99 Blazer 4x4 - Moaning from right front

A few days ago my wife noticed that her Blazer was in 4Hi when she pulled into the parking lot at her work. Neither of us had put it there so I figured that she probably had accidentally tapped the button when reaching for the vent or something. In any case, since then there's been an intermittent moaning sound from the the right front wheel area that is definitely speed related, and also seems to be sensitive to sideways load. I can only hear it when driving at least 30 mph. If I'm going straight it's there, just very quiet, if I turn left it gets slightly louder, if I turn right it's slightly quieter. Any ideas of what this might be? There is no difference in steering effor or any vibration of any kind. Am I just hearing road noise from that tire and I'm overly sensitive to it because I'm paying more attention since the accidental 4x4 setting?

please use the search feature.

Let's see, a search for: Blazer noise front gave me 15 pages of results, the first 250 were completely unrelated or referred to noises such as clunks or clicking from the turn signal.

Your search - Blazer moaning - did not match any documents.

A search for Blazer Front gave me a first result of a link to Bloomingdales and a bunch of other questions about clunking.

Blazer 4x4 noise: A sound insulation company and - you guessed it - clunking and ticking noise posts.

Blazer wheel noise: A performance wheel company and - Halleluja! - More clunking and clicking noise posts!!!

So this isn't a 4x4 problem?

Ah crap. I had a long reply posted but just lost it. Here's the short version: I decided to use the right search button (duh) and found the "humming noise r/f" thread. The original poster still hasn't repsonded that he's fixed the problem, and the thread got so trampled by people chiming in with their slightly different probles that all I know is that it definitely is/isn't the wheel bearing, hub assembly (which is/isn't expensive), or vaccum switch... The original poster seems to be currently blaming the CV joint but that doesn't make sense to me if the noise happens in 2wd when that axle shouldn't be under load but doesn't in 4wd.

Nothing else useful was found...

The first place I would look is the hub assembly.

It may be the wheel bearing. It has the typical light growl noise of a worn bearing. I have replaced them twice, about every 70k miles on my 99 Blazer.
I would take off the tire and check the brakes/rotor
and drive shaft.

What does a worn wheel bearing look like? If you take off the rotors can you tell if it's busted?

The hub assembly on a 4WD Blazer is a sealed unit. Bearings cannot be replaced. The entire hub assembly has to be replaced. I would take the caliper and rotor off and turn the hub by hand. If the bearings are worn, the hub will not turn freely and you should be able to feel it.

What does a worn wheel bearing look like? If you take off the rotors can you tell if it's busted?

Jack the truck up so that particular tire is off the ground.

Then grab the top and bottom of the tire and push in at the top and pull at the bottom. Do it back and forth and see if it moves at all.

BlazerLt
For some reason Gm is having a real problem with the wheel Bearings on this beast. And after running it in 4wd hi on dry roads and when he said the noise changes with side to side load its IS a bad wheel bearing on the right front and I bet the left 1 will fail soon also

true.