84 CUCV overcharging

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helofire

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Chesapeake, Va.
I'm a newbie so please have mercy. I have read all the past threads about alternator problems (15 pages I think) and I have checked all the information that was given. The volt meter shows the needle in the red just over the line that separates green and red. I will give you what I have found and hopefully someone has an answer. Truck not running and batteries disconnected: Battery 1 12.6 volts, Battery 2 12.8 volts. Truck not running but cables hooked up: Battery 1 12.6 volts, Battery 2 12.8 volts. In series we have 25.4 volts. Truck still not running: back of Alt. 1 12.6 volts, back of Alt. 2 12.6 volts at the post which is like in the 9 o'clock position, back of Alt. 2 at the post which is like at the 12 o'clock position 25.4 volts. Now will check the white plug with engine still not running, plug is plugged in. Alt 1 red wire 12.6 volts, exciter wire 0 volts. Alt. 2 red wire 25.4 volts, exciter wire 12.6 volts. Now the truck is running, Alt. 1 red wire 15.1 volts, Alt. 2 red wire 9 o'clock position 15.2 volts, Alt 2 red wire 12 o'clock position 30.8 volts. When you get ready to start truck, turn key on and wait for wait light to go out. Light goes out, start truck both generator lights go out and voltmeter goes to green with needle pointing to top tick mark in green scale. After a minute the needle then goes out of green into the red just separating both colors but in the red. I do here a clicking noise from under the dash on the lower left just before the voltmeter fluctuates and then goes to red. Could both regulator's be bad and overcharging? If that is the problem where would be the best place to get new rebuild kits. Thanks.
 

pmramsey

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VA
I believe if you are operating in low light conditions, the headlights will also be dimming several times until the truck warms up. The glow plug controller continues to cycle the glow plugs on and off until the engine warms sufficiently. This is a standard feature of diesel engines with glow plugs.
 

pmramsey

Member
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18
Location
VA
Does the truck keep making the clicking sounds coming from under the left dash area as you drive? Does it ever stop?
 

Barrman

Well-known member
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84
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Location
Giddings, Texas
Anymore that 14.4 volts points to a bad voltage regulator. I suggest replacement.

Delco 27 si alternator is what the trucks came with.
 

dougco1

Active member
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Location
Cooperstown NY
The 30.8 volts is just a touch high but I think you can run it that way with no resulting damage. The Tms have the min-max per alternators. Ideally I like it when they run around 29 volts with no load.
 

DeadParrot

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Location
oklahoma city, ok
Double check all connections clean and good. Including battery terminals. Also pull off and push on the two wire connectors on the alts. One of the wires is the voltage sense wire that tells the alt how much volts to put out. If that connection is corroded, could be telling the alt to provide more volts then needed.

Have you checked the accuracy of the OEM voltmeter with a second meter? If original, it is ~34 years old and could be no longer accurate.
 

Barrman

Well-known member
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84
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Location
Giddings, Texas
I am not trying to pick a fight with any one.

The reason I suggested replacement of the regulators is I used to think a few extra volts with no load meant no big deal I can just turn on the lights and all will be fine. One of my M1009's was always at the top of the green and 28.8-29.2 volts. One evening I went to drive home and after driving about a mile my headlights one after the other went out. These were almost new $50 Sylvania Silver Star headlights. I looked at the volt meter as part of my scan to see if something was wrong and it was well into the red.

I stopped, turned off the truck and unplugged the two wires from the side of the drivers alternator thinking it was bad and now wouldn't charge so I could get home on high beams. I fired it up and was now in the yellow below the green. I hit the high beams and started driving. Then my high beams blew while the volt meter was back in the red once moving. I stopped again, unplugged the passenger side alternator plug and made it home on running lights and 4 way flashers.


Never forget that the positive of the GEN 1 circuit is the ground of the GEN 2 battery.
 

helofire

New member
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Location
Chesapeake, Va.
Well, finally got back to installing the parts for the alternators. Installed alternators back on the truck and here are the results. Everything is the same as stated in the initial post except for the readings from the alternators (which is a good thing). Alt. 1 now puts out 14.9 at idle. Alt 2 now puts out 14.8 (at the 9 o'clock position stud) and 29.6 (at the 12 o'clock position stud). 29.6 also shows on the batteries. Inside the cab, the needle on the gauge is right on the line dividing the green and the red. If you are in the seat and look the needle is barely on the white line leaning toward the green side. So now my question is, do you think the gauge is bad or there is another problem? I would really like to get the needle in the green at the white tick mark at the top of the green scale. Thanks, all the information has really helped.
 
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