Knocking noise when making left turning.
 

I have a 2009 535i with sport package and 102k mileages on it. I just changed my water pump last 2 weeks. A few days after, I started to hear some knocking noise when turning left ( from the passenger side ). I thought that something got stuck down there. Jack up, remove all cover, check all bolts, everything is tight. I try to test drive coverless. The knocking noise is still there. Jack up again, turning wheel, no noise, no visible obstacles , the same with spinning the wheel on air. I put everything back and test drive to isolate the problems. The knocking noise only happen when I turn with a little gas pump ( if I let out of the gas and let the car slowly go, no noise). I have not done alignment for 2 years. Would anyone point me out what is happening?
BTW, I have 18 wheel with spacer in the front ( not the OEM).

Do you still have the original suspension bushings/ball joints? If so I'd check the thrust arm bushing, it's most likely the source of the knock.

Yes they are original. I check the torque specs but not sure how to check if they are worn out.

I just had the same problem but I only have 65K on mines. Turned out to be the sway bar bushing. Every time I made left turns I would get an old creaking board sound. By reading up on the problem on this forum I narrowed it down to the sway bar bushings. I purchased the bushings before goin to see my mechanic. U really can't tell unless u actually access the bushings bcuz he originally was saying that the suspension was tight until he got close after taking off the belly pans that the screws to the bushing on the left side was loose. He suggested to tighten but I said change them instead since he was already there. No more sounds

I had a similar issue.

Mine was a result of my exhaust bracket being loose and banging on left turns and bumps only

That sound reasonable since when I change my water pump I left it hanging. I will check on that.

This is the solution :). The USPS delayed the package so it took so long to get it. About the job, it took less than half an hour. The original bushings look okay but maybe the rubber was done for. I'm so happy now, thanks for your suggestion.

this happened to me. bolt was tight, but still loose enough to allow a little movement of sleeve.