my friend has a b18c5 that came to me with a nasty rod just got done disassembling the motor and when i got to cyl 4 where the knock was coming from i could shake the rod back and fourth pretty bad. Found a couple metal shavings in the pan but when i took of the rod the bearing was still there completely once piece with the rod could not tell it was there except for the notches where the two meet and the crank surprisingly was not bad at all had a couple hot spots and a little scratches but we were surprised. The metal shaving we found were from the bottom of the skirt that had broken off. Ill post pics tomorrow i was just so amazed that there wasn't damaged bad. By the sound of it you would think it was trashed like it sounded like a hammer hitting a steel pipe as hard as you could.

 

Sounds like the bearing spun.

 

yeah i guess thats what happened but from all the post i have seen of spun bearing they were destroyed and in pieces with gouges ect.