Help with grinding sound only in 4 wheel drive

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Coyote_695

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Hey everyone, just joined about a month back as I got a new for me 18 Raptor. I’ve been reading a lot prior to buying the truck and even more so now that I own it. So far I’m really excited to have it. It a huge upgrade over the Nissan Titan I drove for the last 10 years.

Anyways, intros aside, I’m hoping I could get some thoughts regarding a grinding sound I’m getting that seems to be coming somewhere around the front passenger wheel. This is not the typical IWE noise and only happens in 4 wheel drive. 2 wheel drive works and sounds just fine. It is more pronounced in 4H but is also present in 4A and is most easily heard when decelerating/off throttle. The best way to describe the grinding is like the metal on metal sound you get from worn brakes or the sound you would hear from a lathe.

I have checked and confirmed the IWEs are engaging correctly, I’ve spun the wheels to check for drag and weird sounds, and I replaced the vacuum solenoid and check valve just to be safe. I also capped off the IWE vacuum to lock the hubs in 2 wheel drive to see if the noise would present itself in 2 wheel drive, which it did not. Brake rotors and pads are fine as well.

As far as I can tell, this is only happening when the differential/transfer case are getting power.

Is there a scenario where the IWE and hubs could make a noise like this in 4wd and not 2wd?

Is there anything else anyone would recommend looking into?

Here’s a link to a video of what this sounds like:
 
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smurfslayer

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Welcome to FRF
#OneLessprius

I don’t hear anything either . If the IWE’s aren’t engaging/disengaging properly and left that way for a while you can cause some hard part damage.
 
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Coyote_695

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Figured I’d update my thread here. And I appreciate the responses. That video does make it a little hard to hear but it’s definitely there. This one is a little better in my opinion, either way, headphones are probably the only way to hear what I'm referring to as you have to listen past the road and tire noise. Grinding may not be the right description but rather a rotating metallic scraping.

After a lot of my own diagnosis I ended up taking the truck into a transmission shop.

Initially they identified a bearing on the right axle in the front carrier/diff being the source and replaced it. Noise was still there. They then identified noise from the transfer case and put in a reman t-case, but the noise was still present. They then removed the front drive shaft and tested things out, no noise. So we all assumed that means it’s the drive shaft and put in a new OEM front drive shaft…noise is still there.

So after a month in the shop and a lot of money, there is absolutely no change. So this is either a completely normal sound or the issue is so small that no one can figure out and Ill just need to wait for it to become more obvious.
 
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Coyote_695

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Sounds suspiciously like rear pinion bearing.....had mine replaced at about 65K miles.
I think it sounds like a bearing as well. I'm fairly certain that it is coming from in the front, and is only present in 4 wheel drive (4A, 4H).

Initially, I pulled the IWE vacuum to have the hubs engaged in 2wd so that the whole front end would be engaged which made no noise, so that more or less ruled out IWE or wheel bearings in my mind. Still only occurred when in 4wd. So something is happening when 4wd is engaged and there is some load on the system. But as mentioned, new t-case, front axles were inspected, new driveshaft, so I'm stumped. It doesn't sound normal, but at this point I'm inclined to just accept it until it becomes more obvious.

Really the only other thing I can think of would be the front diff pinion bearing since removing the drive shaft removed the noise. I would be a little surprised if the shop missed a worn pinion bearing (front or rear) after looking everything over so many times, but its certainly possible. Thing is, with the IWEs engaged in 2wd, that front diff pinion and drive shaft are still spinning, and making no noise until 4x4 is engaged.
 
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