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Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

New Proud Owner of an Onan JC


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  #41  
Old 10-12-2017, 07:23:07 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

OK, I've got her home and have done an initial inspection. This is what I've found so far. The original air filter was completely shot. Luckily it looks like nobody had started it in a long time so no debris was in the carburetor throat:


I did have two mouse nests. One in the compartment that houses the start/stop switch and charge meter. The regulator board compartment shows no signs of intrusion or damage. The other mouse nest was inside the air compartment that covers the distributor, coil and carburetor. The one in the meter panel did no real damage. One wire had a little chew marks and about 1/2" of missing insulation but nothing serious. The wire is white and goes to the remote start terminal block. The other did a little more damage but still nothing too serious. The condenser on the coil was a little rusty and there was some rust on the bottom of the panel.:


Some debris was in the cooling fins but that was easily vacuumed out. None of the wires inside were damaged at all. I removed the distributor cap and everything inside was super clean. Even the points looked like new.


I checked the oil again and it was full and virtually clear. I even scraped the bottom of the oil pan with a long screwdriver and found no sludge deposit of any kind.:
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  #42  
Old 10-12-2017, 07:27:39 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

I also pulled the cover to the 12 T wires and found them all in excellent shape and connected to what looked like 12/208 3 phase. That will have to change to 120/240 single phase but that should be no big deal as long as the wires are marked T1-T12. Crossing my fingers there.
There is one mystery hose that connected to the carburetor but no connection on the other side. If someone could tell me what this is and where the other end goes please:


I cleaned her up a little and this is what I have now:




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  #43  
Old 10-12-2017, 07:33:11 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

Here are some more pics:


It was a little hard putting her on the trailer but I did manage to do it by myself.:




This is the serial and model number of the transfer switch that came with it:


If anyone has documentation on this switch it would be greatly appreciated.
Well, that all for now. Next step is to prepare her for initial startup. Obviously a new air filter is in order.
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  #44  
Old 10-12-2017, 07:41:26 PM
Charley K Charley K is offline
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Default Re: New proud owner of a JC

LOL ( the condenser was a LITTLE BIT RUSTY). Just funning you, A very nice machine. I've been looking.....
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  #45  
Old 10-12-2017, 08:12:42 PM
reid070 reid070 is offline
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Default Re: New proud owner of a JC

There is one mystery hose that connected to the carburetor but no connection on the other side. If someone could tell me what this is and where the other end goes please:


That is the hose that would go to the crankcase breather. However according to the manual after spec t uses a pvc valve under the rocker box cover. So why you have it is a puzzle. Perhaps some parts swapping has gone on here. She looks in great shape ,you'll get it running great in no time I bet

Steve
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  #46  
Old 10-12-2017, 08:39:41 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: New proud owner of a JC

Nice find! You might want to pull the cover off the Gen. end and checl for mice damage as well unless you already did that. They seem to like it in there as well.
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  #47  
Old 10-12-2017, 09:15:56 PM
JohnnyC JohnnyC is offline
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Default Re: New proud owner of a JC

I am familiar with your transfer switch. I have the 30 amp version. I got the factory manuals, wiring diagrams and all here, but not in electronic format. Can you snap a picture of the inside showing the PC board where all the relays are located? The ATS will work with either 1 or 3 phase gensets and to configure it for 1 or 3 phase is super simple.

Also, I will bet you a beer that you missed one mouse condo, especially if they were in the control box and the other area you mentioned..
(Hint: See picture below)

JohnnyC
New Jersey
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  #48  
Old 10-12-2017, 10:03:24 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

Quote:
Originally Posted by nothingbutdarts View Post
Nice find! You might want to pull the cover off the Gen. end and checl for mice damage as well unless you already did that. They seem to like it in there as well.
Checked that out as well but the inside of the generator was completely clean. No sign of debris and no unusual smells.
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  #49  
Old 10-12-2017, 10:11:32 PM
JohnnyC JohnnyC is offline
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Default Re: New proud owner of a JC

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Originally Posted by JT240Z View Post
Checked that out as well but the inside of the generator was completely clean. No sign of debris and no unusual smells.
I lost and I owe you a beer. What do you like and where do I send it? You can PM me if you want. Seriously.... Anyway that is good news for you.

JohnnyC
New Jersey
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  #50  
Old 10-12-2017, 10:17:36 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

Quote:
Originally Posted by JohnnyC View Post
I am familiar with your transfer switch. I have the 30 amp version. I got the factory manuals, wiring diagrams and all here, but not in electronic format. Can you snap a picture of the inside showing the PC board where all the relays are located? The ATS will work with either 1 or 3 phase gensets and to configure it for 1 or 3 phase is super simple.

Also, I will bet you a beer that you missed one mouse condo, especially if they were in the control box and the other area you mentioned..
(Hint: See picture below)

JohnnyC
New Jersey
Didn't remove that cover yet but I did look at it from every opening. Good suggestion to remove and inspect it though. It will be on the list of things to do.

I did remove the generator cover and turned her over using the large nut on the end. Turned it clockwise and felt and heard nothing strange. I could feel all four compression cycles for the four cylinders and each felt pretty much the same.

Suggestions on how to do an initial start? It will take me a while to get her in a position where I can feed her NG. The only propane I have on hand is a few 20lb bottles. Can I just feed it with propane from a 2 stage regulator? I have one that can supply 165k BTU at 11 WC that I used to feed a 6.5K NHM genset. I'm not talking about load testing it. Just getting her started and verifying she produces power.

Quote:
Originally Posted by JohnnyC View Post
I lost and I owe you a beer. What do you like and where do I send it? You can PM me if you want. Seriously.... Anyway that is good news for you.

JohnnyC
New Jersey
Technically you didn't loose because I haven't completely removed that cover yet. If you're ever in my area we can share some beers.
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  #51  
Old 10-12-2017, 10:20:15 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: New proud owner of a JC

If it has set for awhile, I like to pull plugs and crank engine over till it has oil pressure.
I have lightly loaded (40 amps) a JC off a 20# bottle.
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  #52  
Old 10-12-2017, 10:28:09 PM
JohnnyC JohnnyC is offline
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Default Re: New proud owner of a JC

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Originally Posted by JT240Z View Post
Didn't remove that cover yet but I did look at it from every opening. Good suggestion to remove and inspect it though. It will be on the list of things to do.

I did remove the generator cover and turned her over using the large nut on the end. Turned it clockwise and felt and heard nothing strange. I could feel all four compression cycles for the four cylinders and each felt pretty much the same.

Suggestions on how to do an initial start? It will take me a while to get her in a position where I can feed her NG. The only propane I have on hand is a few 20lb bottles. Can I just feed it with propane from a 2 stage regulator? I have one that can supply 165k BTU at 11 WC that I used to feed a 6.5K NHM genset. I'm not talking about load testing it. Just getting her started and verifying she produces power.

Technically you didn't loose because I haven't completely removed that cover yet. If you're ever in my area we can share some beers.
Attached is a picture showing the very first time I fired up my 15.0 JC after it was dropped off at my house. Due to the size and resolution of the picture, you may not see the voltage shown on the volt meter and the oil pressure, but you can clearly see 1 BBQ tank of propane and a regulator from my BBQ too. I did not have the demand regulator hooked up for the first firing. The trick is to hook it up as you see, slightly crack open the tank's value until you hear a faint "woosh" sound of the vapor in the carburetor, then toggle the JC to the start position. Once the JC fires over you will need to tweak the propane flow slightly until the motor runs smooth. It may take several times before you get the hang of it. Once the JC is running smoothly, you can check things over such as oil pressure and leaks. You will NOT be able to run a load (anything over 12 amps from my experience) until you hook inline a demand regulator and a second BBQ tank. If you run a load, the tank will most likely freeze up quickly.

OK on the beer. Hopefully someday..

JohnnyC
New Jersey
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  #53  
Old 10-13-2017, 10:54:36 AM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

I may have an even a better way of doing the initial startup. As you can see in this pic, I have the demand regulator and the cutoff solenoid already on the unit.


I'm thinking that all I need is the LP tank and a primary/secondary regulator. I do have a new motorhome LP regulator that will take tank pressure down to 11" WC and will supply 165,000 BTU. Wish I had a larger tank than 20lbs but I guess that will have to do for initial startup and checkout. I may be able to wrap the tank with a heat blanket to assist vaporization of the LP. I may be able to borrow a 100lb LP tank from someone if you guys see the need. Since this thing is rather heavy I'd like to be able to test it out before placing it at its final resting place.

On a side note, the generator not only came with the transfer switch but also came with about 200' of #6 stranded wire, two breaker boxes, and a fused 3 phase master switch. Seems like they took everything out that was even remotely connected to the generator. I didn't know the wire came with it until I opened up the transfer switch and found all the wire coiled inside. No wonder it was so darn heavy. Also found all the original Onan manuals for the generator inside. Unfortunately, there was no manual for the transfer switch itself.
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  #54  
Old 10-13-2017, 12:24:37 PM
Mac Sine Mac Sine is offline
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Default Re: New Proud Owner of an Onan JC

You only need the primary regulator (that could be a 2-stage unit) to reduce the tank pressure to the inlet pressure needed at the KN demand regulator. The maximum inlet pressure value should be stamped in the body of the KN regulator.

Tank size relates to the surface area available for vaporization of the liquefied propane back into the gaseous state. As long as there is sufficient vaporization area to maintain the correct gas inlet pressure at the KN regulator, you can maintain a given load on the engine. Put a pressure gauge in your line so that you can monitor the gas inlet pressure at the KN. If the pressure begins to decrease from your initial setting (and the tank is getting cold), then there is insufficient vaporization area to maintain the load on the engine and you will have to decrease load, or add a tank or tanks to your system or use a single larger tank.
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Old 10-13-2017, 12:59:38 PM
JT240Z JT240Z is offline
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Default Re: New Proud Owner of an Onan JC

Great! I have several full 20lb tanks that I can cascade together if I need to. The primary regulator is a 2-stage regulator that should be able to supply the KN as long as the tanks stay warm enough. This is only to verify engine runs and the generator provides power. Plan to do a full load test once it's connected to NG. Kind of hard to load up a 15kw generator that's sitting on my trailer in the front yard.
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  #56  
Old 10-13-2017, 02:04:03 PM
len k len k is offline
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Default Re: New proud owner of a JC

A 15JC takes ~ 290K BTU/hr at full load and ~ 120K at no-load. So if your reg can make 160K then it's good enough for ~ no-load testing.

BBQ tank is only good for ~ 50k-75k BTU/hr steady state in summer. So I think it will eventually freeze up even at no load, but I think you'll get at least a few minutes of run time before that happens. ( takes a time for liquid propane to get cold, and thus tank pressure to drop below min reg operating pressure).
Other trick is can flow some warm water over outside of propane tank to help keep it from freezing up.


Obviously since you have the demand reg good to use it, so you won't have to play around with tweaking propane tank valve. Check that reg vents are not plugged, mud wasps.
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  #57  
Old 10-13-2017, 02:50:18 PM
JT240Z JT240Z is offline
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Default Re: New proud owner of a JC

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Originally Posted by len k View Post
A 15JC takes ~ 290K BTU/hr at full load and ~ 120K at no-load. So if your reg can make 160K then it's good enough for ~ no-load testing.
Are you sure about those numbers? According to the operators manual, it more like 110cf/hr on propane at full load. Natural gas is closer to your numbers at 255cf/hr.
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Old 10-13-2017, 03:40:30 PM
len k len k is offline
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Default Re: New proud owner of a JC

I remember others saying on nat gas 15JC at full load consumes ~ 280-290k BTU/hr.
This sounds about right since 15JC FL uses 2.4 gal/hr gasoline, or (2.4 x 125,000) = 300 k BTU/hr gasoline.

If you have Onan numbers use them. I was running ballpark estimates. So I just took nat gas full load number and ratioed it (1/2.4) to NG no-load and ASSUMED propane would require about the same BTU/hr. (on gasoline 15JC is ~ 1gal/hr no-load and 2.4 full load)

Other thing is your chart calls out different units than I am , they are not the same......"cubic feet/hr" VS kBTU/hr

Last edited by len k; 10-13-2017 at 04:04:04 PM.
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Old 10-13-2017, 04:57:41 PM
JT240Z JT240Z is offline
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1 cf/h ~= 1000 BTU/h so 110cf/h ~= 110k BTU/h as I understand it. The chart above is straight out the JB JC owners manual.
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Old 10-13-2017, 05:37:24 PM
MBB MBB is offline
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Default Re: New Proud Owner of an Onan JC

Here is a little info on the transfer switch.

Options

A001 3 pole Transfer Switch
B001 Nema Cabinet #1
C005 Controls
D003 Door Assembly with Voltmeter
E004 Accessory Control 3 Wire Start
J004 Exerciser Clock 7 Day
K001 2 Amp Battery Charger
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Last edited by MBB; 10-13-2017 at 05:58:20 PM.
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