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Aternator Keeps Needing To Be Replaced


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For about a month now my alternator has been going out. I replaced the Alternator about a year ago with one I purchased from Auto Zone (they were all rebuilt). But recently in the past month the alternators will go out every weekend. I take them back to AutoZone and get them replaced with the lifetime warranty that I have and still they seem to be going out. Now, I think I may have narrowed down the problem to a few things.

1.) I have no under engine cover and it is possible that when it rains water gets into the alternator and shorts it. But this is inconsistent considering it didn't rain the first week or the second week my alternator went out.

2.) About a year ago when my alternator first went out it was a result from a leaking value directly above the alternator that shorted it. I bought a brand new valve instead of using a screw. It is possible that this valve may have gone bad as well and the same thing is happening. But when I take the alternators out they are clean as when I got them.

3.) Could be that Auto Zone has been giving me bad alternators that go out after a short while. EverytBut getting 4 bad alternators in a row is unlikely. Also everytime I take them in the machine they use to test them has read positive results.

4.) I found my heat shield but unfortunately, the alternator went bad before I could put it on. Hadn't used the heat shield since I took it off a year ago and Its in the middle of winter right now so I don't think they are overheating.

5.) My last conclusion is that maybe the power cable that hooks into the alternator is going bad. But would that kill me alternators? I know it is not the ground cable because I see the grounded cable in front of me.

Please let me know what you think. Your opinion is valuable to me. I really don't want to sell this car just yet.

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Do you know what year the LS is? That might be kind of important.

For starters, I suggest you check the voltage on the alternator with a voltmeter, if you have one, to see if it's using a lot of electricity. Some others have also reported that power steering leaks in the older models could drip fluid on to the alternator, thereby shorting it out. HTH.

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It is a bit strange.

I doubt it is moisture as these things have to be designed to tolerate some moisture

The valve you replaced sounds like the PS steering pump valve that leaks PS fluid onto the alternator and kills the brushes. Even if that still was broken its hard to understand how it could fail in just a couple days. You'd see PS fluid all over the alterntor if this were the case

The heat shield is a possibility. If the electronics in the alternator get overheated they'll fail.

The other is some sort of short causing unusually high current drain which is forcing the alternator to max ouput all the time. You could probably see this by measuring battery voltage, if its around 13.3V DC then probably not this...

Are you sure the removed alternators are faulty? What test made you conclude this?

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Are you sure the removed alternators are faulty? What test made you conclude this?

That's exactly what I thought. What symptoms do you have, dead battery?

Per item 3, you say they test good. Then it's something else.

Per item 5, what about the cable going to the battery or the ground cable (negative) coming from the battery?

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I worked on an SC400 last year with a bad alternator, after getting it off I found the electrical plug to be damaged and one of the leads pulled loose. I had a spare car on my lot and replaced the plug along with rebuilding the alternator, that was the fix it needed. Look at the plug real well along with the main charging lead for damage, frays, or possible shorts.

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If the alternators test good, why is Autozone giving you new ones as replacements?

And when the alternator "goes out" what are the symptoms? Alt light? Dead battery?

...late to the party...did you save me some cake? :P

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