Views : 233,756
Genre: Howto & Style
Date of upload: Nov 17, 2023 ^^
Rating : 4.98 (105/20,562 LTDR)
RYD date created : 2024-05-12T19:02:13.214997Z
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Top Comments of this video!! :3
I spent several years as a rubber chemist back in the 80’s. Diaphragms and other oil-resistant parts are typically made of Buna N aka Nitrile rubber which is very oil resistant, as a matter of fact, it is too oil resistant, so SBR rubber, which is a sponge where oil is concerned is added to the formulation in order to swell and make up for the ingredients in Buna N which will leach out over time when subjected to oil. A typical specification for Buna N will have a couple of volume change values in different fluids : (gas, motor oil, Jet A, etc. ) at different aging temperatures for 22 hours or longer. A Buna N formula consists of Buna N polymer, reinforcing fillers (typically different types of carbon blacks), process oils which make the rubber more flowable so parts can be made. There are also a myriad of other chemicals: antioxidants, anti-ozonants, plus a cross-linking package that can include cross-linkers, accelerators, retarders , process aids, mold releases, and sometimes a kitchen sink depending on how desperate the chemist is.
Putting a pure Nitrile Rubber part in a solvent will leach these ingredients out of the Nitrile, causing the part to shrink and fail in the application. That is a why a “swellable” rubber (SBR) is added. It allows oil or fuel to absorb into the rubber part and make it bigger. It is a balancing act.
Someone mentioned using brake clean to rejuvenate brittle parts. You can see why this would work since it is swelling the Buna N, but at the same time it is leaching other ingredients out, changing the physical properties of the part.
FWIW
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Ever since the first time I had an issue with bad gas. I started going to the airport and buying a gallon of 100 low lead aviation fuel. I am doing this now for about 25 years. Aviation fuel has the additive where I can sit for unbelievable amount of time and not degrade. Granted, it’s more money than your average gas but well worth it. To use your words to save time and money and frustration.
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I buy ethanol free premium for my small engines. Only just now ran out of the fuel that I bought two springs ago (I didn't intend for it to last two summers, but misjudged it and obviously bought too much). While I did add fuel stabilizer to it last Fall, I think the main reason for the longevity was the lack of ethanol.
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I was a small engine mechanic in the 70s-80s. I never kept up with the new machines so im no longer working on them. I would always tell people draining your machine is like leaving a coffee cup on your table when your done. The ring is just like gas in ur carb. gonna leave residue. Im a fan of leaving fuel in because it keeps seals moist. Works for me. Thanks for your input, and Happy Thanksgiving to you and your family. PS........I'm a big fan of Opti for 2 cycles.
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I cant imagine "putting your equipment" away for the season. Out here in the south eastern desert of AZ as soon as a dog pee's anywhere, we will get tumble weeds & all manner of "winter weeds", so the weedeater is used even in the dead of winter 'round here!
Living my best La Vida Loca here in southeastern Arizona
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Great stuff, episode by episode. Guy in his 70's, a lifetime of mechanical experience in timberland, farming, drag and road racing, mo-cycles, and yeah, small engines. Yet I get so much out of your tutorials, even if new slants on older information, all helpful, and the added percs of a good-lookin' woman with a sense of humor, just the right mix of a little sarcasm. 🤙👍
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Hi Bre.
Long time auto tech here, now retired. Puttering with two strokes for 50 years has taught me a lot but always willing to pick up a few new tricks.
You put on a good and informative show.
Often times the old engines that the fuel system is full of oil it isn’t necessarily that oil was placed intentionally. Over the years the gasoline evaporates and leaves the oil residue. Keep in mind that the fuel/oil mix was very heavy often at 16.1
Recently started an old Mccullogh Super Pro 81 that had that situation. A quick cleanup of the fuel system and adding fresh fuel it started up after 3 or 4 pulls.
And you are correct, the oil doesn’t seem to affect the carb gaskets.
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This used to be very common, but they used ATF fluid some people call it after run oil‘s, but it’s basically ATF fluid and you run some of it through your carb or over anything you don’t want to rust and it also puts a little down in your cylinders to give it a nice coating of oil And you can store things long-term because even after years if the ATF fluid starts to come up a little as soon as gas hits it, it gets all fluid it again and it’ll smoke a little bit until it burns the oil off but a lot of mechanics restoring old engines will do the same. They’ll just pump a little in the cylinders with a B diesel or two stroke or four stroke to give it some lube and let it soak into the rings, but if you do it in advance, you’re pushing the fuel out and giving it a nice coat of ATF. And advantage of that over oil is you don’t have to worry about filling it up because even if it gets really old and comes up as soon as gasoline hits it, it melts again. Other people I’ve also used castor oil, honestly, I don’t know how it works overtime but I always used after run or ATF.
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For those who do not have ethanol free gas in their area, it's easy to make your own. There are Youtube videos but basically you just add water to the container of gas, which absorbs the ethanol and settles to the bottom of the container. Since water and gasoline do not mix, you just drain off the water/ethanol mix and you're left with pure gas.
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@Chickanic
1 month ago
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