[Rhodes22-list] Three Ethanol Myths Clarified

[Michael D. Weisner]

This may answer some of your questions about ethanol gasoline mixes and shed
light on the problems we have had with the engines.


Mike

s/v Shanghai'd Summer ('81)

Nissequogue River, NY


 


Three Ethanol Myths Clarified
<http://www.boatus.com/magazine/2011/december/ethanol.asp> 


By Bob Adriance


It's time we get to the bottom of how E10 is affecting our engines

In the few years since ethanol began to be widely used in the United States,
a lot has been written about its properties, the problems it's created, and
how to best cope with its possible effects. Some of the advice has been
based on science, some on hearsay. While E10 is not an ideal fuel - and E15
could cause serious problems for marine engines - at least a few myths about
ethanol have arisen with the potential to do more harm than good:

http://www.boatus.com/magazine/2011/december/assets/img/ethanol.jpg


Myth #1: Ethanol-enhanced gasoline (E10) loses octane much faster than
regular gasoline.



Many mechanics believe that octane loss during winter storage could be great
enough to damage an engine when it's run in the spring. These same mechanics
will often recommend leaving the tank almost empty so that fresh gasoline
can be added in the spring to raise depleted octane levels. While all
gasoline loses octane as it ages, ethanol-enhanced gasoline loses octane at
about the same rate as regular gasoline, according to Jim Simnick, a
technical advisor at BP Global Fuels Technology, and Lew Gibbs, a senior
engineering consultant and Chevron Fellow. The two men have over 75 years of
combined experience working with gasoline and both agree that the loss of
octane over the winter would not be sufficient to damage an engine. Note,
however, to keep any gasoline, including E10, as fresh as possible; they
said it's good practice to always add fuel stabilizer - an antioxidant -
whenever the boat will be idle for long periods.

The recommendation to leave a tank mostly empty is bad advice; it could
significantly increase the amount of water that gets into the tank. When
enough water enters through the vent, the ethanol will separate ("phase
separate") from the gasoline. Leaving a tank mostly empty does three things
to increase the chances of phase separation:

It increases the volume of open space in the tank (its "lung capacity") so
it can "breathe in" damaging moist air. An almost-empty tank leaves more
space on tank walls for condensation to form. Leaving less gasoline in the
tank means there will be less ethanol to absorb the condensation.

It's interesting to note that in areas of the Midwest that have been dealing
with E10 for over a decade, topping off tanks is common practice. (As an
alternative, completely emptying the tank would eliminate any chance of
phase separation.)

If phase separation occurs, the highly corrosive ethanol/water mixture will
settle to the bottom of the tank and remain there even after fresh fuel is
added in the spring. The only way to remedy the problem would then be to
drain the tank and add fresh gasoline. The best way to avoid phase
separation over the winter (aside from emptying the tank) is to leave the
tank 95-percent full (which allows for expansion) so that there's less moist
air in the tank, less space for condensation to collect, and more gasoline
to absorb whatever moisture does accumulate.


Myth #2: E10 attracts water, so it's important to install a water separator
to prevent the water reaching the engine.



Mercury Marine, which recently hosted a Webinar on ethanol myths, noted that
ethanol does not "grab water molecules out of the air." It is hydrophilic,
which means ethanol holds water. With regular gasoline (E0) as well at E10,
the primary cause of water collecting in tanks is condensation on tank
walls. But unlike E0, which can absorb almost no moisture, E10 can hold up
to half of one percent of water by volume, and the water molecules will
dissolve in the fuel. The "solubilized" water will bypass the water
separator and burn harmlessly through the engine. Only if phase separation
were to occur would a water separator do its job, but by then the fuel
itself would be the problem. The phase-separated water/ethanol mixture would
settle on the bottom of the tank near the fuel pick-up and would quickly
stall out or even damage your engine. And because ethanol is used to boost
octane, the remaining (low-octane) gasoline at the top of the tank would
also have the potential to damage your engine.

Note, however, that a fuel filter (10-micron) is essential to keep gunk from
reaching your engine. Ethanol is a solvent that dissolves resins, rust, and
dirt that have accumulated on older tank walls. Especially when you first
make the transition to E10, it's important to carry spare filters and a
galvanized bucket to store used filters prior to disposal. Even in new
engines and tanks, E10 will sometimes form a mysterious gooey substance that
will also clog filters. Richard Kolb, the manager of Emissions and
Regulations for Volvo Penta, believes the goo is caused by water mixing with
one or more of the 108 approved compounds that can be used in gasoline.
These compounds vary among suppliers, so one solution is to change to a
different brand of gasoline. Another is to use carburetor cleaner, which he
says has sometimes remedied the problem.


Myth #3: Certain additives can prevent phase separation?



Both Gibbs and Simnick said that the additives that eliminate water may work
incrementally to protect against phase separation, but Joe Simnick stressed
that no additives will stand up to a good slug of water. Lew Gibbs added
that the best way to prevent phase separation in E10 is to "keep it dry,
keep it dry, keep it dry." That means keeping the tank filled to prevent
condensation. Mercury Marine has also noted that, contrary to statements
made by some companies that produce fuel additives, there are no additives
that can make stale or phase-separated gasoline usable.

E10 is certainly not as trouble-free as E0, especially the first few
tankfulls. But for newer engines, those built after about 1991, there's no
reason the initial problems can't be overcome. No less an authority than
Mercury Marine says, "After the transition period from E0, E10 may actually
be a superior marine fuel as it tends to keep low levels of water moving
through the fuel system, keeping the 
system 'dry.'"http://www.boatus.com/magazine/assets/img/StoryEnd.png

Bob Adriance is Editor of Seaworthy, the BoatUS Marine Insurance
damage-avoidance publication, and author of Seaworthy, Essential Lessons of
Things Gone Wrong (published by International Marine/McGraw Hill, available
at www.Amazon.com
<http://www.amazon.com/gp/product/007145327X/qid=1137435438/002-5727410-9825
655>  and major bookstores).

 

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