3304PC Precombustion Chamber Problem found

New loaded head came with precombustion chambers installed. I just happened to find this problem when salvaging the old head. I didn't catch it right away. I suspect that this came out of the non-firing #2 cylinder. You could also see the old head was cracked through the precombustion chamber threads and exhaust valve on #3.

Common problem???

Thats what happens when the coolant isnt checked regulary and operated with low coolant levels. Also starting engine right away and putting under load without warming up first.

Not uncommon but not common either. They are all two piece construction, furnace brazed together and occasionally let go at the seam. You were lucky to get it out in one piece.