Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Electric Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Onan 20ES L25208B


this thread has 67 replies and has been viewed 3714 times

Reply
 
Thread Tools Display Modes
  #1  
Old 10-22-2016, 11:08:34 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Onan 20ES L25208B

serial: 0900315980

I bought this generator from a guy that said he removed it from a local school as part of an upgrade. It had low hours (low hundreds), and appeared to be in a very good shape. I believe it was there to keep the lights on in case of a blackout, and they were upgrading with generators that could provide enough juice for AC as well.

Can one tell if this is an LP or Nat Gas unit (i thought the only difference should be the regulator)

It has a cut 1.5" pipe for the gas. It have a good battery for it.

I'd like to attach it to a 40lb tank and get it started before I invest into bigger LP tanks.

What regulator do I need in between? What should my next steps be in order to get it tested?






Reply With Quote
Sponsored Links
  #2  
Old 10-23-2016, 12:02:18 AM
akirkland akirkland is offline
Registered-I
 
Join Date: Jan 2016
Location: Portland, Oregon, USA
Posts: 395
Thanks: 79
Thanked 211 Times in 152 Posts
Default Re: Onan 20ES L25208B

Provide 11" water column to this unit. The demand regulator is upside down, this is how an LP unit is normally set up, check the demand regulator and make sure the spring is removed. It is under the white plastic adjusting screw/cap, which in turn is in the demand regulator tower under the aluminum cap.
Reply With Quote
The Following 3 Users Say Thank You to akirkland For This Post:
  #3  
Old 10-23-2016, 12:02:30 AM
Ray Lynch Ray Lynch is offline
Subscriber
 
Join Date: Aug 2014
Location: New Windsor, New York, USA
Posts: 444
Thanks: 312
Thanked 283 Times in 184 Posts
Default Re: Onan 20ES L25208B

Komrade
Looks like a "D" instead of a "0" at the beginning of the Onan serial number. Generator made April 1990.
Ray
Reply With Quote
The Following User Says Thank You to Ray Lynch For This Post:
  #4  
Old 10-23-2016, 12:24:23 AM
akirkland akirkland is offline
Registered-I
 
Join Date: Jan 2016
Location: Portland, Oregon, USA
Posts: 395
Thanks: 79
Thanked 211 Times in 152 Posts
Default Re: Onan 20ES L25208B

The demand regulator is to the left of the fuel flex line. Check fluid levels, visually check engine for any obvious problems. Whoever cut the fuel line probably was not careful with the ac output wires. Make sure the ac output wires are safe, wire nuts or tape is good. Units this age frequently need cooling system service, check water pump for looseness, check belts, check battery cables for tightness,corrosion, check immediately. For oil pressure on startup, watch for leaks, check ac voltage, frequency, be ready to shut it down immediately if you see a problem.
Reply With Quote
The Following 2 Users Say Thank You to akirkland For This Post:
  #5  
Old 10-23-2016, 07:29:38 AM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

do I need to worry about this unconnected wire?

Reply With Quote
  #6  
Old 10-23-2016, 09:42:04 AM
Billy J Shafer's Avatar
Billy J Shafer Billy J Shafer is offline
Subscriber
 
Join Date: Nov 2004
Location: Centerville, Texas
Posts: 16,372
Thanks: 8,340
Thanked 13,690 Times in 6,443 Posts
Default Re: Onan 20ES L25208B

Most ES units could also run on gasoline. I just worked on one. Post a photo of the block same side as carb. Don't worry about that wire. It is only for a test. You don't need it I agree on checking the wires. When they removed the one I worked on. They just used a cutter and cut the wires while they were still powered up on the DC side. I would also remove the fan guard and trim it up. To give the fan a little more room. If not set down flat. The blade tips can hit the guard.
__________________
I don't talk to myself. This early in the morning. Why the hell should I talk to you.

Last edited by Billy J Shafer; 10-23-2016 at 09:53:04 AM.
Reply With Quote
The Following User Says Thank You to Billy J Shafer For This Post:
  #7  
Old 10-24-2016, 10:34:39 AM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

What's the best way to go from 1.5" pipe to a propane tank hose

Anyone want to help me save a lot of time by talking to mostly (but not always) clueless Lowes and Home Depot associates?
Reply With Quote
  #8  
Old 10-24-2016, 11:43:44 AM
Birken Vogt Birken Vogt is offline
Email NOT Working
 
Join Date: Sep 2009
Location: Penn Valley, California, USA
Posts: 1,570
Thanks: 2
Thanked 498 Times in 356 Posts
Default Re: Onan 20ES L25208B

You wanting to run it off a bottle temporarily? Not sure about the question.

This is what you need: http://www.ebay.com/itm/New-Fisher-R...YAAOSwZJBYBVvT

Plus associated fittings to get the pipe from the regulator to the generator.

Lowes, etc. usually does not have a regulator big enough to run this thing.
Reply With Quote
The Following User Says Thank You to Birken Vogt For This Post:
  #9  
Old 10-24-2016, 01:29:25 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

Thank you very much for posting a link to the regulator I need.

What pipe size output would this have?

That way I could order this, and purchase the rest of fittings to get it to 1.5" pipe inside the generator.

P.S.
looks like

1/2" FNPT

http://www.squibbtaylor.com/product-...d=6512&cid=302
Reply With Quote
  #10  
Old 10-29-2016, 10:32:06 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

I got the recommended regulator. Will work on detaching the pipe and figuring out how to connect it next week

Here are a few more pics

Other side, as requested


3 wires


what's this one for?


the controller wires were cut, and will need to be insulated (I have the remote controller)

hours (<700)
Reply With Quote
  #11  
Old 10-30-2016, 07:49:09 PM
Max Thompson Max Thompson is offline
Sponsor
 
Join Date: May 2009
Location: N.W. Missouri, USA
Posts: 5,764
Thanks: 5,001
Thanked 5,345 Times in 2,904 Posts
Default Re: Onan 20ES L25208B

Not sure where you are going to 1 1/2" pipe. I doubt there is anything inside the cover of your set larger than 1" and much more likely 3/4".

You would be better talking to the local propane supplier or a plumber than the folks at the big box store.
Reply With Quote
  #12  
Old 10-30-2016, 08:19:57 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

Possibly I am not that good with the tape

I took the cut piece of pipe with me and will stop by a hardware store next week.

Thanks,
Reply With Quote
  #13  
Old 11-05-2016, 08:35:08 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

Please watch the generator running

If we limit air flow, the governor stops acting up.

Do we
1) need to introduce load?
2) need to tune anything?
3) need a bigger can of gas for higher evaporation? (the 100lb tank I have needed some adapter to be filled, so we used a 20lb instead)

In addition, on the following setting we are getting 220V on the big single wire, and every other wire out of the three.



Does that make sense?
Reply With Quote
  #14  
Old 11-05-2016, 08:48:54 PM
Max Thompson Max Thompson is offline
Sponsor
 
Join Date: May 2009
Location: N.W. Missouri, USA
Posts: 5,764
Thanks: 5,001
Thanked 5,345 Times in 2,904 Posts
Default Re: Onan 20ES L25208B

Sounds like the generator output is not wired correctly if you are wanting 120/240 single phase. Open up the junction box on the side of the gen-end & see how the leads are connected in comparison to the wiring diagram that should be printed on the back of the cover.
Reply With Quote
The Following 2 Users Say Thank You to Max Thompson For This Post:
  #15  
Old 11-05-2016, 09:12:04 PM
Billy J Shafer's Avatar
Billy J Shafer Billy J Shafer is offline
Subscriber
 
Join Date: Nov 2004
Location: Centerville, Texas
Posts: 16,372
Thanks: 8,340
Thanked 13,690 Times in 6,443 Posts
Default Re: Onan 20ES L25208B

Go to the Gov control and readjust the Gain setting. If it is wired for 3 phase and you are trying to read. On the single phase meter scale you will get odd readings. The Gain control will settle the gov down.
__________________
I don't talk to myself. This early in the morning. Why the hell should I talk to you.
Reply With Quote
The Following User Says Thank You to Billy J Shafer For This Post:
  #16  
Old 11-06-2016, 12:01:07 AM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

Thanks, found some instructions in other treads, as well as the service manual (900-0035)

https://www.smokstak.com/forum/showp...2&postcount=53

I did have a question about 'wiring' (i understand we should get the RPMs stable first)
Does this unit require re-wiring? I thought the purpose of the switch on the picture is to replace having to 'rewire'

Thanks
Reply With Quote
  #17  
Old 11-06-2016, 07:36:42 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 2,705
Thanks: 175
Thanked 656 Times in 526 Posts
Default Re: Onan 20ES L25208B

that is a switch for the meters not connection.
Reply With Quote
The Following 2 Users Say Thank You to armandh For This Post:
  #18  
Old 11-06-2016, 08:06:33 AM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

makes sense now. thanks.
Reply With Quote
  #19  
Old 11-06-2016, 06:40:56 PM
Steve Dawkins Steve Dawkins is online now
Sponsor
 
Join Date: Feb 2005
Location: Virginia Beach, Virginia, USA
Posts: 694
Thanks: 392
Thanked 247 Times in 135 Posts
Default Re: Onan 20ES L25208B

In post #10, the three wires hanging down with yellow/red wirenuts are color coded Brown, Yellow and Orange. This is the typical color coding system for the phase conductors in a 277/480 volt system. There is probably a fourth wire that is color coded white or gray. It will be the neutral conductor. That may be the large wire laying in the bottom that is capped with a yellow/red wirenut. According to the nameplate, the generator will produce 30 amps @ 480 volts. The brown, yellow and orange wires look like #10 AWG, which is rated for 30 amps. What is the amperage rating of the output circuit breaker? if it is 30-40 amps, I suspect the generator was set up for 277/480 volt operation. If it was wired for 120/208 volts, the output would be 69 amps, so it would probably have a 70-80 amp circuit breaker. The single phase rating on this unit is 13kW, which will be 54 amps at 120/240 volts. If that's the voltage you will be using, you will need a 60 amp circuit breaker.

Measure voltage between the brown, yellow, and orange wires. If they read above 400 volts, the generator is configured for 277/480 volts. If that's the case, if you read between each of those three wires and the large one laying in the bottom that is probably the neutral, you should read 250-300 volts depending on the voltage trim adjustment on the control panel.

The smaller wires that are cut are probably the 12V DC B+, Remote Start, & Ground wires that connected to the automatic transfer switch, as well as 120 volt wires for the engine block heater. You should find some of these wires terminating in the generator control panel. They will be on a terminal strip of the engine control board, and the terminals will be marked "B+, RMT, GND."

The factory wiring will be all white wires that have possibly been painted green. They will all be stranded wires. The field installed wiring will be different colors. Some of it may be stranded, and some may be a single solid conductor. Solid wiring is not good to use in generators, due to vibration. The solid wire can loosen on a terminal, or break off.

Last edited by Steve Dawkins; 11-06-2016 at 06:58:28 PM.
Reply With Quote
The Following 3 Users Say Thank You to Steve Dawkins For This Post:
  #20  
Old 11-06-2016, 08:59:17 PM
Komrade Komrade is offline
Subscriber
 
Join Date: Dec 2014
Location: Paw Paw, West Virginia
Posts: 64
Thanks: 45
Thanked 6 Times in 4 Posts
Default Re: Onan 20ES L25208B

Quote:
Originally Posted by Steve Dawkins View Post
.

Measure voltage between the brown, yellow, and orange wires. If they read above 400 volts, the generator is configured for 277/480 volts. If that's the case, if you read between each of those three wires and the large one laying in the bottom that is probably the neutral, you should read 250-300 volts depending on the voltage trim adjustment on the control panel.
I believe that is what we were getting..

Will "hit the books".. Thanks you all for being such a great community. I hope to contribute back.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Onan 20ES Genset Starts but then immediately stops - Need Onan Electrician EricWhoRU Onan Generators 48 04-21-2016 03:45:56 PM
Onan 20ES Questions Utah Onan Onan Generators 14 11-22-2014 12:41:08 AM
Onan 20ES usajudo Onan Generators 6 11-03-2014 07:58:49 PM
Onan 20ES - Before and after lot665 Onan Generators 8 04-08-2014 08:31:06 AM
Onan 20ES Maintenance TonyAalund Onan Generators 11 06-06-2009 03:43:23 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 08:32:11 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277