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Wobbly fan TDi V6

Discussion in 'A4/S4 forum(B5 Chassis)' started by Tom_B, Apr 28, 2012.

  1. Tom_B
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    Tom_B Member

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    The car has some vibration - not bad , but noticeable at about 2 k revs. When I had a look at the motor ticking over I noticed that the right hand fan (standing at the front looking into the engine bay) which is made of plastic is not running true. Does this matter and could it be causing the vibration felt through the car?
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  2. murran
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    murran Active Member

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    a bit of wear/rock in the viscous fan is pretty normal. doubtful if its the viabration you can feel.
    can this be felt when holding 2k while parked or is it while being driven? or both?
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  3. Tom_B
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    Tom_B Member

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    Felt when driving and pulling through the rev range. There is also a kind of low frequency vibration that can be felt through the whole car bparricularly through the pedals. But strangely not through the steering wheel which is rock steady. I had the rear bearings replaced in January and had all the wheels aligned then. The vibration was barely perceptible in January but has got stronger over the months. Doesn't feel good. Almost impossible I know to identify when you are not in the car! Any ideas? Many thanks.
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  4. murran
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    murran Active Member

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    only while driving can you feel it? is it a quattro? might be a drive line viabration if its only on the move? prop center bearing?

    does it occour at the same sort of engine speed in each gear? is it more apparent in the higher gears, higher road speed, but still at around 2000 rpm you mentioned?
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  5. murran
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    murran Active Member

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    when you can feel it, does it go away if you press the clutch down and let the engine idle and "coast"?
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  6. Tom_B
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    Tom_B Member

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    It's an Auto Quattro - there are two components to the vibration a kind of roughness at the 2 k point and then the lower frequency vibration which is a bit like driving over a slightly rough road surface. It sort of stays constant but I just realise that most of the time the car will be cruising at just under or around 2 k it kind of smooths a bit at higher speeds when the revs would be above the 2k point. I'll yak it out tomorrow and make some more exact observations. Drivetrain feels about right though. She's a 12 yr old car with 147000 miles done.
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  7. murran
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    murran Active Member

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    the lower frequency noise sounds like a drone from the exhaust tbh.
    in the front pipe of the exhaust there's a flexible section its supposed to isolate engine viabrations from the exhaust.
    over time this flexible secition seizes up with rust on the outside and soot/carbon on the inside.... this allows the engine viabrations to transmit through the exhaust. causing the low frequency revs specific drone i think your describing??
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  8. Tom_B
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    Tom_B Member

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    Is it easy doable to replace?
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  9. murran
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    murran Active Member

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    not sure, usually the flexi bit is part of the same section the cat is in. ergo expencive!!
    in the past at work ive removed the full front pipe inc. the cat and welded in new flexi sections.......
    they look like this......
    50MM/45MM FLEXIBLE ALLOY CAR EXHAUST CONNECTOR/ADAPTOR | eBay

    any decent exhaust place would be able to weld you a new one in.

    any ideas from any other forum members?????
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  10. Tom_B
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    Tom_B Member

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    So would it make sense to remove the cat if I replaced the flexi section? Thanks for your time and interest btw.
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  11. murran
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    murran Active Member

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    you can de-cat it if you want, its up to you.
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  12. adamss24
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    adamss24 Well-Known Member

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    I think it's the propshaft centre bearing if it does it only on the move at that engine speed.
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  13. Tom_B
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    Tom_B Member

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    Is the propshaft centre bearing complicated to replace?
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  14. Tom_B
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    Tom_B Member

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  15. Tom_B
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    Tom_B Member

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    Europarts is also mentioned as a supply company - any experience with them?
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  16. murran
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    murran Active Member

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    its just removing the prop (exhaust to come off aswell as the transmission tunnel heat shields). marking it up. split it (think theres a circlip) and remove the bearing.
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  17. Tom_B
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    Tom_B Member

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    Many thanks - I will have a go and report back.
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