So I searched forums and best I found was timing chain last over 300k miles but the tensioner should be replaced around 150k miles. Please help me understand when these chains or parts should be replaced as I am shopping for a G35 I am willing to pay and many have over 100K miles. My Acura TL is supposed to replace at 100K miles and Toyotas are the same. So when does the G35 chain need major service like that? Or other major preventitative work in the engine?

 

There is no recommended maintenance interval on the chain or tensioners. It is a replace as needed item or preventative maintenance item. I have never had to replace one and we have clients with well up into the 280,000 mile range on some G's with no noise at all. Unless you start hearing a noise from the chain I wouldn't worry about it.

 

Wow nice to know there is a certified tech on the forums!

 

When you hear a chain rattle is when you would need to replace them. That's usually caused by the main guide rail breaking though. It requires more work then just changing the tensioner to fix that though. I replaced mine around 120K, since my water pump was shot and I messed up the timing when I went to fix that. I had to take the timing cover off and figured I would replace all those while I was in there. My guide rails and tensior was still in pretty good condition except some minor plastic wear.

It's an expensive fix though, I was quoted by Nissan for about 1200 just in labor.

 

When do you hear the rattle? All the time or just at start up?

 

Usually, you hear it at startup and then it goes away after the oil pressure has built up.