If the heater supply tube's o-ring was leaking, wouldn't it go into a cylinder and burn, not leak out on the engine block? I can see and feel the lines coming off the heater supply tube and there is no sign of leakage there. I can see the coolant tubes and feel them and they are dry, so I do not believe the heater supply tube is bad. the coolant is oozing out of the cracks between the trans and engine block, pretty positive about. I dry the crack and coolant appears within seconds. If the block was cracked, wouldn't I see bubbling in the coolant tank and wouldn't build it up too much pressure and set off the tank cap?