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Old 26-05-2020, 07:22   #1
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Join Date: Aug 2016
Location: Vancouver BC
Boat: Hunter 466
Posts: 10
NL M673L3 ground fried

I have a Northern Lights M673L3 generator in our 2003 Hunter466. Have owned the boat since 2006. Because we converted most of the amenities to 12VDC from 120VAC shortly after we got the boat, we rarely use the generator (once a year when we drain the batteries) and it doesn't even have 100 hours on it. Not having had a generator on any of the other boats I've sailed, the poor thing has been neglected. Paying for that now. Just did my first oil change last month.... well it is less than 100 hours!

Part fo the problem is the way Hunter crammed the thing into a small locker between the two aft cabins. Can't even get at the water pump">raw water pump to check the impeller without removing the walls and rotating the unit around on the housing base!!

Anyway... to the problem.

The set was a bit rough to start for the past few years, but once running, it purred along. Then last summer, after the boat had been serviced on the hard for a couple of weeks, genset excluded, we were unable to start the thing.

A bit of background. The mechanic had taken her out for a sea trial and could not get the engine to start. I had switched off the all the fuel lines to the engine and genset while it was being serviced. Not sure if the guy tried both the engine and the genset to try and figure out why the engine wasn't starting. But after a call to me, he switched the fuel on and completed the sea trial.

we have been unable to get the genset to work since. The better half tried starting it up a number of times, and perhaps cranked the starter too long.. there was smoke coming from the genset locker, which smelled electrical. I thought that he had blown the starter motor, but after looking at it, it seemed fine. But I did notice a burned ground wire (was green) connecting the controller box to the engine. Yesterday, after battling to rotate the genset so as to get at the controller box to take a look, I see that the ground wire had been very hot and was more or less shot. In the process it had annealed itself to a white wire coming out of the run relay ("RR").

So my question is:

...why would I have so much current flowing through this ground wire?? Or, since it seems that there had been salt water misting in the locker due to an improperly set nut on the stuffing box, which sits just below and is open to the genset locker, had there been some corrosion which reduced the conductor integrity causing the overheating of the wire?

Any replies welcomed!
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Old 26-05-2020, 14:10   #2
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Join Date: Aug 2016
Location: Vancouver BC
Boat: Hunter 466
Posts: 10
Re: NL M673L3 ground fried

so an update

I replaced that fried ground wire, put some shrink-wrap around the damaged white wire going to the PR (preheat) relay.. put everything back together again, and she worked!! Only problem is, I found out why there was all the dried salt in the pan under the generator... it wasn't mist from the poorly adjusted packing nut.. after having just replaced the impeller yesterday, I discovered that the raw water pump is leaking at the back.... water gushing when it runs (no flow when it is stopped) and I have read elsewhere that this is a common issue with under used NL generators... next project is to replace that..
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