This is my 01' S2000 with about 178XXX miles. This specific sound hasn't started occurring till recently and my oil is good and changed. I've changed the serpentine belt and I may change the bearing as well soon. But some say it's a TCT issue too, and from some videos on the web it sounds similar to mine.
https://vimeo.com/362305643

 

I just replaced my TCT with a Billman and that does not sound like TCT noise to me nor what I had going on.

 

The sound is there at first but sort of comes and goes as it pleases. It's never ever since constant sound, so I can't point it out directly. Maybe it's a bearing? I don't know. I need help and answers.

 

Take the serpentine belt off and start the car. Does the noise stop? If so it is limited to the tensioner bearing, idler bearing, water pump, alternator or AC compressor. It is much harder most times to troubleshoot a bearing without load on it, but if you limit it to those things, you can start to test for play, etc and see if you can locate it. If the tensioner or idler pulley, you can actually buy the bearing itself by knowing which one to buy (I have bought them so can go look at which one it is) and replace it vs spending bigger money on a tensioner or the entire idler pulley. The bearing is about $10 and the same part number works for both. Super easy to swap with a press, but I know others here have done it with hand tools and a vice as well. It does not take a huge amount of force to press out or in.

But, start with eliminating things that you can, and removing the belt and checking for the noise is the easiest way to limit it to those specific items.

 

In the case it is the ilder or tensioner bearing, this is the correct one

 

Yes sounds like a pulley, definitely not TCT.

 

I just purchased the bearings. I bought two one for the tensioner and one of the idler. From what it seems, the idler bearing is completely shot. It definitely seems like the source of the noise, but we will see tomorrow when they come in and I replace the. The idler bearing was so bad it was making some sort of squealing noise just spinning the pulley on my finger. So i'm hoping that was the 1000% source.

 

Cool, may be a cheap fix then! Be sure when pressing the new bearing in, that you pick something that matches the outer circumference so you are pushing on that and not the middle of the bearing. When you remove them, you are pretty much stuck pressing on the middle since there is a lip on the back of the pulley that prevents pressing on the outer race. But they are not hard to press out so the bearing should not come apart and leave you with the outer race stuck. But to be sure, clean it well and maybe even spray some penetrating oil of some sort around it and let it sit for a short bit, and press it out slowly to ensure the outer race is moving with the rest of the bearing.

 

I have a feeling it's the source. It's definitely a pulley issue because when I took off the belt and the car ran with no issue. I heard no squeals, but once that belt is on its awful. As you said it may be a cheap quick fix which is definitely great to know! If that's the real case, I'm really happy that it will be fixed that cheap. I expected it to cost more to fix whatever was wrong. So I hope my luck stands true and it's the problem. What everybody on here has says, it's a pulley. So I'm replacing them, all I can do.

 

Should I add any grease to the bearings when I put them in? Like Urea Grease or even basic bearing grease?