Run Away Engine

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Brian Rupnow

Design Engineer
Project of the Month Winner
May 23, 2008
Reaction score
Barrie, Ontario, Canada
Run-Away Engine.

Back about a thousand years ago, when I was thirteen or so, I had an intense fascination for small gas engines. This wasn’t a totally bad thing, because hydroelectricity had only reached the part of Ontario that I lived in about three years before that.

Just about every house in the neighborhood had an old wringer-washing machine with either a Briggs and Stratton or Iron Horse engine on it, setting out on the back stoop, replaced by a washing machine with an electric motor on it. Heck, they’d even give you a dollar to drag it away to the dump.

I had a boat on the local lake with dual paddle-wheels on it driven by a Briggs and Stratton engine. I had a go-cart with an Iron Horse engine on it. I even had a gas engine mounted on my bicycle but it proved to be too top heavy and unmanageable for even me.

Somebody, I can’t remember who now, had given me an Iron Horse engine. (They were the ones with the cylinder setting on an angle instead of vertically), and were a bit more powerful than a Briggs. They had it on a small buzz saw, but could never get it to run properly, so they gave it to me.

The engine had no shroud on it when it came to me, but that was always the first thing to get discarded on these engines. They ran just as well without the shroud as they did with it. I actually think the shroud (which covered the flywheel and one side of the cylinder) was more of a safety feature than a cooling necessity.

I pulled the sparkplug and checked it for spark, thus testing the magneto as well as the sparkplug itself. The carburetor was a rather mysterious thing to a thirteen year old, and was incorporated into the gas tank itself. All you could really check for was if there was gas in the tank or not, and if the sparkplug got wet with gas when you tried to start it with the sparkplug wire removed and the choke on.

The engine wasn’t bolted down to anything, and I never thought about it needing to be bolted down to “try it out” and see if it would run or not. Somewhere on it’s journey from washing machine to buzz saw, to me, the kick starter mechanism had disappeared. This again was something often discarded (The accepted way to start these engines with a “disappeared kick-starter” was to wrap a cord around the pulley on the side of the flywheel and give it a mighty pull.

--So---That’s exactly what I did. With a great roar the engine started, and promptly fell over on the flywheel side. The flywheel stopped rotating, and the engine was then rotating at about 3000 rpm!!! If you ever seen the Tasmanian devil in an old Bugs Bunny cartoon, that was what I had.

I knew that this was not a good thing—and that what you did with a run away engine was pull off the sparkplug wire.—So—I reached in to do exactly that.

Some part of the cast iron engine hit the back of my left hand just at the point where my index finger joined the rest of my hand. It tore out a divot of flesh and kept right on running. The divot was right down to the bone, and I bled like a stuck pig!!! Then the engine had the decency to stop by itself and lay there in the dirt, sneering at me.

We never went into town to see the doctor for that one. Mom poured half a bottle of iodine on it and did my hand up in gauze and white medical tape. (The kind that pulled your skin off when you went to remove it.)

It healed up eventually, and left an almost perfect capital A shaped scar. Over the many years since it has mostly faded away, but I have never since tried to stop a run-away engine.

Brian Rupnow---2019