Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

One of the bigger changes from David Kerzel's original design was using o-rings for piston rings, in this case two of them.  Even if you add a bit of lube into the fuel, the back o-ring won't get any unless you add it from the outside.  You are also limited in how much oil you can add in the fuel or you will just foul the spark plug.

I think it's telling that the only spare part that Banggood sells for this engine is o-rings.  I'm thinking about adding a drip oiler to mine like the original Kerzel design as it's probably even more important for this engine to help with the longevity of the o-rings.  Unfortunately, it's a tricky job to perform when the engine is completed as even a tiny burr at the edge of the hole will instantly ruin an o-ring.

For longer runs, I also keep a bit of water in the engine to better transfer the heat from the cylinder to the outside of the engine.  The cooler the o-rings stay the better.