1987 3.0L MerCruiser Alternator

danielw71

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Apr 5, 2012
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Tback of my alternator fell off.
After looking at mercruiserparts.com I came up with 5 different possibilities they are all out dated, I cross referenced part numbers and iboats.com has a few to choose from starting at 168.99 to 201.80 they were Sierra 68 amp, Arco 105 amp & Mallory ? amp.
I also found on ebay.com a Delco 110 amp that matches for 69.00.
All alternators are marine, is there a reason I should not get the Delco?
 

Don S

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62,321
Re: 1987 3.0L MerCruiser Alternator

Why do you need such a big alternator for a 3.0L? You do realize that the bigger the alternator, the more HP it takes from the engine to run it.

As long as the mounting for the alternator is the same, you can use the larger Delco, just be sure to use a larger orange wire to the starter. It is only 8 ga now, sized for the 50 - 65 amp range.
 

danielw71

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Re: 1987 3.0L MerCruiser Alternator

Ok thanks the wire broke when it fell so I will have to change it anyway.
6 ga should be enough right?
How much of a differance would it make in the HP?
Since the Sierra was 65 amp and the Arco was 105 amp I was not sure if it would make a big differance, as to the useage I dont evan have a radieo right now but if I can save $100.00 to $200.00 I think it would be worth it.
 

Don S

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Re: 1987 3.0L MerCruiser Alternator

Take your alternator to your local starter/alternator/electric motor shop. They can probably fix your alternator cheaper than any dirt cheap off shore high amp alternator. And it will probably last longer ................ if you don't drop it.
 

danielw71

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Re: 1987 3.0L MerCruiser Alternator

LOL
I was going to take it to someone but two of the wires for the stator are broken and the rotor has been rubbing stator pretty bad I think was rebuilt before and not done right.
I guess I need to add checking the bolts holding the alternator together to my winterizing list.
 

jeremy_nash

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Nov 14, 2010
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Re: 1987 3.0L MerCruiser Alternator

if it was the one from "DB ELECTRICAL" on ebay, they are local to me, and I am running that alternator on my 1988 3.0
 

danielw71

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Re: 1987 3.0L MerCruiser Alternator

if it was the one from "DB ELECTRICAL" on ebay, they are local to me, and I am running that alternator on my 1988 3.0

Yes that is the one I ordered.
Did you use the origanal wiring?
 

HT32BSX115

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Dec 8, 2005
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10,083
Re: 1987 3.0L MerCruiser Alternator

LOL
I was going to take it to someone but two of the wires for the stator are broken and the rotor has been rubbing stator pretty bad I think was rebuilt before and not done right.
I guess I need to add checking the bolts holding the alternator together to my winterizing list.

Ok, then take it to a reputable rebuild shop so they can do it "right"!

I'll bet there's more than one available.....
 
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