i think i may have the same sound and problem with my pump. I changed my t-stat almost a year ago and now that summer is back, my truck will barely ever run at under half temp (usually just a tick over the half mark and sometimes about a finger's width [until the clutch fan kicks in]). These 110 degree days are not very fun lately!

Today it was 110 degrees with 37% humidity. That's pretty dang hot around here.

 

i had the same exact problem lol. Its not to bad anymore since i have a bran new rad. but i thought i had it fixed at the end of last summer but thats just cuz it got cool enough