Ok truck is a 06 cc lariat with 35000 miles. A few months ago i noticed a subtle whine or whistle when motor is in 1300-1500 rpms with no load while driving. I can park in the driveway idle it up and hear the whine but can not find it anywhere. Noise goes away with more throttle and dies off when letting off. I have been to the ford store and mechanic said he never heard a better 6.0, but went to the performance diesel shop and they can hear the noise but do not have a clue. they said let it develope (has not got any worse)
Does not seem to have lost any power, just a anoying sound that truck did not used to make.
Any help would be apperciated i have went through every forum on the net about 6.0 whine and whistles but all seem to be about head gaskets and degas caps where this is more of a pump whine or could even be desrcibed as road noise howl while parked LoL.