Hi all
My '99 Cherokee Sport (4.0) just started making a whirring noise. The sound is similar to the belt, but it comes from the rear of the engine/trans area. It can be heard as soon as I start the engine and is constant, not changing with rpms or speed. i just changed the crank sensor and the whirring began after I started the engine for the first time after the crank sensor install, dont know if that's related. Any thoughts?

Checked all fluids today, all good. was hoping it was something simple, but no dice