in my 99 blazer 4wd automatic,i get this moaning noise when i hit about 50-55mph.
it seems to be coming from the right front underside area.
sound familiar anyone?

search for - humming niose r/f, posted by glenn peters. Thats me.

i checked it out, but didn't see any solution....
have you figured it out yet?
a guy i work with took it for a ride, and his first guess was the wheel bearing/hub. we couldn't get it up to 50-55 mph, because it was rush hour, he did hear the noise though.
we then brought it into the shop, and put it on the lift. we found the r/f tire to be badly cupped, and that the idler arm, pitman arm, and all 4 ball joints need replacing. we also corrected all the tire pressures, and rotated the tires.
i haven't had a chance to get it up to highway speed yet, to see if it made any difference. tomorrow, i will try and see if it does it in 4wd.
btw, we work in a car dealership, i work in parts, and the other guy is an ASE certified tech.

I'm an ase certified tech.Just haven't had enough time,wheel bearings do go bad it's common on blazers from what I hear. Wasn't my problem, I'll keep you posted!!!!

i had the opposite side replaced a while back, when the car was under warranty, it was making a different noise though. it's 2000 miles out of warranty now.
thanks, and i'll let you know if we figure it out too.

Have sone one check out acctuator on the front axle, thats where I'm gonna start! Once I get a chance!!!!!!!!!!

think maybe they stick? or get partially engaged?

think maybe they stick? or get partially engaged? i can hear it when i switch into 4wd....
i talked to a chevy dealer today, and they couldn't think of any common problem that would cause this.

Read my latest post under humming noise r/f !!!!

Dude absolutely no luck yet,how about you????