2003 5.4 4x4 drive train noise

[atkijaco]

Help!. I have a strange humming noise coming only while under acceleration, when I let off the gas the noise subsides. It is audible at all speeds but the harmonics seem to be loudest around 40-45mph.

-It does not change while turning so I don't think it is a wheel bearing
-CV shafts are not spinning, switch is in 2wd so I don't think I have a stuck lockout.
-Sounds like a harmonic noise to me, coming from the front
-New tires just installed and the noise is still there
-Front diff just serviced, nothing alarming in the old fluid.

Could it be a noise from the rear diff and the harmonics are just moving forward?

Possibly a bearing in the Tcase?

 

[Mediamonkey11]

Any kind of associated vibration? If so, where can you feel it?

Easiest and cheapest fix would be ujoints.

 

[atkijaco]

no vibration. Just the whine. I tested today by putting in neutral while rolling about 45mph and reved up. The noise did not show up. It only shows up when the vehicle is under a load, during acceleration or maintaining speed. As soon as the gas pedal is let off the noise goes away.

When I serviced the front diff I check the ujoints, no play or anything alarming there.

It honestly sounds similar to the normal humming or slight whine when the vehicle is in 4H. But I have verified it is not, the cv's are not spinning.

 

[David Del Rio]

I know this is a super old thread, but did you ever figure anything out about this situation? Mine does the same.

 

[Yupster Dog]

but did you ever figure anything out about this situation?

You should start your own thread so it keeps all the info about your truck in one spot so anyone who wants to help only has to scroll one thread. year/trim/engine and all mods

Add anything that has been done. (Maintanance, broke/fix) Such as have you changed the trans filter? color of fluid?
Has the differentials and transfer case fluids ever been changed?

https://www.expeditionforum.com/threads/correct-way-to-start-a-thread.47954/