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High pitch whine under boost

Discussion in 'A3/S3 Forum (8L Chassis)' started by Scullies, Mar 28, 2013.

  1. Scullies
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    Scullies Well-Known Member

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    I was luckily enough to have the turbo bolts come loose, over the weekend and the gasket got blown in half. I have fitted a new gasket and tightened the bolts, I used cap bolts and drilled a hole in the heads to I could pass a piece of stainless wire thought the heads and tie them all together. Hope this stops them from coming out.

    Now when I get for a drive, there is a very high pitched whine coming from the engine bay, it only happens when the boost gets above 11psi. Its almost like a big ass supercharger noise but louder.
    At idle the engine sounds normal, even while driving at speed with low or no boost it sounds normal.

    I have checked for boost leaks by using the compressed air method, went up to 20psi and didn't find any leaks. I even checked the DV in case it wasn't closing properly and boost was creeping past and making the noise.

    could I have a cracked turbo housing or damaged bearings in the turbo.
    whats left to inspect.

    the bolt design

    Attached Files:

    #1
  2. s3clarke
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    s3clarke Money grabbing s3!

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  3. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    as above.. if gasket blew some of it may have passed by the turbine wheel Happened to mt gt35 previously...
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  4. Scullies
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    Scullies Well-Known Member

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    oh dear :sadlike:, mine sounds much like your sound clip, just louder but I guess its the camera thats making it sound softer.

    Guess its more of an excuse to get the stroker built again.
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  5. s3clarke
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    s3clarke Money grabbing s3!

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    yes mate mine is really loud. the video was taken with my phone put on the dash board :racer:
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  6. Lemon S3
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    Lemon S3 Alex

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    Do you have full power as mine was making this noise under boost but not getting full power and it turned out to be the hose from the turbo to the charge pipe was loose.
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  7. @udi A3
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    @udi A3 Site Sponsor Site Sponsor

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    Mine did this and was a loose inlet manifold bolt. Check all your joints are tight
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  8. Scullies
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    Scullies Well-Known Member

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    Well I went to start the car yesterday morning and the manifold/turbo joint started blowing again. So I had a look, and I could feel the gasses flowing when I put my hand near the turbo. So I backed the bolts out and tightened them again. Now there was no high pitch whine at boost. I was happy, but went for a short drive and before I got home the exhaust was blowing AGAIN!
    I remember when I took the engine out the car and stripped it down, the bolt holes in the turbo had inserts in them. Like timeserts, is that standard?
    Would it be possible for the timeserts to be working loose while the bolts are still tight?
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  9. Scullies
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    Scullies Well-Known Member

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    Possibly fixed the turbo bolts backing out and the whining under boost.
    I took all 3 bolts out the turbo again and found that all 3 timeserts were loose. So I modified the bolts, I used a punch and deformed the thread in one spot about 5mm from the end. My thought was to get the bolts to lock into the timeserts and tighten then while I tighten the turbo up. Also fed s/s wire through the holes I drilled in the bolt heads. 2 days of driving now and no loose bolts or high pitch whine under boost.

    Time will tell.
    #9

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