Lead in Gas Tank?

[fourarmed]

Not exactly a boolit question, but more people will see it here. I opened up an old 015 Stihl chainsaw to get to the fuel filter, and the gas tank was heavily lined with a hard, white deposit. Could this be lead? It will scrape off into a powder form. The saw castings had a 77 stamp in several places, so I am guessing this is the year of manufacture.

[Reload3006]

I would be more inclined to believe that it was aluminum oxide. but sure its possible but highly doubtful as leaded gas disappeared in or around 1980

[Bret4207]

It's not lead. I see this all the time with older saws. It's some reaction between the alloy and fuel or something that I believe is a sort of acid. Never, ever store a magnesium/aluminum saw on concrete. The acid in the concrete will eventually eat the saw up leaving the same whitish powder.

[odfairfaxsub]

concrete equals caustic

[geargnasher]

Sort of, but just regular concrete that hasn't been acid etched or had something spilled on it like salt is fairly inert.

Concrete is, however, a moisture wick. It absorbs ground water through capillary action and filters it up thorough to the surface where it deteriorates cardboard boxes, rots wood, and rusts or corrodes any metal in contact with it. There might be some galvanic action going on too, not sure about that.

As far as what's in the fuel tank, oxygenated fuel will eat up any kind of metal, and depending on the region you buy fuel, you could have some of that. Ethanol is a moisture wick, and the 10% they're dumping in all our pump gas in an invitation to rusty fuel tanks. Too bad we won't be able to sue the EPA for damages when it happens. I would think the premix oil would help stop this corrosion, and maybe it IS helping, but not enough.

All that being said, you might try putting a couple dozen clean, pea-sized rocks in the fuel tank with some fuel and shaking it up until the rocks knock all the white stuff out.

Gear

[stubert]

I am in the power equipment bussines, the white powder is a reaction from alcohol in the fuel, alcohol attracts moisture. Alcohol and water, when mixed together corrodes aluminum alloys. We see it mostly in carburetors.

[Bret4207]

Stubert, chainsaw wrench here too. Yesterday I saw what would have been a very collectable McCulloch 740 that a guy left on the floor in his milk room for 15 years or so. He went to hand it to me and the rear handle let go! Darn shame.

[stubert]

Brett4207: It's funny, We complain about the alcohol, but it is a steady source of income.

[MtGun44]

Alkali concrete will wick water in many situations and now you have a corrosive environment,
not good for storing aluminum or magnesium alloy devices.

Sad to see a good saw rot out like that.

Bill

[Bret4207]

Brett4207: It's funny, We complain about the alcohol, but it is a steady source of income.

HAR! Yup, and rocks! "No, I didn't hit a rock with my lawn mower, it must be a factory defect!!!" Of course the divot the size of Milwaukee in the blade and sheared key are dead give aways.:bigsmyl2:

[canyon-ghost]

Concrete, ready-mix, contains some Aluminum and tons of Calcium on it's own. I hauled the stuff for 4 years. It has several compounds of Calcium that gives it a high base composition. The main hardening agent is air-entrainment, just a foamer that puts tiny air bubbles throughout to temper the reaction.
Consider this, in liquid form, it has a 3 hour shelf life, then goes hot (it has that strong chemical reaction). It's not as docile as you'd think.

[dmize]

Plain old water evaporation will do the same thing,I also believe something else in gasoline will do the same thing. I have seen the same thing in car and tractor carbureators and fuel tanks that have been sitting way before alcohol was in gasoline.
People pull those same stunts with lawn mowers too?? I thought it was only cars..