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

A little update.  I got in my 5mm sight glass from McMaster-Carr, which is a bang on replacement of the original one (that broke during disassembly).  Even if I didn't bust it, I would likely have replaced it, shinny new glass always looks nice.

Other than worrying about the threads on my pressure valve, I believe I have its seal all sorted.  Unless I find something better, which is doubtful, my 5mm OD x 3mm ID (wall thickness 1mm) Flexible Silicone tubing cut to a hair over 1mm in length is working well.  I did buy some 2mm brass bar stock off Amazon, which fit perfectly into the center of my p/v stem.  The original brass bar in the p/v was just slightly undersized, IMO.  It kept wanting to slip into the seal.  I snapped a new bar of the Amazon stuff and filed the length to fit, so it was long enough to be just over the edge of the seal but not so long as to touch the sides of the inner valve wall.

Its hard to get a clear photo but you should see how the silicon seal isn't touching the inner valve wall, nor is the brass pin touching the wall but the pin is just long enough to give max downward pressure without slipping into the seal.  After a steam up test, zero leaking from the stem.

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