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Engine basics => Engine set up tips => Topic started by: frank mccune on July 26, 2014, 05:34:53 AM
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Hi All:
How can one determine if there is any oil in a fuel?
I evaporated the fuel outside in the sun and wind, i set the fuel on fire to see if there would be any residue in the container but I did not see any evidence of an oil residue. Does this mean that there was no oil in the fuel?
If one placed the fuel in a container of water, would the oil separate and be seen? Perhaps it would rise to the top.
Any suggestions?
Tia,
Frank
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You should have been left with oil after the evaporation with sun and wind part. When I've seen people write about this, they've reported boiling the fuel away on a hot plate. While this doesn't sound entirely safe, it should boil off all the "fuel" components and leave you with just lubricants.
I don't know what setting the residue on fire tells us (other than you like to set things on fire).
I don't know how to tell if what is left is castor, synthetic, or a mixture.
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What I've seen with both castor and synthetic oils is that by adding a bit of water all the oil instantly drops out of solution. Usually about 5% water is all that's needed but it's temperature dependent in that the colder the fuel the less water is needed. If you do it in a syringe then you can get a fair idea how much oil is in the fuel. I don't use nitro so I can't say what effect, if any, nitro might have.
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Hi Tim and others:
What I set on fire was a portion of fuel in a clear glass dish to see if any oil residue would be left in the dish. When the dish was as clean as if I had burned only alcohol in it, I thought that this indicated that there was no oil in the fuel. Perhaps I was on the wrong track and using invalid testing procedures.
I will test some fuel today by adding water to the fuel.
I also applied a sample of fuel and a sample of alcohol to clean cotton test strips and I found that there was no oil residue remaining on either test strip.
I researched this question via Kiekhaufer(SP) the manufacturer of Mercury Outboard engines and they stated that their tests showed that their engines would run for about 40 seconds with no oil in the fuel. That is about how long my O.S. Max .40S lasted before it needed a new ring installed.
Again, thanks for the replies
Frank
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Some synthetics burn cleanly away in an open flame.
Are you using a brand name fuel? While inconsistencies exist in blends, I have never heard of a brand name fuel lacking oil entirely.
Phil
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Try making your own. - As long as you can get hold of methanol and castor oil, it's pretty straight forward. (A word of caution here; be careful handling any of these chemicals especially methanol and nitromethane. These are both pretty volatile in their pure state more than when mixed together.)
A pair of safety glasses come in useful for the mixing process, thus:-
For most modern glow engines a 5% nitro mix with 20% castor content should be suitable.
For 2 litres (just under half a gallon) I use this method:-
1) Mix 400ml castor oil with 100ml nitro in a measuring jug.
2) Pour into a suitable fuel container.
3) Measure out 750ml methanol then add this to nitro/castor mixture.
4) Put the lid on and give a good shake!
5) Measure out another 750ml methanol and add this second half to the mixture.
6) Shake again to ensure fuel is well mixed, and fuel should be ready to use.
Good luck,
Tim
(Model Technics over here in the UK do a full range of fuel ingredients, although I'm not sure if they'd send fuel mix by air!)