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Old 14-06-2013, 09:11   #1
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Black Exhaust Water

I have a NextGen 5.5 kW diesel generator.

Today when I ran it under load, I noticed that the exhaust water was very dirty and black "soot" (or something) was in the exhaust.

When I took the load off (2 kw), the exhaust water ran clear.....only to go black again when I turned the load back on.

Has anyone got any ideas about what could be causing this and what I can do to rectify it?

There is no unusual noise coming from the generator at any time and I have the same fuel that I have had for the last two months.

Thanks
John
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Old 14-06-2013, 09:24   #2
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Re: Black Exhaust Water

try run it under full load for 10 minutes. It should burn off any carbon build up.
maybe its just been run too lightly loaded for too long
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Old 14-06-2013, 09:28   #3
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Re: Black Exhaust Water

None of the following suggestions are in order of importance - just random thoughts.

How many hours on the generator? If a lot, you could need the injectors serviced.

Have you been running it a lot with a low load? It's possible that there is soot buildup that is just burning off under higher load. Run it at load for a while and see if it goes away.

Check the frequency and voltage with and without load to see if the load is drawing them too low. You may need to adjust the governed speed to bring these back up.

Is this a capacitor controlled head? If so, the capacitor could be getting weak and dropping the regulated voltage or causing the head to put a greater load on the engine. They will do this for a couple of weeks before failing completely. Try changing the capacitor and seeing if the problem goes away.

Mark
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Old 14-06-2013, 09:32   #4
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Re: Black Exhaust Water

Quote:
Originally Posted by colemj View Post
None of the following suggestions are in order of importance - just random thoughts.

How many hours on the generator? If a lot, you could need the injectors serviced.

Have you been running it a lot with a low load? It's possible that there is soot buildup that is just burning off under higher load. Run it at load for a while and see if it goes away.

Check the frequency and voltage with and without load to see if the load is drawing them too low. You may need to adjust the governed speed to bring these back up.

Is this a capacitor controlled head? If so, the capacitor could be getting weak and dropping the regulated voltage or causing the head to put a greater load on the engine. They will do this for a couple of weeks before failing completely. Try changing the capacitor and seeing if the problem goes away.

Mark

The SYMPTOM sounds very scary, but none of the solutions sound too bad.
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Old 14-06-2013, 10:00   #5
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Re: Black Exhaust Water

Thanks all.... and the symptoms seem very scary to me! I do not want to seize the gen because i do something silly.

The Generator is new with only 500 hours on it and has worked flawlessly up until now....although the capacitors have needed replacing a few times, so I do not think the injectors need servicing.

I normally run the generator to power my watermaker which is 2KW, and occationally charge the batteries. When charging the batteries it is not under much load, but I will run it for 4 to 6 hours or so to power the watermaker every 5 days.

I do not have a way to measure the frequency but I have just run it under load again. The voltage is constant at 120V.

After putting the load on, the waters are running clear now.....so maybe that was the problem. It maybe just needed to run a bit longer to "clear out". Fingers crossed! I did run it under low load for 2 hours yesterday and maybe that was the problem.
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Old 14-06-2013, 10:10   #6
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Re: Black Exhaust Water

Quote:
Originally Posted by John Duckworth View Post
Thanks all.... and the symptoms seem very scary to me! I do not want to seize the gen because i do something silly.

I don't think you need to worry about that in this case.

The Generator is new with only 500 hours on it and has worked flawlessly up until now....although the capacitors have needed replacing a few times, so I do not think the injectors need servicing.

I agree.

I normally run the generator to power my watermaker which is 2KW, and occationally charge the batteries. When charging the batteries it is not under much load, but I will run it for 4 to 6 hours or so to power the watermaker every 5 days.

2KW is still only ~35% loaded, and the battery charging could be about the same or much less depending on the size of the charger.

If possible, it would be good every so often to also turn on a water heater, AC unit or anything else that together can pull 4-5kW out of the generator. These things like to see high loads every so often.

I do not have a way to measure the frequency but I have just run it under load again. The voltage is constant at 120V.

Probably not the problem. If you have a generator, having a multimeter that can measure frequency is useful.

After putting the load on, the waters are running clear now.....so maybe that was the problem. It maybe just needed to run a bit longer to "clear out". Fingers crossed! I did run it under low load for 2 hours yesterday and maybe that was the problem.


Mark
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