I learned that my local trash collection company has hollowed out the catalytic converters on my diesel garbage truck, or at least the one that services my house. Normally I am not home when they come by, but today I am. Sitting on the upper deck overlooking the ocean when up comes the garbage truck. I recognized the sound of the hollowed out Diesel Particulate Filter (DPF) "cleair" hang on aftertreatment system (they run an older Cummins ISM and needed to put the system on to meet emissions standards, particulate matter and NOx reduction). At work we had over 100 of these systems on our older buses, they are long gone now. I got to be "the guy to call" when there were problems and as such got to see a lot of failures. When the substrate brakes away (vibration, age, or a hammer) the guts begin to fall apart. When empty they make an unmistakable hollow sounding roar. Just like the garbage truck that comes to my house.
I doubt anyone in the area has a clue about this, who would? But now that I know this, wondering if I care enough to make a call... It is a bit loud and kept me from hearing the soothing sound of the waves, birds chirping and a small private plane overhead. Naa don't care besides the truck has long gone. Maybe next week I'll feel differently after being stuck here in my room another week.