Stumped with this front end noise...

[stuartr]

Need some help. I have a 2008 merc mounty that has had a on going noise in the front end. It is a whoo whoo that is the worst between 20-45mph. It does change a bit with the steering don't stop and start but the rhythm is different. I have changed both wheel bearing, both cv axles, yesterday the whole front differential. I am out of options! I did notice that when I took the front drive shaft down the u joint was a bit stiff. I greased it and it seemed to loosen up. Could that have been my issue all the time. WOuld there be any need to replace it? I wouldn't think a u joint would have a noise that changes with the steering? But anyway any ideas as to what this thing is doing? I have replaced everything up front with no luck in fixing it. Also is there a way to run a awd without the front driveline. I tried a while back and it wouldn't even move without it. I thought later I should have disabled the trac control. Not sure if that would have helped though. I just don't know what else to look at.
Thanks for your help,

 

[stuartr]

I wish there was a way to tell if it was the front brakes. I don't think it is but makes me wonder. Applying the brakes doesn't change the noise anyway though. But I done some brake work on it a while back and had to run a new and old pad till I could get the slides in the calipers to break loose and that seemed to make a difference in the noise so any idea how to possibly test this?

 

[Explorer_PL]

Look at my post that was refreshed few days ago. U joint will resonate the noise and make it sound like the front diff going bad. Also, bad transfer case bearings will transmit the noise. How did you know it was coming from the front ? Many times my rear bearings would sound like it's the front.

 

[stuartr]

THe rear bearing feel really tight. I still don't know what it is....