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Old 04-07-2017, 02:39 PM   #1
frankenstien
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Default 1966 Chevy Caprice charging system issues

finally got the car, what I thought was road worthy, drove the car around town getting it appraised, official classic/antique insurance on it, then drove it to work, I had turned it off probably 4 times, restarted no issues. car sat for 10 hours at work, got off work, started fine, turned on lights, noticed they were dim, and my turn signal lights weren't working like they should, stopped to get gas, wouldn't start, jimped it, ran fine, went home, still really dim headlights.

pulling in my driveway, accidently stalled it and that's where it died again, I swapped in my other battery i had on the shelf, started it and pulled it in the garage.

while testing the altenator between the positive terminal on the alt. and battery ground, i was getting between 7-10v, would change a bit with engine rpm but not much, so i brought the battery and alt. to napa to have them test each, just to make sure, alt bench tested good, as did the battery. They said they can do another test with the alt/batt. in the car, so i did that, test resulted in 12.04V unloaded and 12.04V loaded, and machine said "no voltage". So i thought alright bad alt, on top of the bearings in the alt sounded terrible, so 1 new altenator later, here i am still getting about 12.2V at the battery, so I unplug the altenator completely, connector and power wire, same 12.2 v while running.

so to me it seems that the power isn't getting from the new ALT to the system. I am going to clean the connection that is behind the battery that comes from the horn relay/altenator.

this is where my dunce hat fits well, would the voltage regulator have anything to do with it? I am not familiar wit external regulator systems, and didnt even think about it having one, but it does, and what looks like a little capactitor on the side of it.

any ideas? what am i doing wrong here?

will disconnecting the battery while its running to see if the alt is working hurt the system?

sorry for the long winded explination
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Old 04-07-2017, 10:25 PM   #2
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Default Re: 1966 Chevy Caprice charging system issues

IIRC disconnecting the battery on earlier cars won't hurt them, it was a common practice to test alternator output that way. With the advent of ECM controlled alternators I believe that may have changed. I've had alternators checked at parts stores before, that passed the test , but didn't charge the battery (in a 99 XJ) Usually alternators will show 13-14 volts output when working correctly. Yes the VR could be a problem, and may be your problem.
Another old time test is to put something steel (ferrous metal only) against the rear bearing of the alternator while the engine is running, you should feel some magnetic pull if the alternator is working, this is old school, not rocket surgery.
The round metal tube on the VR is a condenser and filters electrical noise. The VR should have a plastic connector with 4 wires connected to it, I would check all the copper contacts in the connector and VR for corrosion, clean and apply dielectric grease and reassemble. BTW, when you unplug the two wire connector at the alternator you remove the excitation to the alternator and it will not charge.
If originality is not a concern, a later internally regulated alternator may be a good choice.
YMMV, Good luck!
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Last edited by wasillashack; 04-07-2017 at 10:44 PM.
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Old 04-07-2017, 10:28 PM   #3
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Default Re: 1966 Chevy Caprice charging system issues

If you have an external voltage regulator you need to replace it. It's what tells the alternator to "turn on". The alternator will bench test good as the machine will command the desired voltage.
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Old 04-07-2017, 11:02 PM   #4
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Default Re: 1966 Chevy Caprice charging system issues

Quote:
Originally Posted by wasillashack View Post
IIRC disconnecting the battery on earlier cars won't hurt them, it was a common practice to test alternator output that way. With the advent of ECM controlled alternators I believe that may have changed. I've had alternators checked at parts stores before, that passed the test , but didn't charge the battery (in a 99 XJ) Usually alternators will show 13-14 volts output when working correctly. Yes the VR could be a problem, and may be your problem.
Another old time test is to put something steel (ferrous metal only) against the rear bearing of the alternator while the engine is running, you should feel some magnetic pull if the alternator is working, this is old school, not rocket surgery.
The round metal tube on the VR is a condenser and filters electrical noise. The VR should have a plastic connector with 4 wires connected to it, I would check all the copper contacts in the connector and VR for corrosion, clean and apply dielectric grease and reassemble. BTW, when you unplug the two wire connector at the alternator you remove the excitation to the alternator and it will not charge.
If originality is not a concern, a later internally regulated alternator may be a good choice.
YMMV, Good luck!
Originality is not a concern, I just recently got the car up and going, was planning on driving it this summer, before gutting it and taking the body off the frame etc. I'll check the connector on the VR tomorrow
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Old 04-07-2017, 11:05 PM   #5
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Default Re: 1966 Chevy Caprice charging system issues

Quote:
Originally Posted by murphyslaw View Post
If you have an external voltage regulator you need to replace it. It's what tells the alternator to "turn on". The alternator will bench test good as the machine will command the desired voltage.
That would make sense,if its jot telling it to turn on, it will never show the 13-14 v I'm looking for.

I found this diag article step 6 shows how to bypass the VR and make the alt go to max power

https://www.google.com/amp/www.hotro...uick-test/amp/
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Old 04-08-2017, 01:20 PM   #6
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Default Re: 1966 Chevy Caprice charging system issues

Jumpered the blue/red wire, ran the rpm up a bit, voltage started climbing, ran to about 15v turned it off, went and picked up a voltage regulator, haven't had a chance to put it in, but looks like the smoking gun
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Old 04-11-2017, 07:57 AM   #7
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Default Re: 1966 Chevy Caprice charging system issues

Boy was I wrong, got the VR, still no work. Did some research, the power supply for the #4 terminal on the VR goes through the "generator" light on the dash, the bulb wasn't making good contact with the printed circuit, got it working and the charging system is good to go
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2015 Ford Expedition EL - Wife's rig
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Old 04-11-2017, 11:59 AM   #8
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Default Re: 1966 Chevy Caprice charging system issues

Thx for following up with the source of the problem. Oddball stuff like this keeps us on our toes.
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Old 04-11-2017, 01:12 PM   #9
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Default Re: 1966 Chevy Caprice charging system issues

Yeah, this is the oldest car I have worked on, I'm used to my 74 truck, internal reg. Alt, easy breezy.

I usually try to finish if I find the problem, hate searching and finding threads with similar issues and the person never came back to finish it out.
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2005 GMC 2500HD Duramax Diesel- 452hp/962tq on P3's dyno

2015 Ford Expedition EL - Wife's rig
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Old 04-11-2017, 08:50 PM   #10
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Default Re: 1966 Chevy Caprice charging system issues

I bought a 65 Impala SS new and it was my 4th car! I think I'm getting old.
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Any man who thinks he can be happy and prosperous by letting the government take care of him had better take a closer look at the American Indian.
~ Henry Ford

We are told not to judge Muslims based on the actions of a few.

I suggest we give the millions of responsible Americans gun owners that same courtesy.
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Old 04-11-2017, 09:50 PM   #11
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Default Re: 1966 Chevy Caprice charging system issues

im not quite there yet, and my caprice is far from new lol
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2015 Ford Expedition EL - Wife's rig
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