Alternator confusion

[Ronin]

Looking for a new alternator now... this one couldn't be salvadged due to cracks in threads/casing.

Google is telling me 8 903 016 is a part number for a 150A Bosch alternator for a 6 cyl. petrol engine but I can't find any.

Help!

[MikkiJayne]

078 903 016

[Ronin]

Thanks Mikki! ordered one for 34.99 with next day postage.. mad. It even came with the missing plug,

[MikkiJayne]

That red wire with the white connector is for the starter solenoid. Only the 3.7 uses that spade terminal on the alternator - not entirely sure why but I think it may turn it off under load to save fuel.

[Ronin]

Ahh, that explains why it was missing on my 2,8 to begin with. I've also noticed im missing the whole air duct thing that connects to the pipe thing on the rear :O

Superior knowledge coming from you as always

[Ronin]

I've gotten to the bottom of the issue. It was the alternator clutch allowing slippage in both(!) directions..

Why does the 2.8 have it and 4.2 or 3.7 don't? It just seems like an unnecessary complication.

[Nick Jones]

Dunno why are a thing on VAG stuff at all. Must be something odd about the way they design their harmonic dampers or something. I can tell you that when they are seized solid on 4 cylinder diesel cars it produces a whole host of of strange and unpleasant symptoms. My son has a B6 A4 1.9TDi that was previously my brothers and that came to us with a long history of "power steering problems" It's had several belts, a tensioner, a fluid change and flush and a recon PAS pump (mis-sold as new!). Still it would squeal and screech when manoeuvring with a most disconcerting pulsing and kicking the back through the steering. Strangely enough, 30 seconds on google told me this would be the one way clutch on the alternator seized in both directions (gave me a WTF moment as it was news to me such things even existed!), but it proved to be true and fitting a new one (much harder than writing this), transformed the car.

I know the one on my 2.8 has gone the same way, though the symptoms are slight enough to ignore and also the one on Senior Managements TT, also with minor symptoms. I'm ignoring them. The TT in particular looks like a complete sod to deal with.

Suspect the V8s don't have them as the power strokes overlap sufficiently to render them completely pointless rather than just moderately pointless as on the V6 and petrol 4 pots.

Nick