[Vwdiesel] TDI alternator pulley

[dieseltdi at verizon.net]

The thing is, the clutch pulley is replacable.  9 times out of 10 there is nothing wrong with the alt.  Hayden


Sep 16, 2010 03:57:43 PM, val at valchristian.com wrote:

I can't address whether it was the pully which trashed the tensioner,
but I recall checking the hydraulic damper each time, as cautioned.
In each of my cases, the sprag clutch died, allowing freewheeling in
both directions.

The initial symptoms, for TDI owner benefit, were flashing or intermittent
battery/alternator light, as the clutch would sometimes grab. Within a week
it wasn't grabbing at all. 

I replaced the alternator with one from Autozone, with the principal benefit
being "lifetime" replacement. The second alternator went in at about 58k miles,
and the third at 114k miles. I presently have about 149k miles.

I had hears that some people got rid of the sprag clutch, but I decided that 
there was a method in the madness which put it there. It is the leading cause 
of alternator failures on TDIs.


> 
> It's is a 'sprag clutch' (couldn't find a good example pic) and the reverse
> direction resistence isn't really of much value as long as it locks in the
> 'forward' direction.
> It's there to reduce the spinning forces internal to the alternator when the
> engine is shut off.
> The tensioner died of it's own accord.
> imho
> 
> BrianG
> Iowa
> 
> 
> Date: Wed, 15 Sep 2010 22:27:17 -0500
> From: Shalyn Shourds 
> Subject: [Vwdiesel] TDI alternator pulley
> To: vwdiesel at vwfans.com
> Message-ID: <4C918E95.4030503 at flash.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> A while back, I saw that my '00 Jetta TDI accessory belt pulley was
> bouncing all over the place. I searched the TDIclub site and there
> seems to be a history of alternator pulleys failing causing the tension
> on the belt to exceed the dampening ability of the tensioner. Tonight,
> I pulled off the belt and looked over the system. The typical alt.
> pulley failure mode appears to be that the one-way clutch doesn't lock
> in either direction. I did establish that the pulley locks in one
> direction. I also noticed that in the other direction, it has far more
> resistance than I would expect from a bearing, but I don't know what's
> typical of this kind of clutch. Should it be completely free-wheeling,
> zero resistance? I also ascertained that the little hydraulic strut on
> the tensioner is completely blown--oil leaked out everywhere. I
> definitely need to replace it, but did it die, or...was it murdered by
> the alt. pulley?
> 
> Thanks,
> 
> -Shalyn
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