This is somewhat VW/Audi specific, I think...

I understand the function of an overrunning clutch on the alternator pulley - it allows the stator to "coast" when engine rpm decreases suddenly. Does anyone know if there would be any long term ill effects of switching to a solid pulley however?

My family's daily driver is a 2001 VW TDI, and the pulley clutch on a nearly-new alternator is starting to lose it's "bite" in cold weather. I have an old alternator with a seized clutch on the bench, and I'm wondering if it would bite me in the ass some time down the road if I simply swapped the jammed clutch over...

Every other car on the planet has a fixed pulley. Don't see how the clutch pulley is an improvement.

I'd do it.

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1986 SE 350 V8

You too? We had an alternator pulley go on our 03 TDI Bug. If it's a seized VW pulley I would think that you should be fine. Other people that have gone with a solid pulley have had issues due to size/alignment of their new aftermarket pulley. Hit www.TDIClub.com and search for alternator pulley, you'll find a lot of info there. Be sure to read up on how to remove the pulley as well, sadly it's as easy as most cars out there.

EDIT: Forgot to ask, did you check the pulley with the belt off?

[This message has been edited by mikejhjr (edited 12-20-2011).]

Thanks, I've been poking about on tdiclub.com already. I'm not sure if it's their search engine, message volume, or simply ineptitude on my part, but each "hit" that I looked at seemed to be a mention in passing of my keywords rather than any solid information. I'll have another look...

I haven't checked the pulley with the belt removed yet, but IMO the symptoms are a dead ringer for a failing clutch. It's exhibiting all the symptoms which one would expect from a slipping alternator belt, but with metal-on-metal "slipping sounds" instead of belt squeal when the components are cold.

quote Originally posted by mikejhjr: You too? We had an alternator pulley go on our 03 TDI Bug. If it's a seized VW pulley I would think that you should be fine. Other people that have gone with a solid pulley have had issues due to size/alignment of their new aftermarket pulley. Hit www.TDIClub.com and search for alternator pulley, you'll find a lot of info there. Be sure to read up on how to remove the pulley as well, sadly it's as easy as most cars out there. EDIT: Forgot to ask, did you check the pulley with the belt off?

...

edit: managed to get somewhere with searches this time. It looks as though a solid alternator pulley on a diesel engine isn't the best combination. Diesels have stronger pulses in crank speed than gasoline, and the overrunning alt. clutch is there to help smooth out the belt run.

Comparison video of solid pulley vs. different overrunning pulley models below... not a VW diesel, but a four cylinder nonetheless.

[This message has been edited by dguy (edited 12-20-2011).]