my 2001 blazer does that and changes when in 4x4 what is it i replaced ball joints idler arm and got front shoks but no luck

 

its the torsion bar crossmember mounts. on both sides. i think the mounts are about 20 bucks for 1. i would replace both. what your looking for is the long bars going from the bottom A arm to about the middle of the truck that goes into a crosmember into what are called torsion keys with one bolt holding the keys up. the mounts are what holds the crossmember to the frame.

 

tie rods and idler and pitman arms wont fix it, have you checked power steering box

 

I'm having the same problem with my 93 blazer 4dr 4x4, glad I came across this post.

 

her is what i think is most probably the culpret. i had a similar problen when i first got my 91. i looked it over up and down took it to shops for pro advice no one could tell me where that dammm noise was comming from i thought it was in the front end too i replaced everything from ball joints ,a arms , cv idler any thing that had to do with th front end i replaced it . it was whene i got all my parts together for the a arms and ball joints did i find the source of the dammmmmmmmm noise i released the tension from my torsion and ill be dammmmmmed if that torsion cross member diidnt fall to the ground all tha $$$$$$$ for a ****y design flaw by gm the only thing holding this this thing is a rubber boot on each side (note your fuel lines run the inside rail and could be dammaged if not attended too) scoured junk yards three citys away could not find one that wasnt damaged but worry not if you look to the earlier years you will find that they are direct bolt, frame to cross member it takes a little work and drilling but it bolts up reinstall torsion bars and youl never here that dammmmmm noise again. the best way to check for this problem is crawl underneath with a good size pry bar an try to pry the cross member from the frame you will notice emediatly good luck and i hope i have solved your delema

special note;; this is a very dangeres proceedure. extrem caution should be exersized at all times. you should not substitute cheap tools to perform this task!!!!!!!!!!!