SLO RDE

Hello I put a new alternator on my 76 this weekend and took it for a drive my voltage gauge is almost maxed out when I am driving.I can't see where I could have gone wrong with the install.How much easier could it be could it be because I ran my battery low and It's just recharging it? (just a guess)The only things Ive done lately is run a power wire from my starter for my electric fan and ran two power wires from my fuse box to the radio I can't see that causing a problem when Iam idling at the house the gauge is in the middle where it should be.Thanks once again before hand. Dale

jackson

First, verify battery is OK. Put a charger on the battery & then have the battery checked for a short.

Occasionally, you can get a bad new or rebuilt alternator. If the battery's ok, my hunch is that the alternator's internal voltage regulator is bad ... allowing the overcharge condition. Most parts houses have a free service where there can check condition of battery & alt ... that can easily diagnose overcharge.

Don't continue to operate the car when overcharging.

Monty

I've had that problme before as well. It's either a faulty voltage regulator, or you have a short between the charging/sensing line of the alternator and the battery. Several years ago on my '82, when it was stock, the fusible link in the charging line that runs from the oputput post of the alternator to the battery was severly corroded and shorted out, breaking the link bwetween the alternator and battery. The alternator senses this low voltage and the voltage regulator increases output as a result. I measuered the voltage on the output of the alternator and it was between 24 and 30 volts. I traced the wire, detected the broken fusible link, replaced it and everything was normal.

GaryS

You can test the alternator yourself with a multimeter set on DC volts and the scale at 20. You should see 12+ volts at idle and 14.6 +/- with the engine running over 2000 rpm. If you don't have a multimeter and your alternator is easy to pull out, take it to Auto Zone, Advance Auto, Pep Boys, etc and they will test it there. You don't want to drive a car with a faulty voltage regulator unless you want to start replacing items that get fried from overvoltage. If they confirm the overvoltage, take the alternator back to where you got it.
Gary

drspeedy

BUT...
I have the same problem as you- my alternator is new, but the dash voltmeter says 16@2K+ RPM. Test the alt with a multimeter, but it showed fine. I took it off and wheeled it in to Pep Boys. They tested it, said "No problem". I took it across the street to Advance, same thing. I went so far as to replace the pig tail to try and eliminate any bad connections- still says too much voltage in the car. Multimeter test is ok still. I wonder if newer alternators just give a higher reading for some reason... I don't completely trust it though, and won't be surprised (or happy:mad ) if it kills this battery. Not much, help, I know, just noticing a coincidence.:yesnod:

-doc

SLICKMAN

Mine is orginal from 78 and it reads between 15 - 16 volts and the battery is fine and still going strong.. Just a bit of info for ya :yesnod:

MotorHead

Mines way over to the right too, just stays there near below 18 V have had no problems. :D

It's supposed to be around 15-16 Volts I think

Hey Monty with that twin turbo you could lay claim to the world's fastest street legal C3 ! :eek:


[Modified by MotorHead, 7:09 PM 10/7/2002]

HEARTBEATUSA

Have you checked your battery? alt./volts should only read above positive when there is a load or a depletion in the battery volts

mrvette

I think you answered your own question there, you should run your electric cooling fans directly from the output stud of the alternator, NOT from the battery cable....this is true of any accessory.....follow the logic of the GM wiring diagram and you will see this is so....

kill the cooling fans, rev up the engine, and I bet everything return to normal.....just for a 1 minit test....

GENE