Hi.

this is my first experience with VQ35D engines and I have a few questions about them. As we know this engine has a timing chain that may generate sound. My previous car also was with chain and after the engine was started, you could able to hear a rattling sound. My Nissan quest has 134K miles and also has the same sound but it seems louder. Is it normal?

https://www.youtube.com/watch?v=fpebbXvnYiw

sometimes it is louder, sometimes it is absent. I have not found any correlation between this sound and other conditions.
Sometimes after driving a low-frequency sound like a gurgling (or even knocking) may be heard. It is relatively quiet in engine symphony but may be identified anyway.

https://www.youtube.com/watch?v=W_0kGJPyEgE

Is it a normal sound for Nissan V6? Where is it from?
Thank you for reading

I don't think that's chain slap. Slap isn't common in VQ's anyway, what's common is worn-down tensioner pads which make a distinctive "bumblebee" sound as the chain eats into the metal tensioner piston. I believe I hear a tiny bit of that underneath the general clatter. Hard to tell from the vid about the clatter itself, sounds like either an exhaust manifold leak or something rapping in the top end. I don't really hear the sound you're talking about in the second vid.

Small update. It was the timing chain. The main reason for that sound is the broken plastic part of the timing chain tensioner. Spend two days and replaced the chain myself. After that, the engine has started to work more smoothly.

In process