09_f150

Ok on the highway yesterday my truck started making a loud humming sound. I had to finish driving it home cuz I had no other way. It made it but the rear end noise is very loud. Seems like I cant hear it till like 10 mph. When driving through town I noticed when I let off it would get quite and then turn into a grinding noise, I could feel it slowing the truck down. At low speeds driving it sounds kinda like a rumble. Like something rubbing I guess.
It's quietest when I let off and barely touch the gas as in like not gaining speed or letting the transmission decel the rear end. Searching I only found peoples was either faint or when turning. Mine is very loud and going straight.

Today I pulled the fill bolt and fluid came out. Looked alright, not milky or Metallic. I noticed the driveline had a little bit of play in it. Idk how much is acceptable. I can take pictures or videos if that will help. I'm hoping it's just a bearing or something I can do. I don't know anything about rear ends so any help is much appreciated.

Another thing. I checked the brakes and nothing seems to be rubbing. Noise seems to be coming from the middle. The driveline yokes (idk how to spell that lol) look fine also.

alsatropine

iTrader: (2)

Hate be the bearer of bad news but sounds like your rear end is about to go.. I'd be real careful and have it rebuilt quick..

alsatropine

iTrader: (2)

Oh and by the way you will have a little slack where the driveshaft connects to the the rear diff.

Murray Clark

I took my 2009 F150 in for the 100,000 km oil change and they recommeded a rear diff and tranfer case oil change. After the change, on the highway above 70KPH there is a lound humming noise coming from rear end. Took the truck and checked oil and the change was to spec. As you get up to 100KPH the noise is very loud.
Any ideas?

Manuellabour247

I'm assuming the rear end is in an 09 F150 per your screenname. If so, is it a limited slip or non-limited slip? That will make a difference. Limited slip needs a friction modifyer for the rear end. If you have changed the fluid and did not put in the modifyer, you likely toasted your limited slip (clutches). Double check your u-joints as well. While you will have some rotational "play" in the driveshaft, you should not hear it ping back and forth. Should be a solid clunk as your pinion gear connects with the ring gear in the rear end.

Does it make a noise when you put it in gear (forward or reverse) from a stop?

kobayashi maru

Noise from rear-end when accelerating or decelerating but not when speed is constant... This sounds to me like the teeth on the gears are worn/damaged and not meshing properly.
It's also conceivable the pinion gear has moved out of alignment. It might be possible to re-align it in this case but will likely require tedious trial and error.