What are the signs that my alternator is going?

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Sep 28, 2009 | 03:48 AM
  #1  
Hi everyone,
I started my 96 this morning to drive to work. The car was not driven at all on Sunday, and it seemed fine when I used it on Saturday. When I started it, I noticed that it was moaning/whineing a bit, and my dash lights were a bit dim. When you would rev the engine, the lights would not get any brighter. Any ideas?

Thanks,
Zack
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Sep 28, 2009 | 04:09 AM
  #2  
Either a bad bat, or bad alt from the sounds of it. You can get both checked (w/o removing) at your local parts store. They are all to happy to sell you a new one if either is bad, so a lot of them will do it for free.

The easy way to check the alt is to pull the Gnd off the bat with the car running. If it stays running, your alt is fine. If it dies, bad alt - get a new one. I know this info has been covered on here before - and I recall posting the same instructions in fact. Please search ... too many threads as it is.
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Sep 28, 2009 | 04:44 AM
  #3  
Quote: Either a bad bat, or bad alt from the sounds of it. You can get both checked (w/o removing) at your local parts store. They are all to happy to sell you a new one if either is bad, so a lot of them will do it for free.

The easy way to check the alt is to pull the Gnd off the bat with the car running. If it stays running, your alt is fine. If it dies, bad alt - get a new one. I know this info has been covered on here before - and I recall posting the same instructions in fact. Please search ... too many threads as it is.

Thanks, I know the testing information, I was just not sure about the whineing/moaning sound, because it didn't do it Saturday?


Thanks,
Zack
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Sep 28, 2009 | 05:44 AM
  #4  
I WOULD START WITH A BATT ... AFTERMARKET ALT ARE NOT VERY GOOD I HAD TO REPLACE MINE LIKE 4 TIMES FINALY WENT TO DEALER AND PCIKED ONE UP... IT COST A LITTLE MORE BUT GOT A GREAT PRICE http://www.txnissanparts.com/Scripts/default.asp
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Sep 28, 2009 | 06:03 AM
  #5  
Quote: I WOULD START WITH A BATT ... AFTERMARKET ALT ARE NOT VERY GOOD I HAD TO REPLACE MINE LIKE 4 TIMES FINALY WENT TO DEALER AND PCIKED ONE UP... IT COST A LITTLE MORE BUT GOT A GREAT PRICE http://www.txnissanparts.com/Scripts/default.asp
When you type in caps it looks like you're SHOUTING!

OP - does the whine sounds like a belt whine?
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Sep 28, 2009 | 11:57 AM
  #6  
Ah ... a whine! I'd make certain it's not an A/C pulley (very common on our cars!) or a tensioner pulley. You can take a long screw driver and make a fist over the end and hold the tip to the tensioner pulley bolt, put your cupped hand to your ear, if it is loud, you found your problem. You can do this with the A/C comp as well, or the alt. Another way to check the noise / whine is to remove the belt and see if the noise stops. Then you can spin each pulley by it's self by hand and chek them.
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Sep 28, 2009 | 01:18 PM
  #7  
Well with the car running, I pulled the neg batt cable off, and the car died. So I guess the alt is shot?


Thanks,
Zack
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Sep 28, 2009 | 04:18 PM
  #8  
Oh and what alt does my car need a 110 or 125 amp alternator?

Thanks,
Zack
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Sep 28, 2009 | 04:47 PM
  #9  
I think it does not really matter, but id go with the 125amp. At least you get a little more amprage for stereos and what not and from what ive priced there the same in cost.
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Sep 28, 2009 | 04:55 PM
  #10  
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Oct 6, 2009 | 11:55 AM
  #11  
Mine does the same thing, but tensioner bearing or the bearing in the ac, will normally whine all the time, because they are always under load. The ac might whine more when it is on. but if your brake and batt light blink normally it means your alt/bat is shot. or maybe your belt is loose or in poor condition?
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Oct 7, 2009 | 04:27 AM
  #12  
Quote: Mine does the same thing, but tensioner bearing or the bearing in the ac, will normally whine all the time, because they are always under load. The ac might whine more when it is on. but if your brake and batt light blink normally it means your alt/bat is shot. or maybe your belt is loose or in poor condition?

Really??? My A/C makes less noise when it's on. Been making noise for a long time, but it still works.

As for the 110 vs 125 .... around here, the 125 is much more expensive (not sure why either) .... so I went with the 110. I run a system and have zero problems. (I also have a 2 farad cap tho)
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Oct 7, 2009 | 06:10 AM
  #13  
Do you have a mutlimeter?

With the car off your battery should read 11.XX volts.

When it starts it should work it's way to 14.XX volts.

If you start it and it sits around 12.XX, you're alternator needs replacing.

If your battery is reading < 11-12 volts when the car is off, replace your battery.
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