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Onan Generators

What Have You Done to Your Onan Generator Today?


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  #1741  
Old 07-10-2015, 06:14:25 PM
Max Thompson Max Thompson is offline
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Default Re: What have you done to your Onan generator today?

Quote:
Originally Posted by gtj811 View Post
After about an hour it started to surge as if the governor was sticking.
Governors do not usually "stick", sometimes the linkage will bind or the sensitivity adjustment may need to be tweaked.

More often it is a carburetor adjustment issue. Carb adjustments & governor adjustments go hand in hand & it can be a balancing act to get both just right. This is covered in detail in the service manual.
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  #1742  
Old 07-10-2015, 06:29:59 PM
len k len k is offline
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Default Re: What have you done to your Onan generator today?

Manuals seem to say have to cycle thru carb and gov adjustments couple times to home in on the correct settings. At least on NHE types, likely most other engines too.
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  #1743  
Old 07-10-2015, 07:32:18 PM
YellowLister YellowLister is offline
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Default Re: What have you done to your Onan generator today?

Put a 12 amp load on each phase of the cw today with a electric blower.. dident even flinch
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  #1744  
Old 07-11-2015, 09:38:25 AM
Tracy T Tracy T is offline
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Default Re: What have you done to your Onan generator today?

Anticipating my generators first excersise cycle. It should fire up any minute now!

And @ 9:35 we were off and running!
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  #1745  
Old 07-13-2015, 02:25:25 PM
BillMcF BillMcF is offline
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Default Re: What have you done to your Onan generator today?

My 1967 gasoline 4CCK developed a problem a couple months ago. It ran well after a 15-minute warm-up, but after an hour with a 2kW load, it surged uncontrollably at idle and could no longer handle a 4 kW load. Nothing I did to the mixture or governor solved the problem. It wasn't missing, so I knew the spark was okay.

Over several weekends, I disassembled and cleaned the carburetor (including idle passage), checked fuel delivery, mixture, compression. I also reset the timing and points gap. The timing was okay, but I had to move the points box to one end of its travel to make the points open at the 19-degree mark. That seemed suspicious, so I put a timing light on it, and saw that that timing was very far advanced. Checked it again by rotating the crankshaft with a wrench, and it was correct. Why the mismatch?

At first, I suspected the timing light, so I borrowed one from a friend. It agreed with my timing light, so I tried setting the timing with the timing light. It was very difficult. A tiny change in the points box position made a huge change in the timing. A 16th of an inch was enough to go from very advanced to very retarded. At this point I was feeling a bit retarded, since the manual made it sound so easy. After much effort, I got within a couple of degrees of correct but could not get any closer.

Unfortunately, after an hour at half load, the idle surging came back. This time I put the timing light on it and saw that the timing was jumping back and forth in sync with the surges. The swing was huge, around 40 degrees!

Could it be the points box? I use a non-running CCK as a source of parts, so I pulled its points box and noticed that it had a brass bushing at the bottom. The other points box just had a big hole, about 1/2" wide; the end of the plunger rod must have been dancing about on the cam!

I swapped the points box and couldn't believe how much easier it was to set the timing. Needless to say, problem solved. Every time I work on this machine, I learn something new.
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  #1746  
Old 07-13-2015, 04:21:43 PM
len k len k is offline
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Default Re: What have you done to your Onan generator today?

On cars when I set the dwell ( point gap) I found best to not tighten lock down screw much, then pry the points around to set the gap.
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  #1747  
Old 07-16-2015, 08:06:21 PM
YellowLister YellowLister is offline
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Default Re: What have you done to your Onan generator today?

Got my enclosed magnaciter jb running and generating today.. I've had it for about 2 years.. had to clean the slip rings really good to make juice.. and found its 480 277v

It came with a control box lid that said it was 120 240v..

Runs good though.. need to put the enclosure back together and not sure what ill do with it now..

And figure out why it will only run in crank start mode.. in electric start it dies once u take your finger off the start switch
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  #1748  
Old 07-16-2015, 09:43:46 PM
Leon N. Leon N. is offline
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Default Re: What have you done to your Onan generator today?

Yellowlister obviously that is a three phase machine. Your hand-crank only start is most likely due to the start ignition relay not making contact. This relay is bypassed when you go to the hand-crank position. Of course, it could also be due to a wiring problem or a corroded terminal somewhere.
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  #1749  
Old 07-17-2015, 12:23:41 AM
YellowLister YellowLister is offline
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Default Re: What have you done to your Onan generator today?

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Originally Posted by Leon N. View Post
Yellowlister obviously that is a three phase machine.
why do you say that its obvious ? well now I know... that If the output wires say m0 or instead of m4 or t4 its 3 phase.. my 3 phase cck, cw and this jb all have m0 instead of m4, or t4..

yep.. need to go though all of the start stop relays connections.. could also be a faulty oil switch
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  #1750  
Old 07-17-2015, 06:34:49 AM
Leon N. Leon N. is offline
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Default Re: What have you done to your Onan generator today?

Yellowlister, take a look at the Owners manual. 480/277 con notates 3hase. This is a higher voltage version as Onan says. If there is a T0 lead, then that is the neutral. You should measure 277 volts from any of the three leads to the neutral. This arrangement can be used as a straight three phase machine by isolating the neutral. This configuration is termed a delta. By isolating the neutral, to me that means do not ground the neutral.

Where as if you use all 4 leads, then you have a Y configuration 3 phase output, that is 277 lead to neutral and 480 lead to lead. In this arrangement you must ground the neutral T0 to the generator frame to protect the magneciter from damage.

I would suggest you provide the full model number, and maybe someone can provide the build sheet for your specific machine. You may have a unique, customer ordered arrangement that is not obvious from what you are indicating.

WRT to that control box cover, I'd bet someone switched covers along the way. From what you say, that is the wrong cover.
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