What transfer case do you have, (NV233 3 button, or NV236 4 button)?

 

3 button, and supposedly when I bought the truck it was recently replaced by the previous owner, although i have no proof. It does look a little nicer than other underside components.

I have been messing around with it a little, and i couldn't make the sound happen when i was in 4-wheel drive, knowing what little i do about it. I can get it to happen if i accelerate up a hill and let off the gas when i'm nearing the top, but only if i'm going 40+. Neutral does not make it go away once started, but coming to a full stop makes the sound stop every time.

I almost wish stopping didn't make it go away so I could actually poke around and get a better idea of what was happening.

 

Here's something to try: Under the battery tray there is an actuator with one vacuum line attached to it. Unplug the line and plug it with a bolt, golf tee, etc. Drive the vehicle in 2WD and see if you can make the noise happen.

 

I had the exact same problem in my 98. Belt...(or so I thought) would only screech at 35 MPH uphill. Drove me insane for about a week as it would come and go at random times. Checked all the pulleys, new belt, ECT... Finally after pulling out a pound of my now precious hair I stepped on the brake while climbing a hill with the embarrassingly loud screech happening and it stopped.

Right front rattle spring had broken on the disc brake pad and would allow the squeeler to hit the disc at an angle.

 

Seriously? I would check tonight but Chantel has us battening down hatches here in western PA. I will check when i get home from work. I feel like this sound is too loud to be the squeeler, but we'll see. Ill be back with an answer. Thank you so much

 

Problem solved! Thank you 1000monkeys.

I took the caliper off today on the fr left and sure enough the one squealer had worked itself off and was caught on the top of the rotor. For whatever reason, when i came off the gas going uphill the squealer started hitting the crossbars between the two sides of the rotor and made the mystery noise. (Just like a baseball card rubbing against the spokes of a bike tire)

I dont know what caused it to happen like it did. But i got excited and drove about 20 miles trying to make it happen and the noise didnt happen once. I have my blazer back

 

I am not too sure why I did not think about that on if the sound went away when you hit the brakes. Glad you got it figured out!

 

You're Welcome! Just glad I could help.

 

Good one 1000monkeys!!

 

Thanks.