2004 Rear End Problems- help!

[Exploder141]

Hi Everyone,

I'm getting noises coming from the rear of a 2004, almost positive it is the rear differential but I guess it's possible it's coming from somewhere else in the back. It has almost 100k miles on it right now and probably never taken off road.

It has light-moderate whirrs, howl and groans for the last couple of months. It seems to be getting progressively louder. The sound starts around 10-15 mph, only when the accelerator is depressed, never any noise when purely coasting. Sound is now present at all speeds when on the gas pedal after 10-15 mph. It doesn't make any noises when turning. Also makes a fairly light whirring noise when decelerating. At higher speeds the noise becomes more high pitched and howly, more growly at low speeds. At this point can still be drowned out with the radio.

I changed the differential oil just now and it was a brownish color. Didn't notice any large pieces or anything unusual on the gears from what I could see from the drain plug (which isn't much of course). There were however tiny silverish specs (no huge specs, like small glitter sized) in the differential fluid. There was any of these tiny specs that it might a couple of light streaks in the fluid. It had 75w90 in it originally. Put in 80% Royal Purple 75w140 synthetic in there, and about 20% Lucas Heavy Oil Stabilizer to thicken it up slightly more. The noise is still there, maybe improved very slightly but hard to tell.

Anyone have any ideas what my problem is here? Almost positive its my rear diff wearing out, but what specifically is it? Is it worth rebuilding or can I probably ride on it for years until it fails? Is there another diff fluid worth trying? Maybe Redline Shockproof? How many hours of labor are involved in a diff swap?

Any advice here is really appreciated. My funds are pretty limited now so I really need to work out how to best deal with this.

Thanks

 

[rockey95]

I just put my 04 Explorer in the shop this morning with a fairly loud hum that has been going on for a couple of months now, I thought it was something in the rear end but it turned out to be the right rear wheel bearing, they are replacing it now, seems that it has to be pressed on but either way it will be ready this afternoon and hopefully it will take care of the hum that has been going on.
Thanks

 

[Exploder141]

That wheel bearing hum you were getting all the time right, not just on acceleration? Also you're getting it on turns right?
I'm getting this noise ONLY when on the gas pedal. If the foot is off, the growl/whine goes away.
I will double check my bearings though just in case.

 

[Exploder141]

I was just reading the service manual (this was for a 2003 explorer and I do have a 2004, but I'm guessing the procedure is exactly the same) and noticed that it said on it drain and fill procedure for the 'rear axle', that after you fill it to the bottom of the fill plug. You then take of the rear wheel sensor and unbolt it and add another pint through that hole.
Never read about anyone else doing that. Its from the Ford service manual but not in the Haynes manual and in no one elses description on this procedure that I've seen.
Anyone have thoughts on this??

 

[imp]

I just put my 04 Explorer in the shop this morning with a fairly loud hum that has been going on for a couple of months now, I thought it was something in the rear end but it turned out to be the right rear wheel bearing, they are replacing it now, seems that it has to be pressed on but either way it will be ready this afternoon and hopefully it will take care of the hum that has been going on.
Thanks

By now, this image is becoming a star around here! My 2004 left rear wheel bearing, torn apart to reveal it's damage. Started humming while away from home, 2000 miles, drove it all the way back & then some, the noise gradually getting worse. I guessed it was not a pinion bearing failure in the center section, as the pitch was too low. But could have been a differential carrier side bearing, for sure.

My stethoscope told me, when running on jackstands at about 30 mph, the sound was not originating in the center section. Placed on the suspension support knuckle, there it was! Wheel bearing. Turning the wheel & axle by hand produced no feeling of roughness or play in the failed bearing. After removing the knuckle from the vehicle, turning the bearing by hand revealed nothing abnormal! That's when I tore the bearing apart! Here's the outer race of one of the two roller bearings:

 

[rockey95]

got the Explorer back yesterday afternoon and the "hum" is gone, running great again without any other sounds, $250.00 is what they charged me, I've used them before on other items and they normally are very reasonable and trusty.

 

[Exploder141]

Anyone have any luck with changing the differential fluid to something 'heavier' or 'thicker'? Like Lucas Oil Stabilizer or Redline Shockproof Heavy?

 

[Exploder141]

A friction modifier is not going to make any difference to an open differential is it?

 

[imp]

A friction modifier is not going to make any difference to an open differential is it?

Of course not. The friction modifier is intended to stop chatter of the clutch plates in the limited-slip differentials. imp