sadly i have seen a new one break on install.. the crappy cast steel sux on its toof... how can you tell.. when you remove i tlook at how its broken.. it was a torque did nto feel right thing.. pulled it back off the tooth fell off..
normally i see them fail when broken timming belt.. ok you fix the rod/head so on. but the force o fit actually popped the crank bolt loose..
sadly vanagon/dasher the old 1.5 ive seen quite a few come loose by say someone forgetting wrench on crank.. hit key.. then they can never get i ttight again vs say a bunny where they would air gun it on..
i am just courious why yours failed.. brain farts happen and my guess i swas torqued but not 90* turned.. or the crank sprocket failed.. tooth shapped off when trying to do the turn..
but pulling head.. set of valves.. checking rod heights.. can be fixed pretty easy... sadly id pull th eblock so i could lock the crank via other end to do the turn on the crank bolt..