ethanol in gasoline & marine engines?

eryka · #1 (**permalink**) 08-11-2006

I've heard some anecdotal evidence of problems since the mandatory addition of ethanol to gasoline sold inthe US including marine fuel, does anyone have good info? Problem report 1: the ethanol helps mobilize any water in the bottom of your tank, running it thru your engine and leading to possible corrosion. Problem report 2: the ethanol attacks certain rubber based parts (which?) leading to drying and cracking. Not a problem in diesel (yet, I suppose) what about outboards?

TrueBlue · #2 (**permalink**) 08-11-2006

I have also heard of some corn-based ethanol issues concerning 2 cycle outboard engines and the use of biodiesel as well. I don't use Ethanol gasoline in our 2-cycle outboard - just as a precaution, until I learn more.

This does not affect my boat, since it's diesel and I have metal tanks, but reports have been published for some time now, warning boat owners with fiberglass fuel tanks. The ethanol mixtures (E-10), reputably dissolves the fiberglass, eventually eating through the tank walls. Resins released from the fiberglass ultimately coat injectors, valves and upper cylinders of gas engines, leading to some serious damage and expensive repairs.

sailingdog · #3 (**permalink**) 08-11-2006

Several problems with ethanol mixture gasolines that are on the market:

1) The ethanol attacks the resin in older fiberglass tanks, as TrueBlue pointed out. This causing serious engine damage.

2) The ethanol is prone to absorbing moisture, either from water in the gas tank or from the atmosphere. It only takes about 1.5% water to cause the ethanol to degrade to the point where it no longer acts as an octane booster, which is its primary function in gasoline. Then the 93 octane gasoline you bought acts and burns like 85 octane gasoline... not too good for your engine.

3) The ethanol-based gasolines have a much shorter storage life for the above reason—about 60 days maximum. Beyond that, moisture absorbtion and other issues cause the gasoline to degrade.

4) The higher temperatures caused by higher percentages of ethanol (such as E85), which also adds oxygen to gasoline mixture, causing engine damage in most marine engines. This is currently being studied by several outboard and inboard engine manufacturers.

5) The ethanol, in higher percentages, does attack some rubber and plastic parts.

eryka · #4 (**permalink**) 08-11-2006

Thanx, you two! TrueBlue, where do you get non-Ethanol gasoline for your outboard (we have a 4-stroke, if it makes a difference). And Sailingdog, from your #2 we should be using the highest octane we can find, if it's going to absorb water?

sailingdog · #5 (**permalink**) 08-11-2006

Unless your engine requires high-octane fuel, don't bother buying anything more than your engine needs... the lower grades often don't have ethanol in them—as there is no need to boost the octane levels in them, and without ethanol in them—will last longer, and be cheaper to buy, than the more expensive, higher octane grades.

At one of the four gas stations near my marina, there is one "economy" grade of gasoline that does not have ethanol in it at all. It is only 86 octane, but my Honda 20 HP four-stroke outboard seems to be pretty happy on it.

TrueBlue · #6 (**permalink**) 08-11-2006

eryka,
By law, all fuels containing ethanol must have the mixture posted at the pump. I would guess 5 out of 10 fuel stations we use (marine & otherwise) have the "Contains 10% Ethanol" sticker on the pump. I have learned which stations to avoid.

It seems that unless regulated otherwise, all gasoline will eventually have varying percentages of ethanol. If the current legislation for 20% is approved, older boat owners without the proper safeguards, may have more serious issues to deal with.

sailingdog · #7 (**permalink**) 08-11-2006

BTW, marine industry testing has shown that even grades with as low a percentage as E20, which is 20% ethanol, cause elevated engine temperatures and problems with engine longevity.

TrueBlue · #8 (**permalink**) 08-11-2006

sdog,
E10 (10% ethanol) is currently added to many fuel station's tanks. But, I don't believe E20 has been approved yet within the US. That is what Boat U.S., and other boater's advocates, are fighting against.

PBzeer · #9 (**permalink**) 08-11-2006

Unless I'm mistaken, ethanol is now used in gas in place of MTB. Higher percentages are still optional, such as E20 or 35. When they first started selling E35 in my former area (and it should only be used in cars that are designed for it) it was 30 cents a gallon cheaper than regular unleaded. Within six months, it cost the same.

sailingdog · #10 (**permalink**) 08-11-2006

Yes, Ethanol is being used in place of MTBE, which is both an octane booster and a water-soluble carcinogen. AFAIK grades of E-blend gasolines are not widely available in the US yet, but they do have some test locations supplying the stuff to a limited market. Ethanol also acts to oxygenate the gasoline, and makes it burn a bit cleaner, helping to reduce smog formation.

The switch to ethanol as an octane booster/gasoline oxygenator, is the reason behind the enforcement of underground tank inspection and replacement a few years ago. Mind you, one reason an octane booster is needed is that tetra-ethyl lead, was the primary octane booster used for many years, and was phased out due the the hazards of lead-poisoning in the 1980s.