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Onan GenSet - project rebuild


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  #1  
Old 06-19-2017, 08:20:40 AM
gmdoctor gmdoctor is offline
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Default Onan GenSet - project rebuild

I've been looking for a generator for a good backup for my house/shop for years. The newer models (cheap ones), never seem to last. I'm here in the panhandle of Florida and it seems we have more power outages than i have ever experience. Last week i came across an older Onan and it was nearly fully intact. Mice have made a home in it for quite some time, and have enjoyed the wiring and insulation. Long story short, i got the engine running on propane, but i have nothing to test the genset portion. i will post pics as i can. Model No. 15.0JC-18R/15026AB and Serial # K830684756
As far as i can tell it has a build date of 1983. The carb looks like it was submerged in the gulf for years (appearance only) so gas will not move through it. If anyone can help me locate a good schematic for this i'd be eternally grateful. The engine side i can just about figure out, but reference material is always great to have around. As for the Gen side, i am totally dependent upon the masters in here. but i just need to get this thing cleaned up and running again. Anyone have a good source for parts for these older sets? I'd love to find a reliable source. Thanks in advance!!
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Old 06-19-2017, 08:42:35 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan GenSet - project rebuild

Look at the amp meter. If it is charging it is producing power. How much you will need a volt meter to find out. Give us time we can get you all the manuals and information you need. I would leave it on LP/NG. The gasoline side can be a pain sometimes.

Onan Parts is a seller of parts on this site.
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Old 06-19-2017, 09:10:42 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Thanks for the quick response Billy. I am a firm believer in OE parts. And i didn't look at the amp meter when i got this thing to run before i started to pull it down. I noticed it having a bunch of parts missing and thought it best to see what i may need to fix this before i put it into use. It has a bunch of wire emanating from the generator. they are separated and tied into 4 groups. i am leaving this for a later time to get straight.
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Old 06-19-2017, 09:12:34 AM
Ray Lynch Ray Lynch is offline
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Default Re: Onan GenSet - project rebuild

gmdoctor
Welcome to the site.
Manuals are available at the attached link. Do not run the set more than a few minutes without having the side tins installed. Otherwise it could overheat.
Good luck with your set.
Ray

http://www.twinslan.net/~n0nas/manuals/onan/
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Old 06-19-2017, 09:19:07 AM
Kevin K Kevin K is online now
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Default Re: Onan GenSet - project rebuild

Your model 15.0JC-18R/15026AB doesn't show up in my database, but a 12.5JC-18R/15026AB does. They are most likely the same machine, but yours has a 15Kw generator end. The good news is your has an extended stack, which gives you the full 15Kw on single phase.

I have attached the build sheet for the 12.5JC-18R/15026AB. I would guess the wiring diagram should be the same for your machine.
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File Type: pdf 125jc18r15026ab.pdf (25.0 KB, 28 views)
File Type: pdf 612-5559.pdf (145.1 KB, 29 views)
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Old 06-19-2017, 09:21:28 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Thanks Ray, good advice. I never let it run more than a min. I just wanted to see if it would run at all. Thanks for the link!
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Old 06-19-2017, 09:23:46 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan GenSet - project rebuild

Did you pull the voltage regulator cover off and then pull the voltage regulator off the control box to look for mice damage? I know you said you found some but didn't say where. They also like it inside the generator end, you might pull the end bell cover off along with the little rectangular mesh cover off the charge resistor and blow it out real good with air if you already haven't.

I just recently bought a 15.0JC but, mine was three phase and not extended stack like yours and in single phase it's only good for 12.5KW.
The control box and V/R were all good but, the gen. end had a lot of stuff in it!

Last edited by nothingbutdarts; 06-19-2017 at 09:36:30 AM.
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Old 06-19-2017, 09:30:53 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Kevin, that's awesome thank you. Once again though, the genset being stacked i wouldn't know the difference. I have never had any schooling on this. small portables are easy to fix. this set is foreign to me.

i pulled it down and found one wire completely chewed in half, and another one with no insulation let on it. the later was to the starter.
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Old 06-19-2017, 10:44:49 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

As for pulling the bell end, i haven't gotten that far yet. Do they make replacement harnesses for these models? If not i can make my own. I have a bunch of pictures of everything, but i don't see where i can post more.
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Old 06-19-2017, 10:51:44 AM
len k len k is offline
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Default Re: Onan GenSet - project rebuild

Sounds extended stack (good), nameplate says at 120/240 can make all 15 kw on single phase (62.5 amp rating). Likely a 12 wire genhead ( 6 winding) so have to wire it right to get that 15kw on single phase.

I see a propane tank fitting stuck in the vapor fuel line to carb. It can work if you do a lot of continuous tweaking of the tank valve to get flow to follow electrical load during testing .

But for actual use your going to need a pressure regulator to reduce propane tank pressure down to ~ 11 inch W.C. pressure. Then pipe that to a demand regulator, which will flow fuel proportional to engine's needs.

Tri-fuel carb on my similar 7.5 kw JB had all the idle adjustment screws froze from rust. Took it apart and CAREFULLY heated aluminum casting at the screws and was able to work them out and wire wheel rust off them. Aluminum expands 3X faster then steel screws. I put them back in with anti-seize. Need to not overheat the aluminum, it melts without notice, doesn't glow red. Think even a propane/air turbo torch can get you to melting temp, so have to be carefull.

Last edited by len k; 06-19-2017 at 11:15:06 AM.
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Old 06-19-2017, 11:08:32 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Len, this was someone else's attempt at running this set. it worked only long enough for me to get it to run. The regulator and shut off are just two pieces on my to get list. I noticed that there are other refurbs out there and each have their own way of using LPG/propane. In automotive use, there is always a regulator/shut off solenoid in place. I would feel better knowing that this setup is installed.
And thanks for the spec, it helps knowing that so i can purchase the correct regulator.
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Old 06-19-2017, 11:17:19 AM
len k len k is offline
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Default Re: Onan GenSet - project rebuild

Yes need a solenoid shut off valve for saftey.

Others are better with vapor fuel than I am, they will be along shortly.
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Old 06-19-2017, 08:20:41 PM
Max Thompson Max Thompson is online now
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Default Re: Onan GenSet - project rebuild

While at the twainslan site getting manuals, download tech manual T-015 gaseous fuels manual for fuel info.

You will also need the YD gen-end manual #900-0184 for generator wiring. I have not seen "wiring harnesses" for sale, nor have I had need for one. All the wiring in the control box and engine wiring can be "made". Get a roll of good quality wire, take a piece of the original wire to an elec. supply house and buy a 100' roll, this will be enough for several JCs. So far I have not seen mice do any real damage to the generator leads, they tend to pick on the smaller control wiring.

Look in all the nooks and cranny's for rodent residue. Lots of compressed air will be a big help, use it liberally. I also recommend opening up the starter and doing any PM needed. If you are not comfortable with the starter, let a rebuild shop check it out.

I will agree with Billy, run it on gaseous fuel. This will eliminate many potential problems.

You found a set that has great potential barring any major unforeseen defects.
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Old 06-19-2017, 08:52:57 PM
Leon N. Leon N. is offline
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Default Re: Onan GenSet - project rebuild

Hey Billy; re your comment: "Look at the amp meter. If it is charging it is producing power". Many models have a separate stator winding for charging the starting battery. So I suppose, one could have a damage or burnt out stator power windings and still have a good AC source for the battery charger. Sorry, just a nit.
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Old 06-20-2017, 10:49:41 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Max do you have a link to the twainslan site? also the wiring appears to be 12-14ga stranded copper, i have access to rolls of this. My biggest question is where are you guys getting your parts from? Local places that deal directly with the factory? Is there an online place that i can use to start ordering parts? I have a vested interest in getting this genset up and running quickly as we already are in hurricane season and have storms moving about in and around the gulf. Also i've been reading up on the regulators used for these, I see that Garretson is a recommended unit. Anyone with a more narrow of a list to choose from? There are too many for me to decide which will fit the bill, with my limited knowledge of this. My list of needed parts grows, and i have yet to find an online source to Onan where i can put in my model number to order parts from.

nothingbutdarts- i have pulled the bell end off only to see a rather clean looking end only some surface rust. The area of the charge resistor is clear of any anomalies or debris that i could visibly see. The VR is intact, but was chewed on only on the ends and everything was covered in nest material and old food and feces. so far i have been lucky to have just these small issues. I still have to pull the exhaust manifold and that is going to be a chore. Anyone know of the paint that's available for these to bring them back to original?
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Old 06-20-2017, 11:19:16 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan GenSet - project rebuild

See the link in post #4 in this thread!
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Old 06-20-2017, 11:19:24 AM
gmdoctor gmdoctor is offline
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Default Re: Onan GenSet - project rebuild

Ok guys sorry i'm not paying attention here. found the link to the manuals in a previous reply from Ray and Max got me right to what i needed. Thanks again!!
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Old 06-20-2017, 11:21:22 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan GenSet - project rebuild

https://www.smokstak.com/forum/member.php?u=19607 Onan parts is a member here, look at the contact tab.
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Old 06-20-2017, 06:38:02 PM
Max Thompson Max Thompson is online now
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Default Re: Onan GenSet - project rebuild

I buy parts from Cummins when I do not have what I need rat holed away. I also buy parts on flea-bay when I find a bargain, picked up a JC air filter for about $15 shipped the other day. Already have a few air filters on hand, but $15 is a pretty good price. The same applies for gaskets, ignition parts, low oil switches and even VR boards, I keep a supply of all on hand bought at various times and places.

The Garretson “KN” demand regulator is a good choice. I picked up 2 a while back for around $45, 1 with elec. primer from Century Fuel Products. The other, without the primer was from a flea-bay seller. Century also had the best price I have found on “Asco” elec. solenoid valves. I tried a couple of the $25 Chinese solenoids but they got “very” hot after holding open for a while, I would not recommend them.

VR boards come from Flight Systems, great bunch of guys, fantastic product and service at much better price than Cummins / Onan.

Throttle linkage rod ends come from Mc Master Carr.

Inside your control box, you may have automotive style cube relays since your set is relatively new. If you have the old open ignition / start disconnect relay, we have replacements for them.

If you will be within 15’ of your LP gas supply, ½” black iron pipe will do, ¾” to the first valve would not hurt anything. There should be a primary regulator at the tank, locate a second stage regulator (11” WC) where you tap the line from the tank. I would put a ball valve where you tap the tank line and another at the set ahead of the elec. solenoid valve. You cannot have too many valves and they cannot be too handy. If you will be a greater distance from the tank line, you might want to run high pressure to a point near the set then locate the second stage regulator at the set. This will allow you to run small pipe (3/8” copper) from the tank line to the second stage regulator.

I almost forgot, you need to find another JC for a backup set. Then maybe a JB for night time use and a couple CCKs or BFAs incase you have a prolonged outage and fuel gets low.
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Old 06-20-2017, 08:30:09 PM
Ray Lynch Ray Lynch is offline
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Default Re: Onan GenSet - project rebuild

In addition to Century, the attached link is another source and sells original Garretson regulators made in the USA as well as the solenoid valve.
Ray

https://carbturbo.com/product/garret...co-kn-039-122/
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