I've got a 2011 Expedition with about 120k miles. Just recently I have been noticing a loud humming sound that seems to be coming from the left front area of the truck. At first I thought that it might be road noise from a tire but after a coworker heard the noise today and I paid closer attention, I realized that it's not a tire or bearing. It's quite loud, I start hearing it at speeds over 50mph and it stops immediately when I release the accelerator.

I wish I could pinpoint when I started hearing the sound but I just don't remember. There is no vibration, clunking, shaking, rattling, etc. Just this really loud hum coming from the driver's side front end.

Any ideas?

 

So at 55 mph it hums loud, but if you release the skinny pedal while slowing down to 54 it goes away?

If so, sounds like a driveline issue. 2wd or 4wd?

 

If raised on the jack, Does the axle turn when the tire is turned?
Could be the 4x4 actuators are bad.

 

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Fred - Did you solve this issue? I have a 2007 Expedition and started hearing a similar intermittent hum form my passenger front area when pushing the accelerator slightly at anywhere from 30-60mph. When I let off the gas it stops or if I push the gas more to accelerate it stops. I have all new tires, brakes, bearings, and alignment and haven't solve the issue.

 

Could be Air filter, air filter housing not seated or sealed properly.. or sensor on the air intake (down from the air filter).. for loud humming sound. Has been my issues. The loud humming from the right front side of engine. Only during acceleration and stops when I break. Hums like nobodies business coming from the air filter. This has been my most recent dilemma.