Mercruiser Alternator Problems

[ayaresr]

This is copied from my restoration thread, hopefully it will get more attention in the appropriate forum.
Is in reference to my 5.7L GM V8.
Finally got all of the wiring straightened out on the gauges and got them all working. Mounted a new pickup for the speedometer, and wanting to test that out, decided for a quick ride today. Got to the ramp, went to start the motor, and it just cranked and cranked. It was a slow crank, so thinking low battery, I lifted the engine hatch to throw the battery switch to battery #2, at which point I found the engine compartment was full of smoke. After immediately turning everything off and shutting off the batteries, as well as making sure I had no fire, I started looking for the source (obviously now with no intention of going out today as we didn't feel like swimming). I traced it to the area of the alternator, left it at that and trailered the boat. When we got home I messed with it a bit more and there is a sparking noise from that area, but it seems to be coming from inside the alternator as opposed to the connections on it. Wondering if the windings are shorted or something...anyone with any suggestions? What stumps me is it ran fine on the hose in the driveway yesterday when I was testing the gauges out.
Thanks and sorry for being so long winded!
Ryan

 

[havasuboatman]

Re: Mercruiser Alternator Problems

Are both of your batteries hooked up correctly?
Is the alternator hooked up correctly?
Has somthing gotten into into alternator?
What cooked, that caused the smoke? Something had to have burned to cause the smoke. Sniff the alternator, does it smell like burned wiring?Carefully inspect your whole wiring harness. You are looking for burned or bubbled wiring insulation. If you find none. Remove your alternator and have it tested.

 

[Lyle29464]

Re: Mercruiser Alternator Problems

did you change any gauges? Volt meters and AMP meters need different wiring?

 

[Bondo]

Re: Mercruiser Alternator Problems

Is in reference to my 5.7L GM V8.

Ayuh,.... Who's,..?? Merc., Volvo, OMC,..??

 

[ayaresr]

Re: Mercruiser Alternator Problems

Haven't really had as much time as I need to look at it very closely yet. I did check the wiring on the alt, all was clean, tight, and no sign of problems on the wiring itself. With the battery switch on, I can hear what sounds like sparking or arcing coming from the alt, and as best I could tell it sounded like it was occuring internally. The voltmeter was wired correctly, the only two that I changed between the last time the engine ran ok and when the problem occured would be the oil pressure and engine temp. The previous owner had the sender wires and ignition + on each of them reversed. This week I intend to look into this better, and being a restore project, most of the wiring will be replaced this winter so that I know what I am working with and that I can trust it. Thanks for the starting point and I'll follow up when I know more.
Ryan

PS-Its a Merc, sorry

 

[Bondo]

Re: Mercruiser Alternator Problems

PS-Its a Merc, sorry

Vintage,..??

 

[thedukeryan]

Re: Mercruiser Alternator Problems

This may be a shot in the dark but is it possible that your burned up your belt casuing it to smoke?

 

[ayaresr]

Re: Mercruiser Alternator Problems

Bond-o...believe its an '87 give or take a year...the motor was a swap in done by the last owner.
thedukeryan...certainly something I will look at, though having only spun the belt as fast as a slow crank from the starter would provide, I would think I saw quite a bit more smoke than that would have caused for the amount of time I cranked. Basically when I flipped up the sundeck, the whole compartment was smoke checked.