I am having the same thought as you did. However, I currently don't have a shop and my car is sitting on grass. I removed the valve cover and the upper timing chain cover and noticed the guide rail was broken at the middle bolt. Instead of just seeing the bolt head I seen the bolt and spacer. Somehow it broke off around the bolt. I am assuming that the piece that broke off is somewhere wedge next to the chain making that noise. I am going to remove the oil pan to see if I can see anything. My intentions are to replace everything down the road, to include the clutch, flywheel, etc. I just purchased the car for 700 dollars and it has been sitting for a few years. Again, thanks for all the advice.