Originally Posted by Audios
It seems like its a crap shoot with those 3.5s. I have had a few muranos with over 200k on them and runs silent, yet I bought a Maxima with 38k on it that needed timing chains, and we recently had an 09 infiniti m35 that needed them as well.
It was a design defect, happened to my XTerra too. Nissan didn't bother to smooth out the rough edges left by dull cutting tools used to stamp out the chains, which led to them eating through the pastic tensioner and whining as they rub across the metal pin underneath. New chains since about 2010 or so don't have the defect, they also make the tensioner shoes out of a harder material so once you fix it, it shouldn't happen again. It was about $100 of parts and 2 weeks of my time, and once the issue is addressed I've heard of the 4.0s in the XTerras/Frontiers (the big brother of OP's 3.5) going 250-300k+. Mine's at 172k, runs well, doesn't burn a drop of oil in 5k OCIs.
The reason you say it was a crapshoot is because chains made at the start of a production run with sharp, new tooling came out fine. As the run went on, they got progressively worse, which is why some will start whining at 38k like your Maxima, and others lasted to 100k or more before starting to whine, and others never did. When I pulled the chains out of my XTerra, the ones I took out felt much rougher than the new ones I put in.