[urq] Alternator condition : how to test or evaluate ?

[Patrick Carlier]

The shreaking is almost certainly the bearing(s)
Change them , they cost pennies compared to an alternator failure .
And use waterproof beariungs instead of dust sealed ones .
They last much longer .
If a new bearing is spinned by hand , it will almost immediatly stop .
My guess is that yours spin forever ....

Diode plates . Very very rare that one should
break down , this would be my last suspect .

Windings ... same story .
Very uncommon te see one fail .
Especially in bosch alternators .

Try measuring output voltage with the engine revved a bit higher then idling 
.
Say 1500rpm .
Voltage should rise quickly to 13.8 Volt .
In theory that is , something between 13 and 14V max is good .

Most common failiure are brushes , wich you replaced so they should be good 
. .
And the copper rings are often worn down to the plastic carrier .
Making no or erratic contact .
Usually the battery warning light comes on erraticly .
It's not to hard to fix that either ,  but you must have a lathe at your 
disposal .


Pat






----- Original Message ----- 
From: "Louis-Alain Richard" <laraa at sympatico.ca>
To: "'Urq list'" <urq at audifans.com>; <quattro at audifans.com>
Sent: Friday, November 26, 2010 9:34 PM
Subject: [urq] Alternator condition : how to test or evaluate ?


> HI everyone,
>
>
>
> In my mind, an alternator is a on/off binary device : it works or it
> doesn't.
>
>
>
> Now, I have a fresh Bosch voltage regulator in an old alternator, and I'm
> not convince that this unit is working 100 %. When under load, the sound 
> it
> makes it rather shrieking, like if there was something rubbing inside it.
>
>
>
> I do have a recent battery, but when I do charge it with a 110V charger,
> it's a lot stronger (from the sound of the starter motor) but after a few
> weeks, it drops to its "normal" level.
>
>
>
> So my question is : will a rebuilt alternator keep the battery fully 
> charged
> better than the old semi-rebuilt alternator ? Besides the voltage 
> regulator,
> what are the other bits that can go wrong in an alternator ?
>
>
>
> Thanks in advance,
>
>
>
> Louis-Alain
>
> 1983 Quattro with a stock 90A Bosch alternator.
>
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