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Re: voltage variance, '89 100Q

>Anyone have some thoughts on the following?:  For a while now,
>I've noticed  that when my car ('89 100Q) is idling, the
>voltmeter reading "pulses." It  reads a good +/-14V, but the
>needle pulses, in time with the engine, to the  tune of about
>1/4 V to either side of the mark.  One can also see the interior
> and exterior lights pulse in intensity, as well as hear it in
>the fuel pump's  hum. 

>As long as it only did this during idle, I just made a mental
>note of it, but  now it's doing this at all rpm's, at a higher
>frequency of course. At times  the needle takes to more wild
>swings. In any case, it looks like "warning sign  number two." 
>And I had just been musing that the Audi had been pretty 
>trouble-free lately (probably where the trouble began). 

>My guess is a problem with the voltage regulator and/or brushes.
> I haven't  changed one of these, but it looks relatively
>uncomplicated. NOTE: I had a  rebuilt alternator installed about
>a year/20K miles ago, so I'm surprised at  any problems in that
>area. (The battery is only 1.5 years old, and seems to  turn the
>motor ok.)

I bet you have a bad diode in your alternator. It is a three phase generator,
that has a full wave rectifier that converts it to DC.

I'd take it off, bring it to a local alternator shop, have them troubleshoot it
and put in a new regulator if required.


Paul Waterloo
Colchester, CT

91 200q

EMAIL: 74543.407@compuserve.com