As noted, casting flaws.
One way to know for sure, get a can of spray carb cleaner (cheap Wal Mart brand) spray those areas to clean the surface, air hose them until dry, then sprinkle baby powder all over the areas.
Next, take a hot air gun & heat the areas of the cases & if theres a crack there, the oils in the crack will bleed up into the baby powder showing the crack. It kinda works just like having something magna fluxed for cracks, where when the metal is magnatized, the metal powder follows the crack line.
Works real well with bead blasting dust, like the welding slag type.
Now dont go telling everybody this little trick, ya'll be put the automotive shops out of the magna fluxing business.
:popcorn: Neil
