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Thread: High output alternator option for E46 M3's with S54

  1. #1
    Join Date
    Jul 2008
    Salem, Nh
    My Cars
    01 Z3M Coupe

    High output alternator option for E46 M3's with S54

    With the addition of fans for oil & engine cooling along with an electric power steering pump my alternator was repeatedly failing. With an estimated current draw of around 130 amps it appears that the stock 120 amp alternator was overloaded. I searched the forums and there was some mention of a 140a upgrade that required the connector to be changed.

    Working with a great shop locally called Chelmsford Auto Electric located in MA. they where able to find me a brand new BMW OEM Valeo alternator that outputs 160a @3k rpm's, 170a @3.5K rpm's and 180a @ 5k. They were able to cross to the alternator using the voltage regulator part number and told me it was from a 2005 X5.

    I tried to find it on Real OEM and could not. But the one they sold me fits perfectly and has the same square plug on the regulator. The only thing that needed to be swapped over was the plastic cover on the back which took about 10 seconds to do with just 2 screws holding it in.

    I now see a solid 13.8 to 14.2 volts at the battery with the engine running and all the fans and power steering on, problem solved.

    I don't have a BMW part number but if should anyone be looking for to upgrade their alternator you can give this shop a call at 978-649-4448. Ask for Brian and tell him Dan with the BMW Z3 sent you. The part number for this alternator on my invoice is 88004004J and it cost $339 which is a great price.

    There may be a core charge but I'm not sure as they took back the 120a output stock version that I bought from them early that failed.

  2. #2
    MauiM3Mania's Avatar
    MauiM3Mania is offline Observer/Master Skeptic Moderator
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    Jan 2002
    Central Pacific
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    88M3 99M3 04M3 ITBx16
    Bumped, post copy from E46 M3 sub-forum.

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  3. #3
    Join Date
    Apr 2002
    Broomfield, Colorado
    My Cars
    That's good info, thanks.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
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