Pre 84 Trucks 1st gen pickups

19 volts at the alternator??

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Old Jun 2, 2017 | 06:27 PM
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TheMaxfield's Avatar
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19 volts at the alternator??

i have a 1982 pickup with the 22R. I'm having a Charging problem. I have a brand new (bench tested befor instillation) battery and altornator. They are bolth the corect size for the truck. But I still am not getting a chardger on the battery. So I figured it has to be the voltage regulator.

Before replacing the OE voltage regulator I got 12.2 volts at the battery and 14.7 volts at the alternator. After replacing the voltage regulator I get the same 12.2 volts at the battery and 19.0 volts at the alternator. (all at idle with no load)

Is that right?? I'm scaired it's going to burn out my new alternator. The guy at the parts store told me it was fine but I thought a second opinion would be good

-History-
I just finished rebuilding and desmoging the 82 22R. The guy I got the truck from sold it due to an overheat that blew the head gasket. Well looking at the truck I asked why it over heated and was told the alternator had locked up and broke the belt that turned bolth the alt and the water pump causing the over heat.

The belts new (and tight), the mounting brackets tight, the alternator, and Battery are new.

Thanks guys
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Old Jun 5, 2017 | 05:01 PM
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typically replacing the regulator would be the fix , But I have seen MUTIPUL rebuilt Alternators , right out of the box , faulty .. everything worked before , I would take the Alt back for a replacement


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Old Jun 5, 2017 | 08:48 PM
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Originally Posted by TheMaxfield
...Before replacing the OE voltage regulator I got 12.2 volts at the battery and 14.7 volts at the alternator. After replacing the voltage regulator I get the same 12.2 volts at the battery and 19.0 volts at the alternator....
A THICK WIRE connects battery positive post to alt screw terminal. There should be less than 1-volt difference between the two points.
That being 1982 truck, I would suspect your wiring. Find schematic and check all wiring between battery and alternator. Quite possible that that THICK wire has broken strands or you have corroded contacts somewhere. Good electrical contact requires bare, shiny metal contacting bare, shiny metal.
On 1986 and later trucks, the regulator has an "S" wire to sense battery voltage. If it senses low voltage, it would tell alternator to bump up its output. IF it sees high voltage, it tells alternator to reduce its output. IF "S" wire is broken or not providing good contact between battery and "S" input of regulator, Regulator will think battery voltage is low and tell alternator to bump up output... possibly to the 19Volts that you are seeing.
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