so ive looked around on here, and i cant seem to see if anyone else has it, whenever i turn hard to left there is like rattling comming fron under the car, like something is loose, its like Thump thump thump until i stop turning, but only when turning hard left, NO other times EVER....idk what it could be? only happens once and a while, I thought i ran something over, and it was cought in between something but its random and comes back ever so often?

 

it is the steering column shaft

 

https://www.cobaltss.net/forums/problems-service-maintenance-69/problem-i-have-noticed-cobalts-11452/

heres some pics and an explanation as well as the part # later in thread

no cure yet however

 

I have it too and I know there's a TSB out for it, but haven't taken mine in to get it fixed.

 

its like a ticking when turning hard left heard from almost under where im sitting

 

that my friend is the axle bal bearing case clicking
my car did that with like 60 miles on it, new axles fixed it
have heard lot of SSSC with the same prob

sometimes right when you let out the clutch <CLICK>

those two noises you described are not the same prob, your car likely has both probs
as both are MEGA COMMON in the SS/RL crowd

 

dealer is checking mine out again