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Author Topic: Onan Generator Issues  (Read 5903 times)
DavidInWilmNC
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« on: September 30, 2006, 08:46:41 PM »

I'm trying to get my bus ready for Timmonsville and one of the big projects is to install the generator.  This generator is an old gasoline Onan 6.5 NH (6.5NH-3CR/16004P).  I bought this used back in March and it ran great.  I haven't started it in a couple of months, and now it won't start at all.  When I last ran it, I used stabilized gas and ran the carb dry prior to putting it away.  This model doen't have a separate starter motor but uses the generator windings to spin the engine.

When I tried to start it today, it seemed to crank slowly and not smoothly.  When it last ran, it seemed to crank a lot faster, but not as fast as most engines with an actual starter that I've dealt with.  After about three 10-15 second cranks, the cables were very hot.  Batteries are good (all three that I used).  It's getting gas, and the spark plugs spark.  I removed the spark plugs and it cranked a good deal faster, so that would seem to indicate compression is good.  I removed the cover over the brushes and pulled a brush cover.  The contacts on the armature were pretty dirty, so I sanded them clean with fine sandpaper, blew out all the dust, and checked the brushes.  One of the brushes wasn't seated properly and I thought that was the problem.  It did crank somewhat faster, but not enough to start. 

I know these are/were popular generators in their day and several on this board have had them.  What else should I try to get this generator running?  I've got lots to do and I'd like to have a generator for the trip to Timmonsville!  Thanks for any suggestions.

David
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boogiethecat
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« Reply #1 on: September 30, 2006, 10:43:17 PM »

I always try using a propane torch bottle to get engines running. Take a propane torch apart and get rid of the jet so you can get some decent gas flowing thru it, then stick it down the carb, turn it on a bit, and engage the starter.  It's MUCH better than ether 'cause it can't flood the plugs, and it's really easy to do.  Once the engine "hits" then you can moderate the propane (or just pull it out a bit) to keep the engine running, and then within a short time things will vibrate and loosen up a bit and the engine will run on it's own with it's gas.
Sounds whacky but it's started every long-sitting engine I've ever tried it on (lots) and gets em going every time... I keep a modified torch around just for this purpose and it's saved my bottom on everything from lawnmowers to stake bed trucks many times.
« Last Edit: September 30, 2006, 10:45:29 PM by boogiethecat » Logged

1962 Crown
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« Reply #2 on: October 01, 2006, 02:14:43 AM »

David,

Even if you don't get it running, stuff it in the hole and haul boogy on down here.

It seems as if we have one of the foremost former Onan dealers gracing us with his presense!

Yeah, ol' NCbob, (My Hero!), will be here and he knows anything that is worth knowing about those nasty old noise makers!

Work on something else for now!

IHTH,

Dallas
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NCbob
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« Reply #3 on: October 01, 2006, 03:34:07 AM »

Dave, it didn't take any prompting from Dallas for me to immediately raise an eyebrow to your problem.  Those old NH generators were truly dependable and yours, being a Spec 'P', is one of the later models.

What most people don't realize is that Exciter cranklng requires a fully charged battery for cranking and stout cables because of the very high amperages involved. An absolutely good battery ground connection is vitally important.  My guess would be that once these items are taken care of you'll find it might crank faster.

Other than a gummed up carburetor, which can be easily remedied, you might wish to check your point gap (.016)  Do not sandpaper or file contacts, or replace them.  If you can't locate a set easily, PM me and I'll bring a set to T'ville.

You might do as Dallas suggests...stuff it in a bay and we'll work with you in it at T'ville.  They're an easy fix and a few pointers will make you another satisfied owner.

Bob
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Paso One
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« Reply #4 on: October 01, 2006, 07:08:12 AM »

Bob 
Would you recomend a dedicated battery very close to the NH engine as opposed to running long cables to the 8 D's  I don't know if Dave has a dedicated battery or is tapping the bus battery.  but in my case I noticed a slower crank with longer cables.  But maybe as you suggest I too do not have a good enough ground.  Great Thread Dave  Thanks for letting me hy jack it for a minite.
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Busted Knuckle
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« Reply #5 on: October 01, 2006, 07:21:26 AM »

Paso One, 1st of I'm no generator man or such but with batteries and cables I've always found that bigger, and shorter are always the best way to go! That applies to just 'bout everything I ever worked on that used a battery!  BK  Grin
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DavidInWilmNC
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« Reply #6 on: October 02, 2006, 06:01:20 AM »

Hi Paso,

I'm using dedicated batteries (tried several) that are, at most, five feet away from the generator.  The cables are standard, heavy automotive cables.  I did try on of my old/spare 8D's just to see if there was a difference, but there wasn't.

Bob, I'm looking forward to hearing what one who knows generators has to say about this.  It should be a good learning experience (I sent you a PM, by the way). 

David
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