I have a 01 f150 4x4 that is making a humming noise, it sounds like its coming from the rearend. Does anyone know what this could possibly be? It doesn't feel like its grinding and its a constant noise at higher speeds (45-70) MPH. Thanks for the help

 

This hasnt been touched yet, I was kinda wondering the same thing. Mine does it when I put power to the rear end. If im just coasting, it wont make a noise. People have told me ti was bearings. But they never specified which ones.

 

I had an 01 F150 for 8 years, shortly after I bought it I had a hum coming from the rear end and it turned out to be the gears in the rear end. They changed the gears and the seals and it was gone. For me it was defective gears. I hope that helps.

 

I'm posting a new thread on a similar issue. I get a hum at all speeds above 25 mph, accelerating decelerating and coasting. The faster I go the louder and higher pitched the hum gets. Does that sound like you?

 

At about 15 miles an hour it becomes noticeable. Then as I get faster and put more of a load on the gears, it gets louder. That sounds quite like me. Im at 55,000 Miles. 5,000 more and my warranty on that is up. So now is a good time for the gears to start killing themselves. I do have a little slack in the driveshaft. Or at least more than I had 25,000 miles ago.

 

Its a humming noise that the gears make when they are meshing quite as they should. You can try a differential service but most likely it will require a new ring and pinion gear to get the noise compeletly gone. Its more annoying then anything

 

I've also heard that a little play up and down or side to side on the drive shaft means bad pinion bearings. Back and forth play is normal.

 

Yea there should be no side to side play or up and down. Now gears are a bit tricky and really should be done a professional as they as the bearings and pinion have to be exact or they can cause problems.

 

noise from the rear end when either accelerating or decelerating is USUALLY the pinion bearrings. this comes out from changing the loads on the pinion shaft during those times. accel noise is an outer and decel noise is the inner one. noise suring accel decel or coasting is a lil more complicated. can either be the carrier or axle bearrings as well as a possible problem with the gear mesh in the assembly.
none of these are normal. any bearring play shows a problem. as for the gears you need to open it up and check your gear mesh with marking compound as well as the backlash in the assembly to eliminate those problems.

 

Ive seen back and forth play in alot of trucks without any problems. Now its not a HUGE amount but ive seen some with little play and no problems. But back to the orginal poster I would get it checked out

 

My type of play is a little more than a little. I know I can usually turn it a little bit. Maybe an 1/8 of an inch with it in drive and the parking brake on. But this is just about a quarter inch. Can this cause a serious problem in the future? Or is this just the calm before the storm? Im going to get it looked at reguardless, but im just wondering how fast I should probably jump on this. At least now I know where to look Pinion gear, or bearings. Since its still under warranty, I fear i'll take it o ford, and when they test drive it they'll say "I dont hear anything"