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Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Onan 12.5 3cr1/13aa - g760156039


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  #1  
Old 04-11-2018, 09:35:26 AM
tenfive0 tenfive0 is offline
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Default Onan 12.5 3cr1/13aa - g760156039

I'm usually a daily flee bay and local Craigslist snooper. When I get a chance in the morning with my coffee before heading to the shop I'll get on my laptop and snoop around. I was beat to the punch on this one and found it on Smokstak - Onan Craigslist & eBay forum. Thanks wyM1uy.. I bought it home this past Sunday along with a switch for what I thought was a fair price. I paid a little bit more then scrap price.

It is currently configured to run on Natural Gas and living in the weeds I don't have city hook up. I need to convert it to operate on propane. Don't mean to beat a dead horse and I'm sure this question has been asked and answered thousands of times. What needs to be done to convert it to propane? From what I've been able to absorb and comprehend it might just be a mixture adjustment? I want to at least in the near future get it started and running to test the output before moving forward. I'm sure I'll have more questions moving forward because I'd like to hook it up to the switch that came with it but for now I don't want to put the cart before the horse. Last summer I put a two story bank barn addition on my shop. This summer I'm running wires and electric to the addition and I want to integrate this generator for lighting and an Onan 55KG for 3 phase machinery in to the system. My house is about 30 feet from the shop addition and I plan to run wires from the shop to the house and use the 12.5 for the house also.

Switch at previous location
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12.5 ID Plate
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  #2  
Old 04-11-2018, 09:55:45 AM
Leon N. Leon N. is offline
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Default Re: 12.5 3cr1/13aa - g760156039

For openers what you need is a copy of the Onan tech bulletin, # T-015, entitled: Use Of Gaseous Fuels With Onan Electric Plants, dated March 1967. Send me a PM with your email address and I will send you a copy.

Note, from the engines point of view all you would have to do is read adjust the carburetor a little bit since propane has a higher heat content than natural gas.

Leon
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Old 04-11-2018, 10:28:09 AM
Tracy T Tracy T is offline
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Default Re: 12.5 3cr1/13aa - g760156039

I had to adjust the mixture and if I recall maybe a slight timing adjustment. its been 3 maybe 4 years ago? my memory is foggy but I do remember it was not hard or complicated.
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Old 04-11-2018, 10:46:34 AM
MBB MBB is offline
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Default Re: 12.5 3cr1/13aa - g760156039

Here is some information on your unit.
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File Type: pdf 125JC3CR3113AA.pdf (39.6 KB, 12 views)
File Type: pdf 612-4793.pdf (284.3 KB, 9 views)
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Old 04-11-2018, 07:36:17 PM
tenfive0 tenfive0 is offline
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Default Re: 12.5 3cr1/13aa - g760156039

All that is needed is a mixture adjustment switching from Natural Gas to Propane? Will the mixture need to be leaned or enriched?
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Old 04-11-2018, 08:31:37 PM
Leon N. Leon N. is offline
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Default Re: 12.5 3cr1/13aa - g760156039

Leaned most likely. Propane has 2.5 times the heat content when compared to natural gas!
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Old 04-12-2018, 07:24:07 AM
tenfive0 tenfive0 is offline
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Default Re: 12.5 3cr1/13aa - g760156039

From further research, yes sir you are correct. Leaner is meaner..when converting from natural gas to propane.

I bought the generator with a transfer switch. On the generator there is only a start (up) and stop (down) switch. At rest the generator switch is in the middle between start and stop. There is no switch on the generator itself for the option to remote start. Will the transfer switch need to be energized and or hooked to the generator to start it?
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Old 04-12-2018, 07:44:42 AM
MBB MBB is offline
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Default Re: 12.5 3cr1/13aa - g760156039

Is the transfer switch an Onan? If so post the model and will see if we can get you more information. If it's not pictures help alot.

Looking at the picture if the Green switch and the box above it came with it, post the information on both devices and we can know better what you have.

Last edited by MBB; 04-12-2018 at 07:54:52 AM. Reason: Added info
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Old 04-12-2018, 09:19:06 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: 12.5 3cr1/13aa - g760156039

Just from the model number of the generator, voltage code "3CR" the "R" means remote capable. Under the voltage regulator the is like a 4 or 5 terminal, terminal strip. There should be markings of B+, 1, 2, & 3 on that strip. They are wired to the remote start device.
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Old 04-13-2018, 08:42:18 PM
tenfive0 tenfive0 is offline
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Default Re: Onan 12.5 3cr1/13aa - g760156039

Switch that came with the generator.

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Would it help to get a picture of inside the switch? I have no idea how to wire or hook the generator up with the switch. I usually try to do everything I can for myself if I can. One of the parts inside the switch has 480 volts on it but the outside cover has 240 volts.

Last edited by tenfive0; 04-14-2018 at 10:01:10 PM. Reason: spelling correction.
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