Lmarth

This Steve H guy could pass for an oso alternator expert from the Pacific Northwest!

cloudmaster_321

well, i unmounted the alternator, and found a bunch of corroded hardware. So i replaced all the hardware with new. Put it back together and had no charge. I was thinking i was smart, i followed the wires around and found that a purple/red went to a relay/selenoid. The selenoid was not activitated, it had power on one side, but not the other. The side that is hot went to the starter, also connected to the batter. The selenoid coil power is dead. I haven't figured out where that power comes from, but i know that the red/purple wire goes to the back of the alternator. The alternator has four wires. There two wires that come out the back, one is the red/purple, other is purple. Then the output i believe is on the orange wire, which is hot, and ground on the black wire. I have an install book for the bravo, and it tells me that the selenoid is a starter slave solenoid. So i'm not sure if this not being closed during engine running is my problem, or if it is just closed during starter engagment? What wire is my excitatoin wire, if it is the red/purple, then something is up with the solenoid, cuz the coil power, or the yel/red, is not getting power. sorry for the book, just trying to better understand my problem. thanks

cloudmaster_321

on another look at the book here, it looks like the purple wire is my excitation wire, it is supposed to be coming from the positive side of the ignition coil. What voltage should this be, i would think it would be 12volts from the coil. what am i missing here?

cloudmaster_321

alrighty, so if i have power on the purple wire at the alternator, and i have rpm's above 1500 or so, and i'm not making 14volts to the battery, can i assume that the problem is in the alternator then? I was going to take it off and take it to checkers to have them test it, but i saw the environmental splices for the purple and purple/red, so i didn't want to cut them, but i guess i will have to. Are those wires pretty standard on all '90 vintage alternators so they know what to hook to them while testing. Btw, it is apparently the original alternator, says merc part on it and made in 1989. Was made overseas though, imagine that.....

cloudmaster_321

well, today i verified my field voltage, and started her up to try again. It started putting out 14.5 volts right away, but after awhile, it dropped and battery votage slowly went back don't to 12volts. Then intermittantly, the alternator would go back on line. So i took the alternator off, and took it in my shop (little wood shed). I believe the regulator is the small box mounted on the back by four screws, so i took that off and took a peek inside. What i found was some sort of brushes, in some sort of green holder asembly. Tons of carbon was in there as well, so i washed it all out with electric cleaner and cleaned the brushes and holder. Is there any other brushes in the alternator, or are these the ones everyone has been talkin about. I think i may try it on the boat again now that i have cleaned it, but was wondering if possibly my regulator could be the problem as well. My alternator is a Mercury Marine p/n 12449. Is the regulator something i can get at a merc dealer, or west marine, or do i have to go to an alternator/starter repair shop? Thanks for the help guys.

cloudmaster_321

ttt

Wobble

I couldn't find an alternator shop that would work on the little box on the back of a marine alternator, guess they didn't know how it works. Ended up buying a single wire GM alternator from autozone for about $55 just uses the orange wire which should go straight to the batt terminal on the starter. You just cap the other wires except the ground which is u can attach to a bolt.

This works fine unless you have dual batteries and a solid state charging isolator, Then it gets more complicated.

The gm alt should fit ok, I didn't have room for the spark sheild that they make for them that covers the back of the alt.

If you are worried about coast guard inspection, just paint it black or find the spark sheild that most alt. shops seem to have

cloudmaster_321

well, i did better than that. i went to fondy electric in town here, and they rebuild marine/auto starters and alternators. Bought a new marine regulator and brushes for $35. Easy. I'd just assumer keep the shielded alternator in there to keep my butt in one piece.