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Alternator clutch pulley..

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by demus, Jul 24, 2014.

  1. demus
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    demus Fire in the hole..

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    [Jul 24, 2014]
    I'm hopefully going to change the belts and tensioners in a few weeks, and I've noticed a few times a squeaky chatter sometimes when just started from cold.Its only for a few seconds and can be brought about by turning the rear demist on, stops when you turn it off. Could this be the alternator clutch??If so, can this be bought seperately to the alternator, and are there any funky tools needed to change it..Cheers guys..
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  2. Greeny233
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    Greeny233 Active Member

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    [Jul 24, 2014]
    There isn't a clutch in the alternator, when you switch on the heated rear screen or start the car (high amp systems) it puts a great deal of load on the alternator and either the belt starts to slip slightly or the bearings are worn in the alternator and thats when you hear the squeaky chatter.
    When you come to change the belts and you get the old belt off give the alternator a spin and see if the bearings are noisy or if there is any play in the pulley. If there isn't then it'll be the belt slipping slightly and a new one and the correct tension will solve the problem. If not then you'll need to either get your alternator bearings replaced or a new or reconditioned alternator.
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  3. Welshquattro
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    Welshquattro Active Member

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    [Jul 24, 2014]
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  4. Greeny233
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    Greeny233 Active Member

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    [Jul 25, 2014]
    I stand corrected. Still the same reason for squeaking though. Easy replacement if the pulley is worn.
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  5. Welshquattro
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    Welshquattro Active Member

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    [Jul 25, 2014]
    I must admit I didn't know it had one until mine went.
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  6. A3_130
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    A3_130 Member

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    [Jul 25, 2014]
    Yeah the alternator has a one way clutch which will cause a chattery noise at tick over if it's had it. Easiest thing to do while the belt is off is to see if it will move as it should and if it's broken get one off another alternator to replace it. You probably will need a special tool (like a multi spline but with a different number of points to it) but the tool you need varies between different alternators. When we replaced the clutch on my father's A4 we swapped it for one from a similar alternator off an old golf that needed reconditioning but freewheel clutch was OK. Easy enough job.
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  7. Icarus83
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    Icarus83 Active Member

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    [Jul 25, 2014]
    Imagine the clutch behaves the same as the bearing/clutch on the back wheel of a pushbike.......when pedaling the clutch drives the wheel, but when the rider stops pedaling the wheel motion is not carried back through the pedals and it freewheels.

    Extract taken from: Powering Progress™ in belts, hose & hydraulics

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  8. boytrigg
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    boytrigg Member

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    [Jul 25, 2014]
    easy enough to do just need a special tool to take it of you can get the pulley from euro parts genuine one for 27 quid or 80 quid from the stealer's the choice is yours lol
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  9. demus
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    demus Fire in the hole..

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    [Jul 26, 2014]
    Clutch seems to work as it should, spins one way, locks the other..
    I'll change belts and tensioners and see if it still does it, and go from there...
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