Any way to make a MicroQuiet 4k quiet?

[tap4154]

Has anyone come up with any easy solutions to actually make a "microquiet" 4K generator quiet?

It seems like the noise just reflects all over the place, and I even hear it from the right side of the coach up through the battery box under the steps, as much as anything.

The unit is mounted just behind the driver's side door in my class C.

[ga traveler]

Microquiet is actually quiet. I was a factory trained tech on Onan. It sounds like you have a bad installation. First check the generator for rubbing against the coach. If it is clear, next install some sound proofing all around generator on all the metal and wooden panels.
Summit is a good place to find sound proofing.

[tap4154]

Originally Posted by ga traveler

Microquiet is actually quiet. I was a factory trained tech on Onan. It sounds like you have a bad installation. First check the generator for rubbing against the coach. If it is clear, next install some sound proofing all around generator on all the metal and wooden panels.
Summit is a good place to find sound proofing.

Thank you for the quick response. Maybe mine is not the microquiet, but it's an Onan 4K. There isn't any soundproofing around it at all. Just inside the front panel there's a little bit of soundproofing.

[tap4154]

I guess quiet is in the ear of the beholder. I just would like to make it quieter. I ordered some Noico sound deadening material from Amazon. Just curious though, looking underneath there's two large Torx head screws with rubber grommets, and both of the grommets are loose. I haven't tried tightening anything yet because I'm not sure what those actually do. But it seems like the rubber should have tension on it.

By the way the picture uploaded upside down.

[tap4154]

I think I just found why I'm getting so much vibration and noise from the generator in the motorhome. The insulated hanger bracket on the exhaust is touching the U-bolt that protects it. The rubber hangers are also very rotted, so I'm going to have to replace those too, but I'm pretty sure this bracket clamp touching that big U bolt is the reason I'm getting all the vibration.

I'll take that U bolt off tomorrow and run it and see what happens. In fact I could turn it around and that would give it some room between the bracket and U bolt.

[sibe]

seacr on this, I posted a lot of info as did others,, Mine is the older, 1996 verssion, well 1998 LOL, i changed one out,,
Mine sits under the rear bedroom.... I have added the exhaust silencer and a bit more pipe, this does help about 1.5 db... not alot but the note changes..

Inside on left of the door, is a block of foam, make sure it sets properly or is even there, that helps muffle the air cleaner intake noise.. it is another minor reduction but all adds up.
the rubber bushing that motor sits in help also to keep new or I have shimmed mine to tighten up...

Now for the most of the noise.. It is the AIR COOLING noise that reflects and echos under the RV and off the ground.. This is the racquet most hear...

I have used auto/van self adhering sound deadner all under my rear compartment.. I have added that foam honeycomb stuff/ eggcrate look foam.. on the RV Door, and on some areas close to Genny sides..

Again mine is very open under bed, can we say ECHO...

I also had an old one of those rear horse tail brushes that hand off rear bumber.. that drowns noise from rear.. I was going to hang one or a partial mid way frt to rear to block some noise. never did it.. I tested that theory with a 30 inch by 5 ft foam board I wedged there... Noise from oppiste side was way down..

Some say toss an old quilt/or dense material under the genny as the sound echos off concrete or hard ground...

My noise averages around 62-64 db at around 15-20 ft.. it is near 42-46 at frt of RV and oposite side is 50-54... depends on where I park and what ground is like ...

[Myrons31]

The noise is from the unit. Some surrounds around the three sides and application of some sound deadening should help. I'd say it works but I have not done it. Others have had success from what I have read. I have just grown used to the sound and I usually only run it when the race cars are on track to charge my batteries for the night, so their lovely sound always drowns it out.....

Also, as mentioned, where you are parked can also be an issue. The sound reflects really well off concrete and stone. I notice the sound more when I have the unit at home on the driveway rather than on a grass site at the track....

The vibration in the coach is from the unit "most likely" being mounted directly to the floor of the coach and likely not from the exhaust touching the u bolt. There is usually no dampening between that rack that holds the generator to the floor, so any movement of the gennie just goes right into the house floor. Damaged motor mounts, there are 4 of them, may also be helping with the vibration possibly. I think I have one bad one and just have not dropped it to change out all four.

Also. Tighten those two large bolts on the bottom of the unit. I think they are there to dampen the large movement of the generator on start up. The rubber portions on mine were actually missing when I bought it. Remove them and then fire the generator up and you will see what I mean. That thing jumps all over.

[jjrbus]

I am sensitive to noise and find RV AC and Onan horrible things. They duct the AC output and leave the motor, fan and compressor open to the living area!


Any generator can be quieted down depending on how much effort and money you are willing to put into it. I have done it twice, there is no one size fits all simple do this or that answer.



Best thing to do is Google sound proof generator, quiet generator, sound proof RV or boat generator something along those lines and find what is available and what best fits your situation.



I use a Honda 2000 in a sound deadening box, works for me.

[ga traveler]

Originally Posted by tap4154

I think I just found why I'm getting so much vibration and noise from the generator in the motorhome. The insulated hanger bracket on the exhaust is touching the U-bolt that protects it. The rubber hangers are also very rotted, so I'm going to have to replace those too, but I'm pretty sure this bracket clamp touching that big U bolt is the reason I'm getting all the vibration.

I'll take that U bolt off tomorrow and run it and see what happens. In fact I could turn it around and that would give it some room between the bracket and U bolt.

That is exactly what I thought you would find. Not the u bolt exactly, but something hitting the generator. The generator is sitting in the rubber grommets loosely. Their job is to absorb the vibration. There is nothing wrong with the grommets. Loosen the u bolt and slide the clamp about one inch toward the muffler and retighten. I think you will find a Hugh difference.

[tap4154]

Still early here so I'm not going to work on it yet because it's parked near a neighbor in my backyard. But I appreciate all the responses. I ordered a couple new hanger straps. I think those old ones being so old and hard are transmitting vibrations as well as that clamp up against the u-bolt. In fact the outer hanger I'm going to vibration-insulate it where it connects to the sidewall.

I'll try tightening up those two funny-looking Torx bolts too.

[avfordguy]

Lots of info here

https://www.irv2.com/forums/f87/loud-generator-415092.html

[avfordguy]

Do not tighten the motor mounts ( torx) it will make it worse

Originally Posted by tap4154

Still early here so I'm not going to work on it yet because it's parked near a neighbor in my backyard. But I appreciate all the responses. I ordered a couple new hanger straps. I think those old ones being so old and hard are transmitting vibrations as well as that clamp up against the u-bolt. In fact the outer hanger I'm going to vibration-insulate it where it connects to the sidewall.

I'll try tightening up those two funny-looking Torx bolts too.

[tap4154]

Originally Posted by avfordguy

Do not tighten the motor mounts ( torx) it will make it worse

Thanks, they actually didn't want to turn anyway so I didn't try to force them. I read that thread that you linked, that's interesting. It is a fact that most of the noise is coming down through the bottom. Mine is on the two cantilevers as well and I was also thinking about putting some kind of insulation board across underneath them.

I removed that U bolt and it didn't make any difference at all. I get 75db inside the motor home and a little over 80 outside. I took a piece of thick folded up piece of cardboard I was laying on and when I lift it up at an angle underneath the generator it really cuts down the noise.

I'm thinking some kind of collapsible rectangular bucket that could be put underneath it might be a solution in blocking sound both to the left and to the right. Maybe it could "catch" the noise?

Or even something that just flipped up on two sides to block noise to the left and the right, with some sound absorbing material on it. When folded down it would be easy to store.

To me it seems the worst noise is not coming from the exhaust, it's from the mechanical racket made by the engine itself.

[tap4154]

Just as a proof-of-concept I made up a little sound block out of my piece of cardboard. The sides don't fold up quite high enough yet, but it actually did knock off 2-3 dB inside the motorhome. I can see you definitely would not 4 sides though, because it would block the warm cooling air from escaping. I think this would be safe because it allows air in from the left to the intake, and the warm air from the right to escape.