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umm.. Salty alternator?

So my alternator went kaput a few days ago, and the replacement I bought from a friend was covered in a gritty whitish salty smelling dust. (No, I didn't lick it) He had pulled it out of a vehicle similar to mine in age and manufacture (early 90's Subaru) and it bolted right in and works great. We just don't know how it got salty and whether or not it will affect the performance and life of the part. Maybe it came in contact with the ocean at some point? who knows. The only reason I ask is because salt is a conductor and it appears to have been submerged in some very salty water at some point. I'm wondering about the effect of this on any electrical components. As of now, it is working well and I can disconnect the ground battery terminal and the car does not die.

Also, my car was making funny 'whirring' noises that seemed to vary not with my RPMs, but my speed, and only occurred if I drove the car before it got up to temperature. (It is winter and quite cold) I haven't heard them since I changed out the alternator.


-Will the salt on the alternator affect performance/life of the part?

-Was the funny noise I heard my alternator screaming in agony?

Thanks for your time and answers. Let me know if this was a stupid question.


9 Answers

  • Tony
    Lv 7
    4 years ago
    Favorite Answer

    After reading answers others have given you - you don't need my input. Except that I saw you respond to someone's answer about disconnecting the battery. That's an OLD trick and shouldn't be used on today's modern cars. You could damage sensitive electronics on the car.

    Here's how to tell the health of your battery and alternator:

    Resting voltage (over night - not running) battery voltage should be 12.6 volts (GOOD battery) but no lower than 12.2 volts (old, weak or discharged battery).

    Start the car. Check the voltage. Should go up to around 14.4 volts (but not higher than 14.5 volts). After several minutes the voltage should drop down to around 13.8 volts. Next, turn on ALL the electrics. Battery voltage should not drop below 13.6 volts. If it does then either the alternator is not performing within specs OR the belt may be slipping.

    That's all there is to it.

    Clean battery terminals helps a lot. Good connections to connecting points such as the starter, ground and the alternator are important. If any of them are loose you'll experience problems. OLD battery cables can corrode within the insulation. Corroded cables can limit the ability of the battery when starting the engine. And anything else someone may have mentioned that I neglected to answer.

    The white residue - could be from sitting around on a shelf for however long it sat. Nothing to worry about. Besides, it's a free alternator. If it lasts for five years - you're five years ahead of the game. If it fails next week - heck! You had to replace the alternator anyway. Why not just get a new (remanufactured) alternator. Without the friend's alternator you'd have had to buy one anyway.

  • 4 years ago

    The case of an alternator can get that way just from being exposed to the weather.

    Source(s): Mitsubishi Master Tech
  • M.
    Lv 7
    4 years ago

    I didn't know that salt had a smell! Are you sure that you didn't TASTE it? Normally aluminum oxydizes to aluminum oxide, but maybe YOUR alternator is turning into aluminum chloride?

    Salt is conductive?? Guess what? Aluminum is MORE conductive!

    You removed the negative cable while the engine was running? That means that you are a troll!

    The "funny noise" may have been an alternator bearing or something inside the alternator that failed. If one of the rectifiers/diodes inside the alternator shorted out, it makes an electro-mechanical whining noise that emits from the alternator.

    -Engine overhaul mechanic and electrical system expert, since 1972

  • Anonymous
    4 years ago


  • 4 years ago

    More than likely just normal oxidisation of the aluminium. If it is working fine now then nothing to worry about. If there is a small amount of salt dust on it then it will have no effect. It may just have been used in an area near to the sea in a slightly salty atmosphere. You really need to relax about this.

    Your engine will be noisier while it is warming up, particularly in cold weather. using the car more gently during the warm up phase will be very helpful to its longevity.

  • Anonymous
    4 years ago

    Probably some corrosion on the Aluminium casing.

    It it's still working it should continue to work for a few more years.

  • Anonymous
    4 years ago

    Do not disconnect the battery terminals when the engine is running. Get a multimeter, get the voltage reading across the battery at above idle speed. Readings should be above 13.8 to 15 volts.

    The white powder is not salt but corrosion from aluminum. It is likely just surface corrosion from the alternator body. Anyway, dont worry too much about it. If the alternator fails, you replace it. It is there, it works. Time to drink some beer.

    And there are no stupid questions, only stupid answers (including mine).

  • Anonymous
    4 years ago

    do not lift any battery terminals while the engine is ruining that will kill the alternator if it hasn't all ready.

  • Anonymous
    4 years ago

    It corrosion from the aluminium

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