Help diagnose this engine noise at 5000 RPM, video
 

Odd thing happened today...

I dont typically rev my 4.0L this high but i was on the highway passing and i noticed when the engine revved to around 5000 RPM, there was this sound, i presume coming from the motor. its a very fast "Sheesh sheeesh sheesh" noise until the RPMs drop.

you can hear it in this video as the RPMs jump up, then a very short "sheesh" after they are coming down quick, i can reproduce it every time.

truck is running solid, i cant recall ever hearing this before, although i typically dont rev above 4000-4500 anyways.

is this valve float? or something i should get checked out under warranty?

2007 4.0L xlt 4x4 55,000mi
the tank had half regular and half 93 octane in it.

5 second clip
http://youtu.be/Dj2xJpFULxg



ps, my air suspension is no longer leaking air! score another one for RF help! :)

Will it do it not under load during a free rev? Enough engine oil?

take that to ford, they'll tag you with over-rev i bet. if the trucks running fine, i wouldnt worry about it. especially if you have warranty. a dealer will say come back when theres a problem.

hell, my ranger whines like a supercharger in first at 4500+ i ----ing love it =D

Oil level is perfect, I'm not sure I want to try it without a load on the engine

I'm not sure how this would be considered an over-rev event as its within normal operating spec (I believe). Redline on the 4.0 Is around 6000 RPM.