metal on metal sound while moving

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devincox

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I am hearing a metal on metal sound like when brake pads are worn down completely and the metal backing is rubbing the rotor.
I have checked the brake pads and they are fine (recently replaced).
I checked for play in the wheel bearing assembly but it feels fine.
If I jack up the truck and roll the wheels by hand I don't hear the sound at all.
The sound is consistent at all speeds.

Could it be the transfer case?
What can I do to figure out what is making this sound?

The Truck is a 97 EB 4wd.
 

Habbibie

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Confirm the back brake pads are not metal to metal the ones closest to the piston, those usually wear out before the front facing pads
 
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Habbibie

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Ok that's one thing out of the way, does your truck engage 4x4 hi & low? If it does engage them drive on them does the sound stay or disappear? If it stays your transfercase is the issue of it goes away then it's not the issue, you say you rotate the wheel by hand and no noise which leads me to suspect the wheel hubs being iffy, under weight they'll hum... never heard hugs make grinding noise before though, you're looking for a part that rotates, ball joints, sway bar links and control arms are out of the question cause you'll be able to tell if any are F'd up once you remove the wheel and look at the bushings and boots
 

Habbibie

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Have you taken your wheels off of the hub or did you do the inspections with wheel on? Does the noise go away if you turn in any specific direction?
Anyways can't you narrow it down to a specific side left/right? If you're not sure or you believe it is a noise that is centered than you might have to drain the transfer case & the diff and pop off the covers to do an inspection of the internals, run a magnet through the drained oil

Ps. I still think your brakes are the ones doing the grinding noise, saying this cause
ball joints make a clicking noise when they fail
Control arms make a popping noise
Sway bar links make a screeching noise
Hubs hum
Differentials usually rattles and hum at
 

Trainmaster

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Like Habbibie says, we suspect brakes. It's the most likely by far. Second to that would be bearings. Make absolutely certain you have checked every brake pad, no shortcuts.

How about those parking brake shoes and rusted junk inside the rear rotors that haven't been looked at since Clinton was elected??

If the rotors are rough or crappy they can do this also, especially with cheap metallic pads.

Have you checked for silly stuff like a bent backing plate, or plastic trim, heat shields hitting the driveshaft?

I haven't had to do it with an Expedition, but you can often eliminate differential and transfer case problems by removing the drive shafts one at a time (index them first with markings), but it really shouldn't come to that and driveline problems are pretty remote. You can cautiously run the thing on jack stands and see what you hear and from where it originates.

Bet you find it in the brakes or wheel bearings.
 
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devincox

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I raised the rear of the truck last night and spun the tires but no noise while spinning the rear wheels. However, I totally forgot about the rear parking brake pads. I haven't ever looked at those on this truck. The parking brake does not hold the truck at all, so they are either way out of adjustment or just disintegrated. lol

Given the mileage of the truck 240K+, I will put some new pads on the rear (parking included) and see if that gets rid of the noise.

Thanks for the suggestions.
 

Trainmaster

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That's exactly what made me replace the parking brakes on my 2000. They made noise.

I applied them for the first time in 16 years, and they wouldn't release. I got them released and what was left of their hardware was then rattling around in the drums. It all spilled out when I pulled the drums.

Buy a set of drums too if you expect these things to ever do anything again.
 
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