The truck I drive at work has a Cat 3216. The hottest I've seen it is 1,100 F (around 595 C). It only gets that hot if I let it bog down on a hill, downshifting to get the revs over 1,800 RPM will lower the temps to 950 F (510 C) or so. I emailed Cat to find out how hot it should get, they said...