« Reply #3 on: August 30, 2010, 03:11:58 PM »
From the FSM:
The axle shaft, differential and pinion gear bearings can all produce noise when worn or damaged. Bearing noise can be either a whining, or a growling
sound. Pinion gear bearings have a constant-pitch noise. This noise changes only with vehicle speed. Pinion bearing noise will be higher because it rotates at a faster rate.
Drive the vehicle and load the differential. If bearing noise occurs the pinion rear bearing is the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source. Worn, damaged differential bearings usually produce a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential bearing noise is also constant and varies only with vehicle speed. Axle shaft bearings produce noise and vibration when worn or damaged. The noise generally changes when the bearings are loaded. Road test the vehicle. Turn the vehicle sharply to the left and to the right. This will load the bearings and change the noise level. Where axle bearing damage is slight, the noise is usually not noticeable at speeds above 30 mph.
Based on your description, I thnk the rear pinion bearing is making noise. I think the shop should be responsible for making rear axle right - low oil can cause damage to the bearings. High temperature is not the only indication of a problem. Good luck!
Logged
95 YJ, 31 BFG ATs, 4.0 TB & spacer, Banks header, DynoMax CAT back, 19# inj, AEM CAI, 20 gal mod, Optima yellow
98 TJ, 35 BFG Krawlers, 4.0 liter, ax15, atlas 5:1, armor, Super 88 (under construction)
96 XJ Cheep Cherokee, 33s, 4.0 liter, AW4, future project
89 Waggy, 360 V8 727 dana 44s, it runs