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    #1

    Alternator Problem??

    Guys,

    I got my car back on the road but the battery would not hold a charge. I took it to auto zone and they said the battery was bad. I get a new battery and everything is working great.

    Then one day I go somewhere, go to start it up and it won't start. I assume that both the battery and the alternator were bad.

    I buy a new voltage regulator from pelican and replace the old worn out brushes on the old one. I put the new one in, checked the grounding prong was engaged.

    Just to be sure the alternator was not bad I took it to Autozone where they tested it and it passed all of their tests. So i went back, installed it and jump started the car with the new battery that was dead.

    The car stays running and it seemed the alternator was charging. I let it idle about 5 minutes and then drove it around the block for a few minutes (didn't want to go far and get stranded). I turned the car off and the battery wouldn't even crank....

    What wrong? Is the ground strap on the alternator supposed to go somewhere besides looping to the belt tightening bracket? Is the alternator just bad? Whats a good test to ensure the alternator can be fixed. Or have I given up too soon before the battery was fully charged?

    Any ideas?
    318iS Track Rat :nice: www.drive4corners.com
    '86 325iX 3.1 Stroker Turbo '86 S38B36 325

    No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.
    Tags: None
    #2
    Fully charge the battery. The check system voltage at idle (should be ~13.5v) and at 2500rpm (should be ~14v). Those voltages should not appreciably drop when you load the system with the headlights and/or HVAC.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

    Comment

      #3
      Originally posted by jlevie View Post
      Fully charge the battery. The check system voltage at idle (should be ~13.5v) and at 2500rpm (should be ~14v). Those voltages should not appreciably drop when you load the system with the headlights and/or HVAC.
      Thanks Jim. I charged the battery and idle was just above 12v. Then at 2500 rpm it was sitting at 12v with the rear defroster going.

      This points to the alternator. I made sure the alternator was grounded at the same point where the engine ground is (driver shock tower next to alt). With the voltage regulator replaced and the alternator passing the test at the auto store, what else could it be? I wouldn't think a short or battery drain would draw that much voltage.

      318iS Track Rat :nice: www.drive4corners.com
      '86 325iX 3.1 Stroker Turbo '86 S38B36 325

      No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

      Comment

        #4
        Check the voltage at the D+ terminal.

        Comment

          #5
          what is the D+ terminal?
          318iS Track Rat :nice: www.drive4corners.com
          '86 325iX 3.1 Stroker Turbo '86 S38B36 325

          No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

          Comment

            #6
            That is where the small wire to the voltage regulator connects.
            The car makes it possible, but the driver makes it happen.
            Jim Levie, Huntsville, AL

            Comment

              #7
              Thanks guys, it turned out to be a bad ground. Good to know I replaced the voltage regulator though, it was looking pretty worn down
              318iS Track Rat :nice: www.drive4corners.com
              '86 325iX 3.1 Stroker Turbo '86 S38B36 325

              No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

              Comment

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