My car had been making a whining each morning for about a month. it would whine at idle during warm up and also while driving up to about 2500 RPM then dissappear and then return if the RPM drops below 2500. This would go on for about 10 minutes until the car was good and warm then it would go away until next warm -up period. But only from dead cold so I would notice it more in the morning.
My thoughts were water pump or accessort belt. My engine has 170,000KM so it was overdue for a t-belt.
When I changed my timing belt last week I noticed a dry free spin idler bearing on my T-belt and a tight no free spin bearing on my T-belt tensioner.
I replaced both bearings and installed my t-belt. The bearing is a standard NSK 6005-2RS bearing available for like $10 at any bearing shop.

Whine is now gone. The bearings (not sure which one) where on their way out and complaining to me. I should have listened faster. Way faster

Do not put off service if you have similar issues. This is an interference head. Had either of these bearings seized it would have caused catastrophic damage to a very nice engine.
BTW the old T-belt looked perfectly fine. Zero wear. I bought this car at 150,000KM so it may have been done but the PO had no records.

Changing the T-belt is a very very easy job. It will take you about 30 min. You do not even have to remove the crank pulley. For the cost of an oil change there is no excuse not to.
--
73 ES, 91 240, 98 S90