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w164 Alternator Q

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Christian, Oct 24, 2018.

  1. Christian

    Christian Senior Member

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    Joined:
    Jun 4, 2011
    Location:
    Horsham
    Your Mercedes:
    w221, w164 and Panasonic washing machine :)
    I suspect my alternator is going soon as I still get Low voltage message although both batteries have been changed.
    My question is :does it really have to be OEM MB or any aftermarket ? Or 2nd hand ?
    Pricing is a bit confusing hence my question.
    Any help will be great.
    Many thanks
     
  2. Mark A

    Mark A Senior Member

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    Location:
    Aberdeen
    Your Mercedes:
    08 ML-420CDI, 58 ML-320CDI, 55 SLK-350
    Check the rear SAM (drivers side boot hatch - on the floor not the side) to make sure it isn’t getting wet. My woes started with battery errors and was eventually traced back to a water ingress around the rear light cluster seal.

    You should be able to check the voltage with the engine off and then you should see the voltage increase when the engine is running, +/-13.5V.

    MB don’t make batteries, but I would check with them first (Grangemouth MB is a good starting point) as they can be competitive.
     
  3. PaulG

    PaulG Senior Member

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    Location:
    Epsom Downs, Surrey
    Your Mercedes:
    Ml320CDI 2007
    If you do the spannering yourself and need to keep costs down, just look for a used alternator on ebay, but as above, check what the volts are doing first.
    DVMs are really cheap at the moment and always handy to have around, not just for the car...
     
  4. OP
    Christian

    Christian Senior Member

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    Your Mercedes:
    w221, w164 and Panasonic washing machine :)
  5. CrustyClam

    CrustyClam Active Member

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    Location:
    Warrington
    Your Mercedes:
    ML63 2007
    Mercedes Me Adapter (free) gives battery readings. One useful feature, save a bit of faffing about.

    I had a battery low voltage error suddenly come on when driving on M62 due to pulley tensioner failing, the v-belt shredded quickly due to this.

    Shortly afterwards all manner of electrical issues, loss of power steering to mention but a few, resulting in a recovery.

    I don't know if this is the normal way for them to fail so quickly, or wether it could be gradual giving a battery warning every now and then. Just thought I'd mention, you never know.
     
    Egg1000 likes this.
  6. Blobcat

    Blobcat Moderator

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    Location:
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    Your Mercedes:
    R171 SLK280 3.0, Land Rover 110 County SW
    I'd get the alternator off and get it rebuilt - when the alternator on the 911 I had played up I had 3 options - New Porsche alternator - £1,200, New Bosch Alternator - £600 or the one I went with - £80 complete rebuild by an octogenarian who'd been working on alternators and starter motors for >60 years. Just needed a new regulator pack but had new bearings and a full check.
     
  7. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    Location:
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    Your Mercedes:
    W221 S65 AMG - W204 C63 AMG + Various other MB's
    Do check the charging voltage before going through the hassle of changing the alternator etc!
     
    Blobcat likes this.

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