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Onan Generators

Onan 12.5jc/3cr-1AA


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  #11  
Old 09-13-2017, 12:24:32 PM
gchank gchank is offline
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Default Re: Onan 12.5jc/3cr-1AA

Is that nail polish remover and are you mixing it with a sexy red color nail polish?
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  #12  
Old 09-13-2017, 12:32:39 PM
labans labans is offline
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Default Re: Onan 12.5jc/3cr-1AA

Yes. I could have said Acetone but it is very difficult to buy 8 oz of acetone while you can get 8 oz of Nail Polish Remover for about $3, empty it into a spray bottle, then fill the nail polish bottle back up with ATF ($3 for a quart from Autozone) and pour it into the spray bottle and shake hard before each use.
Too much fun has been made of this mixture, but the fact that it works better than anything else is the proof in the pudding. Don't knock it until you have tried/tested it.
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  #13  
Old 09-13-2017, 12:54:16 PM
len k len k is offline
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Default Re: Onan 12.5jc/3cr-1AA

Walmart acetone in paint dept, ~ $12/ gallon. Also removes tree pine pitch well.

Careful, Some nail polish removers are cut with ~50% water and have other stuff in them (aloa, water based)

Last edited by len k; 09-13-2017 at 02:56:02 PM.
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  #14  
Old 09-13-2017, 02:37:59 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

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Originally Posted by labans View Post
I don't know what you have tried for the soaking, but I cannot recommend highly enough using a mixture of ATF and Nail Polish at 50/50 ratio and you must shake it for at least a minute after mixing.
I am an automotive machinist and after using everything commercially available for 50 years I found this suggestion and I can tell you that there is NO second place mixture as this is in a class by itself.

The mix seems to separate after it sits a while. I have had 3 cylinders of a JC soaking for a year or two.
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  #15  
Old 09-13-2017, 03:30:42 PM
Carteret Carteret is offline
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Default Re: Onan 12.5jc/3cr-1AA

There are many types of ATF nowadays, I would think that DEXRON would be the "original" ATF used in this formula? Ford used (uses) mineral based ATF back when.
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  #16  
Old 09-13-2017, 03:54:47 PM
labans labans is offline
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Default Re: Onan 12.5jc/3cr-1AA

Why are you soaking 3 cylinders for years?
The mix does separate which is why one must mix very well before using.

---------- Post added at 02:54:47 PM ---------- Previous post was at 02:51:33 PM ----------

I have had good luck with plain old Dexron from wherever it is cheapest, for this use. As far as 'additives' are concerned just read the label and get the one with the least additives. And if you wish you can spend the extra and buy a gallon. I just know what works after having tested this mixture over the last 12 months against all the other products I have used over 50 years and this mixture is great.
And if anyone doesn't want to use it, that is fine too!
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  #17  
Old 09-13-2017, 04:17:27 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

Pistons still rusted to cylinders!
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  #18  
Old 09-13-2017, 06:33:36 PM
len k len k is offline
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Default Re: Onan 12.5jc/3cr-1AA

If 3 years didn't do it I don't think oil will do it. With rusted bolts I find heat works MUCH better than any oil. Try getting cylinder hot, then cool piston, and hammer piston. People here like putting ATF and a rag as wick on top of piston and letting it burn.

I had pistons rusted once when I was ~ 15, we soaked it with penetrating oil every day for 2 weeks. Then cut edges of 2x 4 to fit in cylinder then sledge hammered the wood. Wood was ~ 8 inch long. Pitted cylinder required oversized pistons.

But looking back at it I'ld try to get section of steel cylinder the size of cylinder to put the force at piston skirts, so piston top doesn't cave in. Big socket for a bull dozer maybe, or nut for one and grind edges off?? Then hammer the steel. Using steel instead of wood you'll get higher peak impact force on piston, which is what you need break it free.
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