Electrical gremlins again (crazy needle syndrome) - conclusion

[Radek]

Since the rebuilder wouldn't want to touch my alternator, I ordered what I was told would be a brand new, Chinese product from Canadian Tire.  It arrived in a nice box which said "Champion remanufactured alternator".  OK.  I took it out of the box and it looked EXACTLY like the old one.  The only difference was the capacitor at the back, instead of being a black box, it was a shiny barrel.  So I paid for it and took it home.

Upon closer inspection, I think it is indeed brand new.  Stuck to the bubble wrap I found a sticker that said "Made in Mexico". So I put it in the car and then discovered that the pulley was different, it protruded much further and the belt wouldn't sit properly.  Had to take it out again, remove the pulley, put in the old pulley - took me the best part of the evening but finally everything fits and the voltmeter needle is steady.  I think this alternator model fits a number of VW models and they make it new in Mexico.

Thanks to everyone who offered help, very much an educational experience for me.  I wish I paid more attention when in grade 7 electricity was covered!  I remember, though, that the physics teacher was very pretty.
Cheers;

Radek.



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Message: 4
Date: Tue, 8 Jun 2010 21:07:38 -0500
From: Tony Hoffman <auditony at gmail.com>
Subject: Re: Electrical gremlins again (crazy needle syndrome)
To: Peter Golledge <petergolledge at gmail.com>
Cc: radek at istar.ca, quattro at audifans.com
Message-ID:
<AANLkTikx-bQ7pNY1YJm8b02ms9mbugM-exODdT-zO8lY at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

I'll second that, or source one in the southern states, and have it
rebuilt. I've had better luck with socally rebuilt ones than any I've
bought new online. Same with starters. I've got one on the V8, bought
new (chinese) repalced at 310K. Now 330K, it's dead. I should have had
the original rebuilt, it probably would have lasted another 310K.

Tony

On 6/8/10, Peter Golledge <petergolledge at gmail.com> wrote:
> I'd take a junkyard Bosch and put a new regulator in it over a cheap noname.
> Even a rebuilt Bosch from a decent company would be a better bet.
>
> As for the AC on the meters.. don't have a theory on that one.
>
> -----Original Message-----
> From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] On
> Behalf Of radek at istar.ca
> Sent: Tuesday, June 08, 2010 3:40 PM
> To: quattro at audifans.com
> Subject: Re: Electrical gremlins again (crazy needle syndrome)
>
> Here's the latest news:  I took the alternator to a shop to get it
> tested.  They guy hooked it up to a big machine which had an
> oscilloscope on top.  He ran it for a couple of minutes on different
> settings, then declared that the diodes were OK.  Next, he took out
> the regulator and put his finger inside.  His final verdict was that
> the shaft was worn out and brushes were jumping, losing contact.
> Indeed, the shaft was rough to the touch.
>
> So I had a diagnosis, the fix was to get the alternator rebuilt.
> However, he called me today saying everything was falling apart,
> screws breaking and lots of rust inside, and that I'd be better off
> buying a new one.  I think I'm going to get a brand new (Chinese made)
> alternator at Canadian Tire for under $200.  Comes with a three-year
> warranty.  Time to bite the bullet, I guess.
>
> Thank you all for your help and guidance, for an electrically
> challenged individual like me it was a very educational experience!
> What I still don't understand, though, is why would my handheld meters
> show any AC voltage at all, even when measuring across battery
> terminals with the engine off?
>
> Radek.
>
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 7 Jun 2010 08:03:11 -0500
> From: Joshua Van Tol <josh at spiny.com>
> Subject: Re: Electrical gremlins again (crazy needle syndrome)
> To: urq <urq at pacbell.net>
> Cc: quattro at audifans.com
> Message-ID:
>          <AANLkTikDf-10RNdRyqL60Tb0kZgFYco2lPX7Rhzu3t-6 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Testing alternator diodes directly is a huge pain in the butt. Measuring AC
> voltage either with a proper AC meter, or a scope is way easier, and very
> conclusive. When I wrenched professionally, that's the way I always did it.
> Never a problem. There's not any likely sources for AC on the battery bus
> other than a bad alternator. Particularly if the AC goes away with the
> engine off.
>
> Josh.
>
>
> On Sun, Jun 6, 2010 at 9:16 PM, urq <urq at pacbell.net> wrote:
>
>
> [Show Quoted Text - 59 lines][Hide Quoted Text]
> Neither of the handheld meters have a diode when measuring DC either ...
>
> I don't understand what might make the dash meter jump ... maybe there's a
> bad connection inside that is causing the jumping in particular voltage
> ranges.  When you've got two handheld meters telling you there isn't likely
> anything wrong they are likely the ones telling the tale ...
>
> If you suspect alternator diodes then test them directly, don't infer
> there's a problem based on a voltage fluctuation ...
>
> Steve Buchholz
>
> -----Original Message-----
>
> The voltmeter in the dash possibly doesn't have a diode or such to
> keep the AC voltage out. The handheld meter when set to read DC
> voltage will read ONLY DC, likewise with AC. He stated he's getting a
> whole bunch of AC voltage which could make the dash meter fluctuate.
> I'm not saying the dash unit isn't bad, but all that AC in there is
> certainly no good.
>
> Didn't OP state that the dash meter is stable with the engine off?
>
> -Cody (mobile)
>
> On Jun 6, 2010, at 7:45 PM, "urq" <urq at pacbell.net> wrote:
>
>
> ... I thought I read that with external analog and digital meters the
> voltage was stable ... why are people continuing to recommend
> anything other
> than replacing the voltmeter in the dash?
>
> Steve Buchholz
>
> -----Original Message-----
>
> Another vote to check out the alternator, even if it was recently
> rebuilt.
> My son's car ('91Golf) had a recently rebuilt alternator in it and had
> similar problems.
> As it turned out the first problem was that the filed wiring was not
> soldered in properly to one of the slip rings. In another year the
> soldering
> for one of the rectifying diodes let go.
> Clearly shoddy workmanship.
> The car was bought secondhand and came with the rebuilt alternator and
> starter.
> I also had to fix the rebuilt starter, that was also nearly brand
> new, there
> was hardly any wear on the commutators.
>
> Good luck, Peter
>