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

The crank does make some noise but it doesn't seem to hurt anything. My M90 has a lot of hours on it. I noticed the slop in the mains right away and it has never got any greater. Mine has split brass plain bearings. Take it apart and take a look. My split bushings show a trace of wear- just shiny. Be sure and note the position of the timing gear for the cam. The piston and rod comes out easily on the crank for ring service. If it starts really hammering, most likely ready for a new ring or rings.