So this morning I was heading to work with my Dart that has a slant six. As I started up I heard a clanging sound from the engine that went away pretty fast. But I noticed if I gently reved the engine it would start to go clangclangclang briefly on a specific rpm. I checked under the hood but couldn't see anything out of the ordinary. I took the risk and drove the 5km to work, didn't hear a single clang, tried to check for the sound again when I arrived by reving but it was gone. The sound could be described as if someone was tapping on sheet metal or something hitting a metal fan( I checked the fan, it was clear). Going to check it up when I get home but does someone have any ideas where and what to look for?