I have a concern about a new alternator I put on my 02 echo, again it too does not have a tensioner. Belt tension is created by pivoting the alternator away from the engine. This was the first time for me putting an alternator on without a tensioner and so I wasn't sure how tight to have the belt. I read somewhere that there should be about a half inch of slack on the belt which my analysis determined that there was a little less than a half inch. I started the car, it was charging as it should, after a short time I noticed a small almost not noticeable amount of smoke coming from the alternator. I shut off the car sniffed around the alternator, the transparent smoke didn't appear to have much of an odor and nothing felt hot. After finishing up some other work on the car, I took it for a drive no other smoke appeared, sounded normal. While driving and only when accelerating did I hear and obvious whining noise, I came under the impression the belt was too tight. I released probably more tension than necessary, now theres maybe 3/4 inch slack but it still whines, revving the engine in park it definitely sounds its coming from the alternator. It obviously still charges like its supposed to, so I'm wondering if I should just go with it or buy a second new alternator. I don't really have the money for one and I doubt I can return it since the possibility of me being the cause of bearing failure having the belt too tight. I just like to have a second opinion on it, how long could it last running maybe a few hours with too tight of belt before loosening it. Are the bearings really shot already or do you think I should give it more time and see if the whine goes away. I've never known an alternator having any kind of break in period, there supposed to be quiet from the start right. If I did damage the bearings couldn't I still get some time out of it since it's new. Any feedback would be appreciated, thank you.

  • FWIW I've had alternators that whined (quietly) for years without anything else bad happening to it. I suspected the cause was some of the coil windings being a bit loose and oscillating because of the magnetic field, not the bearings.The smoke is more worrying, IMO. Nothing should be getting hot enough to burn.
    – alephzero
    Nov 22 '18 at 21:54
  • Welcome to Motor Vehicle Maintenance & Repair! Nov 22 '18 at 21:59

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