2012 XLT whirring noise

[AlexBanich]

Ok so have an xlt that has had an ongoing problem. It started this whirring sound, so having 120k miles I figured wheel bearings maybe tires. So I got wheel bearings and installed them. Didn't fix the problem. Took it to the garage and they said it had a bent strut. So they change the struts and the shocks cause it needed done. They also did an alignment and re balanced the tires. They said they had to make some alignment adjustments and add a little weight here and there. So it was slightly better but then it started this shaking not too soon after. I take it to another garage who says then alignment is good and they just start from scratch to rebalance the tires. Once again everything seems all but fine. Still a little bit of a shake and whirring but nothing crazy a week later wife says it's so bad she can't drive it over 40mph. So I decide I'm going to put it on jack stands and see if I can locate the problem. Do this and discover that there sounds like a low level whirring in the front and equal driver and passenger side at the wheel well. Then the driver side tire locks up and when I hit the brake it clunks. So my question is this all cause by a failing front differential? I had one go in a trailblazer that whirred till it shattered but not shake the car like crazy. Not saying that its impossible. Just figured I'd ask before I spend the money for the repair. THANKS

 

[blwnsmoke]

There is no front diff. If you have an awd unit, there is a PTU directly connected to the transmission that spins 100% of the time regardless of whether you are applying power to the rear. These have been known to overheat and fail as they only hold about 17oz of "lifetime" fluid. It is quite possible you were getting feedback from the ptu and it has finally let go.

 

[AlexBanich]

What I have is that "intelligent 4x4" and I can't 100% say that is what it is or not. I'm just curious would that cause whirring and shaking?

 

[blwnsmoke]

What I have is that "intelligent 4x4" and I can't 100% say that is what it is or not. I'm just curious would that cause whirring and shaking?

If the internal gears were shot, yes it could cause some shaking. People have experienced shuttering before they let go. The fluid turns to sludge and no longer lubricates the internal gears and boom.

Not saying that is your problem either, but it is possible. Your front drive wheels go through the ptu so the fact that it locked up when you were spinning them, well it is a possibility.

I'm sure others will chime in with far more experience then I.

 

[Crates]

You mentioned the drivers side front wheel locked up and then made a clunking noise, possibly the CV shaft/joint is worn out?

Get it back up on jack stands and have some one put it in drive while you watch the CV shaft rotation.

Someone also mentioned the PTU, have you pulled the fill plug to check the condition of the fluid in there?

 

[AlexBanich]

So here is a little update. Drove it and it seemed like when I spead up is when the shaking really kicks in. The whirring noise stays the same up and down with the speed. I took some right hand curves and that seemed to kill the shaking. Left curves I didn't have any really serious ones to test but they didn't seem to do anything. I turned a 90 degree left to go down my street and got a clunk.

As far as the suggestions I am not in great shape to be under a car from an injury I'm trying to rehab from. I'll try to maybe take the front tires off if I get a chance to put it on jacks again.