Head cracking is caused by Overheating which is caused by Ignorance of a maintainance tip.
Whenever a radiator cap is opened Most in NIssan engines. Air has to be bleeded from bleeding nut located at the rear end of engine usualy.
If u dont bleed the air out. u r bound to have problems like these. Its not the fault of a particular engine. That was the major cause of failure of Nissan vehicles in Pakistan because our local mechanics were not aware of this mechanism.
SD22, 25, CD17,CD20, GA series engines, they all suffered same fate in the hands of local mechanics as most people never approached the local dealerships cause they were expansive.