Are the front axles supposed to turn when in 2wd while rotating the tire? If no, what would cause the hub to stay locked.

Thanks

 

Yes, the front half-shaft (CV axles) turn when the wheels are turning. They are bolted to the hub. If you are in 2wd, then they will be disconnected internally on the front diff. They lock in to the diff when you select 4wd.

Do you believe that your 4wd is engaged even when 2wd is selected? What 4wd system does your Blazer have? Does it have the 3 button selector (np-233 front diff) on the dash, or the 4 button (np-236 front diff) with auto-4wd?

 

I'm asking because yesterday I pulled out of my driveway and started driving and heard a lout bang. At first I thought I blew an air shock so I did a u-turn to get home to inspect.but they were fine. When it happened there was no shock shimmy shake or any change in anything. My second though was torsional stress in the transfer case and something that was supposed to be unlocked was actually locked and broke loose. Transmission seems to be fine. I jacked up the front end and the tires and axles turn free, so I assume if the transfer case was engaged, it's now free. If the Haynes manual is correct then I think my transfer case is the "NVG-236/246 NPS". here's a pic of the buttons;

 

if the vacuum to the solenoid on the firewall is backwards , the front diff will stay locked until the vacuum bleeds off,