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Bertram31.com General Bulletin Board
Re: ethanol & outboards, long reply
Posted By: Peter In Response To: Re: ethanol & outboards (Walter Kaprielian)
Date: Thursday, 1 June 2006, at 5:06 p.m.
Tony,
What follows is my understanding of what the implications are of exposing ethanol re-blended fuels to a moist environment. I've been researching this subject for awhile and I can tell you there is a lot more conjecture and B.S. out there than there are facts. Often it is difficult to tell the difference.
One of the wonderful things about this board is the free exchange of good information. I hope you find this information helpful. I also sincerly hope that others who read this post who find any errors or misconceptions will not be shy to point them out. In the end we all need to understand this problem correctly and thoroughly.About ethanol and water in the fuel:
Water mixes with the ethanol in the fuel up to a point. It doesn't simply pass through the gas and drop to the bottom of the tank like it used to. If water got into the old gas (which used MTBE or some other additive like lead to raise the octane) the water simply passed through and settled on the bottom. Almost no water stayed in the fuel,and almost nothing else came out of the fuel with the water. You could drain off the settled water and be assured that what remained was good, usable gas.
Ethanol gas is different. Up to a point all the water remains in "solution" in the gas, mixing with the ethanol.
-I'm not a chemist, so forgive me if I used "in solution" incorrectly Maybe it sould be said to be in suspension, or emulsified or something else-
As long as the water remains in solution in the gas it will run through your engine harmlessly. Or at least they tell us it is harmless. At any rate you won't see a puddle of water on the bottom of your fuel tank or in your Racor, and your engine will probably keep running.Since the water is in solution neither will any fuel filter of which I am aware separate the water out. The ethanol is acting more or less like DriGas, which it is.
BUT, and here is a BIG BUT...when the water concentration reaches a certain limit, the water and ethanol separate out all at once. This is called phase separation.
The exact mechanism by which that happens; how the phase separationis affected by temperature; at what concentrations of water-to-ethanol it occurs; as well as the quality of the resulting de-ethanoled fuel left behind; and the specific qualities of the ethanol-rich water puddle on the bottom of the tank;.....all these considerations and what the resulting impact might be on your motor and fuel system are cards held very close to the vest by the ethanol advocates. I know this because I've been looking for just that specific information for a while now.
What I have found out is that the ethanol/water puddle can have ethanol concentrations well over 10% and can be very corrosive to many materials used in normal fuel systems, like brass, aluminum, zinc, and some plastics, as well as to fiberglass, rubber and cork, just to name a partial list.
I have also seen it said that there can be enough ethanol concentration in such a phase-separated-puddle that the motors will start and run on this stuff, but not all that well, and possibly causing damage. I find it hard to belive that the motor will run at all. The ethanol content would have to be very high.. but that is what I have found said.It sounds ugly, but wait. It actually gets worse!
The sources of water that contribute to phase separation can enter the fuel supply from anywhere along the distribution line. It could be in the BOB (blend stock gas, pre-ethanol mixing.) Or from the pipeline used to deliver the BOB. Or it could be in the ethanol tank at the distributor where they mix the ethanol into the BOB. It could be in the delivery truck that took the gas from the distributor to the local station. It could be in the storage tanks at the station. It could be in the pumping/delivery system at the station. And of course it could be right in your own tank as well.
The problem is that the product delivered into your tank might be just on the verge of having enough water in it to cause phase separation, but not actually over the limit. It would be like a little time bomb of headaches waiting to go off. The station manager may have sounded his tanks right before you pumped your gas. He may have fond NO WATER AT ALL in his tank. In fact that is probably what he WOULD find because with ethanol fuel you either find NO WATER AT ALL, or a WHOLE LOT OF WATER.You buy some gas. That night it rains and a few drops trickle into your tank via an old and worn filler neck seal, and VOILA! Just like that you have a puddle of ethanol and water on the bottom of your tank, eating away at things; your engines may start but run poorly. Or maybe you just pump your whole fuel system full of this stuff cranking the engines, trying to get them started. Either way it probably causes damage. And worse, even if you drain the water off the bottom of the tank, you are left with inferior gasoline because you tooka bunch of ethanol out of it when you took the water out.
Or maybe the station manager DID find water in his tank, and drew off the water bottom. What is the quality of the gas he is now pumping to you? Did he even realize he was removing the ethanol from his remaining stock? Did he replace the ethanol he pumped out? If so how could he possibly know that he put in just the right amount?
All organizations that I have found which seriously advocate using ethanol KNOW that phase separation is a problem. They KNOW that it is GOING to happen, and yet none of them discuss its possible effects on the performance of vehicles which will experience this particular problem. Neither do they discuss the possible consiquences of diminished performance, or total engine failure.
This next section just for the pilots out there:
And you think we have problems as boat owners? Here is one for the AOPA crowd. What happens if ethanol gets into aviation fuel as it is slated to do. Imagine, your planning a short field take off over tall pine trees from a high field on a hot summer day. You, being a good pilot, do all the paperwork. No short cuts for you. No seat of the pants. Only hard numbers. Yor wife and kids are aboard and you are going to be darn sure you will clear the trees before you push the throttle open. It will be cooler in the evening, so if it is too close, forget it. You'll go after dinner. It will make for a late night, but the kids can sleep in the back. Such is the mind of a safe pilot.
The numbers say it is going to be OK. You decide it's a GO.But the F.B.O. drained a water bottom off his tank at 7 am that morning. You bought 50 gallons of avgas around noon. Yeah, you waited a while and then drained all the sumps and checked for water. Of course you did because you are a GOOD PILOT, a by the book guy. The fuel came out clean, no water, and you really didn't expect any.
What you can't see is that you got inferior gas. That's because there is less ethanol in it than spec. The missing ethanol went down the drain with the water that morning. Your engine performance is down 5% from the book numbers, but you have absolutley no way of knowing that.What a nightmare. Here come the trees...Check airspeed, maintain best angle...best angle! Why isn't the plane climbing faster? Check rate of climb....Why isn't it on-the-numbers? You should be climbing faster than this. AIS off? Pitot partially clogged? It doesn't matter now. It is too late. Your heart is in your throat as you skim over the top branches. You make it, barely, but you should have cleared by at least 50 feet or more. Good thing you left yourself a margin of error. Good thing you are a good pilot!
I know there are pilots on this board. Please take heed if this ethanol crap ever gets into our avgas!
And the advocates of ethanol KNOW something like this IS GOING TO HAPPEN. Can you say "Exploding Pinto gas tanks?" How about "GM side-saddel tanks in pick up trucks?" Well you get my drift. I'll quit my rant.
Nasty.
Back to boats. What to do?
I believe that the same mechanisim that caused the trouble might be the fix as well....Add a little DriGas. That's right, a little bit MORE ethanol. The water and ethanol should then go back into 'solution' in the gasoline and be burnable with no serious damage and the octane of the salvaged fuel will actually go UP slightly due to the additional ethanol.
Now this is just my conjecture, because I haven't seen anything anywhere that actually says you can do this. But I'm pretty sure the ethanol never actually combines with the water to form a new molecule, it just mixes with the water. So it seems logical that adding a bit more ethanol should reverse the balance and the puddle should go back into the gas maybe with a bit of agitation. Anyone out there know for certian?Then the next question raised is how to regularly check for the phase separation puddle. I believe a regular inspection of a sump is the solution. One means of doing this would be adding a pick up tube that can be used to sound the bitter-bottom of the tank. The Coast Guard doesn't want any fitting at the bottom of the tank that could fail filling your bilge with gas. I think I'll stick with the Coastie's on that one. Stick a new strw in it from the top
Another question is that since any gas that hangs around in your tank in a moist marine environment is constantly picking up more and more water, how can you manage your fuel to minimize your potential for problems? I believe that you should run your tank as dry as you dare to be rid of all the old, wet gas before refilling. The new tank of fuel will have a higher ratio of new, not-yet-water-saturated fuel to old, been-sucking-up-water-all-summer fuel,and thus a lower overall concentration of water. Well that is if the water isn't getting into the delivery system before the gas gets into your boat.
Better still if you have two tanks. You can run tank 1 absolutely out, (or at least a lot lower than you might ordinarily dare) and then switch to tank 2. Refill the empty tank 1 with fresh gas and repeat the process starting with tank 2 this time. And if you are not going any distance for awhile, leave one tank empty instead of moldering at the mooring for weeks on end.
Opinions?Another question is about the venting. Most of our old boats have some little chrome vent thingy over the topsides aft. As the engines suck down the fuel, the vent sucks in the air. Spray-laden, super-saturated, really, really, seriously wet air. The vent has probably got to be at least moved somplace that a) doesn't vent heavy gas fumes into a closed tub-ike space, and B) is out of most of the spray. I'm thinking maybe up on the outside of the fly bridge but I have no specific solution. If I had a radar arch I would seriously consider running it all the way up there and locating it on the bottom and/or back side. Or maybe just on the transom would be enough. Ideas? Anyone?
About fancy fuel filters:
There is a lot of literature and hard evidence that ethanol will raise up all sorts of old varnish and crud from any and all storage tanks that previously had "normal" gas in them. A quality fuel filter might be a good guard against some of this crud, but it won't keep the water out. And it won't keep some of the crud out either since a lot of it might be in solution, and not particulate form.
Herein lies the dilemma of the fiberglass tank gasser crowd. Is the ethanol really disolving the tanks? If so is the residue of the resin passing straight through the fuel filters in solution only to gunk up the motors? Many believe that to be true, but if that is true the entire gasoline station industry is in real trouble. The have a lot more fiberglass underground storage tanks and fiberglass piping systems than us few Bertram and Hatteras owners.
Personally I'm waiting for more information, but then again, personally I'm not expecting to put my boat in until late this season, so I feel I can afford to wait and gather more info.If you got to the end of this post, thanks for sticking with me, and I hope you find the information useful. I know there will be some of the Faithful who will have their own bit to add as well.
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