C 230 detonates at idle -only when hot from sitting in traffic. If I turn on the heater temp comes down 10 degrees C and the detonation stops. At highway speeds the temp comes down. Detonation does not continue during acceleration - engine controls seems to be able to compensate. Parts changeout has been as follows: 1. Timing chain tensioner (when I thought the detonation rattle was mechanical) No joy 2. New thermostat no change in operational temps and no joy with the detonation rattle. 3. Fan control unit - no change in operational temperatures and No joy with the detonation rattle. 4. EGR valve and vacumn distribution valve for egr control (An egr code came up) No carbon cloggin was evident and No joy with the problem.
At highway speeds temp gauge reads about a sixteenth of an inch above 80 so I figure the gauge is showing a little cooler than the actual temp and actually gets a little hotter than 100 C in traffic (95 - 97 on the gauge).
THIS IS MAKING ME CRAZY - should I accept the little bit of detonation at idle? My training says detonation is destructive and a no - no. Helllp!