Gas Engine Magazine

Freeing a Stuck Piston with Vinegar

By Staff

This is a brief thank you to someone whose name I do not know. I am 71 years old and a gas engine nut. I have three running gas engines and go to quite a few shows around northeast Ohio. This thank you is to the man who wrote to GEM about two years ago and told about getting a stuck engine loose with vinegar.

Late last summer I got a 3 HP Fairbanks Morse that was all frozen up. I took the head off and got the valves freed up. I then reared the engine up and loosened the connecting rod at the crankshaft. I got a good piece of oak turned to the size of the cylinder. I set it on the piston and started working on it with a sledge hammer. The piston didn’t budge.

I tried some penetrating oils, but still no movement. Next I got a gallon of WD40, filled the cylinder, and let it sit for about six weeks. Still no go!

Then I remembered the story about vinegar. First I filled the cylinder with some store bought vinegar, but a little later I got a quart of good old homemade vinegar right out of the barrel. I let it sit for another six weeks. I watched very closely for the vinegar to soak through, but it did not.

I was next going to make a plate to bolt in place of the head with studs through the plate to the piston, but before that, I gave it one more try with the oak plug and the sledge hammer. It moved! Oh boy, was I happy! I went on with the hammer and oak plug. The piston came out in one piece and the piston rings were even in good shape. I am told the engine was stuck for at least five or six years. Now thanks to the “Vinegar Man” I have another engine that I can get running.

  • Published on Aug 1, 1990
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