MoGas Thoughts

[Bruce Fenstermacher]

Won't diesel fuel mix with gas?

Are you sure the MOGAS you bought did not have ethanol? Did you test it?

That crap kind of reminds be of the slime I got after running some ethanol. Only in my tanks. Never saw it in my gasolator.

After sumping all the gook out by removing the tank sump valve. I took a few gallons of 100ll and poured it in the tank. Shook the wing and drained. Strained out any gook and repeated using the same fuel until I didn't get any gook out. Did the same to the other tank. Then I drained the 100LL through the gasolator. Again never saw any gook in the lower system. Removed the carb finger filter and carb bowl drain and observed what came out. Nothing but clean gas.

This day was the last time I ran MOGAS with the exception of a short period when I could get ethanol free MOGAS at a station that specialized in having it. They bought directly from the distributer and transported it in their own trucks and I tested every batch I bought. I would not trust a station that sold gas with ethanol to have a completely clean system for the stuff that isn't suppose to have any ethanol. Test it, it is easy.

I would talk to your A&P. Tell him what you want to do. He doesn't need to flush your system, you can. He can safety everything afterward or inspect your safeties.

[blueldr]

I really doubt that anyone is spikeing gasoline with diesel fuel in an attempt to "Raise" the octane number.
Many years ago, returning from Cabo San Lucas in Baja California, we received gas in La Pas that had been contaminated with diesel in the tank farm when it was pumped ashore from a tanker. My Ford truck had, back in those days, a Ford 460 V-8 engine and we had a real helluva time trying to work our way north to get home. It wasn't until we got to Santa Rosalita where the fuel had come down from the north in Ensenada that we finally got pure gasoline.
You don't really know what "Pinging" is until you run into a deal like that. The power available was just barely enough the keep the truck moving.

[juredd1]

Dick,

My uncle would agree with you 100% as he been using it for many, many years without issue. Myself on the other hand am a bit confused.

Bruce,

I did not test the fuel and wouldn't begin to know how test for ethanol. I'm guessing if it's easy I can find some info on the web on how to do it. I have been told multiple times that their premium fuel does not have ethanol so just figured they knew what they were talking about. Been buying the same fuel for some time to run in my mower, and other small engine toys.

This just makes no sense to me. Never seen this stuff until I got back home and unless I picked it up along the way from Idaho but I am anal about sumping the tanks unless I just failed to do it on the last AvGas fill up on the trip home. Otherwise as I've said two new clean (Looked in them) 5 gal jugs of 91 MoGas poured through a Mr. Funnel and recall specifically looking at the remains in the bottom of the filter and seeing nothing abnormal. Was it in the tank all along and it got jarred loose after getting back home after 30+ landings of which most of those were on off asphalt strips in Idaho. If it was there I should have jarred it loose on a few of my early landing attempts.

Just no explanation from my point of view. Dirty water was sounding good but still would have wondered for a long time where I got it from but since it burned I am guessing that is off the table. Just figured in the early comments that maybe water would mix to some extent with gas, enough to burn but if not then it ain't water.

Thanks for all the tips and advice guys I'm just frustrated about it but the only thing I know to do is flush the darn system and hope for a better future.

Airspeed indicator issues and now this. I'd just like to go flying with some piece of mind for a few hours.

Justin

[lowNslow]

STP Octane Booster is mostly kerosene/diesel!

Ingredients:
Kerosene 60 - 90%
Petroleum naphtha, light aromatic 7 - 13%
Proprietary additive 3 - 7%
1,2,4-Trimethylbenzene 1 - 5%
Methylcyclopentadienyl manganese 1 - 5%
1,3,5-Trimethylbenzene 1 - 3%
Petroleum naphtha, heavy aromatic 0.5 - 2%
Naphthalene 0.5 - 1.5%
Ethylbenzene < 0.2%

Hmmm... that adds up to over 125% of ingredients??

[KS170A]

Even though when I sumped some out of the drain (Sorry guys don't know what it's called) down under the plane (which still had straight AvGas) into the same container the dirty fuel was heavier as it settled to the bottom. Again I was at a loss but was maybe just to stupid but the plane fired up and went through taxi and run up so I didn't think anything else about it. I went flying and had no issues during flight.

Aside from the burning wood, no one seemed to pick up on Justin's statement that he went flying WITH the discolored stuff in the gascolator. Seems that with a gascolator full of what many are considering to be water, I find it highly unlikely that the airplane would start, taxi, run-up and fly without any issues.

I would agree with the others that flushing out the entire system would at least give you a good base line to start with. Take a good look inside the tanks while they're empty.

[bagarre]

Isn't that what the gascolator is there for?

[hilltop170]

I did not test the fuel and wouldn't begin to know how test for ethanol.
Justin

The easiest way to test for alcohol in gas is to fill a small container with the gas and drop one drop of food color in the gas and gently agitate it. If there is alcohol, the food coloring will completely dissolve into and color the gas due to the water base of the food color. If there is no alcohol, the food color will drop to the bottom and bead up just like any other water drop would.

[blueldr]

Or one could always use the alcohol/fuel tester as is sold by Peterson Aviation with their Mogas STC.

Most all of us will have to agree that leaded fuel is going to have to go. For years now there has been all kinds of controversy about what fuel will be the replacement. At my age, I'm now 91 years old, I doubt that the answer to the replacement product will be settled before I die and I really HATE to miss out on it because I'd just about be willing to bet the bank that it will either the same old Mogas that I've been using for years or a damn close relative that will also work well in your old Model A Ford.

[GAHorn]

The majority of "octane boosters" contain ethanol or methanol. You don't want either of them in your airplane unless it's a turbosupercharged Lockheed Connie or one of bluElders old Dizzy-6/7's with take-off water-boost systems.

Gascolators, by design, capture and store small quantities of junk below the inlets/outlets...as a function of debris/water removal so your engine doesn't die from small amounts. The gascolator can, however, become overcome by excessive amounts and one such problem can occur due to alcohol (ehtanol/methanol) which can seperate out in-flight along with water.

juredd1, I suspect your system was contaminated with old fuel and improper additives and water and your recent activity dislodged it from hiding places in the system. Alcohol can dissolve rubber components and attract water (such as condensation which forms along the tank walls due to the chilling effect of flight at altitude of the humid-atmosphere which enters your tank to replace the fuel you're burning)... then you're faced with water...rust...etc etc.

My advice: Quit hurting your system and use ONLY aviation gasoline. There's a reason your system is contaminated.

Quit flying with contaminated fuel unless you'd like to participate in an off-airport landing accident.

[juredd1]

The easiest way to test for alcohol in gas is to fill a small container with the gas and drop one drop of food color in the gas and gently agitate it.

Thanks for the info I will give this a try this weekend or before if I can get some time.

Quit flying with contaminated fuel unless you'd like to participate in an off-airport landing accident.

I haven't been flying since I come to the realization that I in fact had some issues with an unknown substance in my fuel system.

So even though I have sumped the tanks and drained the gascolators until none of the dark stuff comes out anymore is the consensuses that I still should flush the whole fuel system?

Justin

[hilltop170]

You really need to find out what that stuff is so that you can determine what will dissolve it so it will flush out. Trying to wash out water with a hydrocarbon probably won't work, water is not miscible in petroleum. It may not even be water. So try to get some more out and see what will cut it, then make a plan to clean out the system.

I would try to flush each portion of the system out at the closest point available to that portion instead of trying to flush the whole system out thru all the lines, shut-off valve, and gascolator. If the stuff has any gooey, clots, stringy, or solid stuff in it, it could hang up in the valve or maybe restrict the flow without you being able to tell and starve the engine at full power. Don't take any chances, figure out what it is and clean each section independently.

When it comes to cleaning the lines, I would disconnect them at the tanks and flush them both ways. You don't know what might be sticking one direction that might flush out with flow in the other direction.

You can rig up an effective gravity-fed flushing system by hanging a container as high above the plane as possible, filled with whatever solution will cut the contamination (and not hurt the plane at the same time), and connected to the system with large enough hoses to allow good flow (maybe a 5/8" or 3/4" garden hose that itself has been flushed out so you won"t introduce any more contamination into the system). There will not be enough pressure to hurt anything. When flushing thru the lines and selector valve, don't forget to cycle the valve thru all positions and verify proper operation.

Good luck.

[Greg Bockelman]

Shell hops on the unleaded avgas bandwagon...time will tell if they actually come out with a product and what it will cost.

http://www.avweb.com/avwebflash/news/Sh ... 070-1.html

In the meantime, I thought this list of airports with mogas was interesting. Doesn't say anything about ethanol though...

http://www.flyunleaded.com/mapusairports.html

You know what they say about assuming. But I would bet money that if they are selling it for aircraft use, they know enough to get "clean" fuel. No ethanol.

But I test everything I put in my plane, mogas wise, regardless.