[David R.]

[QUOTE=john charlton;1845667]This is a typical freeze crack it is unlikely to spread probably been like that for years . The crack most likely has self sealed by rust .

I did find it odd that there was no sign of weeping or stains around the crack over the old silver paint on the block.
We used to use black pepper as stop leak, worked better than the commercial preparations, learned it from loggers in the mountains.