Oscillating humming noise/vibration at highway speeds, disappears in 4wd

[mhjo]

Anyone else has come across this issue with their Jeep, or if any technicians on here have heard of this?

We have been trying to find the cause of this vibration, noise started out of nowhere while driving at highway speeds, it starts out at a pulsing vibration, almost like a loose wheel. The vibration stops immediately when you engage 4wd and comes back when switching back to 2wd. (Yes, wheels and rims are balanced, u-joints, engine and trans mounts etc.) 4.0. automateic, NP242

 

[Tim_MN]

Any lift? What brand/type of tires.


Remove the front driveshaft, and travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

Re-install the the front driveshaft, engage 4x4 Hi and remove the rear driveshaft. Travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

 

[mhjo]

Any lift? What brand/type of tires.


Remove the front driveshaft, and travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

Re-install the the front driveshaft, engage 4x4 Hi and remove the rear driveshaft. Travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

Shall do! (no lift). Thank you Sir.

 

[maxbraketorque]

Any lift? What brand/type of tires.


Remove the front driveshaft, and travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

Re-install the the front driveshaft, engage 4x4 Hi and remove the rear driveshaft. Travel the same route at the same speed. If the noise is gone, inspect the driveshaft and slip-yoke for damage and wear.

It does sound like something in the front wheel drivetrain.

 

[FusiliJerry]

While you have the front driveshaft off, check your front yoke/pinion for play in/out (vs. rotational). Loose pinion and/or bad pinion bearings can cause weird vibrations.