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Muffler for Onan generator??

VA-Apraisr
Explorer II
Explorer II
Onan 4000 on my rig and not really a noise issue, but just wondering if anyone has attached a muffler or spark arrestor to the tailpipe? If so, did it seem to be much quieter? Planning on several weeklong trips to the island and may be using it for a/c in September during the daytime and possibly overnight if no breeze. I'm asking because a friend has a truck camper is was told to attach a Cummins spark arrestor and that would drop the noise levels.
11 REPLIES 11

I-Can-Am-Can-Yo
Explorer
Explorer
Mine makes the most noise from the intake. I put insulation foam along the bottom of the access panel forcing it to draw air from the top and sides. Still has plenty of airflow and is a LOT quieter. Had no issues running in 90+ degree heat.

VA-Apraisr
Explorer II
Explorer II
Update: Installed the Roadkill mats on generator access door to RV as well as the drop-panel door to access inside of the generator itself. Also, put mats on top of generator (as per video link above). I also put the mat beneath my dinette seat which is directly above the generator. I'd have to say it was a minimal improvement....yes, a tad bit quieter, but nothing to write home about. As previously mentioned, it's not a super loud unit anyway, but, was worth giving it the ole college try!

Gjac
Explorer III
Explorer III
The only time I ever needed to run the genset for any length of time was when I needed AC. The AC is much louder than the genset and my genset is under the bed in the rear. I did add 1/2 in foam insulation with Al foil on one side because the old insulation was falling down. So with 2 layers of insulation I did not notice any sound decrease. I would save the insulation for the dog house where you will notice the difference.

bobndot
Explorer II
Explorer II
Good luck with this project John.
It seems like it should help. Please keep us posted.
Bob

VA-Apraisr
Explorer II
Explorer II
I ordered a pack of these Roadkill mats and will install next week. Can't hurt to give it a try. Might even install one beneath my dinette bench seat which is directly above the running generator. I've got those silver foam insulating mats in my garage and will use on top of the generator as he showed. Thanks for the link, BOB!!!

bobndot
Explorer II
Explorer II
I think so too.

Stinger Roadkill heat resistant foam mats. This owner tested his mod using a meter to record the difference in sound. With pics of the ONAN installation project.

https://www.classbforum.com/forums/f5/making-an-onan-quiet-generator-quieter-9229.html

jdc1
Explorer II
Explorer II
The noise is mostly coming from the mechanical end....not the exhaust. Auto interior sound mats are your best bet. Peel and stick......put them where ever you can reach. Works great on hotrods.

VA-Apraisr
Explorer II
Explorer II
Haha.....like that answer!! Yes, mine has never really been a noise maker, but my buddy was telling me it might help. YouTube results didn't show any noticeable successes. Thanks all!

bobndot
Explorer II
Explorer II
New Onan's are pretty quiet. When I am inside my rv, I totally forget i have it on. If it's bothering someone parked next to me, they are parked too close.

YC_1
Nomad
Nomad
A genturi will help redirect the sound and the fumes of course but there is little you can do to make a 4K quiet. At least I tried many times and with only marginal success. Most of the noise is the rattling insides and the intake fans.

Good luck and I will follow along since someone may have found a real answer.
H/R Endeavor 2008
Ford F150 toad >Full Timers
Certified Senior Electronic Technician, Telecommunications Engineer, Telecommunications repair Service Center Owner, Original owner HR 2008

gbopp
Explorer
Explorer
Search Youtube for 'How to make a generator quieter.'
There are videos about attaching a second muffler to generators.