Any way to make a MicroQuiet 4k quiet?

[DutchmenSport]

I saw a YouTube video some time ago where some guy put a car muffler on his very noisy generator. It did quiet it down to almost no noise at all.

Well, if you can figure out a way to attach a car muffler to your generator, there's your answer.

Actually, the solution IS the type and quality of muffler you have.

[Bobby F]

My dad had an old construction genny that he used during power failures at the house. I rigged up two car mufflers in series to try to quiet it down.

It cut the exhaust noise way back, but the noise that poured off of the engine itself was still just as loud, and so it didn't ultimately do much good. Eventually had to make a foam box with baffled air inlets, and that did the trick.

[tap4154]

Originally Posted by DutchmenSpor

I saw a YouTube video some time ago where some guy put a car muffler on his very noisy generator. It did quiet it down to almost no noise at all.

Well, if you can figure out a way to attach a car muffler to your generator, there's your answer.

Actually, the solution IS the type and quality of muffler you have.

With this 4K Onan, I really don't hear that much exhaust noise. It has the internal muffler then the exhaust pipe itself runs forward 2 feet, and then out about 2 ft so it's pretty long. I put a galvanized elbow on it to divert it down just to see if it made a difference, and it's exactly the same. Majority of the noise, on mine at least, is coming from the air Inlet and cooling exhaust. Also from vibration, before I got it somewhat isolated from the cantilever arms with the shock absorber bushings.. Now that I just have the bushings just snugged, it really made a difference. I really can't even feel vibration in the floor like I used to. I also had the exhaust hanger clamp that was making contact with the frame, but that's fixed now.

Actually I'd been thinking about getting a motorcycle muffler, and adapting it so it could be put on when I camp, then taken off. But I don't think I'm going to bother. I did order some foam egg-crate type fireproof sound insulation that I'm going to stuff on top of the unit, and to try to finish closing off the left side of it. But seriously, it's acceptable right now, just with what I've done.

[Joyce M]

Some years back I built my own exhaust extended pipe out of PVC..It did show me the exhaust sound is minimal..The loudest came from the engine and the built in cooling blower thingy.....I would not waste any $$$ on the Camco pipe...

[NeilV]

Originally Posted by tap4154

I've seen that before and wasn't sure how it worked, now I get it. It's something you carry with you and then put it on when you camp. I thought it was a permanent deal that you put on.

Have you used it on the Onan 4000?

Only the pipe adapter stays permanently attached to the generators tail pipe while the elbow and stack pipe need to be stowed away for travel. Many will just use the included bungee cord to hang the stack pipe from the ladder or use the suction cup mounts. It only helps though with exhaust noise and not the mechanical noise and vibration from the generators moving parts. Biggest benefit from the Genturi is keeping carbon monoxide from building up under the coach and help prevent it from getting inside. I traveled with 2 dogs and a cat so whenever stopped for extended periods of time I would put up the Genturi so when the air conditioning started the generator, exhaust gas would not build up inside the coach.

[NeilV]

Originally Posted by tap4154

When I say "compartment", when referring to mine, I just mean it has a door. There is no compartment, it's wide open underneath with just two cantilever arms that the generator was mounted on, with no dampening at all. There were no back or sides enclosing the generator, other than its own housing.

So when I put some sound dampening material along the back and right side of the housing, then extended some on the left and right side to kind of create a compartment, also using some foam to close in the top and right side, I sort of created a compartment for it, but it is not restricted at all as far as cooling air flow. It's still wide open underneath.

The rubber bushings, that I have on the top and bottom of the cantilever arms, are not compressed completely. I put threadlocker on the bolts and just snugged them. The bolts extend up about an inch into the generator itself, so I can occasionally check to see if they're coming loose, but I believe the medium blue threadlocker should hold them fine.

The Onan 4000 runs at the same RPM no matter what load is on it. It drops RPM briefly when you turn on the A/C or microwave, then returns to the same high RPM. I also just replaced the flexible exhaust hangers, and nothing else connected to it is stiff or inflexible.

I absolutely agree that a V-Twin that runs at lower RPM, and especially an inverter generator, would be the way to go, but in my little 28 foot Class C, I can live with this as it is now, and frankly I don't need to run the generator that often anyway.

Or maybe I should just join up with you, so I can plug into your generator

Even with an open bottom its a generator compartment which you need to be careful about blocking especially with the way the Casing on the 4000 has cooling vents on both the side and the bottom. The Casing on the 5500 has all its cooling vents on the bottom and is insulated on the 5 other sides having a solid access door panel. On the 5500 if you leave the generator casing/housing access panel off you will actually cause the generator to run hotter and potentially overheat it.

[tap4154]

Originally Posted by NeilV

Even with an open bottom its a generator compartment which you need to be careful about blocking especially with the way the Casing on the 4000 has cooling vents on both the side and the bottom. The Casing on the 5500 has all its cooling vents on the bottom and is insulated on the 5 other sides having a solid access door panel. On the 5500 if you leave the generator casing/housing access panel off you will actually cause the generator to run hotter and potentially overheat it.

Actually the only opening in the casing of the 4000 is on the left front where the air Inlet is. The left, right, top and back are solid. I agree it would overheat if operating without the housing or access door because the cooling air will just disperse, and not cool down the engine. The only opening on the bottom is the area on the right side where the cooling air escapes, and I didn't block that in any way.

[CharlesinGA]

Originally Posted by tap4154

Actually I'd been thinking about getting a motorcycle muffler, and adapting it so it could be put on when I camp, then taken off. But I don't think I'm going to bother.

I think that a muffler you install and remove it a bad plan. There is so much to remember now on setting up and breaking camp now, awnings, TV antennas, shore power cords, lawn chairs, chocks, etc, that adding something unusual like a muffler sticking out is asking for trouble. Kinda like the people who drive off with the awning extended.

Here is a review from Amazon of the Onan resonator with pics of the temporary installation, the guy has an Airstream van conversion and this is what he is doing, attaching and removing it..........

https://www.amazon.com/gp/customer-r...SIN=B00TQXXPUY

Charles

[appsptspcl]

I use an Onan 4000.....and use suction the cups for mounting. No permanate mounting problems.

[tap4154]

Originally Posted by CharlesinGA

I think that a muffler you install and remove it a bad plan. There is so much to remember now on setting up and breaking camp now, awnings, TV antennas, shore power cords, lawn chairs, chocks, etc, that adding something unusual like a muffler sticking out is asking for trouble. Kinda like the people who drive off with the awning extended.

Here is a review from Amazon of the Onan resonator with pics of the temporary installation, the guy has an Airstream van conversion and this is what he is doing, attaching and removing it..........

https://www.amazon.com/gp/customer-r...SIN=B00TQXXPUY

Charles

I appreciate the information Charles, one thing though is that it would be right on the driver side so as soon as I opened the door to drive away I would see it.

But seriously, it's really quiet enough right now. Before it was very harsh and clanky, and now it's down to just a high RPM hum. It is substantially better.

Many of the muffler reviewers say that it didn't make any difference at all, and a lot of them say it made a big difference. I think because mine has such a long exhaust pipe after the internal muffler, with two 90 degree bends, that helps cut down the exhaust noise. If the pipe came straight out to the side from the internal muffler that would be quite a different thing. It would only be about 2 ft long with one bend. In that case the second muffler would be more effective I think.