Ford pickup low voltage at idle

"N8N" > wrote in message
ps.com...
> On Aug 6, 3:16 pm, N8N > wrote:
>> On Aug 6, 1:23 pm, wrote:
>>
>> > On Aug 5, 3:13 pm, Mike Walsh > wrote:
>>
>> > > You have shorted diodes in the alternator.
>>
>> > Shorted diodes would drain the battery when the engine is shut
>> > off. He made no mention of that. An open diode might be possible, but
>> > my bet is on worn-out alternator brushes that aren't making good
>> > contact anymore. It's the most common alternator problem. Brushes
>> > should be checked every so often, like maybe 50,000 miles or so. We do
>> > them at 500 flying hours in our aircraft, and they are Ford
>> > alternators. They don't go beyond about 1,000 hours without being
>> > short enough to need replacement. 1,000 hours at an average speed of
>> > 40 MPH would be 40,000 miles.
>>
>> > Dan
>>
>> Is this an alternator where there's a bearing and brush kit readily
>> available at my FLAPS or do I need to actually send it off to be
>> professionally rebuilt? I have perfect confidence in my ability to do
>> the work, but in some cases (e.g. Bosch) I have been unable to source
>> the parts through consumer-level channels.
>>
>> nate
>
> Forgot to mention, if they fail for you at appx. 1K hours, they
> probably are toast as vehicle has about 140K miles and no record of
> alternator having been touched (PO kept good records, I have a
> surprising amount of documentation)
>
> nate
>
Nate, I've worked on vehicles for 55 years (of course somebody's gonna
say that may be just 1 year experience, 55 times!!!) and if I needed an
alternator that yours would fit, I'd buy & enjoy it! And if your battery
will withstand a load-test with a proper tester, I'd buy a good used battery
also! Luck, & don't worry--unless battery is going dead or such. HTH, s

"Nate Nagel" > wrote in message
...
> wrote:
>> On Aug 5, 3:13 pm, Mike Walsh > wrote:
>>
>>>You have shorted diodes in the alternator.
>>
>>
>> Shorted diodes would drain the battery when the engine is shut
>> off. He made no mention of that. An open diode might be possible, but
>> my bet is on worn-out alternator brushes that aren't making good
>> contact anymore. It's the most common alternator problem. Brushes
>> should be checked every so often, like maybe 50,000 miles or so. We do
>> them at 500 flying hours in our aircraft, and they are Ford
>> alternators. They don't go beyond about 1,000 hours without being
>> short enough to need replacement. 1,000 hours at an average speed of
>> 40 MPH would be 40,000 miles.
>>
>> Dan
>>
>
> You called it, I called my FLAPS at lunch today, they said they needed to
> know which alternator I had to say whether or not they had parts for it,
> so I pulled it when I got home from work (good thing I'd done it before,
> because it's about 95 degrees out, had to wrap a bandanna around my head
> to keep my glasses from getting sweated on, and I was getting eaten by
> skeeters) took it into the garage, started to take it apart, brushes are
> nubbins. Unfortunately FLAPS does not carry brushes for the one I have
> (75A) I'm on hold with Crap Boys right now...
>
> I'd rather throw new brushes into the original than pay $80 for a reman of
> dubious quality. the other option is to pay the $$$$$ to have it gone
> through by the local rebuilder, but they are in Annapolis which is about
> 50 miles away, not open on Saturday, and pricey...
>
> nate
>
> --
> replace "roosters" with "cox" to reply.
> http://members.cox.net/njnagel

Hey Nate, we're not too po-dunky a town, and yet there are 2 shops here
who reman just about any alter. for $30, sometimes $35. Just did one off a
2002 Z28 for me for $30. Check around--but see my post *up* one or 2 first.
Luck, s

MasterBlaster wrote:
> "Nate Nagel" wrote
>
>
>>I found a local-ish
>>parts store with brushes, bought 'em, installed 'em, they work and I
>>certainly feel better about the alternator now that there's some actual
>>spring tension holding the brushes against the slip rings, but I still
>>have the same problem exactly as described above
>
>
> You do realize that just as engines don't put out maximum HP at idle,
> alternator's don't put out max amps/volts at idle either. If you're not spinning
> the alternator fast enough to keep up with whatever load you put on it, no
> regulator or brush set in the world is going to help.
>

I understand that, but what I'm seeing appears to be drawing power off
the battery at idle with only headlights and A/C running. I certainly
don't want to be stranded somewhere with a dead battery simply because I
got stuck in traffic after dark. (A/C is mandatory here in Our Nation's
First Swamp.) Certainly it wasn't like this when new otherwise nobody
would have ever bought a Ford.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

my 71 comet had low voltage at idle.. coil resistance checked good but
it was 36 years old so replaced it and solved the problem


--
chas123
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On Aug 7, 4:04 am, Nate Nagel > wrote:
> MasterBlaster wrote:
> > "Nate Nagel" wrote
>
> >>I found a local-ish
> >>parts store with brushes, bought 'em, installed 'em, they work and I
> >>certainly feel better about the alternator now that there's some actual
> >>spring tension holding the brushes against the slip rings, but I still
> >>have the same problem exactly as described above
>
> > You do realize that just as engines don't put out maximum HP at idle,
> > alternator's don't put out max amps/volts at idle either. If you're not spinning
> > the alternator fast enough to keep up with whatever load you put on it, no
> > regulator or brush set in the world is going to help.
>
> I understand that, but what I'm seeing appears to be drawing power off
> the battery at idle with only headlights and A/C running. I certainly
> don't want to be stranded somewhere with a dead battery simply because I
> got stuck in traffic after dark. (A/C is mandatory here in Our Nation's
> First Swamp.) Certainly it wasn't like this when new otherwise nobody
> would have ever bought a Ford.

There's one other possibility: the battery has sulfated and
its internal resistance has dropped too far so that it can't keep up
with the battery's demand plus everything else. I'd try another
battery (borrow one) and see if it helps. The alternator's heat might
say it's working too hard somehow.
Modern alternators are capable of producing plenty of power
at idle. It's the reason we switched from generators back in the '60s.

Dan

Nate Nagel wrote:
> Nate Nagel wrote:
but I still
> have the same problem exactly as described above, alternator is still
> very hot too. Any ideas?

I can't say for sure, but you symptoms sure seem 'normal' to me. On all
the recent AC Delco alternators I have been using, none will start a
good charge according to the dash meter until I get to 800 rpm and
above. Sitting at a 650 Idle with everything on causes the volt gauge
to drop. Sounds just like your Ford....

I am on my second alternator in this vehicle and the current one was an
expensive remanufactured unit, not rebuilt. My last GM pickup was the
same and even my last Volvo 240's with Bosch alternators were the same,
no charge on the volt gauge at idle.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

I should have said shorted diode. If a positive and a negative diode or both shorted then they will drain the battery with the engine off.
Low current output and high alternator temperature indicate a short somewhere in the alternator, often a diode.

N8N wrote:
>
> On Aug 6, 3:16 pm, N8N > wrote:
> > On Aug 6, 1:23 pm, wrote:
> >
> > > On Aug 5, 3:13 pm, Mike Walsh > wrote:
> >
> > > > You have shorted diodes in the alternator.
> >
> > > Shorted diodes would drain the battery when the engine is shut
> > > off. He made no mention of that.

--
Mike Walsh
West Palm Beach, Florida, U.S.A.

On Aug 7, 11:44 pm, Ashton Crusher > wrote:
> On Mon, 06 Aug 2007 10:23:34 -0700, wrote:
> >On Aug 5, 3:13 pm, Mike Walsh > wrote:
> >> You have shorted diodes in the alternator.
>
> > Shorted diodes would drain the battery when the engine is shut
> >off. He made no mention of that. An open diode might be possible, but
> >my bet is on worn-out alternator brushes that aren't making good
> >contact anymore. It's the most common alternator problem. Brushes
> >should be checked every so often, like maybe 50,000 miles or so. We do
> >them at 500 flying hours in our aircraft, and they are Ford
> >alternators. They don't go beyond about 1,000 hours without being
> >short enough to need replacement. 1,000 hours at an average speed of
> >40 MPH would be 40,000 miles.
>
> > Dan
>
> Hmm, my 92 Explorer with 135,000 miles on it still has the original
> Alternator in it. Original Starter too. No sign yet that the brushes
> are worn out.....

Brushes wear faster when alternator loads are higher and the
field current is therefore higher. Driving a lot at night will do it.
A daytime commuter vehicle will get more time out of its brushes, but
sooner or later they'll quit, and probably in some inconvenient spot.

Dan

On Aug 7, 9:09 am, wrote:
> On Aug 7, 4:04 am, Nate Nagel > wrote:
>
>
>
>
>
> > MasterBlaster wrote:
> > > "Nate Nagel" wrote
>
> > >>I found a local-ish
> > >>parts store with brushes, bought 'em, installed 'em, they work and I
> > >>certainly feel better about the alternator now that there's some actual
> > >>spring tension holding the brushes against the slip rings, but I still
> > >>have the same problem exactly as described above
>
> > > You do realize that just as engines don't put out maximum HP at idle,
> > > alternator's don't put out max amps/volts at idle either. If you're not spinning
> > > the alternator fast enough to keep up with whatever load you put on it, no
> > > regulator or brush set in the world is going to help.
>
> > I understand that, but what I'm seeing appears to be drawing power off
> > the battery at idle with only headlights and A/C running. I certainly
> > don't want to be stranded somewhere with a dead battery simply because I
> > got stuck in traffic after dark. (A/C is mandatory here in Our Nation's
> > First Swamp.) Certainly it wasn't like this when new otherwise nobody
> > would have ever bought a Ford.
>
> There's one other possibility: the battery has sulfated and
> its internal resistance has dropped too far so that it can't keep up
> with the battery's demand plus everything else. I'd try another
> battery (borrow one) and see if it helps. The alternator's heat might
> say it's working too hard somehow.
> Modern alternators are capable of producing plenty of power
> at idle. It's the reason we switched from generators back in the '60s.
>
> Dan

I think it's a long shot, but I'll have the battery checked next time
I feel like venturing outdoors. (I kind of came home from work and
ran and hid in the basement last night. When I got out of my car, I
felt like I was drowning and I went blind from the fog on my glasses.
I love DC, I really do.) I did clean the battery with a baking soda
solution and cleaned the terminals well and slathered them with Sil-
glyde when I first got the truck, but I didn't bust the caps off to
look inside, and there is no date stamp anywhere on it.

Of course, I don't really know who I can trust to check the battery,
as the place that checked my alternator said it was fine and when I
disassembled it I found the brushes worn to little nubs. I guess I
probably ought to keep my eyes peeled for a cheap used load tester,
although that doesn't help me immediately.

nate

On Aug 7, 9:46 am, Mike Romain > wrote:
> Nate Nagel wrote:
> > Nate Nagel wrote:
> but I still
> > have the same problem exactly as described above, alternator is still
> > very hot too. Any ideas?
>
> I can't say for sure, but you symptoms sure seem 'normal' to me. On all
> the recent AC Delco alternators I have been using, none will start a
> good charge according to the dash meter until I get to 800 rpm and
> above. Sitting at a 650 Idle with everything on causes the volt gauge
> to drop. Sounds just like your Ford....
>
> I am on my second alternator in this vehicle and the current one was an
> expensive remanufactured unit, not rebuilt. My last GM pickup was the
> same and even my last Volvo 240's with Bosch alternators were the same,
> no charge on the volt gauge at idle.

Oddly enough, I have the same "issue" with my '55 Stude, but I assumed
it was because I was using a Delco 10SI on a Stude engine with no real
thought having gone into pulley sizing. It's driven off the harmonic
balancer (not a bolt on pulley) anyway, so the only way I could fix
the issue is to find an undersized alt. pulley...

nate