Stator failure?- Northern Lights 6kw

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David Hughes

David Hughes

Senior Member
Joined
Feb 21, 2015
Messages
165
Location
US
Vessel Make
Cobalt 246
Had guests on my boat last week, and while at anchor in Pelican Bay, Cayo Costa, FL ( hot as blazes), after about 10 hours of running the Air Con units, smoke began pouring out of the engine room- more specifically the generator sound containment box, and even more specifically the windings end of the generator. It was a LOT of smoke. They shut down the gen, donned life jackets are were nearly ready to jump. The smoke soon abated after shutdown and they spent the remaining couple of days at South Seas and Tween Waters so they could run shore power. All that is preamble to my question: Has this happened to anyone else and did you have to spend the $4000 for the new stator/windings unit, or did you have it simply rewound by someone. If rewound, about what should that cost? Tomorrow, Gulf Coast Marine Electric ( who I like and trust) is coming over to look, but it would nice to not be a complete ignoramus about it. Thanks!
 
Rare for stators to burn out on NL units, but it does happen. Check with Broward Armature, they have popular rewound units on the shelf.
 
Many Northern Lights generators came with the Marathon Magnaplus generator end.

This is probably the best generator end I've seen in terms of reliability.

If your generator end is ruined, and by the sounds of things it might be you can google "marathon Generator end"

You will find that you can get a brand new end for MUCH less than the $4,000 you mentioned. I found the 6 kw end for $2K and the 8KW end for $2100 using google.

In the heat of florida, larger is better for a generator end, as long as the length fits in your enclosure. For example the 6 and the 8Kw are the exact same frame size so they bolt up the same with the 8 kw being a couple inches longer.
 
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Had to replace the stator on a Westerbeke 8kw. First tried rewinding. The rewinding failed in one hour. Cost $3,500 for the refurbished part.
 
Those gen ends are rather bullet proof...surprised to hear smoked...I see you mention it is in a sound shield. How is the airflow to the rear of the genset (air inlet) - is there some obstruction?

Typically it is better to replace the gen end alone, vs a local re-wind.

That said, rewinding isn't rocket surgery, so it can be done well by someone with the right experience and materials.

On the gen end, it is not a Marathon...it's our proprietary end (Taiyo) and it is not compatible with any other models...the M673 has it own "one and only" end.
 
pacopico said:
Those gen ends are rather bullet proof...surprised to hear smoked...I see you mention it is in a sound shield. How is the airflow to the rear of the genset (air inlet) - is there some obstruction?

Typically it is better to replace the gen end alone, vs a local re-wind.

That said, rewinding isn't rocket surgery, so it can be done well by someone with the right experience and materials.

On the gen end, it is not a Marathon...it's our proprietary end (Taiyo) and it is not compatible with any other models...the M673 has it own "one and only" end.
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You sound like you are with Northern Lights...

Is there a reason on that model you went with the Taiyo generator end??? I say that because the other NL generators I've seen and worked on used the Marathon end.
 
We have used Taiyo on our sub-40kWe sets for the past 30+ years.

Above 40kWe we use Marathon.

Marathon are fine ends...Taiyo ends are equally as good. However they cost more when you get to the larger size.
 
pacopico said:
We have used Taiyo on our sub-40kWe sets for the past 30+ years.

Above 40kWe we use Marathon.

Marathon are fine ends...Taiyo ends are equally as good. However they cost more when you get to the larger size.
Click to expand...

well...

The good thing is that is you have a problem with a generator end, you are not brand specific for a replacement.

Thats something most folks do not realize. The engine and flywheel are with incredibly few exceptions standard SAE sizes.

I've not been hands on with the little NL units except the couple that I own, but have been engaged from the office with many many magnaplus replacements for the small NL units, and the feedback from the field has always been very positive.
 
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673's have a integrated fan/flywheel combination. Good luck.
 
pacopico said:
673's have a integrated fan/flywheel combination. Good luck.
Click to expand...

So the way this works, is if all the measurements Work out to a standard SAE bell housing, and flex plate then ANY brand generator end will work (any brand that uses the industry standad SAE sizing system)

If the measurements do not correspond to a standard SAE size then folks are forced to go back to the generator manufacturer for a replacement.

As I indicated I do not have hands on experience replacing the generator end on the NL 673, so I cannot speak as to wether these use SAE adaption, or some NL propritary size.

What I can say is that once the generator end is off, you can determine the SAE sizes in just a few minutes using a framing square and a tape measure.
 
David Hughes said:
What does mean? That I can't have a new generator end bolted on?
:eek::eek::eek:
Click to expand...

David

If you remove or have removed your generator end (which you will have to do in Any case anyway, you can take some specific measurements that will determine the SAE sizes of the bellhousing and flywheel flex plates.

If they do not correspond to a SAE seandard measurement, then you will have to use a NL supplied generator end. Otherwise you can use any brand generator end you choose.
 
Love to hear what is found, our boat is going to be equipped with that same Northern Lights generator...:confused:
Bruce
 
Guys, I think a mountain is being made out of a molehill here.

Yes the gen end can ALWAYS be changed.

To keep the overall length of those little sets down we use a custom built generator that integrates the fan and the flywheel.

I do not remember which SAE the flywheel housing is, but in this case the flywheel is not a "off the shelf piece".

Those gen ends are reasonably priced, therefore the potential money saved by going to another generator end, and figuring out the flywheel is a potential time and money waster.

Can anyone bolt up a compatible genset to any prime mover - sure! We make 40kWe gensets with four (4) different generator ends for four (4) different markets! And we aren't the only one.
 
Bruce B said:
Love to hear what is found, our boat is going to be equipped with that same Northern Lights generator...:confused:
Bruce
Click to expand...

Don't sweat it, any issues you have will be way down the road and long after you've moved up to the AT 56.
 
David Hughes

So you may well need a Taiyo end. The bigger question is why did your unit fail. Pacopico suggested ventilation. On many Cats the gensets are placed or better said shoe horned in such a way that fresh air is not well circulated especially if the genset is in an enclosure.

How about a circulating fan(s) that is engaged when genset starts up. Many vessels are equipped with ER fans to keep localized temperatures in check.
 
pacopico said:
Guys, I think a mountain is being made out of a molehill here.

Yes the gen end can ALWAYS be changed.

To keep the overall length of those little sets down we use a custom built generator that integrates the fan and the flywheel.

I do not remember which SAE the flywheel housing is, but in this case the flywheel is not a "off the shelf piece".

Those gen ends are reasonably priced, therefore the potential money saved by going to another generator end, and figuring out the flywheel is a potential time and money waster.

Can anyone bolt up a compatible genset to any prime mover - sure! We make 40kWe gensets with four (4) different generator ends for four (4) different markets! And we aren't the only one.
Click to expand...

Thanks very much for the information!!!
 
sunchaser said:
Don't sweat it, any issues you have will be way down the road and long after you've moved up to the AT 56.
Click to expand...

Let me know if you move up,I will buy your new one coming in,sight unseen!!! Of course,at a discount!!! haha ,just kiddin. :rofl:
 
sunchaser said:
David Hughes



So you may well need a Taiyo end. The bigger question is why did your unit fail. Pacopico suggested ventilation. On many Cats the gensets are placed or better said shoe horned in such a way that fresh air is not well circulated especially if the genset is in an enclosure.



How about a circulating fan(s) that is engaged when genset starts up. Many vessels are equipped with ER fans to keep localized temperatures in check.
Click to expand...


Thanks, and I think this is what's needed.
 
Just backing up a second, you said you saw lots of smoke from the generator, then asked about replacing the stator.

Has the actual failure been diagnosed? It seems to be that any number of different things might have smoked, the stator being only one of them.
 
David - looks like you are on the right path: seek the root cause of he failure first.

Sunchaser is correct: the small sponsons on a cat hull don't allow for lots of machinery space, and airflow is often the first casualty.

We have several hundred NL gensets in the Caribbean charter cat market, and with proper application (air, fuel, exhaust systems properly handled at installation) we rarely have casualties. I have seen many small sets like yours with 25,000 hrs on them, with only maintenance items being needed.

As well, I have seen applications where the engine room was over 150F (no ventilation, hot day and direct sun on the hull) and it gets hotter inside the soundshield.

I'm not going to say Taiyo ends never break, it's just not frequent.

First thing I would look at is the air inlet (gen end cooling and combustion air) at the rear of the soundshield. The next would be the air exhaust port on the LH side of the soundshield...if air cannot get in or out its a recipe for trouble.
 
pacopico said:
David - looks like you are on the right path: seek the root cause of he failure first.

Sunchaser is correct: the small sponsons on a cat hull don't allow for lots of machinery space, and airflow is often the first casualty.

We have several hundred NL gensets in the Caribbean charter cat market, and with proper application (air, fuel, exhaust systems properly handled at installation) we rarely have casualties. I have seen many small sets like yours with 25,000 hrs on them, with only maintenance items being needed.

As well, I have seen applications where the engine room was over 150F (no ventilation, hot day and direct sun on the hull) and it gets hotter inside the soundshield.

I'm not going to say Taiyo ends never break, it's just not frequent.

First thing I would look at is the air inlet (gen end cooling and combustion air) at the rear of the soundshield. The next would be the air exhaust port on the LH side of the soundshield...if air cannot get in or out its a recipe for trouble.
Click to expand...


Thanks so much. Again, all great advice, and no the dealer tech has not been out to diagnose yet. I can confirm that the round vent cover with slots in it is all charred. ImageUploadedByTrawler Forum1473631941.760700.jpg
 
Is that charred or corroded? Also - take a look at the wet exhaust elbow...curious to its' condition.
 
Update from Gulf Coast Marine Electric: windings end needs replacing, but worse, engine cylinders were frozen and had salt water in them. It's going to be a total rebuild for about $6000. Which leads to my next question: could the failing and frozen engine cause saltwater to blow out of the motor and into the windings? The tech seemed to indicate there was salt crust on the windings.
 
In the picture in post 22, what is that brown hose that ends at the generator vent openings? Could that have squirted salt water in there?
Normally there is no coolant tie between engine and generator ends.
 
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Is gennie mounted down low in a sponson? If so if gennie was dead and boat in service it is possible to get water to intrude. Depends on the install details.
 
I think ski is on to something. Is the hatch above this genny watertight? The photo you posted shows traces of saltwater corrosion in the pan and mounts. This has been occurring for a while. I think you should find the saltwater leak first. Air intake could also be drawing some salt if the drip is from above.
 
David Hughes said:
Update from Gulf Coast Marine Electric: windings end needs replacing, but worse, engine cylinders were frozen and had salt water in them. It's going to be a total rebuild for about $6000. Which leads to my next question: could the failing and frozen engine cause saltwater to blow out of the motor and into the windings? The tech seemed to indicate there was salt crust on the windings.
Click to expand...

My opinion...

Bag it and buy a new generator.

In my opinion, unless you are getting VERY good labor rates your $6,000 rebuild is either going to be just partial, or the bill is going to be higher than you think.
 
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