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


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  #41  
Old 03-14-2016, 11:05:58 AM
squidtrap squidtrap is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

BStrutton- PLEASE take the advice given, you can look into the other issues while doing so.

The time frame is SHORT, like 15 days total including weekends, he has very bad feedback and it is a large business, dont think he needs the headache. Correspondence with him he can just deny, call him but then call e-bay right after so you can let them know what he is proposing, stand your ground, i would shoot for the moon, (return unit) than go from there.

Just looking out for a fellow stacker, and while case is being done your answers will come in, so right now answer would be no parts available, better case for you, REALLY hope this works out for you, remember it was a total misrepresentation, (LIE) good luck Ed.
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  #42  
Old 03-14-2016, 11:39:31 AM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Hey Guys,

Appreciate the advice. I've been buying & selling on fleabay since they opened the doors, so to speak and this is the first time I've had any issue.

The reason I'm wanting to know about the likelyhood of being able to find oversized pistons is this.. I called the seller to get shipping arranged when I purchased. In the course of doing so he offered to collect payment via CC over the phone.

Now that's my bad. As long as I've been doing this I KNOW to only use paypal but I guess in the excitement of the hunt I got wrapped around the axle.. So my claim 'position' or leverage isn't as strong as you can see, hence the little bit softer or more reasonable approach I'm trying to take to work something out. So I'll probably try to work out something reasonable to keep it -otherwise I may be hosed anyway and the only one making money on this will be the shipper -it was $225 to get it here freight.

Will update as this progresses.

Thanks all.
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  #43  
Old 03-14-2016, 12:32:53 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

Quote:
Originally Posted by BStrutton View Post
Hey Guys,

Appreciate the advice. I've been buying & selling on fleabay since they opened the doors, so to speak and this is the first time I've had any issue.

The reason I'm wanting to know about the likelyhood of being able to find oversized pistons is this.. I called the seller to get shipping arranged when I purchased. In the course of doing so he offered to collect payment via CC over the phone.

Now that's my bad. As long as I've been doing this I KNOW to only use paypal but I guess in the excitement of the hunt I got wrapped around the axle.. So my claim 'position' or leverage isn't as strong as you can see, hence the little bit softer or more reasonable approach I'm trying to take to work something out. So I'll probably try to work out something reasonable to keep it -otherwise I may be hosed anyway and the only one making money on this will be the shipper -it was $225 to get it here freight.

Will update as this progresses.

Thanks all.
You still have recourse through your credit card company...much the same as with paypal. He also violated ebay policy by transacting outside of ebay so you have him there.
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  #44  
Old 03-16-2016, 05:37:52 PM
BStrutton BStrutton is offline
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Thumbs up Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Alright guys so here's where this ended up.. I talked with the seller who (like @gnucklehead said) seemed to be a reasonable guy.. The agreement that we came to is that probably neither one of us wants to pay to ship this thing back and line the pockets of the shipper so.. I am going to keep it and either fix it or part it. I paid $419 originally for it plus $215 freight (which either way I consider spent / gone money).

The seller and I agreed that he will refund $225 to my DEBIT card that I used to pay with. Basically I'm paying $190 for the gen and the $215 it cost to ship for this JB with housing.

That's the financial end. I'm happy with things all considered and feel what we worked out was fair. Got a couple of lessons out of the deal too to refresh my normally cautious approach..

I'll follow up with some more pics & details on the gen and we can move on from there. It'll probably take a few days for the transaction to post and I'll keep an eye out for that..

Thanks.

Alright guys here is some Onan porn to document where I'm at with this thing:

Rusted PTO-side cylinder Pics:
https://www.dropbox.com/s/duhi4hf9py...OSide.jpg?dl=0
https://www.dropbox.com/s/5hr02bggwl...PTO-2.jpg?dl=0

Some Pics of the PTO-side after a couple of days full of Evaporust, razor blade & gentle red scotch brite:
https://www.dropbox.com/s/67ihe96fk4...Razor.jpg?dl=0
https://www.dropbox.com/s/fbln8ke37y...zor-2.jpg?dl=0
https://www.dropbox.com/s/r4rxup9w80...zor-3.jpg?dl=0
https://www.dropbox.com/s/aa0l6ecrnv...Razor.jpg?dl=0

Starter (spins freely):
https://www.dropbox.com/s/nm6puebf7x...reely.jpg?dl=0

Side Views:
https://www.dropbox.com/s/wpxyxtcadg...deOne.jpg?dl=0
https://www.dropbox.com/s/nlcedvhom5...deTwo.jpg?dl=0

Gen End:
https://www.dropbox.com/s/kfhav04ic1...End-1.jpg?dl=0
https://www.dropbox.com/s/zvlbfva33k...nEnd2.jpg?dl=0

Control Box Before & After (minimal -tape, 1 new run & new terminal block for now):
https://www.dropbox.com/s/0mqphjk9wy...Block.jpg?dl=0
https://www.dropbox.com/s/q09esythqg...Block.jpg?dl=0

Flywheel Cover Mouse Condo:
https://www.dropbox.com/s/xavvmudpmz...Condo.jpg?dl=0

Peeks through the oil filter attachment point with the bore scope. Bit of dotted surface rust but hopefully not too bad. Know more once we see bearing & machined surfaces:
https://www.youtube.com/watch?v=SfjM8ZK09tA
https://www.youtube.com/watch?v=bRPtOEXMGeI

Finally this week's Craigslist find. Pawnshop had it. Asking $6 bills gave $5. Snapon KRA 4114/4107 combo. Solid overall shape, needs warranty couple of slides & some clean up. VERY happy camper as my 26" craftsman just wasn't cuttin' it any more

https://www.dropbox.com/s/1yig33r640...-4107.jpg?dl=0

That's the update for now. We'll talk about how to proceed next..

Thanks for all the input along the way so far! http://www.smokstak.com/forum/images/icons/icon14.gif

Last edited by BStrutton; 03-16-2016 at 06:09:47 PM.
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  #45  
Old 03-16-2016, 05:57:08 PM
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Have you pulled the fuel bowl off of the carburetor yet to see if it is contaminated? My question is to how the water or excess moisture got in there. If you are interested in selling the fuel tank set up, If you are going to run vapor only, PM me.
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  #46  
Old 03-16-2016, 06:02:57 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Have not pulled it yet.. Good question. Seller and I were discussing that. It has a non-standard little round muffler on it so I suspect the rain blew in through that POS would be my best guess..

Will keep ya in mind for sure @motorhead if I decide to go vapor only or otherwise part this..
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  #47  
Old 03-16-2016, 06:15:51 PM
yellowlister yellowlister is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

ive saved worse than that.. jb I had, had some pitting on the bore after it was cleaned up.. was locked up.. patience and a lot of mystery oil and atf fixed it..

however.. your control box looks like junk.. cheap enough to convert it to modern relays

looks pretty good inside..
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  #48  
Old 03-16-2016, 06:32:02 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

@yellowlister,

Glad to hear about that option for the control box. Any pointers or link to that? I agree it looks piss poor & even after working it over with the new terminal block and tape job it wasn't getting power to the starter (before I realized it was locked). No click, nothing..

I'm hopeful that I can get it cleaned up enough to run it at least long enough to verify that it makes power or not as I'll need to know that whether decide to put effort into or part either way..

Thanks.
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  #49  
Old 03-16-2016, 06:46:36 PM
yellowlister yellowlister is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

search max thompsons threads.. he has done a few, and even has a diagram that has all the part numbers and how to wire it..
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  #50  
Old 03-16-2016, 11:26:54 PM
scoops scoops is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

yea that cleaned up well.
I too started with way worse that that.

it will run.
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  #51  
Old 03-17-2016, 01:55:55 AM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

So took a look at the head tonight. They're all coked up but nothing that can't be dealt with via the soda blaster and ultrasonic.

Noted a bit of rust on the face of intake valve on pto side, which matches up to the cylinder with the rust. Again, not too bad and the seats are clean & shiny.

https://www.dropbox.com/s/no2orco3bp...Oface.jpg?dl=0

https://www.dropbox.com/s/mmbu5bnr4v...erust.jpg?dl=0

Last edited by BStrutton; 03-17-2016 at 01:56:33 AM. Reason: can't freakin spell
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  #52  
Old 03-17-2016, 02:31:43 AM
Vanman Vanman is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Wow, cleaning up nicely so far. It must be noisy inside that enclosure. The generator is wearing a set of gun mufflers!! Nice to see that they are tan in color and not brown or black

Keith
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  #53  
Old 04-06-2016, 08:35:05 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

https://flic.kr/p/FWuQtn


Update: So I've got the control box out & Thur my relays from Allied should be here. Many of the contacts esp on the open frame relay were so bad off they disintegrate if you move em.

I want to make sure I am clear on this before I start. I've seen a lot of the fine work that Max has done but I haven't seen one that exactly matches my rig. Some seem to have 3 terminal strips instead of my 2 or don't have a solenoid pictured for example.. So my questions are:

1) Attached pic of my control box tray. Annotated relays with what I 'think' they are, nomenclature-wise according to the schematic. I'm I correct on these?

2) In pics of the conversions by Max where no solenoid is shown but two plug-able cube relays are shown, is the intent there that the 12v of the two is actually replacing the legacy solenoid-looking relay? If not, what does the 12v relay do?

3) Best method for getting those grossly rusted fasteners off the emergency relay with minimal risk to the relay since they seem pretty hard to come by?

4) How about those tiny screws that retain the switches on the panel. They surprised me. Not at all corroded like the others but won't seem to budge. I've got some penetrating oil soaking on them currently.

Finally thanks for the recommendations so far. I've got my 18 awg MTW, loom & soon relays ready to go to rewire that whole box. Hope to have the electronics ready to go for the weekend. Intend to hone the top of that bad cylinder in place Sat morning, put the head back on & try to fire it briefly just to check output. If it produces then I'll put together a plan to disassemble & refurb the beast..
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  #54  
Old 04-06-2016, 10:12:20 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Your control box is set up for remote start, that is the reason for the extra relay which you have marked as “emergency relay”. The LOP/OS emergency relay is the top one in the front of the control panel. The big black one below it I believe is the crank limiter. Unless you plan to use an auto start function as with a transfer switch, you can do away with the other relay & the crank limiter would not be necessary.

The 12-V cube relay in my box replaces the starter solenoid pictured in the lower right corner of your box.

I used an extra terminal strip on one of my first conversions to get some of the wires off the small screws on the relay base. I will try to pull your wiring diagram tomorrow & maybe offer some guidance, I may also have some pictures of another box without the extra terminal strip. It is way past my bed time tonight.
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Old 04-06-2016, 10:25:30 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Thanks Max! That makes so much more sense and now that you said that I can see the windings on the emergency relay which now I get is 'panel' mounted which I couldn't tell from the schematics.
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  #56  
Old 04-07-2016, 08:01:54 AM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

I hope I have attached a picture of another box with only the 6 volt relay having been replaced & terminal strips being original.

I am having another fight with my computer, it has not worked to my satisfaction since it was built, sure wish I could "open it up" & see how it works like we do these old Onans. I can not pull the build sheet for this set to get the diagram #, though I am pretty sure it is the same as the one I use with the relay conversion pictures.

If you are in the "testing" phase, I would not worry about rewiring the box yet. I would "hot wire" the engine to start it. Battery + to the coil with an alligator clip or switch in the wire for quick disconnection if needed.
Another wire with a push button switch in line (you can just use a wire jumper but the push button is handy) to the starter shift solenoid to engage it & it should start. All other control wiring to the box should be disconnected or taped off during this process. You will have to keep an eye on your oil pressure since all safeties will be bypassed.
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File Type: pdf control box.pdf (152.4 KB, 45 views)
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Old 04-07-2016, 11:13:29 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Max, the picture is there and the control box is looking good!
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  #58  
Old 04-07-2016, 09:19:04 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Found an hour tonight to get out in the garage & do some soda blasting. A few pics of head / valves. The soda does a nice job, quickly. The one valve pic is top half blasted / bottom half not.
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Old 04-10-2016, 07:07:52 PM
BStrutton BStrutton is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

Alright then.. How about an oil pressure question?

I've got the control box all apart right now but Max suggested I could hotwire it just to test start & making power. Taped off all connectors for testing.

I got the head & valves all cleaned up and put the head back on yesterday and adjusted valves.

Left the valve cover off so I could verify oil flow. New filter & fill.

Fuel off. No hotwire (yet) to coil. Just connect battery & jumper starter.

Unit is cranking over good. I think it makes sense that I should be able to verify oil pressure prior to introducing fuel and spark.

However, I am not seeing pressure on the gauge and I also am not getting oil flow up in the head.

I've cranked it 3-4 bursts of 15 seconds or so with breaks in between.

How much should one have to crank this to see pressure or (if gauge is bad) oil flowing in the head?

Also, given the rust that was living in the PTO cylinder before clean up, I was thinking of checking the compression to get an idea on the rings. But what would be a 'cold' value that a guy would like to see prior to getting this thing started?

Other thoughts? Trying to take my time & methodical approach given the state this thing arrived in. Not easy for me as I'm an impatient SOB

Thanks!
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Old 04-10-2016, 07:22:20 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB-3CR/9804T - Welcome 'red' to the family

You will usually see oil pressure starting to build in 5 seconds of cranking, not sure if it would make it to the valve covers in that time. Double check the gauge to be sure it is telling the truth. I would also squirt some oil into each cylinder before cranking too much.
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