470 Alternator Conversion Replacement

[CuttingEdgeNY]

Hey guys, I have an old Merc 470 that I had the alternator conversion installed - part #18-59531. The alternator is at least 7 or 8 years old now and is putting out 15.3v so I want to replace it. I can’t figure out what alternator will fit that bracket.

 

[racerone]

What is wrong with 15.3 volt output ??

 

[Bt Doctur]

slightly high , did you confirm the reading with a voltmeter at the alt output post?
Most GM single wire ones

 

[achris]

That part number is a Sierra number. A very quick search identified the alternator as a 18-5956 (Sierra number)... Searching that identifies it as a Merc 69729, single wire 68A unit.

If you search either Mercury 69729 or Sierra 18-5956, it will bring up about a million of the things for sale.

As '7 or 8 years old' is not old for an alternator, before replacing the unit check the ground, and the continuity of the output to the battery...
The other option is to take the alternator to an automotive electrician for them to check out.

(I hate this 'it's old, unbolt it, throw it away and bolt on a new one' mentality. Just so wasteful! )

Chris....

 

[CuttingEdgeNY]

Thanks guys, I did not check from the alt posts, just at the battery. I’ll double check all the connections and take a new reading. But for my own edification, 15.3v would be considered too high, right? I’m not looking to burn out expensive batteries

 

[Scott Danforth]

take the alternator to your local starter/alternator repair shop (not your local autoparts store) and spend $35 to have it fixed (its a $12 regulator). or spend a whole bunch of money and replace it.

BTW, singe wire alternators tend to run high outputs if the wire or terminals have any corrosion