Mazda 3 2.3l rod knock 

have its not gonna be easy..its a spun bearing so ur gonna have to change the rod sand the crankshaft if ur not gonna change the rod then at least sand the journal smooth then add the new bearing chk ur measurements because u just might have to get 0.25mm undersize rod bearing

Considering buying a 2.3L with this exact issue - what did you end up doing? Doesn't look like the bearing replacement did the trick...

Ever change out the pistons?

Did you replace cylinder 2 and did the noise go away?

Did you ever figure it out?

The balancer has to be up with top dead center I'm doing this right now to mine

Did replacement of bearing work or did you still engine problems

I wouldn't waste my time rebuilding a 2.3 did it twice, these engines have a design flaw, used oil

Any update?

Engine oil use?