Check your windshield wiper reservoir! Sounds out in left field, but I had a similar issue with my truck when I first got it. (brand new) Ended up the reservoir rattled and I initially thought it was something in the front end, did some searching on here and saw someone else post about this. I wiggled it and sure enough that was the noise. All I had to do was loosen it just a little bit, push it over some, tighten back up and problem solved! I love an easy fix...

Brian

 

Also heard of this happening with coolant reservoir