alternator hook up

[1ruralmailman]

hi all,
have a 86 mercruiser 4.3 liter.was out for rebuild now back in boat,only thing i cant figure out is correct hook up of wires on back of alternator. have orange black purple,and some other color.had them labeled when motor came out.but they got lost in the process.is there anyway to get a good picture or digram as to where each wire belongs?engine serial # does end with 177 as i know this important for almost all parts on this thing.
thanks
rob

 

[Alpheus]

Re: alternator hook up

http://www.boatfix.com/merc/Servmanl/18/18C4R2.PDF

 

[Don S]

Re: alternator hook up

The beginning of the serial number is what makes a difference, not the last 3.

As far as your wiring, your hookup may be similar to the link Alpheus posted, but that is for the 93 to 97 engines. Yours may look a little bit different. Especially if a prestolite.

So, which type do you have, Mando or Prestolite?

 

[Searay87]

Re: alternator hook up

Hi there. I'm no expert and when in doubt it's always worth talking to one to resolve a problem. I just replaced the alternator on my 1987 merc 3.0 130 HP.

The new alternator didn't come with a wiring diagram and the studs on the new alternator were not labelled. I do have an electrical background so I took a stab it and it worked out just fine for me.

The alternator has 4 wires. The two smaller gauge wires were easy, I just matched the colors and the connectors were an exact match. The orange wire with the rubber spark plug like cover had 12 volts on it continuously so I concluded this had to be attached to the battery so I attached to the stud with the insulator on it (looks like a fibre washer) as it cannot be in contact with the case of the alternator otherwise it would short out the battery.

The black wire is the ground and because the case has to be grounded I attached it to the stud that is un-insulated or common with the case.

I started up the engine and measured 14.4 volts across my battery.

 

[1ruralmailman]

Re: alternator hook up

definitly have a prestolite alternator.looks like the one in the pictures ant way as there are no wires hanging loose from it wth connectors,just studs.

 

[Don S]

Re: alternator hook up