Ethanol and Your Marine Engine
Recently, we have had many questions about the effect that ethanol has on marine engines. The government’s decision to include this chemical in gasoline is a perfect example of unintended consequences. Many engines that use fuel injection pumps are now beginning to operate poorly (stalling, skipping, and starting hard) and often make a high-pitched squealing sound. Carter, who manufactures the fuel injection pumps that Volvo Penta uses, has had particular problems with ethanol, and the two companies are furiously blaming each other for the problems as some poor boat owners have had to replace pumps multiple times.
While carbureted engines are not affected as dramatically, gas left in the carburetors for any length of time leaves varnish-like deposits that can cause problems (especially at higher speeds) and require the pump to be disassembled and solvent cleaned. These are just some of the issues. Below, our new technical writer Stacy Lash discusses this further.
The U.S. Department of Energy (DOE) defines ethanol as an “alcohol-based fuel made by fermenting and distilling starch crops such as corn.” First generation ethanol crops include corn, sugar cane, and wheat; however, new second generation “cellulosic” materials such as grain straw, paper, wood chips, and even municipal waste are used to the same effect. In Maine and many other states around the country, fuel suppliers are increasingly offering an ethanol and gasoline blend known as Gasohol, or E10. E10 fuel contains 10 percent ethanol and 90 percent gasoline, and is acceptable for use in all gas-powered automobiles. This doesn’t mean that E10 is a welcome change for the boating industry, however.
E10 may be a safe, alternative, bio-fuel for your car or truck, but, in the setting of a marine engine, E10 poses a unique set of problems. Fuel mixtures containing ethanol have behaviors that can be harmful to your marine engine. The most important of which is how ethanol interacts with water and other compounds commonly found on your boat and in your engine.
You might more commonly associate the term ethanol with alcoholic beverages, and rightly so. After a crop is refined, it packs a whopping 200-proof punch. This is even more powerful than the Guinness world record holding distilled beverage named Everclear, which tops out at 190-proof. That translates to 95 percent pure grain alcohol to be exact. Ethanol begins its life as a product more likely found at a local watering hole, but the addition of the hydrocarbon gasoline makes it unfit for human consumption.
E10 supposedly creates fewer emissions and reduces America’s reliance upon foreign oil. Beyond that, ethanol replaces an additive called MTBE (Methyl Tertiary-Butyl Ether), a potentially carcinogenic substance that oxygenates gasoline as well as increases its octane. As of 2008, 25 states created laws banning the use of MTBE enhanced gasoline. Since that time, ethanol has become the preferred gasoline additive.
Ethanol is hygroscopic, meaning that water molecules have a natural attraction to it. Because of its chemical composition, ethanol is predisposed to both absorb and retain water. Ethanol will absorb over fifty times more water than gasoline alone. This might be beneficial in the context of sponges or bath mats; however, the combination of fuel and water is disastrous to the fuel system of a boat. Petroleum products, on the other hand, do not blend with water. At 70 degrees Fahrenheit, traditional gasoline will only absorb 150 parts of water per million (ppm). E10 will absorb a staggering 6,000 to 7,000 ppm at the same temperature.
Since ethanol molecules uniformly distribute throughout the gasoline molecules, when ethanol performs its peculiar feat of absorption, it effectively distributes water throughout the entire volume of liquid fuel. The clumped-up ethanol and water molecules then settle to the bottom of the fuel tank because they have a higher density than straight gas. The name of this process is phase separation. This is why people shake the can. Interestingly enough, it only takes a small amount of water to produce phase separation in E10-to the tune of just 3.8 teaspoons per gallon of gasoline. Addressing the issue of phase separation is essential because it has the potential to wreak havoc with a boat’s fuel system. Unlike automobiles which have closed fuel systems (why you hear psst when you remove the gas cap), boat engines, under Coast Guard regulations, cannot have closed systems and must be vented. This means that not only does ethanol absorb water, but it keeps getting new sources of water from the water vapor in the air.
Besides being hygroscopic, ethanol is also a solvent. A solvent is a liquid that can dissolve another substance, and ethanol is a very powerful solvent at that. It is capable of eating through resins, rubbers, even metals. This puts your fuel system (lines, tanks, filters), as well as your engine at risk. When we cut apart failed fuel injection pumps there is a fine black powder. This powder (similar to very fine baby power) is from the internal coating of the pump installed during the manufacturing process. The solvent in the ethanol breaks the coating down. When you hear the high-pitched squealing, it is the gas being forced by and around the powder trapped at the end of the pump. If you continue to run your engine, you can break down the powder even finer and push it out of the pump into the fuel injectors and ruin them.
If you own an older formulation fiberglass fuel tank (prior to 1995 or so), ethanol can dissolve the resin inside the tank. This incorporates contaminants to your fuel system in two ways. First, by introducing dissolved resin particles into your liquid fuel; second, by chancing that fiberglass particles loosened by the erosion will break free and get into your system. Outside of the fuel tank, ethanol can destroy fuel lines, gaskets, and other soft engine parts that aren’t resistant to its effects. We have noticed a great increase in the number of outboard fuel primer bulbs we sell.
As if being a solvent and hygroscopic weren’t enough, ethanol is also a potent degreaser. This means that if anything is clinging to the inner-working of your engine, be it grease, sludge, dirt, rust, or other type of infiltrate, ethanol will work its magic and release it into your engine where it will be distributed to parts like your valves, carburetor, filters, and injectors.
Ethanol also causes galvanic corrosion because of its affinity for water. Once ethanol has absorbed water that gets into the fuel system, it creates an environment ripe for corrosion. Even aluminum isn’t resistant to its effects! The water that has been absorbed into the E10 will, over time, erode the surfaces of aluminum parts. Water and aluminum produce aluminum hydroxide. Aluminum hydroxide in conjunction with heat produces aluminum oxide, which just happens to be one of the abrasive ingredients found in sandpaper.
Two other issues of importance are reduced fuel economy and shelf life woes, both of which can increase your fuel costs. According to the Alternative Fuels Data Center, published by the DOE, “a gallon of ethanol contains less energy than a gallon of gasoline. The result is lower fuel economy.” Simply put, it takes more E10 to produce the same amount of energy as a similar amount of straight gasoline. The DOE estimates the fuel economy reduction to be around 3-4 percent per gallon. This problem compounds itself once phase separation has occurred. As soon as ethanol absorbs the water, it leaves two unhealthy layers of fuel in your tank—a contaminated bottom layer and a low octane top layer. Low-octane fuel reduces engine power and performance.
E10 doesn’t perform well over time, either. While straight gas will often last years if properly stored, experts recommend not storing E10 in your fuel tank for more than 90 days. And that figure is the very upper end of the spectrum. Some sources will even state that its death-clock starts ticking at the two-week date. If you’re a commercial boater, this may not be a concern, however pleasure-boaters beware.
Ethanol is “bad news” for your marine engine. But enough about the bad; let’s focus on some good solutions that will help prevent E10 from ruining your investment. While some of the problems associated with E10 don’t have a direct or inexpensive solution, others are a simple matter of vigilance.
The part of your boat that is most vulnerable to E10 is your fuel system. Here is a list of fairly inexpensive ways to prevent or alleviate fuel system issues due to E10 use.
- Start by adding a product similar to Marine Formula STA-BIL to your fuel. STA-BIL protects the hydrocarbons in your gasoline from breaking down at a fast rate, keeping it fresh for up to 12 months. STA-BIL is not a cure-all, and will not address phase separation issues. We sell STA-BIL in both 8oz and 32oz sizes. There are other additives on the market including Marvel Mystery Oil, Sea Foam, and Aronol. Be sure to check with your engine manufacturer to be sure you have chosen the right one, or at least one that will not void your warranty. (Some additives may actually increase the percentage of ethanol in your gas, and that is something you definitely don’t want to do unwittingly!)
- Replace older-style, rubber fuel line hoses with modern barrier lines. This will prevent the ethanol in the E10 from eating through your hoses causing leaks and dislodging particles.
- Replace all rubber and plastic components with modern, ethanol resistant materials.
- Always have spare fuel filters on-hand. Nothing spoils the day like a clogged filter and since boating with E10 is notorious for creating issues that require a filter replacement, having one on-hand will prevent a lot of wasted time. It is also wise to change your fuel filter more often than in the past. Many people change the fuel filter in the spring and wait until the next spring to change it again. If you use your boat a lot then, paradoxically, you might be able to have a single filter change as the gas is used up quickly, but if the boat sits around a bit unused, you might want to change the filters twice a season.
- Install a second in-line water-separating filter between your fuel tank and your engine. This will add another layer of protection to your system. Always hire an authorized installer to perform this type of work.
- You might want to make sure you have a spare raw water impeller onboard. We have had a big increase in the number of impeller failures. While it is hard to believe, it appears that all those older two-stroke engines put enough unburned gas in the water (lakes especially; think of the poor fish) that water sucked in by the raw water pumps (both the ones in the foot of the drive or outboard or the ones inside of the boat) sit in the pumps when the engines are not running. There is enough ethanol mixed in with gas that in turn is mixed with cooling water to suck out the plasticizing agent in the impellers. The impellers get brittle and fail.
- If you are currently using an older formulation fiberglass fuel tank, consider swapping it for an ethanol-resistant plastic one. Over time, ethanol will cause blistering and erosion of fiberglass tanks, something easily avoided by changing materials.
- “It’s generally advisable to plan ahead so that your boat is stored with a minimum quantity of fuel,” says Jeff Stuart, technical support manager for Volvo Penta in North America. Limit filling your fuel tank to no more than you will use in a short time frame. Moreover, when storing your boat for longer than 90 days, be sure to follow proper procedures to ensure your fuel system is ready for use when you need it next. Check with your manufacturer or dealer for recommendations.
- Lastly, if you have the option, consider purchasing standard non-ethanol gasoline for your boat. Some harbormasters have listened to the complaints of their boaters and installed pumps for this specific purpose. It’s worth the call to check.
Call one of our experienced sales representatives to discuss replacement parts or upgrades that will better protect your marine engine from damage due to using E10. 1-877-621-2628.
Food For Thought
In 2010, the Environmental Protection Agency (EPA) began taking steps to allow fuel manufacturers to produce a 15 percent ethanol blend, or E15. In April of 2012, E15 gained approval. Because of the logistics involved in offering this new fuel blend, stations will be slow to add tanks and pumps. The first station in the country to open a pump with E15 fuel was in Lawrence, Kansas on July 13, 2012. Even if this becomes a trend, it’s unlikely that it will occur overnight. Moreover, many stations adding E15 to their menu will do so with the use of blender pumps that allow consumers to choose the level of ethanol they are adding to their gas—10, 15, 30, or 85 percent.
The primary concern for boaters when E15 and higher become more widespread will be selecting the correct mixture to keep your boat in the best condition possible. Obviously, this means choosing the gasoline blend containing the smallest percentage of ethanol. Accidents may happen however, and this will likely be at the expense of the boat owner.
Ethanol isn’t just expensive to boaters. It appears as though it’s had an unwanted side effect on the nation’s food industry, and by extension, global relations.
As of 2011, U.S. corn crops earmarked for use in ethanol production exceeded 24 percent. As ethanol production has reached new highs, so has the demand for corn. But it’s not just the refineries that want it, so does the food industry. USA Today reported just 18-months ago that “U.S. reserves of field corn are at their lowest level in 15 years.” Higher corn prices mean higher beef prices, as livestock are dependent upon corn production. Couple rising corn costs and unexpected droughts that reduced the yield of corn crops worldwide with a higher demand for ethanol and the result was the food crisis of 2011. Rising food costs initially spurred the Arab revolts occurring that year and the consequence was higher oil prices. Unfortunately, both oil and corn prices refuse to stabilize or decrease.
Unless a balance is found, this cycle will undoubtedly continue, especially if E15 and higher become the fuels of choice for automotive consumers.
- Ethanol. US Department of Energy. July 11, 2012.http://www.fueleconomy.gov/feg/ethanol.shtml.
- Ethanol Benefits and Consideration. June 6, 2012. http://www.fuel-testers.com/expiration_of_ethanol_gas.html.
- Gas Expiration – Ethanol Blend Fuels Have a Short Shelf Life. May 5, 2008. http://www.fuel-testers.com/expiration_of_ethanol_gas.html.
- Meier, Fred. “EPA allows 15% ethanol in gasoline, but only for late-model cars.” USA Today, 10 13, 2010.
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Marine Parts Express is a division of Water Resources, Inc., a privately held Maine Corporation.
For all your marine engine parts needs, call us toll free at 877.621.2628, or outside the U.S. at 207.882.6165.
August 31, 2012 / Stacy Bettencourt / 0
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