[urq] RE : alternator whine - SOURCE determined!!

[Bernard Littau]

Yes, on the 5ktq, the alternator has a bunch of ducting to keep it cool.  If
you look carefully, the ducting feeds the air to the back of the
alternator.  All alternators I am aware of in Audi's (and in general) cool
by pulling air from the rear of the alternator to the front of the
alternator.  (The fan blades pull the air out of the front)  If the
alternator is mounted in a location where there is not good flow to the back
of the alternator, it needs that ducting to provide fresh cool air to cool
the alternator.  As Huw suggests, the air around the alternator on the 5ktq
is likely hot due to the proximity to the exhaust and turbo.  Flow in that
area of the 5ktq is marginal at best, as evidenced by the ducts to the
alternator and engine mount/turbo and the heat shields.

Audi alternators are generally in poor airflow areas, likely due to the good
aerodynamics of the vehicles and cramped spaces in the engine compartment.
You might consider adding a 5ktq like airflow ducting to your hybrid.

Best,

Bernard
Woodinville, WA
'88 5ktq

On 11/6/06, Huw Powell <audi at humanspeakers.com> wrote:
>
> > Ahh interesting thought - yeah the cover from both my urq and 200 alts
> > does not fit this one - bolt holes don't line up.  The cover is missing
> > in this case.
>
> I noticed on a 5k I took apart once that the alternator had a bunch of
> ducting stuff to, I suppose, help it keep cool.  Probably because it was
> mounted close to the exhaust manifold?  Not so important on a cool side
> mounting.
>
> > In ETKA, the tin-metal back cover (à la urQ and 200q20v) is called an
> > "intake cover". So, does the air enter from the back to be pulled
> > through the body towards the front and exhausted by the fan? If so, then
> > maybe the source of the noise is in the absence/presence of said cover ?
>
> --
> Huw Powell
>
> http://www.humanspeakers.com/audi
>
> http://www.humanthoughts.org/
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