I got a strange problem that just started a couple days ago. It is a buzzing/humming noise that occurs right around 2000 RPM's in all gears. It does not occur just revving the motor in nuetral. It also only starts once the truck is warmed up. It is coming from under the truck. I sat in the bed and had my wife drive it up and down the street while I listened to where it was coming from and I can hear it best right between the bed and the cab, which makes me think it could be something in the drive train. It just sounds more like a vibration than something mechanical. I have been under the truck more than I care to explain looking for anything that might be loose or vibrating and have had no luck.

The question really becomes if it is something in the drive train or exhaust maybe? It seems strange to always occur when lightly pressing gas and passing 2K RPM. I thought exhaust maybe since it happen after it warms up.

Please help.

Steve

It is a 2005 F150 5.4 4X4 Supercrew.

 

I assume by now you've dicovered the source of your noise, since it was 2007 and it's 2009 now. I started experiencing the same type noise a few days ago. What did you discover?

 

same here - any answer?

 

The funny noise coming from under the truck turned out to be the following. Ford uses a small vacuum device attached to the fire wall to lock in hubs. This vacuum device can spring a leak or the two plastic vacuum lines running to the hubs can leak.. This causes the hubs to float, slowly griding off the teeth (which is the funny noise). When you actuate the 4x4, if you have a leak, the hubs don't actually engage. I (my mechanic, Road & Truck, Thousand Oaks) replaced the hubs and the vacuum device which stopped the sound. A couple of months later, I was pulling my toyhauler across the U.S. when I heard a familiar sound. The hubs were floating again. I managed to get to Savannah GA, my destination. I had Ford check out the truck. The vacuum device had failed again, the hubs were toast, as well as the transverse case. R&R all. I have little trust in the truck anymore. I feel the 2006 F150 4x4 is not the FORD TOUGH vehicle I thought it was. I wish the old manual lock-up hubs were standard. Sometimes new is not better, just easier.

 

would this apply to a 2001 , 5.4 - 4x4?

Any pics of this vacuum device?

 

finally found the solution to my problem.

After 2 months of searching...

Turns out there is some kind of access door/hatch on the front of the tranny. It was a little loose and vibrating at 2500 RPM.

Holy Crap!