So for the past few years my 2012 MCS has been making this sharp knocking noise when going over bumps. Only happens when it's cold out. I was chasing things on the suspension and exhaust (it's definitely not the sway bar bushings or end links) but after riding around in the back seat for a while I'm 99% sure it's coming from the rear section of the sunroof.

Has anyone seen this before? I checked everything, pulled the glass out, and retightened: I can't see anything that's moving inappropriately, or anywhere the glass might be hitting. It sounds like a hard rap, like you're knocking the window with a knuckle.

Suggestions greatly appreciated.

 

Have you tried pushing up on the sunroof to see if it goes away when you go over bumps? The front sunroof panel on ours is rattling a little bit and I think it's rattling in the sunroof track. It goes away if you just barely hit the open switch. I haven't had time to really investigate yet.

 

Yes, that's how I diagnosed the problem. But I can't find where it's hitting: everything looks tight.