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

Mine knocked too. I found that there was slack on the big end of the connecting rod. I added a small
O-ring on the crank pin between the connecting rod and the crank and problem solved. I also put a small
amount of silicone around the exhaust pipe where it passes through the engine base underneath the engine.
It was rattling when the engine ran. The engine runs quietly now. Well,....relatively so.