asstor
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Hi Gang.
I have an interresting case for you. An observation on some NOS pistons and wrist pins I purchased for my M37's T245 engine. The outer boxes stated that they were packaged in 1951. The outer boxes were all in perfect shape with no physical damage or water stains.
Inside the outer box the piston was wrapped in a cotton cloth which was submerged in wax, creating an air and moisture tight wax layer. Inside this was a covering of grease paper, and inside this was the piston - coated in a layer of soft brown grease. The grease was almost like petroleum jelly - no idea if it was cosmoline or something else. The wrist pin was inside the piston, again covered in a grease soaked cotton wrap, and then a grease paper and a thick layer of grease. All this layering surely created a moisture tight package.
After unpacking and cleaning I noticed that the surface of the NOS wrist pins were dull (but smooth) and seemed to be stained, while the aluminum pistons looked as new as the day they were cast - no stains at all. So, I pulled out my handy pc microscope camera.
I took pictures of the wrist pin that clearly shows pitting in the surface. These pits are about 1/1000th inch across and seem to follow the contours of the surface staining.
At first I considered that the pits were inclusions (voids) in the metal. Maybe to hold oil or maybe due to inferior steel used back in '51. That is my question. Are the pits from corrosion or due to the structure of the steel itself?
Here are some pictures of the pitting. (these pits are about 1/1000th inch across). Notice the darker rings or stains that surround many of the pits. The pits themselves are very well defined and appear to be pretty deep and have sharp edges.
Here is a picture that show an area that does not have any pitting.
Any ideas on what the cause may be, but more importantly - are these wrist pins usable? Dimensionally they are spot on, and as I mentioned previously the pits are small - about 1/1000th inch across.
Thanks guys.
I have an interresting case for you. An observation on some NOS pistons and wrist pins I purchased for my M37's T245 engine. The outer boxes stated that they were packaged in 1951. The outer boxes were all in perfect shape with no physical damage or water stains.
Inside the outer box the piston was wrapped in a cotton cloth which was submerged in wax, creating an air and moisture tight wax layer. Inside this was a covering of grease paper, and inside this was the piston - coated in a layer of soft brown grease. The grease was almost like petroleum jelly - no idea if it was cosmoline or something else. The wrist pin was inside the piston, again covered in a grease soaked cotton wrap, and then a grease paper and a thick layer of grease. All this layering surely created a moisture tight package.
After unpacking and cleaning I noticed that the surface of the NOS wrist pins were dull (but smooth) and seemed to be stained, while the aluminum pistons looked as new as the day they were cast - no stains at all. So, I pulled out my handy pc microscope camera.
I took pictures of the wrist pin that clearly shows pitting in the surface. These pits are about 1/1000th inch across and seem to follow the contours of the surface staining.
At first I considered that the pits were inclusions (voids) in the metal. Maybe to hold oil or maybe due to inferior steel used back in '51. That is my question. Are the pits from corrosion or due to the structure of the steel itself?
Here are some pictures of the pitting. (these pits are about 1/1000th inch across). Notice the darker rings or stains that surround many of the pits. The pits themselves are very well defined and appear to be pretty deep and have sharp edges.
Here is a picture that show an area that does not have any pitting.
Any ideas on what the cause may be, but more importantly - are these wrist pins usable? Dimensionally they are spot on, and as I mentioned previously the pits are small - about 1/1000th inch across.
Thanks guys.