JDN_77

Heres my problem and i am kinda stumped, I have an 06 Manual that seems to make an over rev sound or surging sound when it is hot, I haven't noticed it when it was cold or warming up. The RPMs dont move though and power itself seems to not change just a sound and it is very annoying, sounds like you just down shifted and let off the clutch to slow down but not quite as loud. It also does it when I leave it in a low gear such as second or 1st and just slowly cruise down the driveway. The sound settles down after a about 30 secs or so after the shifting. I am thinking the fan clutch is making the noise but I just don't know it is hard to diaganose. I don't have guages or any performance boxes just a stock truck with an exhaust and an aftermarket intake system. Anybody else have this happen?

Grit Dog

Fan clutch.
It will be locked up in cold start sometimes and makes noise. Otherwise it never kicks in unless I'm towing up a steep grade/hot weather and you can watch it pull the coolant temp from 210 down to about 190 pretty quickly.