Alternator about to die?

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risk
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Alternator about to die?

Post by risk » Mon Sep 11, 2017 3:07 pm

Converted my 67 from generator to alternator a few years ago.

Been great and no issues til the other day.

Cold start, alternator light stays on but gets dim when revving the motor. After a minute, maybe less it goes out.

Belt is tight, and checked all connections no problems there.

Is this a sign that the alternator is about to take a crap?

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Marc
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Re: Alternator about to die?

Post by Marc » Tue Sep 12, 2017 1:52 am

I would pull the brushes out and inspect them (and the sliprings). Could be contamination where they contact or insufficient spring tension due to worn/broken brush. I saw one once where the brush lead was fouled on the holder frame which limited the travel of the brush, all it needed to fix was to reroute the lead.

Are you running any kind of relay off of the alternator D+ (e.g. for the fuel pump)? If so try changing it out, it could be drawing too much control current and dragging down the voltage present at the warning lamp.

The original German-made AL82 had the regulator mounted along with the brushholder; the Brazilian-made version puts it in the void space at the fan end of the alternator, making it much more involved to replace (have to remove the bearing plate to access it). Brushes and regulators for both versions are available, just a little hard to find sometimes. Check for any radial play in the fan-end bearing, if it's getting sloppy it may make more sense to replace the whole thing rather than renew the brushes/regulator.

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risk
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Re: Alternator about to die?

Post by risk » Tue Sep 26, 2017 8:28 am

Pulled the brushes this weekend and one looked a little glazed over.. So I sanded them lightly, reinstalled and it's back to normal.

Thanks Marc!

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risk
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Re: Alternator about to die?

Post by risk » Wed Dec 06, 2017 3:57 pm

Red light back on..ugh. Looks like a loose screw inside the alternator under the brush cover. I tried to get it with a magnet but its connected to something. Loose, but still connected. I'm gonna throw on my spare and dig into this one and see whats wrong.

Anyone have any tips on getting the big nut off the fan?

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SCOTTRODS
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Re: Alternator about to die?

Post by SCOTTRODS » Thu Dec 07, 2017 7:34 am

risk wrote:
Wed Dec 06, 2017 3:57 pm
Anyone have any tips on getting the big nut off the fan?
I'm a fan of an impact gun... however, I can't remember if the nut is left handed or not... Marc May chime in on that thought. Been about 6 years since I pulled one. Should be able to look and see what direction the threads are cut.
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risk
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Re: Alternator about to die?

Post by risk » Thu Dec 07, 2017 9:18 am

I guess I should have mentioned I was pulling the alternator with the shroud still in the car.. can't fit an impact in there.

I was able to get the fan nut broke loose and pulled the alternator last night.

The loose screw I was seeing inside turned out to be one holding the rear cover on!
alt1.jpg
This made the armature rub on a wire... I'm guessing this was causing it not to charge, or burned something out.
alt2.jpg
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risk
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Re: Alternator about to die?

Post by risk » Thu Dec 07, 2017 9:20 am

This was a Chinese AA brand. I'm gonna pony up the dough this time and get a USA made.

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Re: Alternator about to die?

Post by Marc » Fri Dec 08, 2017 4:50 pm

SCOTTRODS wrote:...I'm a fan of an impact gun... however, I can't remember if the nut is left handed or not... Marc May chime in on that thought...
It's RH thread. Go easy when using an impact wrench though, people often overtorque that 36mm nut since it's the same wrench size as axle & gland nuts that they're accustomed to taking well over 200lb-ft. The thread's the same as on the pulley end; the torque spec for either nut is 43lb-ft. To remove the fan nut without an impact gun requires holding the shaft from turning by the other end - when it's super-tight that's asking a lot of the little Woodruff key between the pulley and the shaft.

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