thats what i'm wondering.. i looked and couldn't see any cracks with the naked eye. it was fine on the old motor which was changed out in june but who knows.. anything could have happened. found a couple on ebay but who knows if they are any good.
When I worked for Harley we used a dye for case cracks or porosity issues. That may help determine where it's coming from. Adding it and running the motor to circulate it thru the system and then wipe down the part and wait.