Just an observation about the V6 in the R51 Pathfinder.. It seems that many have had to have there timing chain and guides replaced on 05-2009 models but what is interesting is that there are many people who have not needed to replace there timing chain and guides even with high millage. Case in point I have a friend that has a 2009 Pathfinder and he has 156,000 miles on his with the original chain and guides and it is the quietest V6 R51 Pathy I have ever listened to. He really does not care much about what oil he runs either he goes to Jiffy Lube between 6,500-8,000 miles and buys there lowest cost oil change. There are also several on this forum as well as ClubFrontier forum with the original chain and guides with high millage. Just seems to be the luck of the draw.

Just a side note the timing chain and guide issue was supposed to be fixed on 2010 on up VQ40DE 4.0 V6 Nissan motors.

From what I understand, the problem comes from a lack of quality control in the manufacturing process. Some of the chain guides are perfectly fine but others aren't and they develop problems as they wear. I read somewhere that it had to do with the age of the molds they were using in production or something like that. 140k on mine and no problemo so far.

As the stamps for the links wore used more and more, the edges of the links would get sharper. So, that's why there are some that don't have problems and some that do and why the mileage varies so much between those that have had chain issues. Borg-Warner makes the timing chains on these engines. Also, 2010 models are affected by it, too.

How can I tell it's worn out? Sound? Feel? Just recently bought a 2010 SE and am in the process of eliminating possible/probable issues.

Thanks

high pitched whining sound that progressively gets louder?

For me, the sound reminds me of old, Ford power steering pump whine as they were going bad. There are YouTube bids that let you hear what the timing chain whine sounds like.