Have been hearing a helicopter type noise coming from the rear, checked everything out and seems ok, Had checked u joints and driveshaft and those were fine. Noise comes from rear, changed diff fluid today and fluid was black with some beige streaks and noticed some of the gear teeth were smooth almost like they were chromed. Fluid had a dirty pond smell to it. With the new fluid don't hear the noise as much but it's still there. Axle is a 8.25 with 4.11 gears/open diff. Any ideas?

 

When it is setting how much can you turn the driveshaft,should be fairly tight.

 

Sounds like you got water in your diff.You may also have a bearing going out.

 

Driveshaft is tight. Smelt like pond water and wouldn't doubt if there was water from some of the crossings I've done. What are the symptoms of the bearing going out?

 

The howl your getting and slop in them.Did you jack it up and check the wheel bearings by rocking your tire back and forth?

 

Haven't down that yet

 

Keep us posted.

 

Will do that tomorrow and see how it goes. Hopefully it's not bad.

 

Everything seems tight, jacked it up and spun the rear tires. Had some clicking but went away after a bit, weird thing was that when I spun the tires they went in the opposite direction of each other, don't know if that's normal or not.

 

Yes thats normal it means you dont have a posi rear end

 

That's good, just wondering what's causing the noise, not as bad with the fluid change but still there