Generator Smoke and Soot Under Load

[helm]

I had a lot of soot and sheen from my NL generator. I was thinking injectors and all that but I think it was on boat diesel where Tony Athens suggest loading it up then misting water thru the air intake as the issue is often wet stacking and glazing in the cylinders. There was a set amount over time. I don’t have my boat diesel membership currently but you might search it. Cured my generator, and we try to avoid light loads.

 

[slowgoesit]

Without an amp meter, you're just guessing at the actual generator output.

Suggest you purchase a clamp on amp meter. 5500 watts at 120v is 45 amps. Check the actual amps the generator is putting out by clamping the meter on the (+) out line. Then you're not guessing.

Here's one by Fluke. $284.00
https://www.testequity.com/product/...Dt4u6DqJsBE1UiDWTj5xgTD-m4Yw2Gvrsh__exBe0AEJg

Here's another from Harbor Freight: $14.99 in store plus tax.
https://www.harborfreight.com/digital-clamp-meter-96308.html

Knowledge is power!

 

[Cigatoo]

For what it’s worth, we had a NL 5Kw generator that had similar systems. I had serviced about everything 200 hours before I couldn’t fully load it up without smoke. I finally pulled the generator from the boat and took it to a NL dealer. They pulled the exhaust elbow and it was clogged . We were all amazed. They said typically that would have been the first thing they looked at but since it only had 200 hours, it was the last.

I second the clogged exhaust elbow theory. I found mine rotted and clogged. Was a very low hour Northern Light M763. Replaced with a stainless elbow from these folks. https://hdimarine.net/product/nl-1-5-cast-stainless-steel-mixing-elbow/

 

[Bmarler]

When we rewired our boat we installed some new panel meters that display volts, amps at the panels, and another for volts and frequency at the generator output.
Not this meter here: https://www.amazon.com/MICTUNING-Mu...prefix=amp+hertz+meter,industrial,189&sr=1-10
But something like it. It’s nice to know at a glance what you’re actually using and producing.

 

[cafesport]

I still think the grey smoke indicates a cooling or perhaps a breathing problem. The black smoke is unburnt fuel. According to the manual temps should range between 167 and 194. The only time I’ve ever seen a temp over 185 on ours is when an impeller had lost several vanes. If the valves were not set after break in that could account for some of the symptoms. Ours did need to be reset at the 50 hour mark. Our stock elbow went 3500 hours before we replaced it along with a set of brushes. Other than the rubber parts wearing ours has proved to be pretty bullet proof. Currently running at 178 degrees in 74 degree water putting out 4400 watts. Making and heating water plus final stage of charging batts.

 

[Sababa]

I still think the grey smoke indicates a cooling or perhaps a breathing problem. The black smoke is unburnt fuel. According to the manual temps should range between 167 and 194. The only time I’ve ever seen a temp over 185 on ours is when an impeller had lost several vanes. If the valves were not set after break in that could account for some of the symptoms. Ours did need to be reset at the 50 hour mark. Our stock elbow went 3500 hours before we replaced it along with a set of brushes. Other than the rubber parts wearing ours has proved to be pretty bullet proof. Currently running at 178 degrees in 74 degree water putting out 4400 watts. Making and heating water plus final stage of charging batts.View attachment 141467

Not according to my manual.

 

[Sababa]

Without an amp meter, you're just guessing at the actual generator output.

Suggest you purchase a clamp on amp meter. 5500 watts at 120v is 45 amps. Check the actual amps the generator is putting out by clamping the meter on the (+) out line. Then you're not guessing.

Here's one by Fluke. $284.00
https://www.testequity.com/product/...Dt4u6DqJsBE1UiDWTj5xgTD-m4Yw2Gvrsh__exBe0AEJg

Here's another from Harbor Freight: $14.99 in store plus tax.
https://www.harborfreight.com/digital-clamp-meter-96308.html

Knowledge is power!

I happen to have a nice Blue Sea clamp on amp meter that I have never used. I’ll give it a try when I charge in the morning. Thanks!

 

[Sababa]

I second the clogged exhaust elbow theory. I found mine rotted and clogged. Was a very low hour Northern Light M763. Replaced with a stainless elbow from these folks. https://hdimarine.net/product/nl-1-5-cast-stainless-steel-mixing-elbow/

Already replaced with a new stainless exhaust elbow in 2020 so that can’t be it.

 

[cafesport]

Stainless can clog just as quickly if there are performance issue. When you replaced the elbow, which clamp did you tighten first? The grey smoke could be coolant or steam depending. You might give northern lights a call and give them the serial numbers from your genny in order to make sure you have the right manual. The ones online and the one they shipped with the unit I installed say 167-194. Needing a new elbow before a second oil change though it happened to Larry, is pretty unusual.

 

[Sababa]

Stainless can clog just as quickly if there are performance issue. When you replaced the elbow, which clamp did you tighten first? The grey smoke could be coolant or steam depending. You might give northern lights a call and give them the serial numbers from your genny in order to make sure you have the right manual. The ones online and the one they shipped with the unit I installed say 167-194. Needing a new elbow before a second oil change though it happened to Larry, is pretty unusual.

The NL authorized repair guy replaced the elbow, not me. The manual is the original that came from the Nordic Tug factory with the boat in 2001. You probably installed something more recently. I’m sure I have the right manual.

I’m not losing any coolant and I don’t understand how that would explain the soot and sheen coming out of the water exhaust, or that the problem only occurs under heavy load. The temp is dialed in right at 195 (could be 194) and doesn’t budge. I’ll have the elbow checked but seems very unlikely.

 

[twistedtree]

I happen to have a nice Blue Sea clamp on amp meter that I have never used. I’ll give it a try when I charge in the morning. Thanks!

Perfect. I think this is an important next step to determine if this is simple overloading, or if there is an engine problem of some sort.

What’s the current rating? 25A@240V or 50A@120V?

 

[Sababa]

Perfect. I think this is an important next step to determine if this is simple overloading, or if there is an engine problem of some sort.

What’s the current rating? 25A@240V or 50A@120V?

Draws about 18 amps (2160 watts) with the charger at full bulk draw with no smoke and soot. Adding on the water heater takes it to around 28 amps (3360 watts) and smoke and soot start coming out. That’s well below the 5.5 kw rating.

Current rating for what?

 

[SteveK]

What’s the current rating? 25A@240V or 50A@120V?
Current rating for what?

Your generator can output either 25A @ 240V OR 50A@120V @ 60Hz.
The question asked what are you setup for 120V or 240V @ 60Hz and 1800 rpm

OR

is it 50Hz @ 1500 rpm with an output of 220V @ 22.7A

Is this your generator LINK

 

[Sababa]

Your generator can output either 25A @ 240V OR 50A@120V @ 60Hz.
The question asked what are you setup for 120V or 240V @ 60Hz and 1800 rpm

OR

is it 50Hz @ 1500 rpm with an output of 220V @ 22.7A

Is this your generator LINK

Yes, that’s mine, and it’s set up for 120v @ 60hz.

 

[SteveK]

What RPM at 18A load and what at 28A load?

What is your charger brand and model?

ETA found this in manual troubleshooting
Clogged or dirty air cleaner
Defective muffler (back pressure too high)
Injection nozzles dirty
Engine out of time

 

[Sababa]

What RPM at 18A load and what at 28A load?

What is your charger brand and model?

ETA found this in manual troubleshooting
Clogged or dirty air cleaner
Defective muffler (back pressure too high)
Injection nozzles dirty
Engine out of time

Magnum MS2812 inverter/charger.

I don't have a tachometer on my panel. The tone of the generator drops a note when it is fully loaded, but it doesn't sound like the revs go down appreciably.

I have the same manual. Definitely not a dirty air cleaner. Can't check the rest until back in port.

 

[twistedtree]

Based on those measurement I agree that it’s not overloaded. If you are certain there is no intake restriction, then perhaps a value adjustment is a good next step.

 

[Sababa]

Based on those measurement I agree that it’s not overloaded. If you are certain there is no intake restriction, then perhaps a value adjustment is a good next step.

That’s the plan, but not something I feel comfortable doing myself for the first time while out cruising. Hopefully I’m not doing any damage in the meantime.

 

[cafesport]

I just re read your original post, so it appears it was a 20 year old unused generator when you bought the boat and you had mechanics replace everything they saw fit. The intake and exhaust hoses are now 23 years old? Id change those as well. You suddenly using the gen could have stressed them enough to delam and collapse internally.

 

[Sykes]

I have a 1999 5kw NL with 4500 hrs. Mine smokes a little when I am pushing her, 24 amps consistantly, two 16000btu a/c's running. She runs for a few days in a row, I shut her down every 8 hrs to check the oil and make sure everything is fine. How much smoke are we talking?

 

[ksanders]

First thing I would do is to add load and measure the frequency of the output vs the load.

Why???

As you load up a mechanical governed generator it will drop in frequency.

Those small NL generators are rated to be at 57HZ at full rated load.

 

[Sababa]

I have a 1999 5kw NL with 4500 hrs. Mine smokes a little when I am pushing her, 24 amps consistantly, two 16000btu a/c's running. She runs for a few days in a row, I shut her down every 8 hrs to check the oil and make sure everything is fine. How much smoke are we talking?

The smoke isn’t too bad but the soot coming out of the water exhaust leaves a bit of a mess in the water. I could live it if that’s just the way it is and it wasn’t hurting the engine. My original question was whether I should do just that and see if it gets better with time. Nobody seems to support that approach, and since I have a long overdue valve adjustment anyway, my current plan is to get that and a few other maintenance items done (timing, exhaust back pressure test) before I run it hard again.

 

[guy with a boat]

First thing I would do is to add load and measure the frequency of the output vs the load.

Why???

As you load up a mechanical governed generator it will drop in frequency.

Those small NL generators are rated to be at 57HZ at full rated load.

The info I got from NL is to adjust the frequency to 63hz with no load so that it will maintain 60hz under load.

 

[rslifkin]

Most mechanically governed generators will have enough droop that you'll be a bit above 60hz at no load and below it at full load to strike the best compromise. IIRC my Onan sits around 62hz at no load and about 58hz at full load. A 3hz droop (5%) is about the best you'll get out of any mechanically governed unit and some won't even get quite that good.

 

[Sykes]

The smoke isn’t too bad but the soot coming out of the water exhaust leaves a bit of a mess in the water. I could live it if that’s just the way it is and it wasn’t hurting the engine. My original question was whether I should do just that and see if it gets better with time. Nobody seems to support that approach, and since I have a long overdue valve adjustment anyway, my current plan is to get that and a few other maintenance items done (timing, exhaust back pressure test) before I run it hard again.

Keep us updated, I am interested in your results.

Thanks