Hi, when I start the Ford Expedition there is a loud humming/vibration that last for about 1 minute then it goes away. Sometimes it comes back for a few seconds when the truck comes to a stop. Any ideas?

 

Seems to be coming from under the washer fluid reservoir.

 

i have a '00 f250 with the same problem. i thought it was the power steering pump , but when i replaced the pump (not for the humming reason) it still did it. yes , like yours , mine does it for a minute if even that then goes away. never really concerned me, and does not effect the drive ability. this problem is way down on the list of repairs on my truck.

 

I found out it's the compressor for the air suspension and it's suppose to do that I guess.