A quieter muffler for Onan 4400?

Mr Brian · 03-03-2021, 09:51 PM

Though I plan on asking my Onan authorized tech for his formal advice next time we’re in to service the Onan 4400 generator on our 2020 Forester 3011 DS, I wondered if anyone here has modified, updated or substituted the muffler on their similar generator for something that is at least a little quieter?

Mr. Brian

Mr Brian · 03-03-2021, 09:52 PM

Oops. Autocomplete botched the title - and delete is not an option.

BehindBars · 03-03-2021, 10:50 PM

That’s a good question. I would like that the Onan generator be a little quieter, but I have to wonder if exhaust noise is the primary noise. Could a lot of the noise be mechanical, or vibrations from the way it is housed or mounted? You may install a quieter muffler and find that much of the noise is still there.

Let us know what you find out.

Sergiop · 03-04-2021, 12:48 AM

What if you slip a long pipe over the exhaust to see if it gets quieter? Or if you have a 200cc dirt bike that you could take the muffler off it to try on the generator.

I think BehindBars is right, vibrations or other generator sounds might be part of the problem too.

Try something in between the generator and the rv floor right above it? Some kind of sound insulation?

Canadian Eh · 03-04-2021, 12:58 AM

I thought about putting an extension on the existing pipe and run it into a 5 gallon bucket of water. The idea is to replicate a boat exhaust.

kenandterry · 03-04-2021, 03:48 PM

Quote:

Originally Posted by Canadian Eh

I thought about putting an extension on the existing pipe and run it into a 5 gallon bucket of water. The idea is to replicate a boat exhaust.

I don’t see that working at all.
I think you’re just blowing bubbles.

Canadian Eh · 03-04-2021, 04:10 PM

Quote:

Originally Posted by kenandterry

I don’t see that working at all.
I think you’re just blowing bubbles.

The principal comes from boat exhaust, you want to make it loud you open the cutouts and let the exhaust straight out. To quiet the exhaust the cutouts are closed exhaust is pushed through water.

**Mr. Dan** · 03-04-2021, 04:46 PM

Quote:

Originally Posted by Mr Brian

Oops. Autocomplete botched the title - and delete is not an option.

So your autocomplete replaced Onan with "Onanistic"? Wow! What you you want it to be?

BM Welder · 03-04-2021, 05:08 PM

When I had my Jayco Designer I mounted the generator on rubber mounts it was very quiet and very little vibration in the trailer.

Duckogram · 03-05-2021, 07:37 PM

Take a look at a “Gen-turi”...
https://youtu.be/uBPDpMHVWVg

emm-dee · 03-05-2021, 11:36 PM

Quote:

Originally Posted by Duckogram

Take a look at a “Gen-turi”...
https://youtu.be/uBPDpMHVWVg

I have a complete, never used GenTuri system laying around in the barn. Anyone who wants it can have it. You just have to come get it. Located out east of Covingtion, GA

Kirk S · 03-06-2021, 11:34 PM

FYI, Onan discourages the use of Genturi type add ons. I don't understand why.
That being said, Onan previously offered a resonator for their generators and I added one to mine but that was 30 years ago.
The only sound you could hear afterward was the intake air. It was nice.

Mr Brian · 03-22-2021, 07:59 PM

Quote:

Originally Posted by BehindBars

...I have to wonder if exhaust noise is the primary noise. Could a lot of the noise be mechanical, or vibrations from the way it is housed or mounted?

Sorry for the delayed reply.

My thanks to all in this thread for thoughtful advice. I agree that much of what I hear / sense is likely mechanical or vibration, but thought the exhaust would the simplest place to start.

I have yet to talk to my Onan technician, but did find several videos from those who chose to install an Onan-sourced accessory resonator:

...as one might imagine, the results are largely subjective, and difficult to determine as a viewer due to the source microphone and lack of a decibel meter, etc. While some db meters are used in other videos, they are often of other generator/resonator combos. I'm therefore still on the fence about the Onan-sourced accessory resonator - or similar items, until I speak to the technician and learn of his experience.

While I appreciate the mention of the Genturi Exhaust system by Duckogram and others, I'm not anticipating heading that direction at the moment.

As I wait until my next encounter with the Onan tech, I will admit to be intrigued by BM Welder's mention of the rubber mounts on his Jayco's generator (pictures welcome!), as well as others who have installed something (more than just applying additional spray insulation) that is genuinely helpful without detrimentally diminishing airflow or increasing fire danger concerns.

Again, sorry for the delay - and thank you all!

Canadian Eh · 03-22-2021, 08:45 PM

Had a look in today, not much clearance between the top of the gen and the enclosure. You could slip a small rubber bushing between the gen and the frame but it would have to be pretty thin to fit.

nvs4602 · 03-22-2021, 10:25 PM

Quote:

Originally Posted by Mr Brian

Sorry for the delayed reply.

My thanks to all in this thread for thoughtful advice. I agree that much of what I hear / sense is likely mechanical or vibration, but thought the exhaust would the simplest place to start.

I have yet to talk to my Onan technician, but did find several videos from those who chose to install an Onan-sourced accessory resonator:

...as one might imagine, the results are largely subjective, and difficult to determine as a viewer due to the source microphone and lack of a decibel meter, etc. While some db meters are used in other videos, they are often of other generator/resonator combos. I'm therefore still on the fence about the Onan-sourced accessory resonator - or similar items, until I speak to the technician and learn of his experience.

While I appreciate the mention of the Genturi Exhaust system by Duckogram and others, I'm not anticipating heading that direction at the moment.

As I wait until my next encounter with the Onan tech, I will admit to be intrigued by BM Welder's mention of the rubber mounts on his Jayco's generator (pictures welcome!), as well as others who have installed something (more than just applying additional spray insulation) that is genuinely helpful without detrimentally diminishing airflow or increasing fire danger concerns.

Again, sorry for the delay - and thank you all!

You can download a decibel meter app for your phone. They work pretty good.

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