I started to hear a humming noise from the back of my 2005 F-150 and my buddy who is a mechanic (and lives 300 miles away, otherwise I would use him to fix this) told me it was either the axle or pinion bearing. I took it to a mechanic down here (not a Ford dealership) and he told me the entire rear differential needed to be rebuilt, quoting me at $1,183. Can I trust this place, how can he know without taking anything apart that it is the entire rear differential? All he did was take it for a test drive and put it up on his lift. Also, does this sound right for replacing the entire differential? Apparently a replacement at the junkyard was $1,500. The truck only has 85,000 miles on it and I don't see how the whole differential could have gone this quickly, I don't ride it rough. Thanks for all of your input.

 

I would change the Differential lube before replacing the rear....it can't hurt to change the gear oil to see if the noise goes away.

 

You can normally tell what bearing is bad by running it on a lift and checking certain spots with a stethoscope.

$1100 doesnt sound bad, but he better replace every bearing whiles he's in their. A cheaper route would be to just replace what is making noise, be it a pinion bearing or axle bearing.

 

Thanks for the input, I'm getting a second opinion tomorrow so I'll check back.

SuzukiRider: They quoted me with all the bearings replaced so I didn't think it was too outrageous... I'm nervous though because their diagnostic was "free" which makes me think they didn't check as diligently as they could.

 

Got my second opinion and it is definitely a bearing inside the differential. Also, one of my seals went so the differential fluid was low too... not sure how this could have happened with only 85,000 miles on it but I guess that's just how life goes sometimes!

 

Your quote sounds kinda on the high side to me. I was quoted $795 to have all the bearings replaced and as well as upgrading to 4.10s. Parts included.

 

Is yours humming while cruising a certain speed then goes away when you let off the gas? I just bout an 04 with 47K miles and I hear the humming sound going down the road but it goes away when I let off the gas. Then comes back when I press the gas again.

 

OK guys its the outer pinion bearing that is making the racket. Mine is doing the same thing. Me and a buddy of mine are gonna pull the rear end in a few weeks and rebuilt it and replace the axle bearings and seals while we're at it. its really not the parts that cost so much, its the labor. We tackled a rear end service and pinion seal replacement on a E350 today and it was a booger. are ya'll getting vibrations or rear end shake at around 50 mph +?

 

No vibrations here. Just humming. Not sure I'm mechanically experienced to take on this.... Wonder how much this is going to cost me. A great deal on this truck is not turning out to be so great now....

 

No it's humming at all times, regardless of the speed or if I'm pressing on the gas or brakes.