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Thread: New Alternator Next?

  1. #1
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    New Alternator Next?

    Had a problem with a battery going dead ... I believe it was simply a bad battery, but I checked the voltages, just to make sure the alternator was OK.

    I checked the voltage at the battery with the car running ... got 13.5 volts @ idle ... and 13.5 volts @ 3000 rpm ... obviously a problem. So I replaced the voltage regulator with a new one ... still 13.5 volts @ idle and 13.5 volts @3000 rpm.

    - V-Belt is new and tight
    - Replacement battery is good
    - Battery and Alternator connections clean and tight

    Does it look like the problem is more than likely ... the alternator? ... anything else to look for?

  2. #2
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    No e30s, again :(
    More than 12.6 is fine. What is bothering on this? Turn the fan and the lights on and if stays above 12.6 than I would leave it

  3. #3
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    Quote Originally Posted by Geoffzie View Post
    Had a problem with a battery going dead ... I believe it was simply a bad battery, but I checked the voltages, just to make sure the alternator was OK.

    I checked the voltage at the battery with the car running ... got 13.5 volts @ idle ... and 13.5 volts @ 3000 rpm ... obviously a problem. So I replaced the voltage regulator with a new one ... still 13.5 volts @ idle and 13.5 volts @3000 rpm.

    - V-Belt is new and tight
    - Replacement battery is good
    - Battery and Alternator connections clean and tight

    Does it look like the problem is more than likely ... the alternator? ... anything else to look for?

    Probably the quickest resolution is to bring this to an Oriellys auto parts store in Canton and just ask them to put a load test on the battery (it could be an amperage deal when starting) - then ask them to check the alternator.

    The regulator is internal in this alternator - so did you replace that by yourself? If you did and pulled the alternator out - just bring the alternator in to have Oriellys put it on their bench tester.

    Its free.. The only issue on the bench test is you need an older guy to do it - (cause they need to understand how the bench tester works as not every place has the bench schematic for the alternator)

  4. #4
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    Actually, I have no problems at all with the (new) battery ... the car starts and runs fine. But from working on other cars, I'm used to seeing 14 to 14.5 volts at higher RPM's. This car sat all winter in a cold garage ... with a battery that was questionable to begin with. I put a load tester on the new battery and it's fine.

    I also noticed on Winhotel's post here about a code 1222 ... that he was getting 14.2 volts (I assume at idle).

    95BMWIC, I replaced the regulator myself with a new one from Rock Auto ... two screws on the rear of the alternator. I did it with the alternator on the car, battery disconnected.

  5. #5
    richardodn's Avatar
    richardodn is offline Old Guy BMW CCA Member
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    Check all your high current connections and cables. Make sure they are all clean and snug. With poor connections you might see good voltages, but they won't pass the higher amp current.

    + battery terminal
    firewall binding posts for trunk batteries
    starter terminal with battery cable and alternator charging wire
    alternator charging wire connection
    engine ground strap
    battery chassis ground
    - battery terminal
    "Howdy, Folks!"

    1986 Delphin 528e - Roof rack equipped lumber hauler.
    1989 Zinnoberrot 325iX Sedan - I miss this car. (Deceased)
    1998 Avus Blau 328iC - Someone else's project now
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  6. #6
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    No e30s, again :(
    You can add more grounds also. I normally always add one from the strut tower to the valve cover bolts or somewhere on the head
    No e30s again.

  7. #7
    richardodn's Avatar
    richardodn is offline Old Guy BMW CCA Member
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    Quote Originally Posted by superj View Post
    You can add more grounds also. I normally always add one from the strut tower to the valve cover bolts or somewhere on the head
    There's supposed to be a factory ground strap from the valve cover to the firewall. However its purpose is RF noise suppression.
    "Howdy, Folks!"

    1986 Delphin 528e - Roof rack equipped lumber hauler.
    1989 Zinnoberrot 325iX Sedan - I miss this car. (Deceased)
    1998 Avus Blau 328iC - Someone else's project now
    2008 Platinum-Beige X3 3.0si - Current project
    2012 Alpine White X3 xDrive35i - My new snowmobile.
    2020 Estoril Blue 440i xDrive cabrio - This car is a blast to drive.

  8. #8
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    No e30s, again :(
    I believe it. I am just saying that more grounds don't hurt
    No e30s again.

  9. #9
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    Haven't had a chance to get back to it yet ... hopefully this week. To my knowledge, there's really not a whole lot that can go wrong with the alternator itself, with the exception of the voltage regulator / brushes ... other than complete failure.

    I also noticed there's a Volvo guy on-line that sells adjustable voltage regulators for Bosch alternators ... sounds like an interesting idea ... anyone had any experience with these? ...

    http://www.240turbo.com/AdjustableVoltage.html

  10. #10
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    No e30s, again :(
    not i
    No e30s again.

  11. #11
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    Ok, today I finally got back over to work on the car. Started it up and let it run. Now it's showing about 13.8 volts @ idle (new brushes seating in?) ... and with the heater blower on max, and the headlights on, it was showing 13.3 volts.

    I'll probably just let it alone and drive it like superj said ... when I get a chance I'll check all the grounds.

    I drove it for about 50 miles, runs good ... the check-engine light finally is staying off (code 1222) and it's idling smooth since I checked for vacuum leaks (none) and adjusted the AFM spring.

    I also replaced the thermostat since the temp wouldn't rise above the lower blue-zone (probably because I had drilled an 1/8" hole in the thermostat because of feared bleeding problems). The new Motorad 180 degree thermostat has a hole with a jiggle-pin (bleeding was no problem) ... now the temp stays right in the middle of the gauge.

  12. #12
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    No e30s, again :(
    Sounds great

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