Ethanol Hates Carburetors!

Apr 2, 2014

Nearly all car enthusiasts have heard that ethanol in gasoline causes some problems for some cars. In the U.S. and Canada alone, the (estimated) 42 million cars with carburetors are the ones of concern.

Carburetor fuel systems were designed for use with pure gasoline. Ethanol is a “water absorber,” making it very corrosive. It is not added to gasoline at the refinery because it is too corrosive to be put in the pipelines. It is not put in gasoline in storage tanks for the same reason.

It is added to gasoline in the tank transporters as it leaves the storage facility headed for the gas station. Tanker trucks have to be flushed with pure gasoline unless they were built to the latest standards with stainless steel and/or “coated” tanks. Pumps, hoses and seals have to be updated to keep the ethanol from eating their parts. Old storage tanks at the gas stations have to be replaced and seals and piping replaced in the newer tanks because of the corrosiveness of the ethanol fuels.

Sources of Information

While relatively new to the United States motoring public, ethanol has been used for 40-plus years in places like Brazil, giving us a source for information as to how and why to prepare for its use in carburetors.

More information about alcohol-based fuels comes from the owners of racecars and the companies that make parts for racecars. Racers have used ethanol, methanol and other oxygenated fuels “forever.”

The surprise element comes when the guy or gal with a vintage car, muscle car or granddad’s old pickup finds it doesn’t run after sitting in storage for a while.

Lake Speed Jr., the head of Driven Racing Oil, states: “Disadvantages to ethanol fuel blends when used in engines designed exclusively for gasoline include: lowered fuel mileage; metal corrosion; deterioration of plastic and rubber fuel system components; clogged fuel systems, fuel injectors, and carburetors; delamination of composite fuel tanks; varnish buildup on engine parts; damaged or destroyed internal engine components; water absorption; fuel phase separation; and shortened fuel storage life.”

In common English, this stuff is bad.

Unexpected Problems

The reality is that there are all types of vehicles and equipment that require pure gasoline. Many were designed long before chemicals, such as ethanol, had been considered during the design and validation processes.

Critical components, such as engine seals, gaskets, fuel lines and most internal components, were once tortured on engine dynamometers, scorched in hot weather tests and designed assuming nothing less than 100-percent gasoline would be cycled through the engine during normal operation.

As you can imagine, introducing a different fuel into service can bring a new share of unexpected problems. To start, ethanol is hydroscopic, meaning it attracts moisture, which leads to increased levels of water in the fuel system.

The current E10 blend has the ability to absorb 0.5-percent volume before reaching a point where water will actually accumulate outside of the fuel mixture (called “phase separation”). This means that for a typical fuel tank, about a cup of water is being introduced into the fuel and supporting systems.

This water formation can (and will) lead to metal corrosion and the deterioration of plastics and rubber, especially if the vehicle is put into storage for a few weeks or more.

The corrosion issue is most detrimental in carbureted vehicles, which include hot rods, muscle cars and a large number of production vehicles. Many of the critical components of a carburetor, such as the main body and float bowls, are die-cast from aluminum or zinc.

When these materials are exposed to ethanol or the water often contained within ethanol, it creates a corrosive combination that can lead to carburetor malfunction and potential failure. The white powdery substance is zinc oxide. It cannot be just brushed away, because it etches deep into the metal.

The extra moisture that is introduced into the fuel can lead also to buildup or “sludge” that can clog the precision internals of a carburetor responsible for proper fuel delivery.

Gas tanks, needle valves, small springs and fuel lines are all steel and very prone to rust. Outside of carburetors, the materials that are commonly used to manufacture gaskets, seals and fuel lines are not consistently manufactured with ethanol-resistant fluorinated polymers. After prolonged exposure to ethanol, these materials can deteriorate, clog fuel filters and result in dangerous fuel leaks.

Traditional rubber fuel lines are eaten away from the inside, sending gummy particles to clog the inlet valves and jets. If rubber fuels lines are used, they need to be “ethanol-proof”. Those that were put on cars before 2004 are probably not.

E15 and Build-Test Issues

In 2011, NASCAR changed its fuel to 15-percent ethanol (E15). The race teams quickly learned that the ethanol in the fuel systems created problems with the carburetors and fuel pumps.

Since no components in carburetor fuel systems had been designed for this fuel, the teams could no longer build and test an engine and then store it for future use. Joe Gibbs Racing collaborated with a chemical company to find a solution.

Their product is now sold as “Carb Defender” by Driven Racing Oil. It utilizes the fuel to act as a carrier to deliver a microscopic coating to fuel system parts, providing a shield against ethanol, methanol and other oxygenated fuels.

Other companies provide various fuel additives to blend with the alcohols and water in order to disperse them through the fuel system. These have good, but limited, results and are not legal in many racing venues where the fuel cannot be altered.

The other concern is that, unless you are a chemist, you do not know the chemical properties of the new blended fuel. The specific gravity, molecular weight, octane content, rate of flame travel, rate of phase separation, and the timing and carburetor jetting requirements all change when any additive is introduced. This is not likely to be a problem in a 7-to-1 compression weed eater, but is serious for a high-compression V-8.

Storage Issues

For carburetor-equipped vehicles that sit more than they run, ethanol is a serious problem. Some examples are vintage or collector cars, race cars, street rods, muscle cars and show cars.

There are examples of new carburetors being put on cars, driven home and 90 days later they would not start or “run right” due to corrosion in the carburetors. This is an example of how fast the metal corrosion can occur in a steel or zinc alloy part.

The water absorbed by the ethanol goes to work immediately. For modern fuel-injected vehicles, these problems do not exist because they were designed with stainless steel lines and fittings, modern coatings on cast parts, and plastic parts and tanks that are ethanol-proof. Outside the automotive community, the same problems are prevalent in marine, industrial and small engine applications.

The Environmental Protection Agency (EPA) has mandated an increase in the percentage of ethanol in future vehicles. This seems to be a “politics vs. engineering” battle, so it will be interesting to watch as all parties involved try to solve the issues or alter the mandates.

Quoting (with permission) what the SEMA SAN (Specialty Equipment Marketing Association, SEMA Action Network) has stated: “The U.S. Congress enacted the Renewable Fuel Standard (RFS) in 2005 and then set ambitious mandates for the amount of ethanol to be blended into gasoline each year, going from 9 billion gallons in 2008 to 36 billion gallons by 2022. In order to meet the ever-growing RFS biofuel mandate, the U.S. Environmental Protection Agency (EPA) permitted the sale of 15-percent ethanol (E15) in gasoline. The EPA acknowledged that E15 poses a risk for older cars and therefore made it illegal to fuel pre-2001 vehicles. The EPA’s decision has spawned a huge battle across America. A coalition of unlikely partners has come together to fight E15. They include organizations such as the SEMA Action Network (SAN) representing collector cars and their owners, along with the boating industry, lawn-equipment manufacturers and the oil industry. It also includes the food industry and environmentalists (because the land, transportation, and energy costs undermine the benefits). The battle’s outcome is still unknown. The EPA’s decision is being challenged before the Supreme Court.”

“Old car” guys and gals need to pay attention to the changes and be ready to make adjustments to protect these rides.