99 Yukon whistle when it gets hot, wtf is it?

[ocdismex]

I just replaced spider injectors with updated, and repaired ac, now when the engine gets hot and no load it whistles sounds exactly like a bearing or squeaky pully so I removed belt and inspected. During test drive under a load it goes away when you turn the engine off you can hear the vacuum or pressure wheezing like letting the air out of a balloon.