LariatDude

YEah no you're right too, it's something to check. Hell at this point it could be airbox, pulley, transmission, or rear diff related. It's a matter of pinpointing the sound.

OP, this noise only happens under acceleration right? I didn't hear it when you were sitting in park and revving it if I'm not mistaken.

northern pointer

Yes, you're right LariatDude. The noise is NOT there when idling. But it comes up when revving the engine, which of course happens when accelerating. At the end of my video, as I'm sitting there parked, I rev the engine in neutral a couple of times, and the sound is there when revved up, but not when idling. So it's not rear end nor transmission as FordBoy05 suggests, because they're not engaged when idling. So it comes down to something on the engine or the exhaust system, I would think

LariatDude

Is your truck 4x4 by chance? If so, does it make the sound when in 4x4? This post here makes it sound like the hubs are going out: http://www.f150ecoboost.net/forum/31...ow-speeds.html

tareed94

Could it be the passenger side manifold leaking? I remember a lot of people have had an issue with them getting a hairline crack at the block and allowing exhaust to leak.

northern pointer

My truck is 4X4, but haven't tried listening with it engaged. LariatDude, I read the article of your link, and the guys states that his noise is NOT there when in neutral or idling. However, as I stated before, when in neutral and pushing on the accelerator to increase the rpm, the noise IS there on mine. So it's not the 4X4 hubs then. As for the manifold leaking, yesterday I listened under the hood and the drone does sound like it's coming from the passenger side. If there is a hairline crack, how would I go about locating it? And how would I fix it? First I've heard of this.