99' explorer sport front end humming

[Phase 1]

Ok so I have a 99 explorer sport with a 5-speed 2wd with roughly 120,000 miles. I have this insane pulsating humming coming from the front left wheel well/engine compartment that's slowly been getting worse. So far it only starts once I'm over about 30-35 mph, anything lower and dead silent. Once I get to about 55 mph I can't hear it anymore but I'm assuming that is due to road noise. My first thought was wheel bearings so I took the front wheels off and the bearings have no excess play and still spin freely and full of grease. I can't find anything wrong with them. The brakes and rotors are all fairly new and no uneven or unusual wear that would explain it. Replaced the tie rods and the upper and lower ball joints as they were on their way out. That took away what little vibrations there were but not the humming. I'm really at whits end here. Maybe calling a priest to throw some holy water on it will clear it up.... Anyways before I start just throwing money at replacing everything, do y'all know of anything that could be causing this or even where to look next? I've been digging through the forums but haven't found anything that I haven't tried yet. Thank y'all in advance for any info y'all may have.

 

[Phase 1]

Well here's an update. Took it in for a balance and tire rotation and the head mechanic there drove it and took some measurements and he's pretty certain that the alignment is off. Got an appointment for that later this week and we'll see from there!

 

[mwarren03]

Was gonna say, sounds kind of like a bad tire. What was the verdict?

 

[Rhett]

I've had a cupped tire that hummed like that. It got cupped when I had bad hubs / bearings/ balljoints and I got too busy to get regular alignments / rotate/ balance. Yes...please do post what caused yours...

 

[Phase 1]

So results are back in. Once the alignment was done the noise was almost completely gone. What little noise was left the mechanic said was due to some minor cupping of the front right tire. He said it was most likely due to our little town in Texas having more potholes then roads and not rotating the tires enough.