Well yes you are right about this color created by local hardening. I was thinking something else, where the journal bearing become blue itself, not the crank web.
Thanks
So far I took appart 4 3B, 2 pre1985 , 2 post 1985.
The pre 85 have two hole on top of the conRod to cool piston (idle) and lubricate the wall instead of one on the post85… which leave a little less oil for the wrist pin.
Might be a coincidence but. the wrist pin were really worn out on the...