My engine seems to be making kind of a ticking tapping sound. It doesn't seem to do it below 1000rpm. A friend thinks it might be a loose rocker, I dunno. The sound seems to be coming from the pass side of the truck. If it was a rod or bearing or something like that in the engine, what kind of symptoms should I look for? What would that sound like? I have never heard an engine with a bad bearing or anything so I don't know what it sounds like.