Generator Noise

[jdisarro]

Hello Every one, I have an Onan 6 Kw Generator with about 500 houurs on it.
ast night while running I noticed that every now and then/ sometimes every few second the noise it makes would change from just the sound of a diesel generator running to a different sound almost like a vibration but not. it is hard to explain. it would do it intermittently. I flipped the main breaker off....just the sound of a diesel engine. then when I turned the breaker on again it did that noise non stop for a few minutes so i flipped the breaker off again and shut her down. Oil level is OK I checked it. was not running the Ac so i don't think I had max load on it.

Thanks in advance for any help as I am currently in the BVI.

[Blue Stocking]

Inverter intermittently placing a load-seeking mode perhaps?

[msmith132]

Jdisarro, did you find the cause of your problem. I have the EXACT same situation just started tonight, 510 hrs. It sounds like it is misfiring, and the control box displays extra vibration. Very intermittent. Any input would be GREATLY appreciated. Hoping to leave for down-island this week, but not with a questionable generator. Thanks.

[tuomas]

may be far fetched but.. does the generator engine have a timing chain? Problems in the device tightening the chain might make the chain loose which makes a sound like a diesel engine (had this problem in my car).

[a64pilot]

I'd look for a loose sheet metal cover or something that is picking up a secondary harmonic from the engine

[undercutter]

Originally Posted by a64pilot

I'd look for a loose sheet metal cover or something that is picking up a secondary harmonic from the engine

I agree, something came loose. shroud, engine mount, etc.

[colemj]

Check the mounts to make sure they haven't loosened or ruptured the rubber isolators.

Mark

[msmith132]

The vibration is quote violent and is definitely induced by the diesel running roughly or erratically as the exhaust smell also smells richer in waste fuel throughout these episodes. If I firmly grasp the 5 lb control box during the vibration, I don't make any difference in its motion or intensity, so its definitely not just something loose and vibrating lightly.

It is the cyclic nature which makes it troublesome to understand. Sometimes 20 seconds in a minute, sometimes only every 5 minutes.