[Vwdiesel] Free wheeling alt pulley WasRe: Re undersized

Val Christian val at mongo.mongobird.com
Thu Aug 28 20:45:46 PDT 2008

> At 01:56 PM 28/08/2008 -0500, you wrote:
> >As far as pulleys and alternators are concerned, my 04 Jetta TDI actually 
> >has a pulley on the Alternator that freewheels at certain speeds thereby 
> >reducing the load on the engine.  I guess since there is minimal electrical 
> >usage on diesels they decided to save a bit.  Hayden
> >
> No, it doesn't freewheel at certain speeds, it is an overrunning clutch that
> allows the alternator to overrun and slow down slower than the engine when
> decelerating suddenly, (like on rapid up shifts).
> This reduces serpentine belt whip, caused by the rotating mass inertia of
> the alternator and came about because of early tensioner bushing wear-out,
> and also might have had something to do with the crankshaft nose failure on
> early 1.9s.
> It became standard equipment on the TDIs. I have retrofitted one on my 94 TD
> Sandy
Also a major source of failure with the alternator.  I put a non-freewheeling
pulley on mine, and at least I haven't had to keep replacing the freewheeling

Val  N2EPO

More information about the Vwdiesel mailing list