98 Taurus lights dim

The headlights and dash lights dim intermittently. Tonight I monitored the battery voltage. When the lights are normal I have 14.2 volts and when they dim it goes as low as 11.8 volts.. It seems to happen more
on rough roads and blipping the throttle slightly usually brings the voltage back up. The battery connections and grounds look good. The problem seems worse after a few minutes of highway driving.
I'm guessing the alternator is the problem but I haven't had this type of intermittent cutting in and out before and I haven't seen any warning lights on the dash display. Any suggestions?
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With the engine running, watch the voltage while doing a 'tug test' on all the wiring between alt and battery.
You may also have a bad ground connection in that area.
Otherwise, if the car is 120 KMile or more, you may also have worn / sticky brushes in the alternator. which is a one hour, ten dollar repair.
Go to Google , this group, and look for "Tip: easy alternator refurbish"
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On Wed, 28 Dec 2005 12:54:21 GMT, Backyard Mechanic

Thanks, it's got right around 100K. I'll wiggle the wires and look at the brush tip.
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On Wed, 28 Dec 2005 12:54:21 GMT, Backyard Mechanic

The alternator has completely failed at this point. If it comes to more than brush or brush and regulator replacement and I need a rebuilt alternator are there any brands that are better than average or any to avoid?
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NAPA rebuilt comes to mind.... though I dont usually worry about it. I've had good luck with rebuilts from all stores.
But the last time I needed an ALt, I happened to be near a salvage yard... got a used one and a set of new brushes from NAPA, did the 'refurb', including lubing rear bearing {a very small amount of lube!} and put it on... at about 1/3 cost.
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On Fri, 30 Dec 2005 15:48:13 GMT, Backyard Mechanic

Well you were right about the brushes one was worn down to the wire the other was over a 1/2 inch long. Probably close to full length. The slip ring under the bad brush is shot so I guess it is good that I chickened out and picked up a rebuilt unit. I don't think the slip rings are available from the local parts stores. I did find a place that supplies rebuilders, so I know they can be obtained at the wholesale level. Maybe I'll see if I can get the local rebuilder to sell me the part and fix this one as a spare.
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Dont worry about it...
That slip ring will work just fine, esp as a 'spare', just smooth off any rough parts
What you want to do is clean up all the brass thrown around the diodes and reg with carb cleaner.
Or go to a salvage yard and get a used alt and do the brush/bearing lube job.
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