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Discussion Starter #1
I cranked my T-Bird up tonight, and the red battery light stayed lit, and the voltmeter reads low at idle. When I kill the headlights, or rev the motor, it comes back up to normal.

Is this an alternator issue? It's been down below freezing all day. Could the battery be on its last legs, and just not taking a charge?

I'm gonna try taking it down to Autozone and see if they can test it. Hopefully, it can wait til Friday to be fixed, when I have more money and warmer weather.

Car is a 1996 with a 4.6.
 

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Sounds like it, yes. The fact that it isn't putting out enough juice to keep the voltage up at idle - but is at a higher RPM - is a giveaway.
 

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Discussion Starter #3
Well, at least an alternator is a relatively simple & cheap repair. Although this makes two alternators in as many months I've had to replace. The one on my 1978 Grand Marquis went out the Friday before Christmas. Only the 1D10T light didn't warn me, and the battery went flat in the middle of an intersection on the feeder to the freeway. That night was fun!
 

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If you shop for replacements, see if you can find one from TYC. Word has it they were the OE manufacturer for Ford - and can be had for brand new (not remanufactured) with less markup than the name brand stuff. That's what I bought when I tested mine and saw that it was a little low on output.
 

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The brushes are probably bad.

This is an easy fix.

Yank the battery cables. This is Important! :) Neg first, then positive.

Use 1/2" long breaker bar to remove serpentine belt. There's a hole for it in the tensioner. Use care not to knock the belt off the other pulleys; it makes it much easier to get back on.

Yank alternator. 3/8" takes the battery connection at the alternator, the other ones unplug. 2x 10mm in front to remove it.

T20 removes the voltage regulator and brushes.

Sand the copper part (rotor) the brushes ride on with 220 or higher sandpaper until it's all smooth. :)

Spin the rotor hard; listen for bad bearings. If there's play or bearing s bad; I'd get an alternator depending on talent. You can buy bearings as well, cheap. But they're much harder to get in. :)

Put the NEW brushes and (old or new) voltage regulator back in.

Reinstall alternator.

It should work for another 100k or so...
 

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Commutator Rings

Good directions Grog..

I'd just like to add a couple things.. :)

Take a good look at the Commutator Rings inside the Alternator..They sit behind the Voltage Regulator..The brushes ride on these:
Alternator Commutator Rings.JPG
These are rings inside the Alternator that are porcelain covered with Copper windings...

Here's what they look like when they're new:
New Commutator Rings.JPG

When the commutator rings get completely worn out..You can see the White from the porcelain:
Worn Commutator Rings.JPG

Basically the Alternators brushes eventually wear out the commutator rings...At that point you either have to get a New Alternator or have it rebuilt by someone..

When the brushes on your Alternator go bad..You can usually just replaces the brushes on the Voltage Regulator, and that fixes the problem..

Napa has them in stock..I can get you the part number if you need it..

Hope that helps.. ;)






Rayo..
 

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Nice pic!

Those are way more worn out than the two I've rebuilt; even the one that had 233k miles barely had a groove in the copper.

That's the area I said to sand; you want a nice surface for the new brushes.

If they're worn that deep, you want to replace the copper slip-ring; it solders in pretty easily.


I bought this kit; I needed bearings.

Victory Lap FDA-04 Alternator Repair Kit
 

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Discussion Starter #8
Well, if I had checked in here before I did the work, I probably could have saved some money. I just put a rebuilt alternator from the parts store in it and called it a day. The good news is, the car is fixed. The bad news is, I just paid $100 for an alternator.

Oh well. Live and learn.
 
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