is the bearing for the accessory belt tensioner the same on the GS300 and 400. I have a bunch of new ones if that I got when I did mine on my 300

 

Good question . It seems the actual type of bearing may vary a bit. Best is probably if one can be without the car for a few days to press it out and see what is in there.
I am sure we can help if it is not clear. These bearings shall be bought if generic type with extra play (C3 or C4 marked) because they get tighter when pressed in .
I had to do mine one more time because I forgot about this and the bearing was a bit tight after assembly. You should be able to feel that the bearing is rotating as easily as before when assembled and
also prefferably be able to feel a very small play . Beware that the serpentine tensioner wheel is assembled with a leftie screw. I managed to strip threads by not knowing and had to buy a new tensioner.

 

I did change the idler and the tensioner pulleys, and I also stripped the threads.. It loosens over time but I tighten it and it seems ok, I'll put some thread locker in the future, maybe it will hold. And for the sound I heard it on few other cars while looking for videos so maybe it is nothing to worry about right away. I just moved out from my fathers for college so I don't have much money to spend, unless it is serious.

 

I hear you on the college thing. Super high pitched whines like that usually aren't too big a deal. I can tell you from experience, twice, that failing water pump bearings can sound like a loose heat shield or skid plate. So if you hear something lower, rattley-er, check it ASAP. Larger bearings, like those found in all the pulleys, will make a lower pitched noise than what you're hearing.

 

The bearing case is stamped on the outside if I'm not mistaken. Or maybe someone has an old one they can pull the numbers from

 

Here's my squeak I noticed a couple weeks ago.
Happens on cold starts when weather is colder than 20*

Goes away after a few mins when the engine warms up.

http://vid313.photobucket.com/albums...psmc9gsua6.mp4


What can it be?

 

I always say to start by removing the accessory belt and spinning the pulleys. Start with the belt tensioner one