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

Neither of the cylinder end caps have threads ... they are both just interference press fit. I've used Diesel fuel, Tap Magic, PCL and Kroil as penetrants to free up stuck metal. Sometimes some of them even worked! Another thing you might try is heat, as heating the outside of the cylinder should expand it before the heat gets to the piston and expands that too. Not too much heat mind you .... just a good hot can't quite hold on to it kind of too warm should be all it needs.

Keep us informed on how you are getting on with this worthy project.