Hello,
Today I pulled part of the front end of the car off. I reached up into the crankshaft pulley/harmonic balancer to find a Metric Hex size bolt that sheared off and found another exact same bolt on the ground that appears to be in good condition still. With these bolts loose or missing is there any possibly of the risk of any metal components fall backing into the engine or a cylinder potentially? Still trying to figure out the cause of the noise. Shear pin?