It probably needs a valve adjustment, but these (like many Nissan motors) use shim and bucket lifters, to bring the clearance back to spec you need to order the proper thickness shim. I've explored doing it since my 1.8 has 325 000KM on it, has sounded like a TDI at idle for a long time. It can be done i just am not sure how the shimming works, whether Nissan sells just shims, or do you have to buy a whole new lifter?
Plus you have to take out the cams to put the shims in.
Plus you have to take out the cams to put the shims in.