Metallic rattle under the hood
Been having this problem for a little while, seems there is something loose under the hood making a he!! of a racket. Metallic rattle, best description is an exhaust shield bouncing or vibrating. Doesn't happen all the time, but probably in a week 50% of the days I'll hear it. Almost never hear it with the car in Drive. When it does show up, if I put it in Reverse, foot on brake, it's very apparent and constant, Neutral/Park it's hit or miss. If I stop then restart the car you can hear it briefly during startup, but again, in N/P it doesn't stick around. (this is not the timing chain rattle sound).
I've been to the dealership before, told them of the sound said "sounds like an exhaust shield" so of course they tightened around every shield, (I never did ask how many). Sound was gone for 4 days, then came right back. Not sure if they temp solved anything or if it was that normal behavior of the sound. again, it's very sporadic occurrence.
I have inspected only the shield at the front/top of the motor, covers the exhaust manifold (mesh shield). The shield is frequently loose to the touch, but it's not the bolts, they are very tight, checked with a wrench myself. There are grommets around all of the bolt holes in the panel, it's like those grommets are meant to be fluid and allow the shield to shift. If I tinker with it cold, normally the sound is gone for a few days. I've never been able to get out and tinker with it while the car is actually making the noise, I have to be in R, foot on brake or trust the Parking brake, and the shield is extremely hot when the car's been running a while, I'd need to keep an oven mitt in the car for troubleshooting.
Anyway, anyone ever experience this sound? Also, I can't be certain that the sound is even coming from this shield, or if it's another shield, or something completely different. I contemplated just taking it off and drive for a week or so, but it's so hot out right now, I'd hate to cause problems if that shield is actually protecting the nearby hoses. I have a visit to the dealership next week, going to try to get this completely narrowed down.