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Technical Matters

Ethanol:

  • Ethanol is one-third less powerful when burned than gasoline. This has a negative impact on gas mileage.
  • Ethanol is "hygroscopic." That is a fancy way of saying it easily absorbs water. In fact, ethanol is so attracted to water it absorbs water vapor in the form of humidity from the air. This water leads to condensation in fuel tanks, fuel lines and carburetor fuel bowls. The high content of water in E10 fuel also will swell the paper filter media found in fuel filters not designed especially for flex-fuel operation.
  • Water in fuel systems also leads to water contamination and/or fuel phase separation. If contaminated or separated fuel gets into the engine, serious and sometime irreparable harm occurs in the engine.
  • Gasoline mixed with ethanol has a shorter shelf life and goes stale quickly.
  • Ethanol is highly corrosive. It helps rust to form wherever air meets metal once submerged in it. Ethanol is also a solvent and it will disintegrate fiberglass, plastic, and rubber.

Fortunately, there are ways to keep classic cars safe from the danger of ethanol gasoline.

Seven Steps To Avoid Ethanol Fuel Problems In Your Classic Car

  1. Use ethanol-resistant hoses or nylon tubing to replace any plastic or rubber fuel lines.
  2. Replace fiberglass fuel tanks with a stainless steel tank.
  3. Use a water separator filter in the fuel line leading to the carburetor. Since water collects in the filter, you can easily remove it.
  4. Change out any O-rings in the fuel system to ethanol compatible rings.
  5. A carburetor fogging solution prevents condensation from filling fuel bowls.
  6. Use a flex-fuel-compatible fuel filter as it stops degradation of the fuel filter media.
  7. Use a non-alcohol based fuel treatment to prevent excessive water collection in your fuel. Ethanol based fuel treatments worsen problems caused by E10 gas.

Ethanol, made from corn or grain, is added to gasoline to oxygenate it, replacing the older additive, MTBE. Names for gasoline mixed with ethanol include E10, gasohol, corn fuel, alcohol fuel, and reformulated or renewable fuel.

The key problem is that ethanol absorbs water from the atmosphere. In fact, fuel with 10 percent ethanol absorbs up to 50 times more water than standard gasoline. Older gas tanks found in many classic cars vent to the atmosphere, increasing the likelihood that moisture will be absorbed into the gas tank at a rapid pace.

The end result of water in the fuel is phase separation. The fuel separates into two distinct layers: a thick layer of gasoline mixed with a little ethanol on top, and a thinner layer on the bottom consisting of water mixed with most of the ethanol. And it doesn't take much water for this to happen—phase separation occurs in a gallon of 10 percent ethanol blend with just 3.8 teaspoons of water.

Fuel Phase Separation Problems

What happens to your car and it's performance when water causes fuel phase separation?

Reduced fuel longevity: A gasoline/ethanol blend absorbs water until it triggers phase separation. The blend has a 90-day product life in a closed tank, but lasts just 30 to 45 days in a vented tank often found in classic cars. With 10 percent ethanol blends, owners are supposed to replace the fuel in vented tanks about once a month by driving or draining, taking into consideration the humidity in the atmosphere and temperatures.

Lower fuel octane: The ethanol in a gasoline blend provides some of the octane rating. When phase separation occurs, the octane rating of the remaining fuel can drop by as much as three points.

Poor engine performance: The fuel pump could easily pick up a slug of the water/ethanol slurry at the bottom of the tank, interrupting the flow of gas to the engine. This will cause the engine to miss, run rough and possibly stall altogether.

Corrosion and rust: Water in the bottom of the fuel tank and inside the fuel lines will cause corrosion and rust, and the solvent properties of the ethanol will loosen that up, along with bits of sediment and deposits. The resulting debris floating in the fuel could clog fuel filters, fuel lines and carburetor float valves.

Specific Parts Affected by Ethanol

Fuel tank: Ethanol could dislodge sediment and deposits in older gas tanks and fuel lines. Loose debris in the fuel could clog the fuel filter, or cause engine flooding if the carburetor float valve sticks.

Fuel pump: Rubber diaphragms inside the fuel pump may have problems with ethanol exposure.

Carburetor float valve: Float valve needles on early cars were brass, and these were replaced with plastic needles or brass needles with Viton (a specific type of rubber) tips. Ethanol can cause the plastic needles to swell up and stick either open or shut, which causes either massive flooding or starves the carburetor for fuel. Some owners have resorted to shaving down the plastic needle to get it to ride smoothly and seat properly. Instead, you can install an all-brass needle and seat, or a Viton-tipped needle if available for your car model, which are not affected by lower levels of ethanol.

Carburetor floats: The Zenith-Stromberg floats found specifically/only in the TR4 and 4A made of foam covered with a skin may deteriorate when exposed to ethanol. Other plastic floats, like those used by SU, may also be affected.

Hoses: Ethanol could dry out or deteriorate rubber hoses.

Seals: Ethanol could shrink, swell or deteriorate seals, depending on the material.

Gaskets: Ethanol may deteriorate the rubber in rubber/cork composite gaskets. Fiber washers and gaskets are not affected.

Aluminum and aluminum alloy parts: Aluminum and alloys fare fine with 10 percent ethanol, but are damaged by 25 percent ethanol.

Avoiding Ethanol Problems

Run your engine on fresh fuel from a major supplier in a location with lots of traffic.

Add fuel stabilizers when you put gas in your car to lengthen the life span of the fuel.

Buy higher-octane gasoline to be certain your engine gets the minimum octane necessary for good performance.

Keep track of the dates you buy fuel, how much you bought, and how much is in the tank when left sitting for a period of time. Keep a log book for reference.

If you have a closed tank, make sure it is truly closed. Listen for a hiss of air escaping when you take the gas cap off after driving.

Test your gas tank periodically to see if water is accumulating or phase separation has occurred. Treat accordingly.

If you don't have a fuel filter before the carburetor (many British cars only have a screen), consider installing one to catch loosened rust and sediments from the gas tank before it clogs engine components. Moss offers one with a glass bowl for at-a-glance inspection, yet it features a period-correct look (Fuel Pressure Regulator/Filter #377-435). Check your fuel filter often.

Consider adding a second fuel filter between the tank and the fuel pump to protect the fuel pump from damage from loose debris from the tank (Moss part #377-310).

Keep engine parts well lubricated to counteract the solvent effect of ethanol.

Regularly inspect all fuel system components, seals and connectors from the tank to the carburetor. Ensure there are no leaks and the system is in good shape.

Ethanol Free Petrol

Esso

Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). We would therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland.

BP

BP ULTIMATE BP Ultimate is the highest octane retail fuel that BP has on the market. It has an octane rating between 98 and 100 and does not contain ethanol. It is suitable for all cars but pre 1986 vehicles designed for leaded fuel may need to add an additive to prevent valve seat recession if they do not have hardened valve seats. BP Ultimate also contains a high dose of additive to protect the fuel system and to remove deposits that foul intake valves and the combustion chamber causing poor combustion and knock.

Roger Critchely Commented:-

"Very interesting article about ethanol. I run my car on Shell V-power which is 99RON. Shell say; "This means that, in the UK, Shell regular unleaded and Shell V-Power unleaded are likely to contain some ethanol, but it will not be present at more than 5% (in accordance with current UK specification requirements)." Although the car stood at Minsterley for 8 months with a ¾ full tank and started with no undue problems. Hopefully this meant that was no fuel separation or maybe the tank was so full that there was little surface area to absorb water.

I also use Tesco Momentum also 99 RON. The car runs best on this but the Piston Heads forums suggest that this contains more ethanol than Shell V-power.

I have used BP Ultimate but find that my TR6 does not have the same performance and can suffer from pinking and run-on. The answer to this could be to retard the ignition or use an octane booster."

Shropshire Group

  • Address/meeting place
    The Aston, Wellington Road, Newport, TF10 9EJ
  • Contact Name
    Roger Critchley & David Somerville - Joint Group Leaders
  • Telephone
    01743 790253 and 01925 245925
  • Mobile
    07811 260166 and 07960 664258
  • Email address
    recritch@aol.com

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