I have an '07 Supercrew with the 5.4L engine and approx 52000km on it. I've done various searches on here but can't seem to find anyone with the same engine noise issue I have.
I get a squeeling noise from under the hood only when the engine is under load and above 40km/h. It makes the noise at any speed above this (maybe I just can't hear it at lower speeds) when I accelerate or when the engine is de-accelerating. During acceleration the squeel gets louder until the transmission shifts then starts out quiet again & increases with engine speed. It doesn't matter if the truck is hot or cold or what the weather outside is doing.
I have it in to Ford & they can hear the noise, but aren't sure what is causing it.
Any ideas?
Thanks

 

What has Ford done to try to isolate it? Have you tried running it without the drive belt to see if it's accessory-related?

 

Ford said they "tried a few things" but couldn't isolate the problem. I haven't tried running it without the belt yet.

 

As far as it goes, it could be a bearing in one of your pulleys or your idler gear going bad. I've had friends have that happen on their chevys. Not dissing, just saying. The bearings in their old/newer trucks would just go bad, and it would squeel at higher RPM's when the bearings got hot. My buddy with an older 350 diesel was driving along, pulling a horse trailer when the squeel started in hers. 2 miles down the road the idler pulley locked up and the belt pulled it right off. So it is a good chance that could be your problem.