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Continuous alternator failure??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 74Chev, May 2, 2003.

  1. 74Chev

    74Chev 1/2 ton status

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    This problem started when I upgraded to a higher output alternator. I am using Bosch #Al559x which is 105amp. output. I believe it is stock for a mid 80's Cavalier or Corsica. The first one lasted about 1 week, then voltage dropped to 12v. The second has only about 50mi. on it and when I started it up tonight after sitting about 1 week it is back to 12v. I checked for power at all the important connections and it is good. I don't have a multi-meter so I cannot check voltage at different points. I have to rely on my auto meter guage. I have dual yellow top batteries wired into a marine type switch. The alternator output wire is 8ga. running directly to the starter wire post on the switch. I have the sensing wire hooked to the junction block on the firewall. It seems that the requlator is not engaging. Why are these alternators failing? I have very good wiring and good connections but something is obviously wrong. This is getting ridiculous. Any ideas appreciated.
     
  2. jhrody

    jhrody 1/2 ton status

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    I went through 4 100amp alternators on a '74 Nova I had, all within a few thousand miles. Eventually I found a bad negative connection to the battery. Ran a new cable and another connection to the body and the alternator problems went away.
     
  3. gumneck

    gumneck Registered Member

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    I have a 1969 C-50 with 366 cu. and I thought I had a bad alternator. Replaced it and the new one did the same thing. Killing my battery. Replaced the plastic connection piece that plugs into back of alternator and walla. I mistakenly assumed the first alternator was bad cause it was old and I'm also a parts replacer as a opposed to a real mechanic.

    tom
     
  4. 87sm465np208

    87sm465np208 1/2 ton status

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    REally, so you can put that ol alternator in a truck and it will work, hmmmmm how much was that alternator and how does one aquire one of them? /forums/images/graemlins/thumb.gif

    /forums/images/graemlins/usaflag.gif /forums/images/graemlins/truck.gif
     
  5. TX Mudder

    TX Mudder 1/2 ton status

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    I had a lot of problems getting my alternator to work right. I ended up picking up a 100 amp 1 wire alternator for $89 fromt JEGS. Haven't have a single problem since - really like it!
    -- Mike
     
  6. NITRO

    NITRO 1/2 ton status

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    u can pick up a reman alt at autozone for $22. then just have it modified for more amps. its been working for me.

    NITRO
     

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