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Onan Generators

Onan 7.5JB-3CR/9804T - Welcome 'red' to the family


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  #21  
Old 03-07-2016, 09:17:51 AM
JohnnyC JohnnyC is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

When I rebuilt my 15.0JC almost 2 years ago I ran into the same problems. Mice in the control box and generator head. You may have missed one spot and that is in the behind the air intake cooling tin above the starter. I had a freakin condo in there and crap from the nest was falling into the starter's Bendix gear and ring gear on the flywheel and caused problems.

Check out my video on YouTube and you will see the damages and the fixes I did.

https://www.youtube.com/watch?v=c8jVNfrCQuI -- sorry no sound, just video


JohnnyC
New Jersey
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  #22  
Old 03-07-2016, 10:03:24 AM
Leon N. Leon N. is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

If I were you I would not disassemble the generator or even disconnect any wires at this point. Main reason being, once you loosen those magneciter wire connections you risk having a high resistance connection when you put it back. I would not want to replace any of those crimped connectors on the exciter board.

As I have shown, mice peed all over my JB control box. That was some 20+ years ago and although I purchased replacement wire, wire connectors and terminal strips, I have not got around to clean it up any further. I am embarrassed but maybe this Spring I will get to it.

Yes, maybe mice did get in behind the rotor either squirming around and between the rotor poles or more likely by entering the hot air exit from the generator.

Maybe you can put a vacuum hose in through the generator hot air outlet and suck out any acorns or nesting material. Perhaps by hand turning the rotor a few degrees will aid in getting more stuff out.

As for that loose ball bearing, I am not aware of that being used anywhere in your JB. It certainly did not come from the generator bearing. Looks to be too big and furthermore that bearing is sealed. I did replace mine and still have the old one which can be rejuvenated as discussed on the Stak back a while ago.

One other thing you should be aware of, although I do not mean to discourage you, but if your JB was designed for "gasoline-only" then some of the internal parts were not as, shall I say, beefy the same parts used in plants designed to operate with gaseous fuels.

Good Luck in your refab.
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  #23  
Old 03-09-2016, 07:35:44 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Just a quick update for the fellas that were watching this one and maybe felt like it got away You did good.

Took the time to go through the control box & rewire what couldn't be patched and tape up what could. Still wasn't getting any power to the starter & disassembled the housing all the way so I could get to everything.

Hadn't thought to do it yet cause the ebay listing specifically said they had checked that the engine was free.. Well -it isn't Can't turn it even with plugs out from the flywheel end so guess it's seized.

Next steps PS fluid/acetone mix, rinse, lather & repeat. If no progress by this weekend will probably go ahead & pull the head if I can find the time.

Anyhow, that's what it is. Stay tuned.
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  #24  
Old 03-09-2016, 11:51:46 PM
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Motorhead Motorhead is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

If you paid for it via Paypal then you have financial recourse with the seller. I would suggest that you contact the seller first then Paypal. Don't wait too long.
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Old 03-10-2016, 06:43:10 AM
RETCPO RETCPO is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Keep ALL correspondence with the seller THRU E-BAY!
E-BAY and PAY PAL are the same corporation...
I have had a couple issues and because I sent ALL emails thru E-BAY judgment was in my favor.

Good luck
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Old 03-10-2016, 09:30:55 AM
Ray Lynch Ray Lynch is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Quote:
Originally Posted by BStrutton View Post

Hadn't thought to do it yet cause the ebay listing specifically said they had checked that the engine was free.. Well -it isn't Can't turn it even with plugs out from the flywheel end so guess it's seized.

Next steps PS fluid/acetone mix, rinse, lather & repeat. If no progress by this weekend will probably go ahead & pull the head if I can find the time.

Anyhow, that's what it is. Stay tuned.
Provided everything comes apart ok, pulling the jb head is not a big job. This will let you check the valves. Also the oil line that is mounted to the underside of the valve cover. Head, valve cover and exhaust manifold gaskets are available for replacement as needed.
Ray
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Old 03-10-2016, 11:17:48 AM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Definitely gonna have to pull the head for further exploration. Hopefully this weekend. Was able to get enough light down the spark plug hole to see what appears to be some pretty bad rust but mainly on the cylinder closest to genend -not really evident on the other cylinder..

Also thinking to pull filter & oil filler & see if I can get an inspection camera in there to see the bottom end at all..

@Terry Smith, based on your comment about the PO, I was wondering if you have any idea about what the time frame was that the construction co had it running. Just curious as to when it last ran..

I guess the gen just 'knew' that I had 1000 other things to do this weekend
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  #28  
Old 03-10-2016, 11:59:23 AM
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

TAKE PICTURES of what you do and find......BUT, I wouldn't do ANYTHING to the set until you contact the seller and paypal! $599 to buy a non running, seized generator, even a 7.5B, isn't a good deal in my opinion.
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Old 03-10-2016, 01:18:39 PM
Kevin K Kevin K is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Contact the seller through eBay, NOW. Don't wait, or do anything to unstick the engine. The original ad said "Surplus from a local school system. Sells AS-IS, we did not test this unit other than to make sure the engine is free". Since the engine is stuck, you have a case. If the engine was free and any other problems showed up, you would be pretty much out of luck. If he doesn't make it good, including transportation, escalate it step by step through the eBay resolution process. Don't give up, and don't let the seller bluster and bluff you into going away.

This seller has ten bad feedbacks in the last year. Now, anyone selling on eBay can accumulate a bad feedback or two, but if you read the descriptions, it appears the seller has played this game before.

"Bait and Switch parts I received where not the ones in the listing"
"This seller lied and said the engine turned but its locked. 95xt engine."
"Item was not as described. late shipping. engine had very little compression"
"didn't send all the parts promised and blamed it on my trucker..."

And then there's this bad feedback:
"Do not buy site unseen from this seller. Purchase needed 3000.00 in repairs"
To which the seller replied:
"FIRST WE HEARD ABOUT IT -- 2 MONTHS LATER ?! "

Not only is six hundred dollars plus shipping too much to let go, but more important it's the principle of the thing.
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  #30  
Old 03-10-2016, 02:03:06 PM
KPack KPack is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

600 plus shipping is a pretty hard lesson . I would do as told through eBay it's not going to cost you anything to protest you may get your money and shipping back if you want too.
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