08 Ltd 4.6L Front drive line buzzing noise/vibration

[pjw73nh]

08 Ltd 4.6l. 136k miles. About 100-200 miles after a front differential oil change (suck out and replace with "Motorcraft 80w-90 premium rear axle lubricant") the car developed a buzzing noise/vibration coming from what appears to be the front drive-line someplace. It sounds very much like tire noise (it's not). The only difference is that it is at EVERY speed. Even right down to a few MPH as coasting to a stop. It is felt in the steering wheel very similar to what knobby tires would sound/feel like (I have street tires). It is commensurate with vehicle speed and makes no difference if the vehicle is in drive, neutral, 2 or 4 wheel drive, accelerating, coasting, decelerating, turning or braking.

Loading either side of the vehicle by steering left and right (as if testing for bearing noise) makes no difference in the sound or buzzing/vibration. Both front wheel bearing were replaced 50k miles ago with Timken units.

It's hard to tell, but it doesn't APPEAR to be worsening with time or miles, but I suppose it could be so gradual that I don't notice it.

Thanks in advance.

 

[Gorb]

Is it possible that rear and front axle fluid are different?

 

[pjw73nh]

Is it possible that rear and front axle fluid are different?

Well, I wasn't sure so just to be on the safe side (I know that sometimes car manufacturers change the oil specs from what is stated in the owners manual) I checked the internet and found an updated Ford Motorcraft oil use chart and it called for the oil I used. When I went to the dealer, the parts person looked it up by VIN and said that in fact the new chart I was reading from was the latest. So I have to assume it IS the correct oil.

I did the rear diff and the transfer case as well with the dealer recommended oils as well.

 

[pjw73nh]

Not much of an update. Noise has not gotten any worse, but I did notice that IN ADDITION to the buzzing, at highway speeds, you can hear a rhythmic/resonance of the same sound. Sort of a vum-vum-vum-vum sound. Like the underlying buzzing described above, it is commensurate with speed. Almost like it's a 1/4 or 1/4 speed resonance to the buzzing. I am wondering if it might be a U joint.

Yeah, I know it's tough to describe sounds over the internet. And yes, I know wheel bearings are VERY difficult to detect in these vehicles. I've never done the back ones in 130k miles, but it really doesn't sond like it's a back one. The noise and buzzing vibration is very much up front. Floor, steering wheel etc. As I mentioned above, the best description is it feels like very knobby tires.

When I get back on my feet, I am going to pull the front drive shaft and see if I can isolate the sound.

 

[Explorer_PL]

.. I was just going to say, disconnect the front driveshaft.

 

[pami9899]

Not much of an update. Noise has not gotten any worse, but I did notice that IN ADDITION to the buzzing, at highway speeds, you can hear a rhythmic/resonance of the same sound. Sort of a vum-vum-vum-vum sound. Like the underlying buzzing described above, it is commensurate with speed. Almost like it's a 1/4 or 1/4 speed resonance to the buzzing. I am wondering if it might be a U joint.

Yeah, I know it's tough to describe sounds over the internet. And yes, I know wheel bearings are VERY difficult to detect in these vehicles. I've never done the back ones in 130k miles, but it really doesn't sond like it's a back one. The noise and buzzing vibration is very much up front. Floor, steering wheel etc. As I mentioned above, the best description is it feels like very knobby tires.

When I get back on my feet, I am going to pull the front drive shaft and see if I can isolate the sound.

Did you ever find out what was the problem

 

[Kain316]

No

Is it possible that rear and front axle fluid are different?

If I remember correctly he did it by ford maintenance specs. And correctly used rear axle lube. My guess would be that there is a bad lockout assembly, input shaft bearing, or a tcase bearing issues