Ford pickup low voltage at idle

N8N wrote:
> 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
>

I put a hand throttle in my Jeep. That way I can bump the idle up to
1200 for when I am using my big lights and winching someone.

Meanwhile I have never had the battery go dead from slow idling along
trails with defrost, wipers, lights and stereo on for hours at a time.

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!
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N8N wrote:
> 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
>

Follow up: according to the local Advance Auto Parts, my battery is
fine. I'm sooooo confused.

If anyone knows of a good auto electric person who will work on a whole
vehicle (not just rotating components) near Falls Church, VA I'm all ears.

nate

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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. 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
>
As a side note:

Check the harness and connector where it plugs into the alternator. I
have had several harness show significant corrosion and degradation
there. The symptoms were erratic charging. If you are over 100k miles
you may also have some worn brushes. I have rebuilt several of those
alternators on my workbench. It is not particularly hard to do.

I do live in Michigan and vehicles are subjected to extreme corrosion
from the amount of salt used on the roadways in the winter months.

anumber1 wrote:
> 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. 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
>>
> As a side note:
>
> Check the harness and connector where it plugs into the alternator. I
> have had several harness show significant corrosion and degradation
> there. The symptoms were erratic charging. If you are over 100k miles
> you may also have some worn brushes. I have rebuilt several of those
> alternators on my workbench. It is not particularly hard to do.
>
> I do live in Michigan and vehicles are subjected to extreme corrosion
> from the amount of salt used on the roadways in the winter months.

The connector LOOKS OK but I have been told before that it's recommended
to replace it whenever the alt. is R&R'd so if I can't find any other
issues I may replace it. It really doesn't seem like the problem but I
am running out of ideas.

I did just replace the brushes (which were worn out) without obvious
improvement in symptoms.

Usual use of the truck is after work (i.e. dark) and A/C on full blast
is a given considering the recent weather, so this is actually not a
hypothetical.

nate

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