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Thread: 84 CUCV overcharging

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    Default 84 CUCV overcharging

    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.

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    Colonel pmramsey's Avatar
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    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.

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    Readings are the same after engine gets up to operating temp.

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    Colonel pmramsey's Avatar
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    Does the truck keep making the clicking sounds coming from under the left dash area as you drive? Does it ever stop?

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    appears to stop after the gauge moves over to the red.

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    Anymore that 14.4 volts points to a bad voltage regulator. I suggest replacement.

    Delco 27 si alternator is what the trucks came with.
    "If you didn't build it, you can't call it yours."

    1952 M35 W/W Gasser
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    1967 M715 6.2/NV4500
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    1985 M1009
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    DBL post deleted
    Last edited by dougco1; 10-07-2019 at 06:55.
    Proud Owner Of;
    1986 M1008 Easter Find
    1986 M1009
    1985 M101A2
    1985 MEP002A
    1952 M100

    Responsible For;
    2003 M1078A1
    1995 M016A
    2007 M GATOR A1 Civil Support
    2002 M GATOR A1
    1998 MEP802A
    2001 MEP803A
    2004 MEP804B
    2010 M1101
    1967 Pioneer Tool Trailer

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    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.
    Proud Owner Of;
    1986 M1008 Easter Find
    1986 M1009
    1985 M101A2
    1985 MEP002A
    1952 M100

    Responsible For;
    2003 M1078A1
    1995 M016A
    2007 M GATOR A1 Civil Support
    2002 M GATOR A1
    1998 MEP802A
    2001 MEP803A
    2004 MEP804B
    2010 M1101
    1967 Pioneer Tool Trailer

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    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.

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    Looks like I have a little work to do. will get back with results. Thanks.

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