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Alternator Amperage Question

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Old Jan 19, 2011 | 04:48 PM
  #1  
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Alternator Amperage Question

Hi,
I have a 1999 Ford F150 4X4 4.6L V8.
Today the alternator went out on my way home from work. I am going to go with a junk yard one because I dont have the money for anything else.
My question: The place im buying it from has two amperage rating alternators for the same price ($40) and both have a 30 day warantee. Would it hurt anything to get the higher rated one? Reason I ask is, after taking the old one off, I dont see an amp rating anywhere on it so I dont know which one it is. The old one is a remanufactured ultima alternator.
So, will either of the alternators fit? Is the mounting the same? Of course il compare the one im getting to the old one, id just like to know ahead of time. Thanks
 
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Old Jan 19, 2011 | 05:27 PM
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Its a regular cab XLT. Dont know if it has the towing package or not.
8-Ribbed Serpentine Belt
 
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Old Jan 19, 2011 | 06:02 PM
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n5926g
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From: Hernando Ms
At this point,I would just take the defective one with you to the salvage yard,and "eyeball" it. If the mounting holes are the same,and the connectors are,then Id say your good to go.Concerning the Amperage capacity,I have no clue,but IF the Salvage yard unit turns out to be the higher output one,your ahead of the game.If not,and least you have the OEM spec one.I would however take a good look at the pulley to be sure it matches your belt.

PS.... Typically the higher output unit will have a noticeablly larger case
 
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Old Jan 19, 2011 | 08:56 PM
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i think the alternators availabe were 100 amp and 130 amp. Both are about the same size. I think the bigger one has a 7 grove pulley and the smaler one has a 6 groove. That may not be exactly right for every year. Either will work on your truck. You can put either pulley on either alternator.. Go for it.
 
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Old Jan 20, 2011 | 06:17 AM
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So what about an 8 groove pulley?
 
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Old Jan 20, 2011 | 08:12 AM
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I measured the case and compared it with the sizes listed on a parts store website. It's the larger diameter case.
 
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Old Jan 20, 2011 | 08:45 PM
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From: Olathe
Just to note there are only two types of rib configurations 6 and 8. Also the only two stock alternator outputs are 95 amps and 130 amps.

In answer to the original question no there should be no issue with getting a higher output alt. (I'm about to go from 95 amps to 200 amps myself.)
 
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