Failing Alternator??

Another question: While at last week's DE at Summit Point, I noticed, once, the alternator /battery idiot light flash while the car was idling. Not a glow, but a bright on-off flash and only once. Then again, several days later, the same thing happened while the car was idling in the driveway. One bright flash.
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Are these flashes the initial signs of an impending alternator failure? Or is there something else I should be checking?
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Car is 83 SC with 122k miles - Receipts show PO had new alternator installed during December 1991 at 92k miles.
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As always, thanks for your help.
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Chuck

Well, the idiot light signifies no alternator output, but whether it is the brushes, or regulator section, or bad winding, etc. is hard to say. I would recommend removing the alternator from the engine. Take it to a shop specializing in motor.generator/alternator repairs, and they will be able to test and diagnose it properly. Charges to have one rebuilt generally run around $100, versus $300+ to get an exchange ubit.

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Warren Hall
1973 911S Targa

Warren - thanks for the response - I was hoping it might not be the alternator since it was new only 20k miles ago, abeit it was nine years ago. According to the receipt from the P-car repair shop which did the work, PO paid over $800 for the new alternator alone and another $200 for installation. Yikes!
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Chuck

Well, you may want to check the ground lead for the alternator, but I doubt it could be any of the engine/trans ground connections, or you would have instrument or miss/stutter problems, rather than just the occassional warning light!

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Warren Hall
1973 911S Targa

I've incorrectly assumed the worst so many times I am now a big advocate of checking simple things first. If Warren says there are few that could affect this, then I believe him. But I would surely check wiring connections FIRST.

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'83 SC

You might also check the distributor cap and the voltage reg. The distributor is point-less but the contacts can become scored; etc. I have an '83 as well and have remedied an intermittent idiot light by cleaning/swapping out the cap. Just a thought before you test the alternator...

Lee
'83 SC Targa

Just for the curious out there, the main transaxle to body ground has to be good, or you would have starting problems. The alternator has multiple ground paths, and the main one is from the alternator frame directly to the fan housing it is bolted to, which is, in turn, is in contact with and clamped securely to the engine block. The ground strap (lead) to the relay/fuse/CDI 'console' is primarily for the CDI-unit, to make sure the highest possible Voltage is present at all times for the 'hottest' CDI output spark!

But, other possible connections could also cause fluctuating Voltage to the battery, and also cause the 'idiot' light to flicker:

1. The 'hot' lead (at the alternator output stud) ... check for corrosion or looseness of the 'ring' terminal bolted there, red wire, approximately 10-12 gauge wire.

2. The alternator lead at the starter 'hot' lead ... check for corrosion ... not likely to be loose or the starter operation would be 'flakey' at best!

The ONLY real nuisance about alternator troubleshooting, at the back, where all connections are, is that you have to remove the fan belt and fan housing clamp strap, then remove the fan housing itself ... but the 'benefit' is that you WILL be very familiar about a lot of details you had never thought about before! It might be a good idea to allocate an entire afternoon for this 'learning experience' ... you won't be sorry!

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Warren Hall
1973 911S Targa

Oooo, sounds like fun!

Warren, with a "first phones" license older than a store clerk (or jerk-ette), I'd guess you understand alternators. I don't really.

I'd clean/check wire connections, then if there were still trouble, you're right about rebuilding. Any competent rebuilding shop should be able to test and repair the unit without high expense. You might have to tell them it's from a tractor or something.

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'83 SC

Thanks for the responses - Hmmmmm, I guess I know how I'll be spending the 4th. Perhaps, I'll try the real easy solution first, the distributor cap, and then work from there.
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Good lengthy post this morning on the Rennlist with procedures/description how to remove the alternator. I copied it and would be happy to post it here if anyone is interested.
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Chuck

Please do try the "easy" solution first. Complicated and expensive solutions are nice, but simple and inexpensive ones usually work better.

Another thing that has been in my mind regarding your flashing distributor light, is that this symptom is not typical of alternator problems in my experience. if the belt came off, then yes. But alternator lights usually glow or flicker when there is a problem.

I still suspect something simple is happening.

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'83 SC