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Discussion Starter #1
The alternator on my '89 Graduate is acting strangely. Perhaps the wisdom of this forum can help.

When I start the car, the charge warning light comes on and the meter reads below 12 volts. This changes just as soon as a tap the gas. Per a previous thread, this appears to be normal "self exciting" to get it started.

Now for the weird stuff. When I give it any kind of a punch (and I mean any kind) I get a squealing sound from the alternator. Not like a belt (which is tightened to spec and dressed), but more like a grinding high pitch. If I baby the throttle it minimizes and eventually goes away after a few minutes.

What can cause this? Brushes? Bearings? Can it be fixed or is it nearing TU?

BTW I tested out the charging system with a voltmeter and it is just barely in the "normal" range from the guides and videos I've seen.

I appreciate this forum's patience and tutelage. Electrical and charging issues still contain a bit of mysticism to me.-M5
 

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presuming it is not a water pump squeal.....
you could try pulling the regulator/brush set from the back of the alternator (remove the air cleaner box top part, then 2 screws on rear of alt. and the brush/regulator just pull out as a unit) and inspecting them....brushes shouldn't be too short (1 cm maybe is good) and should be both evenly worn down and of course should be dry, not all oiled up!

but if it is not charging to spec, then I'd just exchange alt. out....or try a new Bosch regulator/brush set as its easier and cheaper to try!
 

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Discussion Starter #3
Regulator and more......

Well- the alternator squeal is gone.

I ordered a new regulator and cleaned up the original alternator. The brushes on the old regulator were just about 1 cm so they were needing replaced.

After re-installing the grinding squeal was gone, but there was still a belt squeal. Funny thing was, it was a new belt that is supposedly spec'd for an '89 S3 (32.5" length). With that the adjuster was all the way to the end and it still wasn't quite tight enough.

I took a quick trip down to my local auto parts store and got one in the same spec only in 32" and that made all the difference. No more squeak and I still have some room left on the adjuster.

I have noticed that 89 was kind of a kooky year for the Spider. Some seem to have S3 parts while others seem to have S4 parts. I wonder if that has anything to do with sometimes mismatched parts.

FWIW the alternator (original Bosch) does a better job at charging, albeit still on the lower end of normal.

I did pick up a matching REMY from Rockauto just in case. It was about $100 with shipping and these things are becoming rarer and rarer. Figured worst case scenario I'd have a spare if they ever became unobtainium, based.

Thanks for the guidance SpiderSeries4-M5
 

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Had a similar issue. Some of the nuts and bolts came slightly loose which then caused a misalignment. The sound I was hearing was the rotor rubbing on the stator. Stator is shorted but alternator is still charging at 9V on idle. Will be replacing that before I make the drive to Providence for the convention.
 
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