Do you trust the mechanic 100%? If not, get a second opinion on that "cracked block" That doesn't just happen! The usual way is if the car is continuously overheating, and/or someone puts cold water into a hot radiator with the engine off.
Please don't freak out yet! I had a mechanic try this on me before, that's how I know. I found an honest guy, finally, and all I needed was a hose repaired and new coolant
