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Grinding Noise Gets Louder in 4WD

Discussion in '3rd Gen - 2007 - 2017' started by Rexpedition, Sep 15, 2020 at 11:51 AM.

  1. Rexpedition

    Rexpedition Member

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    Hi Everyone. I've got a lurking issue that I hope someone here can help identify...

    2012 Limited. 4WD. 3.31 gears.

    Grinding noise when rolling... like wheel bearing, but more steady and does not get loader when loaded in turn - BUT did get loud when I hit pot-hole on pass side.

    Noise gets MUCH louder when switched to any 4WD mode.

    Had a drip from pass front axle seal that was metallic - so i thought it was obviously the source of my problem. Took pass side apart and replaced bearing and seal on output of front diff (changed oil)... noise still there

    Soooo, the metallic drip still makes me think something in the diff... but the diff is fully 'disconnected' in 2WD? So why still grinding just not as loud?

    Could it be a wheel bearing and just doesn't sound like normal failing wheel bearing?

    Could it be a bearing in center diff?

    Is front diff still driven, just hubs unlocked, in 2WD?

    Thanks guys. I just don't want to tear into the other axle if I don't have to.

    -Tony
     
    Last edited: Sep 15, 2020 at 4:59 PM
  2. 07navi

    07navi Full Access Members

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    The entire front drive train moves due to drag from grease and supposedly from the clutch drag in the transfer case but moves slowly. This was recently hashed over with vigor. Collect those drippings and look at them in the sunlight.
     
  3. Rexpedition

    Rexpedition Member

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    I caught some of the hashing.... I'll say that my noise does not change much (except in volume) when 4WD is engaged - so probably not a problem in diff.

    Doesn't drip anymore - but is the oracle supposed to speak to me in the shiny oil? :D

    I might drain some just to see if i still have an issue in there..... But it's got to be a wheel bearing - right??
     
  4. 07navi

    07navi Full Access Members

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    If you can't wiggle the wheel when jacked up and it doesn't feel rough with the wheel off maybe not.
     
  5. Muddy Bean

    Muddy Bean Full Access Members

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    I had this and it was an issue with vacuum to the 4wd system. It wasn’t fully disengaging. You can actually hook up a vacuum pump to a hose near the brake booster and it will fully disengage the 4wd and maybe stop the noise. If that fixes it, you can chase down the cause of the vacuum loss.


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  6. 07navi

    07navi Full Access Members

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    Those vacuum problems are pretty simple and it can growl in varying degrees depending on how much it partially engages. Get a little vacuum tester to check it and you can use it to replace your brake fluid etc also.
     
  7. Rexpedition

    Rexpedition Member

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    I really wanted to jump up and say - that's it!

    ...but it still growls once engaged? And louder? Maybe one side is not engaging??
     
  8. mnachreiner86

    mnachreiner86 Active Member

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    How many miles on it? I just went through this on mine at 208k. Seeped from the axle seals back in the winter and I figured I would take care of it later. Later got grinding that seemed worse in 4wd than 2 wd. Went through everything I felt capable of doing, iwes, check valves and solenoid, wheel bearings, tires, checking cv shafts etc before I had my brother in laws dealership get into it. Initially he thought all the same stuff I had already done until they kept digging. Had to have the front diff rebuilt. Everything was pitted up and full of flake once we got in there. The puking axle seal is telling you that fluid is burned up and being pushed through the seal after failure. Pretty costly repair. The difference with iwes would be that the sound would go away would put in 4wd, not get worse. I hope yours isn’t what mine was, it wasn’t too cheap.


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  9. 07navi

    07navi Full Access Members

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    A front diff going bad is rare. Did it leak or get water in it? There are probably hundreds of good ones in wrecking yards.
     
  10. mnachreiner86

    mnachreiner86 Active Member

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    That’s not as true as it used to be. Per the senior masters there, there have been more Front differential failures in the 04+ trucks with an I WE system because everything is turning all the time as opposed to the older systems. High mileage and lack of fluid changes increase the problem


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