While warming up the engine for an oil change, I noticed a periodic noise, kind of a ratcheting sound. I looked and it seemed to happen in sync with a rotating part on the right side of the engine. This part is a small wheel with an arm attached to it that rotates back and forth. It possibly activates something that is causing the noise. Any help with what this is would be much appreciated. I would like to have some information before taking the car in (if necessary). If my description is lacking I can take a photo and post it. Thanks!