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Bertram31.com General Bulletin Board
Re: Question for the ethanol affected
Posted By: Peter In Response To: Re: Question for the ethanol affected *LINK* (Harv)
Date: Monday, 3 April 2006, at 3:00 p.m.
In many states where they have already adopted the use of ethanol there are state guidelines for retailers (gas stations) changing over from selling old fuel with MBTE to new fuel with ethanol. These include flushing out and cleaning the old storage tanks because mixing ethanol and MBTE may cause a sediment to form.
I mention that because in Carl's post above he says he cured his problem until he fueled up again in NY. Did the mixing of the two types of fuel have anything to do with his problem re-appearing? Definitive answers to questions like that are difficult to find in our situation, but maybe mixing MBTE and ethanol fuels caused it.
Do some of the horror stories we have heard have more to do with mixing the two types of fuel than ethanol dissolving the fiberglass tanks, or stirring up old sediments and varnish? Who knows for sure?Conclusion: Once you have made the switch over, it seems prudent to try to avoid mixing the two types of fuel. If you have to make a temporary switch, run your current fuel down to as close to empty as you can, and then do the same when switching back.
Secondly, if your retailer isn't flushing out his tanks at change over time, it seems prudent to avoid filling up at that marina/gas station until several truck loads of the new fuel have been run through his system.
Permeability issues: Ethanol has greater permeability than any component of the older fuel. Therefore some of the ethanol will migrate through the walls of plastic tanks, which is also true with current fuel formulas, but to a lesser extent. On a particularly hot still day if you open the bilge of a boat with a plastic tank, you might notice a mild gas smell. This isn't the same as leaking, but can result in a stinky bilge and that problem might be worse with ethanol.
As for E-10 actually dissolving a fiberglass tank in good condition, the prospect doesn't seem likely, BUT the increased permeability factor will exploit any weakness in the tank. If the inner coating of the tank is in any way compromised, the ethanol will migrate into the glass structure and cause a failure by a mechanism similar to blistering. This in turn might lead to the ethanol dissolving any components used in the resins that are not fully cured.
Just going to a new form of resin will not solve this sort of failure. Any newer glass tanks, or glass-resin fixes to older tanks, need to be very carefully laid up and then post-cured at an elevated temperature to ensure full cross linking within the resin.Inadvertant higher concentrations of ethanol are possible; Enough water in the fuel can cause the etanol to phase separate from the gas causing higher concentrations than 10% ethanol in the bottom of the tank. This higher concentration CAN damage fiberglass. The source of this phase-seperated puddle of ethanol and water in your sump could be from your own tank getting some water in it, or from fuel pumped into your tank from water-contaminated fuel at a marina.
The above referenced state guidelines point out that the retailer should completely seal his tanks from water intrusion, much more extensively than for current fuel. Fixes include re-worked fill pipes and fill pipe covers for storage tanks and carefully sealed joints throughout their piping system...including updating any "Flex pipe" or elastomeric joints in the piping system. (See below.) Is your marina/gas station doing this?Ethanol eats the old rubber compounds. If you have not updated all of your rubber gas lines, vents and hoses since about 1980, it would be wise to do so before the season starts. It also eats cork gaskets. In higher concentrations it can errode aluminum, brass, zinc, lead, and I think I read somewhere cast iron. I have not seen anything about copper, but it wouldn't surprise me if that too were on the list of E-20 fuel incompatible materials. If we stop at E-10 we probably won't need new carburators and fuel line fittings, but if we go to E-20......
Conclusion: a 316 stainless steel tank with stainless steel fittings tig welded by a reputable shop and a master craftsman is the best choice for a long term tank fix. Include a quick drain sump to periodically drain off any water. And then you still must pay attention to the retailer that is selling you your fuel to be sure he is being as careful about the contamination issue as you are.
One new question for the crowd;
We know etanol evaporates quickly from the gas....Are etanol fumes lighter than air or heavier? If they are lighter, what happens when you hit the blower switch?
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