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Onan Generators

Parts Identification for ordering

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Old 12-01-2005, 08:12:30 AM
chuckster61 chuckster61 is offline
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Wink Parts Identification for ordering

Goodday all, My ONAN is:12.5 JC-3CR/HS25AA Serial number H790440649.

If you can help I would like the service manual number (so I can order from cummins), year of manafacture.
Also need part number for the electric choke. Finally can anyone explain how this choke works. It powers up at crankand is supposed to close the butterfly, It stays hot all the time the genset is running. How does the choke start opening up after warmup.

Does anyone have plans for a load bank testing device. I am a master electrician, suppose something like a bunch of dryer elements wired together, just not sure how to control load amounts for different size gensets.

Thanls All
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Old 12-03-2005, 07:57:32 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Parts Identification for ordering

This unit was built in Aug 1979.Will have your numbers later today.Heading out to work.
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Old 12-03-2005, 08:13:01 AM
Gunny Gunny is offline
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Default Re: Parts Identification for ordering

Here's how the choke on gasoline (JB and JC) Onans work. There is a bimetalic strip in the choke housing that is heated with a reisitive heating element. When cold, it holds the choke in the closed position. The heater element gets power when the engine starts and heats the bimtalic element, as it heats up it gradually pulls the choke off. As they age they tend to not close the choke as tightly as they did when they were new and make them harder to start as they get older. Adjusting the choke about once a year keeps upwith this. The hetaer element sometimes fail and the choke won't pull off, the engine runs real rich. The choke assembly does get plenty warm after the engine has been running for a while, warm enough so you won't want to touch it for long. My gasoline JC has a manual choke.

Stove elements work OK for a resitive load bank. Contactor to turn on the ones you want. They do get hot so be careful around them.

Onan should be able to supply manuals. Like Billy sez, made August of 1997. Voltage code is 3R, 12 lead reconnectable.

Most excellent machines, very rugged and durable, give long life with good maintanance. Consider converting to propane.
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Old 12-03-2005, 11:23:09 AM
Jim Davis Jim Davis is offline
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Default Re: Parts Identification for ordering

That is the link to your parts catalog. Page 41 shows a replacement choke kit number 153-0430 to replace "thermo-magnetic choke" and it also shows individual parts.
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Old 12-03-2005, 11:44:21 AM
Steve Dawkins Steve Dawkins is offline
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Default Re: Parts Identification for ordering

For a load bank, visit some local air conditioning contractors that specialize in residential service work. They replace HVAC units, and will probably have a few old air handling units laying around. If you can get your hands on one that has electric heat, it's easy to make a load bank. In your area, heat pumps are very popular and generally have electric elements for backup heat in case the heat pump fails. These air handlers will have the heating elements, controls and fan built into one box. You can add some toggle switches to control the heat. Often, the electric heat in these units will be set up in 5 or 10 kW stages, and you can control them with separate toggle switches.
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