[curtis73]

So, long story short:

My buddy has a show/ski boat with a 351W in it. The externally regulated alternator died. Replacing it with a reman was going to mean $220 and a week to order it. In the meantime, I happen to have an alternator from a 2001 chevy pickup that actually is a direct bolt in.

It has a 4-pin plug on it - the one with one large pin and three little pins. According to the wiring diagram, the only ones used are the two in the middle - one gets switched power and the other goes to the gauge/warning light.

So... with everything mounted I thought I would test some stuff out. I took the belt off, hooked up the battery to the main lug on the alternator, and spun it with a drill. (hoping it would self-energize). Alternator free-wheeled offering no resistance and voltage remained at 11.9v. With the drill spinning, I gave 12v to the appropriate contact and it almost immediately bogged down and.... still 11.9v. Thinking that my 2000 RPM drill wasn't enough, I put the belt on and started the engine. Given the size of the alternator pulley and the crank pulley, it probably spun to 3-4000 RPM and still 11.9v on the multimeter.

I verified wiring on the donor truck, and keep in mind that this was producing 14.4v in the truck literally two days before.

How do I properly wire this alternator? (and by the way... don't worry about the marine alternator... this is a show boat with an exposed engine above the deck)

[SSedan64]

Look thru these links, may help: http://www.madelectrical.com/electrical-tech.shtml

[EOD Guy]

This might help

[75gmck25]

When you connected 12 volts to the L terminal (dash light), did you put either a light or a 35-350 ohm resistor between the wire and the 12 volt source. The CS alternator will not operate properly if there is no resistor or light in the circuit.

This link has some easy to understand CS 130 wiring information.
http://www.scribd.com/doc/23641349/S...co-Remy-CS-130

Bruce

[curtis73]

I had connected 12v individually to L and I, both bogged down the alternator but didn't make any more juice. I now have the 12v switched on I and it seems to be working... kinda.

I fully charged the battery overnight last night. Today it showed 12.6v. I ran the boat for about 6 hours today trolling (caught some nice white bass and largemouth, too) and the Amp gauge showed that it was charging a couple amps. But two different volt meters confirm 12.3 at the battery while running.

The boat kept a charge all day and started up just fine every time, but I just don't understand why its not putting out the same 14.4 as it was on the truck just a few days ago.

For now, its working. Whether or not its working RIGHT remains to be seen, but I appreciate the help guys.

[Ground zero]

I've been working on alternators a quite sometime already,,,usually if voltage drops below 12v even at high rpms,,,this indicates an open or defective diode in it,,,a perfect working rectifier ( set of diodes ) can produce 13.0v+ @ 750rpm...hope this helps,,,

[trees]

Automotive alternators and inboard or inboard out drive motors don't mix. Because of the potential explosive fumes in the bilges of these units, special spark arresting alternators are used, thus the very high price. I would not take the chance, but spend the bucks and wait for it to arrive. A pleasure craft does not need to turn into a death trap.

Trees