[mike_b2]

I have a 2001 4.3 S-10, and a few weeks ago on a longer trip the rear end started making whining noises when under power and going over 25 mph. The noise went away when coasting. It is not related to engine RPM, just increases in pitch with speed. I took the truck to a mechanic on the road and he said that there was a lot of play in the transmission, and suggested to have someone look inside and suggested the Pinion (that was on the road and he could not help us further). Upon returning I took the truck to a shop, and they also suggested the pinion. they took the diff apart and said that the pinion was bad and replaced it (possible some other gears). However, the whining is still there. Does anybody know where that noise comes from, and what I need to do?

Thanks.

 

[Rhotpursuit]

Was there metal in the fluid? It will destroy the rear end...bearings included, if they weren't the initial cause.

 

[mike_b2]

Thanks. I'll talk to the guys who replaced the pinion. They filled it up with new fluid, so they should have seen if there are shavings in there. Other than the diff, is there anything else that could cause this whining noise? Since it is not related to engine RPM, I figure it can come from the transmission (but the sound definitely comes from the back end), perhaps the drive shaft, and the differential. Or could that also come from some other parts?

 

[Briglicon]

Ring and pinions should be replaced as a set and properly adjusted with a dial indicator, and then patterned to ensure proper meshing of the gears. The symptom you describe sounds like the inner pinion bearing or left side carrier bearing is no good. I would assume the pinion bearing was changed with the gears because it's more difficult to try and save a beating than to just replace it. Doesn't mean they changed the bearing race or inspected the carrier bearings. Rhotpursuit is right. Metal contamination can prematurely fail the internals, but that usually takes a pretty good while.

 

[Bobarama]

I thought I had a rear diff noise. Turned out to be front wheel bearings.