David Leonard wrote:

So just for fun, I took a piece of scotch brite to the "discolored surface" of my side housings (the ones that overheated).  I guess it was just a carbon coating because it came off in less than a minute of light rubbing.  Here are the before and after shots.  No evidence of cracks or distortion, so I plan to use them in my re-build.

Dave,

   You might want to have them magnafluxed, just to be safe.  As I mentioned
before, it takes about 600 degrees F to turn steel blue.  However, the blue
is a surface discoloration - actually a form of oxidation - thus it will
come off with scotchbrite the same a rust.  The different colors that the
metal turns as it heats up (straw, purple, blue) are due to different oxides
that form at the various temperatures.  The blue may be gone, but the
underlying metal has still been at 600* while the rest of the iron has not.

Dale R.
COZY MkIV #1254