Belt - Tensioner noise

[Budro12345]

I have a 2009 silverado 5.3. Replaced both the idler pulley and tensioner pulley. Have a rattle in the belt or accessory drive. If I remove the belt and start it goes away. Barely hear it at idle but sounds like an empty spray paint can with the marble after 1500 rpms. If I tension the belt tensioner just a bit more with a ratchet the noise goes away. The tensioner does move a bit while the truck is running. Do you think its the tensioner itself that has gotten weak or bearing somewhere else? Tensioner has about 180k on it. I know this sounds crazy too, if I spray WD-40 on the back of the belt it goes away as well. Water pump has about 15k on it. Any help would be appreciated.

Edited October 30, 2020 by Budro12345

[davester]

I would suggest using a mechanics stethoscope to narrow down where the sound is coming from (carefully, as you'll be probing near the spinning bits).