Nissan navara owners are well aware of the fragile nature of these motors and numerous problems have been encountered in all the different models of 2.5 turbodiesel engine. Many different theories float around about why the failures are happening but basically it comes down to needing to be extra attentive to maintainance and changing your oil more regularly than usual. Noteable weak points are timing chains and rod bolts as well as a tendency to crack the alloy cylinder head