[Vwdiesel] blinking alternator light ??

[Val Christian]

Probably NOT a factor on the 93, but I had a recent surprize on my
2003 TDI, which is similar.  All of the sudden the altenator light
came on, and I managed to get the car home, as the system voltage
dropped through 9.5 volts.  The ABS light came on, along with just
about everything.  Just like the dying plane in the simulator.
Lights flashing, and me shutting down systems (although in that 
car, the headlights stay on, etc.).  

I assumed that I had a brush problem, because an alternator with
73K miles just doesn't fail like that.  So I pulled the brushes.
They were fine, but there was some corosion on the the rings.  So
with the engine idling, I "turned" the rings, and they looked
pretty fine.  Put the brushes back in, and things worked for about
2 hours.  Then the alternator died again.

I noticed that the alternator was making some intermittent noises
when connected with the car running.  If I disconnected it, the noises
went away.  Subtle or there.  

It turns out that there is a ratcheting clutch on the alternator,
which permits the alternator to freewheel when the engine drops RPM
faster than the alternator might.  That failed.

I ended up with a replacement alternator from AZ, which doesn't 
have the ratcheting clutch, which until I learn otherwise, is 
fine by me.  

The rather worthless Bentley said nothing about the alternator
having a clutch integral in it's pulley.

Val




> > I believe the tach reads off the alternator "W" post.  Therefore it 
> > seems
> > likely to be an alternator problem, such as dying diodes, or maybe an
> > intermittent short.
> >
> >> hey all
> >> my 93 Eurovan DIESEL was doing something weird last night
> >> battery/alt light was coming on intermittently, faint, then bright,
> >> then in between, etc
> >> tach would zoom up to normal, then falter, then die, then back up...
> >> I checked belt - fine, tight
> >> all electrical connections seem OK
> >> thoughts about what might be happening? it's been COLD here last 2
> >> nights
> >> are these symptoms of a dying alternator?
> >> or am I not trouble-shooting hard enough?
> >> thanks for any thoughts