When do you hear the knock? My engine makes a slight knocking noise between 2,000-2,500 rpms... I was told a while ago that I was hearing 'wrist pin knock' and that it was relatively common. The noise began at around 80,000 miles and I now have just under 130,000. The valves also make a little racket (especially during cold start-up) but they make a 'tick tick tick' sound rather than a knock. I don't think I've heard an F22 yet that didn't have quiet valves.