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Onan 15kw help


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  #21  
Old 03-10-2017, 02:09:26 AM
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Default Re: Onan 15kw help

The ice cream trucks that used 10-15 kw generators were the ones that sold SOFT SERVE ice cream. I remember them as a kid in the early 60's
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  #22  
Old 03-10-2017, 08:20:41 AM
stretch67 stretch67 is offline
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Default Re: Onan 15kw help

Turn the VAC U Flow cooling duct down to vent out of the bottom of the truck.

The Car Audio people have some pretty good sound insulating materials.

Attention to detail on sound attenuation is key.

Even a 5 DB reduction is huge difference.

The JC is a great unit, and with proper care will last long time.
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  #23  
Old 03-10-2017, 08:22:24 AM
Max Thompson Max Thompson is offline
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Default Re: Onan 15kw help

My first question is; what does it have for a muffler now?

Not relevant to the noise, but I wonder if there is a flex section in the piping to the manifold.

As was stated earlier, a JC is relatively noisy, but in your situation with proper insulation and a "good" (good can = expensive) muffler they can be quieted considerably.

Second question; how much generator do you need? What are your electrical loads?
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  #24  
Old 03-10-2017, 09:31:17 AM
kosmo101 kosmo101 is offline
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Default Re: Onan 15kw help

i actually thought it was overkill too. The ones up north have 18 or 22kw units. amazingly huge. For one soft serve machine 208-230v but two separate cords. The machines are basically two in one. So double the power needs. recommended on three phase to have 19amp and 17 amp . I may switch this machine to another I have which seems to need less power.

Then we have a shaved ice machine..not sure of the power needs on that. Ac unit sucks a ton of power. One light, one fridge, small freezer and shake machine.

Im going to test this weekend to see what my needs really are. More power cant hurt but there has to be a money aspect to this as im not looking to spend an unlimited amount of money.

I will trace out from the manifold to the end pipe to see what is going on. i cant tell just yet if its the engine itself being loud or the muffler/exhaust is an issue. Again it sure sounds like there is no muffler on it..that loud. it sounds like my 6500 unit with no muffler but much louder. Guess it would help if i had another one to judge against.

I assume it is the normal/stock muffler. Is there one i could swap to in order to try to get it quieter.

with the unit in the back of a truck, vents on both sides and the top on one side, how would insulating really help? we can pull the rear door down to keep the sound a bit muffled but when i tried that it sure was still amazingly loud. Maybe even worse as it echoed inside this area? Will snap photos...

thanks!
kevin

So in looking at similar units.. it appears the exhaust manifold is out of the back of the unit but shoots up...is that correct? Meaning venting vertically past the top of the unit? Wondering how mine ended up under the truck.. very tough to get in this compartment to see behind the unit.
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  #25  
Old 03-10-2017, 09:41:34 AM
Wayne 440 Wayne 440 is offline
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Default Re: Onan 15kw help

Quote:
Originally Posted by BigBlockChev View Post
The majority of the noise is not from the muffler it is from the engine. Don't expect it to get much quieter by just changing the muffler. It is a vacuflow cooling system so you will need to properly connect the discharge on the front of the engine to the outside air and also provide some inlet airflow louvers, don't make them too small. The key to noise reduction is to seal up the generator compartment except for a baffled inlet and outlet. Lining the generator compartment with sound deadening material will help somewhat as well. It is possible to quiet down an aircooled JC but it won't be easy unless you have very good attention to detail, sound will leak out everywhere it can through little holes. Cheers Dan

The above advice is how it is done. All vents, openings, etc. must be baffled, i.e. no direct line of sight to the outside. Single layer sheet metal portions of the enclosure can "retransmit" or reverberate sound, apply sound deadening material to same. Doors and covers should seal tightly. If possible direct vents away from occupied areas, straight up is a common choice in stationary applications.

Quote:
Originally Posted by kosmo101 View Post
...So in looking at similar units.. it appears the exhaust manifold is out of the back of the unit but shoots up...is that correct? Meaning venting vertically past the top of the unit? Wondering how mine ended up under the truck.. very tough to get in this compartment to see behind the unit.
I covered that possibility earlier--

Quote:
Originally Posted by Wayne 440 View Post
The exhaust manifold can be turned to point the outlet down, and then all that is needed is a hole in the air shroud for the pipe exit. I have seen some that looked like they beat the hole out with a hammer and cold chisel.
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  #26  
Old 03-10-2017, 11:32:00 AM
Max Thompson Max Thompson is offline
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Default Re: Onan 15kw help

From the equipment you listed, the starting power requirements could be quite high.

There was not a "stock" muffler per sae. Mufflers were an option and different ones available for different requirements. Most anything of the proper inlet & outlet size (1 1/2" ips inlet on most), that you can fit under the truck will work.

You may as well start devising a plan to remove the set from the truck. Sooner or later it will have to come out. With all lines and exhaust disconnected (the exhaust will likely have to be sawn off where it goes through the floor) it can likely be slid out onto a platform of concrete blocks & a piece of plywood. A sheet of 1/8" steel sheet on top of the plywood would make it slide much easier. You could possibly raise it up and get some 3/8" rod or 1/2" pipe under the mounting rails and roll it out. Probably in the #700 neighborhood. If you have access to a "lift table" or motor cycle lift it could be pretty easy to remove.
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  #27  
Old 03-10-2017, 11:38:31 AM
kosmo101 kosmo101 is offline
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Default Re: Onan 15kw help

Why do you say to start thinking of it coming out? Maintenance? just curious your thoughts.
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  #28  
Old 03-10-2017, 12:16:09 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 15kw help

Quote:
Originally Posted by kosmo101 View Post
Why do you say to start thinking of it coming out? Maintenance? just curious your thoughts.
Maintenance yes.

The starter is mounted on the back side. It will be very difficult to adjust the rocker arms or get inside the control box with the limited space over the unit.

If you do any insulating (sound deadening) to the compartment, you will have to get to the back side.

If I were going to rely on this set to run my business and keep several $ worth of product from being lost, I would pull it out and give it a through going through Before I put the truck into service.

Removing it (with the right equipment) would not be a big job. Though I may not be a very good judge of the degree of difficulty. Having 9 JCs floating around the place, I am pretty adapt at moving them around and up & down.
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  #29  
Old 03-10-2017, 12:20:10 PM
kosmo101 kosmo101 is offline
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Default Re: Onan 15kw help

understood. as you mention, that is why i am considering maybe pulling it out as well. if it doesnt work when we get to an event, im dead. im used to smaller honda units so no idea how reliable these are. checking out the quiet diesels and also a yanmar unit. A bit out of my element on the reliability of such makes.

I was going to ask to borrow a neighboring shops forklift to remove or maybe use a engine hoist. I also need to possibly remove the soft serve machine from inside.. that should be fun.

happen to have a good unit for sale ? figured since you had nine units.. it may be worthwhile to ask!
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  #30  
Old 03-10-2017, 12:54:47 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 15kw help

Quote:
Originally Posted by kosmo101 View Post

how reliable these are.

I was going to ask to borrow a neighboring shops forklift to remove or maybe use a engine hoist. .

happen to have a good unit for sale ? figured since you had nine units.. it may be worthwhile to ask!
When properly maintained, the J series are very reliable and will outlast most of us here.

A fork lift should make short work of removing the set from the truck.

Not saying they could not be bought, but none advertised for sale (we do not buy and sell on this board).

You may have a great generator right now, give it a chance. If I did not think they were great sets, I would not bother accumulating them.
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  #31  
Old 03-11-2017, 11:01:17 AM
Jim Marcozzi Jim Marcozzi is offline
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Default Re: Onan 15kw help

This compartment lacks sound deadening material. We use a 1.5" thick hi-temp closed cell foam/fiberglass material with a silver metallic backing to reflect the heat. Put it all over the walls and doors. Seal it tight- especially the truck side of the box.

MY favorite muffler that I use for 20KW< mobile generators is from a late 80s Toyota Tercel.

And that exhaust plumbing is too small and needs heat shields and/or exhaust wrap. The wiring harness also needs moved away from the exhaust and covered with a heat shield. Make sure the exhaust is an inch out beyond the body, angled down 45 degrees to avoid anyone getting burned by hot exhaust that near the truck. AND INSTALL A GOOD CO DETECTOR INSIDE OF THE TRUCK! This is important.

The vacu-flow exhaust is a disaster. Rotate the blower snail 180 degrees and exit the cooling exhaust downward. I prefer to blow the cooling system's exhaust directly over the muffler to aid in cooling of the muffler when stationary.
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  #32  
Old 03-11-2017, 11:21:13 AM
Vanman Vanman is offline
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Default Re: Onan 15kw help

The only problem I have found with cooling air exhaust pointing straight down is the huge, billowing clouds of dust that it makes whenever the vehicle is moved over any surface that is not clean.

I'd make it sideways or straight up, of course the latter would require some means of keeping rain out when the set is not running.

Keith
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  #33  
Old 03-11-2017, 11:32:06 AM
LRomero LRomero is offline
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Default Re: Onan 15kw help

Under also turns the vehicle into a resonator. If the gen is opposite side of the customer serving side, then route all exhaust straight out the front side of the compartment. This will keep the sound from bouncing around under the vehicle and also contend with the dust cloud as previously mentioned.
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  #34  
Old 03-11-2017, 11:48:49 AM
kosmo101 kosmo101 is offline
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Default Re: Onan 15kw help

Here is a video of it running. Battery was dead.

https://youtu.be/MUNp0Oo5A2I

I think I'm going to just pull it..
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  #35  
Old 03-11-2017, 12:14:17 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 15kw help

Sounds like it has no muffler. Take a mirror and check on the back side, but if it is not under the truck, I doubt it has one.
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  #36  
Old 03-11-2017, 12:17:26 PM
kosmo101 kosmo101 is offline
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Default Re: Onan 15kw help

I dont know much about the reliability so really a bit apprensive using it for the year with a business. its so filthy dirty and done ass backwards that i would want to get into this compartment to clean, and redo it.

Im not understanding the terms you are using...VAC U Flow cooling duct ? I assume this is the type of system on my gen but what does it mean exactly? As I see the exhaust manifold is at the rear of the unit as it sits and must be turned downwards. If it was vented straight up out the roof, would the noise be lessened?

it sure seems the noise is the engine itself almost.. just a big unit..loud. not sure replumbing, sound deadening or a different muffler would even matter.

Maybe i need to look into a quiet diesel unit or water cooled?

Problem is ive never heard one run that was 100% reliable and ready to go so as to compare it to something. It sounds like a raspy motorcycle when it runs.. so loud .

thanks

It does have a muffler as i had the same thought. i traced that pipe going through the floor under the truck and it is there. i even felt around the exhaust pipe and there is exhaust coming out... maybe a hole in one of the pipes off the manifold. i gotta get in there to see. We may just unbolt and pull it out to see it in an area where we can get around the whole unit.

Just doesnt sound/run well to me even aside from the loudness... shoudl purr.....
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  #37  
Old 03-11-2017, 12:36:00 PM
Jim Marcozzi Jim Marcozzi is offline
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Default Re: Onan 15kw help

I've never seen the "dust cloud" thing for more than a few seconds after starting the generator. Once the dust below blows, it's gone.

The unit sounds like there's no muffler or a serious leak. MY JC12.5K was quiet. So quiet that you could almost not hear it running when 50' away.
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  #38  
Old 03-11-2017, 12:58:36 PM
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Default Re: Onan 15kw help

I would imagine a soft serve machine or 2 taking liquid to freezing has to move a lot more btu

than just keeping something cold
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  #39  
Old 03-11-2017, 01:02:08 PM
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Default Re: Onan 15kw help

If you watch where the exhaust pipe comes out under the engine. On startup you can see the smoke coming out. So I would say broken exhaust pipe. The Vac U Flow system is the big blower on the front of the engine. It should not be reduced to the size that it is. Should be the same size at the exhaust duct. If pointed down it will move some dirt. Most I worked on came out sideways.
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Old 03-11-2017, 01:41:46 PM
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Default Re: Onan 15kw help

Listen to it cranking! Sounds like one cylinder with little compression, leaking out of the exhaust valve. Also agree that it sounds like a broken exhaust pipe.

If the vehicle is stationary when the set is started, then yes, the dust cloud from a downward pointing cooling air discharge is short lived. But if it's running when you pull off the road? Whoa. DUST!!! At the very least, if stuck with downward air discharge, I would fit it with a 90 degree elbow of equal cross section to that of the outlet, and make it, ideally, blow out of the side of the vehicle.

If I were installing one I'd have vertical exhaust (partially because I think rain flappers are cool lol ) and also because that will be the quietest. And you and your customers are least likely to smell it. I'd also have vertical cooling air discharge with it's own flapper, well placed and baffled fresh air inlet, and full coverage of every and all interior surfaces with the sound deadening materials mentioned earlier. With that you could stand right next to it and have a normal conversation.

No matter what generator set you might install, it will generally require this kind of attention to installation detail if you want it to be quiet.

But first you need to figure out which cylinder has low compression and why.

Keith
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