Serpentine Belt Change
 

Looking for info on how to release the belt tension so I can change my serpentine belt on my 2011 Lucerne with 3.9 V6.
Youtube shows how to do it on a 3.8. Pretty easy - just use a wrench on a nut and pull. Same as the tensioner on my Mustang V6.
I tried a socket on the nut but it just loosens the nut.
Thanks