‘03 Liberty weird humming noise on-throttle only.

[Russ 77]

It’s an ‘03 Liberty 5-speed manual “Rocky Mountain Edition”. I only get a weird, and kinda loud, hum while on the throttle, no matter the speed. It is
There’s a slight decrease in the hum while turning right on the highway, and possibly a slight increase while taking a left. I haven’t noticed any difference in the noise while turning only at city driving speeds.
I changed the rear driveshaft u-joints in March and it made no difference.

 

[tommudd]

Check wheel bearings
if more hum/ noise when turning left, then right wheel bearing and vice versa
also they can feel tight but still be worn out somewhat
That is where I would start checking from your description

Next step would be checking and/or replacing the CV/ intermediate shaft

 

[HoosierJeeper]

Also check the rear CV on the front driveshaft. Mine hummed for a few years and then became a chain dragging sound. Boot cracks and flakes away, grease dries out, joint falls apart.

 

[billyoungm]

My u-joints were bad and it caused the pinion seal to fail and leak out all the gear oil. Have you checked your gear oil in the axles?

 

[GoatTheBoat]

My u-joints were bad and it caused the pinion seal to fail and leak out all the gear oil. Have you checked your gear oil in the axles?

Yes, I have checked all my driveline fluids. The rear axle took almost nothing to top up, while the front axle and t-case were at the right levels. The rear axle has that weird rubber cover for topping up fluid, and that was the only area of the axle that showed any signs of slight leakage.

 

[GoatTheBoat]

Thanks for the other suggestions. I’ll get them checked as soon as possible.

 

[Big Al]

When I first got my KJ, there was a loud hum cruising at 50 MPH.
It's Still there
Had this before on my high mileage Ford F-250.
Is the Rear end toast in my KJ?
Took the rear end cover off and sludge came out along with metal bits and pieces.
Magnet was packed with metallic sludge.
The side gears and bevel gears are shot. Chunks taken out of them.
The crown and pinion look OK
I would drain and check the condition of your gears in the rear end.
Put Lucas 70W-140 synthetic with the friction modifier as I have trac loc.
No different, I need a new set of bevel gears and side gears, on the fence if I'm going to change any bearings in the rear end.