Yes, I think they call it electrolysis. Looking from the coolant side the holes are perfectly formed, like they were drilled.
@Mursal @startinghandle @Happy hillbilygood morning glensman I hope that you keep us updated what the actual problem is
There was a liner fitted to repair the old block. I'm not sure about replacing it, there hasn't been a final decision made about it yet.The original block hasn't a liner, so there was a liner fitted to repair the old block?
You cant draw the old liner out and replace?