Alternator Question

[Vittorio Bares]

Small update - while I was writing the first email - I let the car idle
(looking to charge the battery). When I returned, the voltmeter gauge
was showing well over 13v - and measuring voltage from the post of the
alternator to the motor showed 14v (just under).

When the radiator fan would turn on, the voltage would drop to 12v (just
under). 


Vittorio Bares
Senior Manager, DA
Professional Services
NUANCE COMMUNICATIONS, INC.
 

-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com]
On Behalf Of Vittorio Bares
Sent: Sunday, December 09, 2007 2:26 PM
To: Mark R; Steve Sears
Cc: quattro at audifans.com
Subject: RE: Alternator Question

Back at it - I've replaced the alternator w/a refurbished one - I now
have 2 fully working units (tested at AutoZone) :\.

Went back an cleaned contacts behind the snub nose (alternator bracket).
Cleaned contacts to adjustment bracket.

Voltage is dropping when revving the motor.

The diagnostic display for voltage on the climates control remains at
12.0 (channel 11). This is regardless of what the needle on the gauge is
doing. It used to properly indicate the voltage.

Needle shows just over 12v on idle. Verified w/volt meter.

Voltage off of the alternator (+ post to engine ground) is about 12.5v
(seems low). I presume (it has a 14v regulator) it should read 14v from
somewhere - anyone know where to measure that from?

Anyone know how to check continuity of exciter wire (blue) from
alternator? Bentley says to check current across wire to alternator
exciter post - I set my multi-meter to DC 250ma and the needle shot over
max (?) Bentley says it should be between 150-180ma - indicates if its
low to replace climate control board - doesn't say anything if its above
?

Steve suggests in the attached thread to check voltage from the battery
- since the battery is charged via ground (I believe), would one try to
directly from one of the alternator mounting brackets to the negative
post on the battery (a direct ground)?

BTW - this is on a 1990 Audi 200 avant.

Thanks!

Vittorio -
 

-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com]
On Behalf Of Mark R
Sent: Monday, September 24, 2007 1:36 PM
To: Steve Sears
Cc: quattro at audifans.com
Subject: Re: Alternator Question

Steve's got it right... often overlooked is the primary wiring.  Audi
didn't use the greatest wiring when new, and now you'll often find
corrosion under the sheath due to moisture wicking.  Remember, the
alternator has to have the ability to get the current (amperage) out as
well.

Another quick and dirty test is to check voltage at the battery versus
the alternator post (if available when engine is running).  Set up the
wiring before starting the engine.  If you see a voltage change (drop
along the wiring), you'll need some attention there.

Cheers!
Mark Rosenkrantz


On 9/24/07, Steve Sears <steve.sears at soil-mat.on.ca> wrote:
>
> Vittorio,
> If the alternator is one of those 110 amp units, then the two bolt 
> pivot is correct.  If it is the 90 amp unit, then it should have a 
> long bolt and nut at the pivot.  If you were to hook a long jumper 
> cable directly between the snubber mount to the battery ground, would 
> you get a different reading?
> (The engine ground to chassis across one of the engine mounts may be
bad).
> You might also check the condition of the battery cable splice.
> Cheers!
> Steve Sears
> 1962 and '64 Auto Union DKW Junior deLuxes 1980 Audi 5000
> 1987 Audi 5000 Turbo Quattro
>
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