sign of fluid on the floor ;) )
    #31
  33. DaveA3
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    DaveA3 Audi A-Trizzle!

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    [Jul 21, 2011]
    now i see why it could be inner.

    Also following the tyre thing sandip said above are the balancing plates still on there? Ive had some come off in the past that completely ****ed up everything
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  34. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    I didn't really look at much else to be fair as I thought it was the wheel bearing.... D'oh.
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  35. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jul 21, 2011]
    Well, I think you should come back once you've checked the car properly :p
    #34
  36. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    Guilty as charged.... lol.
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  37. s3dave
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    s3dave TFSI Hybrid

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    [Jul 21, 2011]
    As the bearing gone in squarley, may be you damaged it putting it in?
    #36
  38. Welly
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    Welly VX220 SC Driver :)

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    [Jul 21, 2011]
    I didn't press it mate, I got my local VW Audi specialist (well, my mate who works there) to do it for me and bring it back.

    He said it all went in fine with no problems.
    #37
  39. antwan
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    antwan Member

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    [Jul 21, 2011]
    Could it be the bearing on the opposite side ? I've been caught out before, sometimes noise carries across axles.
    #38
  40. S3 Nattie
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    S3 Nattie Quattro ist für sissies

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    [Jul 21, 2011]
    I have a really annoying squeaking noise from my passenger side wheel so be interested to see what cures your noise.
    #39
  41. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jul 21, 2011]
    I'd be checking this. Its usually fairly obvious when its that far gone though simply by spinning each wheel and seeing which sounds rough.
    #40

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