My engine started making really bad grinding and squeaking noises lately. I have done the following, but can't figure out which pulley is causing this:

1. Removed belts spun all pulleys except harmonic balancer and they seemed normal.
2. Replaced both drive belts.
3. Replaced both idler pulleys.
4. Disconnected AC belt and noise is still there.

So, I have narrowed it down to alternator, power steering, harmonic balancer, or the other idle pulley. My next step is to remove the extra pulley and use a different belt, but other then that I'm stuck. I uploaded three videos and maybe someone can have a listen; I also adjusted the tension before, after, and while the engine was running. It would go away for a little bit, but then come back.

Is it possible for the tensioner brackets and bolts to go bad?

 

Sounds like a power steering/water pump bearing, to locate put a very long screw driver on the parts with your ear on the handle. (engine running) You should be able to pinpoint the area the noise is coming from.
Gary

 

I have a stethoscope and I put it on the timing chain tensioner cover, water pump cover, alternator, and power steering pump. I didn't hear anything out of the ordinary from those parts; I cant really put them on the pulley themselves due to the spinning speed. I'll try again later when I get home.

 

Well you called it the power steering pulley has some play and shaft is slightly bent. I also took all the belts off and noise was still there, so it is either the harmonic balancer or water pump.

 

Took it to a mechanic today and he said he's pretty sure that it's the water pump and wanted 500 to change it. I decided to tackle this project on my own and replace the tensioner as well. I bought RTV sealant, OEM water pump, and ordered a tensioner from the Nissan dealership....wish me luck!