Any way to quiet a generator?

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Bill and Debbie

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Jun 7, 2014
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374
Location
Poulsbo, WA
Have a Onan 7500 Marquis Gold. Anyone make a devise for the exhaust which would quiet the sound a bit. Don't want to run a pipe to the top of the rig. Need something like a silencer....thanks.
 
Noise comes from both the exhaust and from engine noise. Years ago I took my Class C to a muffler shop and had them add a flat car muffler (much larger diameter pipe so back pressure wasn?t an issue). That plus some homemade baffling around the cooling grillwork (still allowing plenty of airflow) and the genset was dramatically quieter.



 
There are several YouTubes on modifications to reduce generator sounds. After viewing them I wasn't totally convinced that it was worth the effort. None of the ones I saw, however, did anything more than muffler modification.
Bob
 
My onan is smaller, but I put on one of onan's resonators.
Using a Db meter on my phone...so nothing too good....it helped overall I think but only very slightly.  negligible really.  I don't remember the numbers now.... I can probably dig them up if you really want to know.  I think I even video recorded it on my phone...but it was hard to hear anything
I'd say the affect was more of a tuning of the sound.  It might maybe be described as a bit more pleasant...but again, not significant.

I was looking at some tractor mufflers in a Tractor Supply store once, and saw one that I think would have worked better.  the onan thing is a straight flow through pipe with perforations into the outer chamber.  The muffler actual had a baffle.  I doubt if the one I was looking at would give it too much back pressure....possibility I suppose, but I seriously doubt it...
 
My onan Marquis Gold 5500 is pretty quiet compared to other onans I've had.  My generac generators all have been pretty quiet too. I did buy a muffler for a garden tractor on Ebay for the onan 4000 that was in my Daybreak. Most of the noise was from the generator itself not the exhaust. The muffler I bought had a larger diameter pipe so I had to find an adapter to make it work.
 
With my Onan 4k genny, most of the noise seems to come from the engine and not the exhaust.
 
I know you said you don't want to run a pipe to the roof, but I think a Gen-turi type of setup is likely about the most effective noise and exhaust fume reduction method available at a reasonable cost. I have seen a Gen-turi type pipe setup permanently installed at the rear of a coach with the generator installed at the rear corner.
 
I have an 5500 and I can barley hear it. (of course mine is gas, not diesel, that may make a difference)

I Strongly suggest the Gen-Turi for all RV generators.  It does not (As near as I can tell) Quiet it as much as change it (Deeper, more throaty sound. lower frequency/tone/note) but then that is not what is designed for.

When my coach was new it took 2 hours for the Generator to set off the CO alarm

I ran it 4 hours this AM with narry a beep.. THe Gen-Turi takes the fumes UP, UP UP and away.

In a campground (Boondock) situtation the neighbor's Generator fired off my CO alarm.

Not so if neighbor has the Gen-Turi.

I strongly recommend it.
 
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