1GM10 questions

[reidmefirst]

Kind of a 'funny' story...

The former owners of my boat, as their final act of ownership, charged up the boat's two batteries and connected them back into the boat. Unfortunately, they connected the main battery cables up in reverse. It took me a couple of sails to figure out why some things in the boat, just weren't working quite right...

The 1GM10 starts and runs in this condition, although it seems to have killed the alternator. Worth noting that while the motor started and seemed to run fine, the alarm buzzer never sounded and the tachometer did not work, although at least the 'alternator failure' light was lit...

So question #1: I do wonder if anything else wacky may have happened with the motor, that I should think about. After sorting the cables it does seem to start a lot more easily. And, added benefit, the yanmar panel alarm sounds like it's supposed to, the tachometer works like it's supposed to, and my depth and speed instruments are actually working now. But, did I do any damage?



Question #2: While I was poking around in the motor compartment I also noticed one of the connectors, not connected (hopefully there's an image attached to this post). The connector is a white wire with red stripe, and black wire, hooked into a two-pin connector that comes from the main wiring bundle behind the alternator (the bundle connects up to the instrument panel in the cockpit). From the 1GM10 manuals, the color codes mean it is supposed to be the 'sail drive rubber gasket failure alarm' signal wire. Trouble is, I can't find any place to plug it in, and the 1GM10 service manuals don't show where it plugs either. Does anyone know where this actually connects? Given that the drive shaft seems to go through the hull quite far from the actual transmission, maybe it's totally unused on our boats?

[Pete]

Id your boats a shaft and prop setup ? If so you'll not have a place to connect as there is no seal to fail. Think you might be seeing wiring diagram for a sail drive ?

[Pete]

Regarding your alternator, it's likely cooked but perhaps not a total loss. Take it any starter/alternator automotive shop and if they can't repair can replace. Often it's a simple as replacing a diode.
Diesels can often run in either direction as combustion occurs as the result compression only. Did you have the boat in gear so that forward and reverse as selected worked properly ? If not it was probably running 'backwards' . I expect it will be fine.. Anything else on the boat sensitive to polarity if working will be fine. Good luck.

[reidmefirst]

Ah, makes sense. Nope, boat doesn't actually have a saildrive. I hadn't even known what that meant, just figured it was a trademark name for a driveshaft seal, or something goofy, I guess it's a weird 90-degree-angle transmission thing. Anywho, thanks, at least I know what it means now!

And yeah, the motor was running forwards/correctly even with the starter motor going in reverse. Weird.

I'll probably repair the alternator myself -- bought a second alternator from a tractor supply store that works, and I'm good with a soldering iron so will investigate the rectifier circuit...hopefully I can fix it myself, document how it's done for others, and have a spare alternator out of the process...

[Pete]

Sounds like you know what you're doing. I suspect you'll be fine. Good luck and keep us posted.