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Thread: Identifying alternator - 80 or 140 amp?

  1. #1
    Join Date
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    '97 540i Dinan, 98 740iL

    Question Identifying alternator - 80 or 140 amp?

    I'm about to pull my oil filter housing to change the housing-to-block gasket, which is where I think my small but annoying leak is coming from.
    To do this requires removing the alternator, which is also "whirring" a bit, suggesting worn bearings.

    This car "('93 525i) could have either an 80 or 140 amp alternator. Is there an easy way to identify which one I have? If not, will the 140 amp bolt up without any mods?

    thanks
    Charles
    '98 740iL E38 201k, TCG at 190k, 5HP24 at 195k
    '97 540i/6 E39 Dinan blower & stage 1 suspension 114k
    '93 525i E34 "Golf Ball" (hail damaged) 334k

  2. #2
    Join Date
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    Why not just knock a new set or bearings into the alternator?

    Go ahead and bite. Plenty for everyone.

  3. #3
    Join Date
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    '97 540i Dinan, 98 740iL
    Well, the slip rings and brushes, not to mention the diodes and the electronics in the regulator, all have lots of hours under heat and vibration. It may not be the original (with 312k miles, probably not) but it looks well-used.

    By the time I buy the parts to rebuild it myself, and do that job, it's worth it to me just to get a decent Bosch rebuilt unit.

    Besides I still have to know whether it's an 80 or 140...
    '98 740iL E38 201k, TCG at 190k, 5HP24 at 195k
    '97 540i/6 E39 Dinan blower & stage 1 suspension 114k
    '93 525i E34 "Golf Ball" (hail damaged) 334k

  4. #4
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    hiss by my window

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  5. #5
    Join Date
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    '97 540i Dinan, 98 740iL
    Thanks, that's exactly the info I was looking for! My car has heated seats so I will assume it has the 140 amp anyway.
    '98 740iL E38 201k, TCG at 190k, 5HP24 at 195k
    '97 540i/6 E39 Dinan blower & stage 1 suspension 114k
    '93 525i E34 "Golf Ball" (hail damaged) 334k

  6. #6
    Join Date
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    Hah! Fiveeightandten, I used to see that dude driving around all the time, he had a red e36m3. Nice guy too, got to hang out with him a couple times, the good old days...

    Go ahead and bite. Plenty for everyone.

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