Many of us have heard a ticking sound coming from our engines. In a previous SRT Engineers Chat session, it was explained as follows: "You will not hear the valve seating at or near idle conditions unless you have seriously aerated the oil system and hence the lifters. You will also not hear the moly wearing off the piston skirts. A piston that is too small in a bore too big will result in a cold slap that can be heard at cold (I mean cold like -20 deg F) idle. We do a lot of testing and guage pistons and bores very carefully to make sure you as our customer cannot detect the piston movement in the bores - hot or cold. I expect what you hear is the injectors which do make a clicking noise that can be heard and gets slightly noisier as the injector temp is elevated. The noise is caused by the injector pintel as it opens and closes and while we have not been able to eliminate the noise due to the required operation (you need the fuel) we have done some work with minimizing the noise with isolation."