Grinding noise when accelerating !!!

[Gruz7]

Last weekend I went for a ride through some jeep trails near my house (poor idea to begin with) and I had to climb a couple hills with rocks.
My expy is practically a bone stock 4x4 and I was scraping the skid plate over almost every bump up to the big hill.
I went into 4HI and first and went up half the hill relatively quickly and I got stuck on a large rock that jammed underneath the front axle or skid plate. Something in the undercarriage of the truck.
I spun tires for about 4 seconds and then backed off the hill and checked everything. It all seemed ok besides what might have been a dent in my skid plate but it was dark out and I'm not sure if it was.
The next day I happen to notice that around 1000rpm while lightly pressing the throttle and in D the truck makes a, sort of, grinding, rough, noise. This noise goes away as soon as it accelerates past 1000rpm. It sounds as if it is coming from directly underneath the front row of seats and it's just really a rough noise. I don't know if I could've bent a key component or cracked something but this appears as if it is just going to be an annoying noise and it may not be too serious but I have no idea.
Some extra info:
I had been driving through about 1 foot deep or a little deeper water in 20°F weather in (mainly) 4HI and first.
The truck always has a somewhat vibrating noise in the front drivers seat area that seems like it was behind the speedometer. I'm not certain if this contributes to the knock or grinding noise but it's there still.

Thanks for any help that you guys can give and please let me know ASAP if you know what this could be.

Here's a pic of the truck

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[stamp11127]

I would get underneath and do a thorough examination of the driveline. Something isn't right, it will stop when it fails or grinds enough clearance between the parts.

 

[Gruz7]

I would get underneath and do a thorough examination of the driveline. Something isn't right, it will stop when it fails or grinds enough clearance between the parts.

Will do.. I'm changing oil this week again so I'll get to that as well it just seems like the skid plate stopped whatever rock or whatever hit the undercarriage but I believe this noise when slowly accelerating is new. Thanks.


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[american steel]

wheel bearing on either side.
didn't read the whole comment. this might be your front drive shaft or transfer case.
check all of your front suspension parts including your control arms make sure they are not bent. which can create problems but this really sounds like a wheel bearing even new bearing can go bad fast when off roading. lift your front up wobble both tires if they move top to bottom in and out bearing needs replacing. it shouldn't move at all.

 

[Gruz7]

Thanks for the help with the wheel bearings I'll check to be sure but I think it is because the skid plate is now bent and its colliding with a component in the underbody I believe it's part of the exhaust system.
Take a look

The last picture shows how whatever is behind the skid plate is now pressed against it and I think that's the source of the rattle/grinding


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[Gruz7]

The truck has an aftermarket magnaflow cat back system and the skid plate is now pressed right against it and, truthfully, it seems that's where to rattle could be originating from


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[american steel]

take the plate off

 

[Gruz7]

take the plate off

Yes I will be removing the plate tomorrow when I'm out of class.. I'd prefer to keep the them on overall though so I'll probably just attempt to bang out the dented bend in the skid plate and then reinstall it to the truck to keep the FX4 look to it


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[AggieExpo]

I think your on the right track. As your engine is revving up your motor is torquing to the passenger side. Until it finds the right gear and starts to coast. The movement from the engine while acceleration makes the cat contact the skid plate. I would as you put it remove the skid plate see if the nose goes away. If it does Bang out the dent and put it back in place.

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[Lithiatwats]

Sounds like the plate is interacting with something now that it has been dented- at whatever frequency 1000rpm equals causes this to "sing" to you.

Wheel bearings rarely grind, they howl... Grinding from the hub area is almost certainly IWE vacuum issues partially engaging the front hubs under acceleration (when vacuum is lower) Again how is off roading all of a sudden going to cause this?

Bet when you straighten the underside out all will be well!