Alternator Keeps Going Bad – Why?

We got a car in our repair shop the other day that the owner of the vehicle stated he had replaced the alternator 3 times in the last 6 months, and of course it was in our shop because……drum roll please……it needed ANOTHER alternator.

When removed the alternator we immediately noticed the problem causing his repeated alternator failures. Engine oil is leaking and dripping down and inside the alternator causing the alternator to burn out. (see the black stuff on the left part of the picture, that is dried up engine oil from his leak, I bet there is just as much on the inside as the outside)

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He can replace the alternator all he wants, but if he does not repair the oil leak the problem will continue. The alternator has vents or slots on the case to help cool the inside of the alternator.

These vents can also allow outside debris such as engine oil, coolant from a coolant leak, flood water from the road etc. etc. to enter the alternator and burn out the electronics.

His alternator also has some blue marker text on the top of the alternator which is usually a good indication that this alternator came from a JUNK YARD and is not “new”. It might be a “new” alternator for his car…but it is not a newly built alternator.

Speaking of “new” alternators. Rarely do you buy a NEW alternator, you usually buy a rebuilt alternator. Although it is shiny and looks new, it was once on someone else’s vehicle, they bought a rebuilt alternator and in exchange gave their old alternator back to the repair shop or auto parts store so that alternator could then be rebuilt and resold to the next customer. This is very common and nothing to be gunshy about.


Austin Davis

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."
  • Austin Davis

    Hi there, first off I would NOT trust Pep Boys to give you any real useful mechanical information other than for tires and oil changes. This is WAY out of their league and they know it and want you to go somewhere else.

    I have seen many Maximas with internal oil leaks, and remember there was recall about some models years ago for internal oil leaks but I want to say they corrected that problem on 2000 and newer vehicles???

    What I would do is go to a real mechanic, or the dealership…probably the best place to start with and pay them to investigate and find the source of the leak. It could be something BIG like a timing cover gasket (which is common and very expensive) or it could be something simple and was just overlooked by Pep Boys.

    Like I said, Pep Boys is just not really good at diagnosing things in my opinion and their focus is more on replacing common items like belts, tires, brakes etc.

    it would be worth $75 or so to get a real diagnosis. If the oil continues to get inside the alternator you will be replacing alternators soon.

    No offense, but not sure I would recommend spending $1,000 on an oil leak in a 13 year old vehicle. I see this happen all the time, $1,000 today, but next month the transmission fails, then the A/C compressor next month etc. etc.

    It might be better to use that $1,000 and what ever you can sell your car now as is and use it as a down payment on a newer lease trade in vehicle 2 years old and less than 30K miles and still under factory warranty.

    My favorite car these days as a replacement to this one is the Kia Rio.


  • Val

    I have the same problem. From where is the oil coming? Pep Boys told me it was from a $30 part, but would cost $750 to replace. I’m trying to figure out from where the leak is coming because a neighbor is willing to buy the car “as is” to fix it. The Pep Boys guys said different things “case” and “valve cover” and power steering. Any idea, so I can tell the neighbor. ??? 2000 Nissan Maxima

  • Have you found an answer to your problem?

    You make a good point about junk yard alternators. However, not all alternators being sold are rebuilt and sellers should not list remanufactured alternators as new.

    I have worked in the industry for a while and one way to avoid old alternators is to buy New OEM. These come attached with the manufacturers sticker (which would be damaged if the alternator was used). We mostly sell OEM since it is the best quality.