i just got my 2001 expedition eddie bauer with the 5.4l motor. every time i'm sitting still whether i'm in park or drive r reverse or neutral I hear something vibrate and put a slight drain on my alternator. when I open the door to go check under the hood it stops right as I get out. I figured it was coincidence. so i had my girlfriend sit in the driver seat and put it in park, drive, neutral and i stood by the noise. finally it came on and I felt where it was coming from with my hand cuz its massive vibration. right behind the pass headlight kind of under the washer fluid resovoir is a silver box lookin thing. I touched that and its kinda hwarm and its vibrating like mad. now i'm not sure if that thing is vibrating or something close to it is vibrating and shaking it cuz I was checking this in the dark, in the rain. i'll prob swing by the local ford dealer because the truck has limited powertrain warranty and i'll ask them what it could be. if anyone has a photo of that area of the engine bay on a 5.4l engine i'll point it out. any help would be greatly appreciated. thanks

 

I've come to realize its the air pump for the air leveling suspension. It comes on alot usually when i come to a stop. is there any way to adjust the sensitivity of this thing?? thanks and any input is greatly appreciated

 

You may have an air leak in the system or a height sensor going bad.
I would have it checked out.

 

See my post "struggling air pump?"

This seems to be a problem as I have seen this posted before. Of course, I have never seen a good reply.

The best reply I've seen is that the gromets are bad, and in order to get factory ones you have to purchase the entire unit (even though the pump might not be bad). I heard that you can purchase generic gromets and make them work, but I was hoping to get that confirmed here -- hence my post.