Hey guys, new here. I have an 01 XE 4x4 with about 88,000 miles that hasn't had a problem since I bought it. For quite a while I've had a slightly low pitched engine rattle when i start up the engine on cold mornings. This isn't the lifters so far as I know because the noise from those only lasts about 5 seconds after starting then goes away. This other rattling noise though starts about 15 seconds after starting and lasts until the engine is near warmed up and only occurs at idle. Some notes:

- Noise goes away when RPMS are up above ~1000
- Not a consistent, uniform rattle (kinda sounds like a diesel engine a little)

Aside from this rattle noise, the engine has been bullet proof. No noises, smooth idle and operation once the engine is warmed up.

Any suggestions would be welcome. Thanks!

Loose head shield? Leaking exhaust header?

Those god damn heat shields!!
It's been a big problem for the Xterra.
I'm going to rip mine off when the weather gets better.