1984 Nissan Truck Knocking

Greetings. Ans: It depends on the knock noise and origin. If it sounds deep (low pitched) and coming from the bottom section, then it very well can Ba rod or main bearing problem. I have the same w/ such problem. If it sounds abit of a tinging noise and around the upper (valve cover) section ten U might have slipped the timing belt a tooth or 2 and jumped time. Not an easy task for the non mechanically inclined or lack of familiarity w/ the Z/K engine series. There is a trick 2 getting the belt on w/out dropping the tensioner down behind the cover towards the crankcase. If local 2 Atl I can suggest a few capable mechanics. The milage suggests the belt is due changing depending on the care, climate and drive history of vehicle. Good luck.