Re: 115 hp mercury bearing pictures
The cages don't do much except ride lightly on the crankshaft/conn rod and keep the bearings more-or-less evenly spaced so they don't slide all to one side or the other, or into each other.
If you'll note the ridges at the outer portion of each cage, this is what contacts the conn rod & crankshaft, not the center of the cage where the dark markings appear. That part never touches, they're not meant to handle that type of abrasion, only to "float".
The cages, as I recall, are plated at the factory (with silver? I can't remember!), maybe that cage didn't get plated all the way or it's just a strange marking down the middle.
I'd clean 'em up with solvent & a soft bristle brush, and check to make sure there are no points of extreme wear, where the bearings contact the slots in the cages. Make sure the cages aren't mixed up, and they're round & not warped in any way.
The default, of course, is to replace with new bearings & cages when rebuilding, but in all practicality (and budget), the condition of the conn rod and crankshaft surfaces will tell you whether the bearings are good or not.
If everything is nice and clean, no burn marks, chattering, signs of overheating (blue metal), chips, etc, you can clean 'em up and reuse. Just be sure to keep 'em on the cylinder they came off of, no indiscriminate mixing of used bearings and cages between the cylinders is advised!
One last caveat, if these are cracked-cap rods and the conn rod bolt threads directly into the rod, you should always use new rod bolts. They are typically stretch-type and there's always the possibility of breaking a used bolt, that would really ruin the overhaul!
Older-style thru-bolt-type rod bolts can be re-used but it's a good idea to renew the Nylock self-locking nut or thoroughly degrease & use a drop of Loctite Red on the nutted portion.
HTH & G'luck with the rebuild........ed
