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Onan Generators

Onan 15.0JC-3CR/8457AA


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  #1  
Old 10-14-2017, 09:55:30 AM
EICBob EICBob is offline
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Default Onan 15.0JC-3CR/8457AA

Greetinga all....
I am looking at this as an addition to my collection, the owner indicates it needs a starter and a gas tank. Was wondering if this is a Magneciter style or not. Also if it could be converted to tri-fuel?

Serial number is 0874848264

Thanks in advance!

-Bob
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  #2  
Old 10-14-2017, 10:03:28 AM
JT240Z JT240Z is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Not Magniciter if I read the year and spec series correctly. Looks to me like an 87 model and series AA. That would mean it's a YD Generator head. Just picked one up myself. What do you plan on doing with it? Mines going to be standby for the house.
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  #3  
Old 10-14-2017, 11:27:44 AM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Quote:
Originally Posted by EICBob View Post
...Also if it could be converted to tri-fuel?
Yes. I don't wee what ANY gas engine with a carb couldn't be converted.
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Old 10-14-2017, 11:56:48 AM
nothingbutdarts nothingbutdarts is online now
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Default Re: Onan 15.0JC-3CR/8457AA

Someone of higher power here just might be able to post a build sheet for this set and we could maybe even see what type of carb. it has????

The serial # might not be correct? Are you sure the first number/letter is an o??? I kind of think it's age is 1987 but the O is making me unsure. However the spec. of AA is a newer late 70's into the 1980's spec I think.
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Old 10-14-2017, 01:07:18 PM
EICBob EICBob is offline
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Default Re: Onan 15.0JC-3CR/8457AA

If I can swing the deal it will be my backup power plant for my house.
Here is a pic of the data plate

-Bob
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  #6  
Old 10-14-2017, 01:16:35 PM
len k len k is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Sounds like a lot of power for a house unless you want to run lot of electric hi-power loads at once. Stove, oven, dryer, water heater, A/C .....

15 JC will use ~ 1 gal/hr no-load gasoline, and 2.4 full load
7.5JB ~ .6 no-load and ~1.2 full load

7.5JB will start a 3 ton A/C
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Old 10-14-2017, 02:00:30 PM
EICBob EICBob is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Hi Len
I have 7.5 JB that I recently got working and that was going to be my backup plant.

Also just got a 4.0 CCK as a salvage from my old employer, this 15.0 would be nice to have, providing that as I mentioned the deal works out.
Would have to figure a way to get it home

My home does not have electric heat, but does have, as a lot of us in New England, a deep well water pump that on start up tends to irritate generators a bit. I also have the usual cast of things like the furnace, pellet wood stove, the refridge and freezer, some servers running my web services and of course lights.
Kinda like to have enough head room in standby plants.

-Bob
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Old 10-14-2017, 02:34:35 PM
nothingbutdarts nothingbutdarts is online now
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Default Re: Onan 15.0JC-3CR/8457AA

OK, I was wrong, looks like August 1974 build. This might be a Magniciter. Is there another tag on it or do you have a picture of the control box? If there is a penthouse mounted on top of the control box it is a YD end, if no penthouse than Magnaciter.
Also usually there is another tag with magniciter ID numbers as well.

I do have a June 1974 build JB that is a YD end and a spec. AA.

Which would you prefer????
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Old 10-14-2017, 02:37:31 PM
len k len k is offline
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Default Re: Onan 15.0JC-3CR/8457AA

If you need the power you need it. My point was with a JC you'll need double the fuel tank size for same run time as JB. Even at no-load JC is almost double JB's thirst.

spec Z was last magnaciter

spec AA should be a YD genhead with electronic voltage reg in penthouse over the control box.

Don't know wells , but would guess JB can start it. Since it can start a 3 ton A/C (~ 88 locked rotor amps), even before he cleaned demand reg vent to make it respond better. ( nat gas fueled)

Last edited by len k; 10-14-2017 at 03:02:01 PM.
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Old 10-14-2017, 08:17:47 PM
EICBob EICBob is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Hi Darts...
Here are a few more pics of the unit, am still waiting on the owner to say yea or nea on my offer. It does appear to have the penthouse above the control box, along with a few other Franken-engineered add ons!
As for a preference to gensets, since I have not had the joy/pain of a Magnaciter set yet, it is hard to say, but knowing that they get really angry if the magic smoke is let out of the black devices, the ones that contain the PFM variant of magic smoke, I think I would prefer a YD genset.

-Bob
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Old 10-14-2017, 10:39:15 PM
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Default Re: Onan 15.0JC-3CR/8457AA

What are you offering for the set? Do you know if it even turns over?

I was playing with a 15.0 JC today I picked up the end of last year, I paid $330.00 for it and didn't hear it run, 3 phase and non extended stack so only good for 12KW and gasoline carb. only. I did make sure it turned over though.
I was able to get only 50 amps. a leg out of it in 120/240 configuration today after a 3rd regulator was installed. With 50 amps. the throttle was wide open and nothing left in the engine to get more output. The distributor in it had the advance mechanism rusted solid, I picked up a distributor a little bit ago and installed it today before testing. I'm pretty sure it has a lot of hours on it. I also live at 8,800' so lots of derating because of that.
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Old 10-14-2017, 11:27:36 PM
Steve Dawkins Steve Dawkins is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Before buying that JC, you may want to open covers and inspect the wiring and controls for rodent damage. Also remove the top cover on the penthouse and inspect the voltage regulator. That wooded area could be an ideal venue for Mickey and friends to set up their condos.
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Old 10-15-2017, 12:15:56 AM
nothingbutdarts nothingbutdarts is online now
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Default Re: Onan 15.0JC-3CR/8457AA

I believe dmeed just bought this unit today.


https://www.smokstak.com/forum/showthread.php?t=172370
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Old 10-15-2017, 06:48:31 AM
EICBob EICBob is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Hi darts...
Thanks for the update, I just looked at the post from dmeed....
Oh well...

-Bob
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Old 10-15-2017, 09:44:47 AM
Leon N. Leon N. is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Re Jim's comment: [I don't wee what ANY gas engine with a carb couldn't be converted. ]

Yes this may be true but for those old 1960's ish Onan refurbishers, there are important internal part differences between the gasoline-only designs and the tri-fueled designs.

I think this subtlety should be pointed out for the serious Stak refurbishers who want to "fully restore" there gems to the standards Onan employed.

Without going into the differences, I must say I was surprised but when I stopped to figure out why it does make sense. Just glad my JB has the more durable parts.
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Old 10-15-2017, 10:16:28 AM
JohnnyC JohnnyC is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Some of the parts differences between a gasoline only and a tri-fuel genset is in the heads (or head for a JB). If you have a parts manual and look at the section of the head, you will see different listing for various head components.

Will your JC run on gaseous fuels if it was designed for gasoline? Yes. Will any damage result? Not sure, but I never heard of anyone's J series genset melting down when running on propane or natural gas when it was designed for gasoline use only. I'm sure others here may chime in if they heard of any problems.

JohnnyC
New Jersey
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  #17  
Old 10-15-2017, 11:05:18 AM
Ray Lynch Ray Lynch is online now
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Default Re: Onan 15.0JC-3CR/8457AA

I have a gasoline only JB that was converted to propane. Swapped out the original gasoline carb with a tri-fuel. So far so good.
Did my research here on the Stak before switching. Feedback was positive from those operating converted sets.
Ray
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Old 10-15-2017, 01:23:56 PM
JohnnyC JohnnyC is offline
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Default Re: Onan 15.0JC-3CR/8457AA

One thing to be aware of which you may already know is an Onan gasoline genset will have standard pistons, not high compression pistons. If you convert to tri-fuel and when running on natural gas, your output WILL be less. When running on propane your output MAY be less than gasoline.

My experiences running gasoline, natural gas and propane on a 4.0 BFA, 6.5NH and 7.5 JB is all three fall significantly on natural gas, but propane and gasoline will give me full output. Oh, I had a 5.0 CCK that was factory setup for natural gas and propane and the best I could do on natural gas was a little over 3,500 watts and that was considered acceptable. All my gensets were in top running condition during all my tests.

JohnnyC
New Jersey
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Old 10-15-2017, 10:23:23 PM
dmeed dmeed is offline
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Default Re: Onan 15.0JC-3CR/8457AA

Oh my

Didn't realize you were looking at it, Bob.

The seller didn't indicate that anyone else was interested when I called...

David Meed (dmeed)
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Old 10-17-2017, 06:18:39 PM
Kell1961 Kell1961 is offline
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Default Re: Onan 15.0JC-3CR/8457AA

The unit was built in Aug of 74 and is most likely a static excited unit.

The tri fuel and vapor only had different heads. If I remeber that has harder valve seats due to higher temp and no lead in vapor fuel.
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