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Old 12-05-2017, 09:56 AM   #3
DavidM
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City: Litchfield, Ct
Join Date: Aug 2012
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Years ago after having a 5 KW Northern Lights generator installed in our new boat by Bayshore Marine in Annapolis, Jeff the owner advised me about loading the genset.

He said that they do a nice business overhauling generators that spent months in the Caribbean with the genset running 24/7. At night there are no loads other than A/C and the A/C only runs 15% of the time. The no/light load situation lets unburned diesel and lube oil bake on the cylinder walls forming a glaze. The glaze isn't hard to get off, just takes a few passes with a hone, but it does require removing the engine and pulling the head.

Why are gensets prone to this condition whereas propulsion engines routinely run at light loads. It is because gensets must run at full rpm all of the time. That means that lots of air is being sucked in with little fuel burned which results in incomplete combustion and fuel condensing on the cylinder walls causing the glaze.

So I always try to load my genset to 25% to avoid this.

Hopefully Ski will describe his experiences which include running his genset all night with no problems but only for a week or so a couple of time a year. I think it takes extended light load running to cause the glazing.

And a good way to avoid the situation is to run hard for a couple of hours every once in a while. That will help burn off the incipient glaze.

David
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