Hi Brent,Sorry I have never taken one apart. I've heard others say there was sometimes brick dust inside--maybe others can comment. Unless you run the engine for days at a time, I doubt it makes much difference. On other engines they appear to be empty.
Hi Brent,Excellent job. I hope your leather is flexible enough; it should be very soft leather.
Info on displacer piston I have had some original apart and no two are the same . Most have A 1/8th thick by 1 inch wide band rolled to fit inside displacer piston . It is riveted on 3 or 4 places to keep it in place in center of piston One had A tin can 1 inch thick laying on center band .not air tight .kept insulation from going to bottom .Insulation looked like Rock wool used in our home in ND in the 1940s one had A 3 star piece of metal laying on it and looked like A roll of asbestos dropped in there on top half of piston I have not seen A piston with any thing in bottom This info is Ericsson engine only
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A little more info on last post One piston had a 1/8 inch thick plate laying on center band with A 1/2 inch hole in it kept temp from rushing back and forth all pistons had the center band and I think it was to keep transfer piston from tin canning on pressure and vacuum stroke This info for Ericsson engines only I need to do more research on 10 Ericsson Do not know for sure how many changes were made on them all posts put up by me are open for correction
I think Buster was referring to what he has found inside displacer pistons (your earlier question). Don Worley has spent some time (and money) finding the most suitable leather for Ericsson engines. You can get one from him that will fit and work without additional cutting, soaking, drilling or experimentation--and they're relatively cheap.
Hi Brendon,If you are speaking about the substance inside the dis-placer piston, in my engine it is mineral/rock-wool (which seems to be similar to an early fiberglass). I hope this is not exposed in any way as the engine will not run without a perfectly sealed dis-placer piston. DO NOT OPEN IT! If it looks good and there is no sealing issue, leave it alone and put it back in when restoration is complete.