Effects on aluminium engines

As the subject implies, I am wondering what long-term effects the gas has on a typical aluminium engine such as a B&S aluminum bore?

I’ve done some searching and found conflicting accounts of adverse effects on aluminum or the pot metal used on carburetors. For those who have used small engines for extended periods, have you seen evidence of deterioration of any parts?

Edit: charcoal preferred, but accounts of other methods are also welcome.


I am willing to bet results will vary with the wood used. I some wood will be more corrosive then outers. Charcoal probably has a tendency to limit this as you are burning more of a pure carbon in the gasificer.

Lost track how long the first clone started on char gas, maybe 3 years. Never noticed a problem but never tore it apart. One thing that might help is that once they run on gas I never switch back to gasoline. Steel lined bore.

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I use charcoal on all my small engines , the only issue I do have is when an engine has been allowed to sit idle for a few weeks after running .
Both the throttle butterfly and choke will always seize up , the longer left sitting the harder it is to free off and needs stripping to get it free again .


What do you think the cause of this is Dave?
Carbon _/ soot left behind?

As Jeff said, I never had a problem except when switched back to gasoline. I never tore that one down but saw the soot in the carb turn to goo. It did all my mowing on char gas for a whole summer. Ran very well , could not tell much difference in power and would idle so slow. The next spring I went to mow for someone else and used gasoline and after about àn hour it started
To lose power as if it was over heating. I finished up with the other mower and never looked back. One of these days I’ll have to have a look.


Tom I am not 100% sure I have had some soot now and again come through with no ill affects , but sit the engine for a few weeks and it is well stuck , so when I strip the butterfly off the shaft I then had to take the float bowl off and use a very small drill in line with the shaft that holds the butterfly on to be able to knock the shaft out of the body .

when the shaft comes out it looks clean as a whistle no score marks or carbon/soot at all , is it a combination of the brass or steel a shaft against a aluminium body ,or just so fine of a soot I cant see it .

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its a tiny weeny bit of oxidising between the shaft and the body, coming from the H2 in the gas


Hmm, you know I do take the carb apart and do a ton of hacking. I really don’t recall for sure but when I reassemble I might put a dab of light grease or oil on the shaft when I reassemble it.

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Aluminium cylinders have a wery resistant coating in them, called nikasil here, sort of a superthin enamel, so this shuld protect the bare metal well. Pistons however, do not.

Without it, the engine wuld die within minutes.
It was a custom here to tune mopeds, mostly lathe the cylinder to a biger bore. Newer ones had alu cyls, and after boreing they had to be send to a factory to put new nikasil on. If this was done poorly, the microscopic layr wuld chip off, cause the piston to rub, or alost weld its self to the bore.

It is my understanding that many small engines, such as a Briggs and Stratton, do not use any coatings. B&S coolbore cylinder is just the aluminium alloy forming the block with no sleeves or coatings applied.

Any issues with corrosion of carburetors, heads, intakes, pistons, etc?

Most of my engines are aluminium, some with steel cylinder sleeves, some without, but for nearly all of them the block itself is entirely aluminium as well as many other parts, ergo my questions.

I don’t suppose anyone has pictures of a head or other surfaces after prolonged exposure?