a simple 'first check' is to remove the alternator belt from the alternator,
and spin the alt. by hand, and see how it feels, and how loose the bearings
are.
I find quite a few 2.1 waterboxer alternators 'running in normal service'
...........with quite loose bearings in them.

also check the mounting below the alternator - those are famous for getting
loose, breaking studs, etc.
you could also remove the alternator from the engine,  then remove the brush
package/voltage regulator, and see how worn the brushes are.

It's not clear which of the 3  types of vanagon you have ........
waterboxer, air-cooled, or diesel.  They all use an alternator, but knowing
year version and model might make it easier for some people to help you.

----- Original Message -----
From: "Joe Fernandez" <jfride@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, June 22, 2009 7:47 PM
Subject: Alternator hum or whine

> Hi listees-
>
> I recently noticed a hum/whine from my van when I turn on the lights. Very
> clear, I can turn the lights on/off and hear the whine turn on and off. It
> sounds like the alternator when I poke around the engine compartment.
>
> The archives show some alternator bearing discussions that mention a whine
> (also water pump, but mine's less than 5k old, replaced by van-cafe). Any
> suggestions for next steps? Check for play at the pulley?  Take it apart
> and
> rebuild? Ignore?
>
> Charging voltage is normal, around 13.8 volts. '86 westy weekender with
> 77k
> miles, original engine/heads.
>
> Thanks all.
> Joe
> Santa Cruz, CA