rotory@earthlink.net
Gone Traveling
Making an Onan Quiet Generator Quieter - Mike Mas
Hello - I thought I would share one of my recent projects - For the most part the “Q” Onan generators which stands for “Quiet” have very respectable noise levels today, since unlike earlier generators which had thin steel cases with no insulation, modern generators use composite cases and some insulation.
Onan generator noise levels can be easily reduced further if Onan would add a throttle/ load speed control, so instead of running near wide open all the time, they could just idle when not under heavy loads somewhat like a Honda generator. Instead Onan runs their engine almost at full rpm even with no loads at all, which wastes fuel and adds extra noise.
For the most part - I find both my Onan 3600 LP generator on my Leisure and my Onan 2500 LP on my Sprinter very quiet. Even though the noise levels are respectable, I figured if I can spend a few hours and make it quieter, it would be an improvement.
Fortunately, I ended up with half a box of Road Kill from my last project, so I decided to use it on my genny to reduce its noise level further. If you’re not up to speed on Road Kill;
https://stingerelectronics.com/catalog/sound-damping-roadkill/
It's an amazing product which I use on aircraft, cars, trucks motorcycles, etc. which consists of a layer of thick composite type rubber which is foil backed on one side and sticky on the other, so you can apply it to almost anything and its heat resistant as well. For vans with generators side mounted or under belly, you can add this to the generator box or even the undersides of the floor to help deaden noise, let me tell you, this stuff works!
On my Leisure Wonder the generator is very quiet already thanks to the fact its mounted behind a thick fiberglass door and the exhaust exits on rear drivers side, but since the generator is on the "Patio" side, I wanted it as quiet as possible.
Before I began the project, I first wanted to record the sound level on my iPhone DB meter. As I opened the app, I registered 56 DB in general noise with everything shut down. Next, I started the generator and stood back 6 feet and registered around 79-80 DB, which is very quiet for a generator when considering a vans diesel engine registers about the same noise level.
To begin the project on my coach - I decided to first cover my Leisure’s generator door with Road kill since some noise was passing through the door itself. On this coach the door is fiberglass which deadens the noise somewhat, however many coaches use a thin aluminum door which will actually amplify noise from the generator, this is where you'll see an amazing difference.
Next, I removed the generators inspections panel and and added some Roadkill to the areas the that were not covered from the factory to kill so noise.
To keep the noise from spreading to the right and left of the generator, I added a few pieces to the right and left side panels of the generator housing box to deaden some of the noise.
After I completed all my stick-on RoadKill applications, I noticed there was a void on top of the generator between the coaches floor, so I cut some non-sticky double sided foil backed insulation material we had in the shop from a roll, then slide it on top of the generator and held it in place with some foil tape. This will help deaden noise from reaching the floor of the coach.
After I wrapped the job up, I moved the coach back outside and started the generator again. With a full load, I noted a major difference of 5 DB less noise for a reading of only 75 db, which is now no louder than a Powerstroke or Sprinter diesel engine running at 1500 rpm, therefore making the project well worth the time that it required.
Regards - Mike
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Hello - I thought I would share one of my recent projects - For the most part the “Q” Onan generators which stands for “Quiet” have very respectable noise levels today, since unlike earlier generators which had thin steel cases with no insulation, modern generators use composite cases and some insulation.
Onan generator noise levels can be easily reduced further if Onan would add a throttle/ load speed control, so instead of running near wide open all the time, they could just idle when not under heavy loads somewhat like a Honda generator. Instead Onan runs their engine almost at full rpm even with no loads at all, which wastes fuel and adds extra noise.
For the most part - I find both my Onan 3600 LP generator on my Leisure and my Onan 2500 LP on my Sprinter very quiet. Even though the noise levels are respectable, I figured if I can spend a few hours and make it quieter, it would be an improvement.
Fortunately, I ended up with half a box of Road Kill from my last project, so I decided to use it on my genny to reduce its noise level further. If you’re not up to speed on Road Kill;
https://stingerelectronics.com/catalog/sound-damping-roadkill/
It's an amazing product which I use on aircraft, cars, trucks motorcycles, etc. which consists of a layer of thick composite type rubber which is foil backed on one side and sticky on the other, so you can apply it to almost anything and its heat resistant as well. For vans with generators side mounted or under belly, you can add this to the generator box or even the undersides of the floor to help deaden noise, let me tell you, this stuff works!

On my Leisure Wonder the generator is very quiet already thanks to the fact its mounted behind a thick fiberglass door and the exhaust exits on rear drivers side, but since the generator is on the "Patio" side, I wanted it as quiet as possible.
Before I began the project, I first wanted to record the sound level on my iPhone DB meter. As I opened the app, I registered 56 DB in general noise with everything shut down. Next, I started the generator and stood back 6 feet and registered around 79-80 DB, which is very quiet for a generator when considering a vans diesel engine registers about the same noise level.
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To begin the project on my coach - I decided to first cover my Leisure’s generator door with Road kill since some noise was passing through the door itself. On this coach the door is fiberglass which deadens the noise somewhat, however many coaches use a thin aluminum door which will actually amplify noise from the generator, this is where you'll see an amazing difference.
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Next, I removed the generators inspections panel and and added some Roadkill to the areas the that were not covered from the factory to kill so noise.

To keep the noise from spreading to the right and left of the generator, I added a few pieces to the right and left side panels of the generator housing box to deaden some of the noise.

After I completed all my stick-on RoadKill applications, I noticed there was a void on top of the generator between the coaches floor, so I cut some non-sticky double sided foil backed insulation material we had in the shop from a roll, then slide it on top of the generator and held it in place with some foil tape. This will help deaden noise from reaching the floor of the coach.

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After I wrapped the job up, I moved the coach back outside and started the generator again. With a full load, I noted a major difference of 5 DB less noise for a reading of only 75 db, which is now no louder than a Powerstroke or Sprinter diesel engine running at 1500 rpm, therefore making the project well worth the time that it required.
Regards - Mike
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