Captain's '82 300D Purists Must Die Prius Repellent
Captain's '82 300D Purists Must Die Prius Repellent
The EGR's vacuum thermovalve. If I can assume you're like 99.9% of the rest of the people here with a "non operational" EGR then that valve is only taking up space. The valve's port can be drilled and tapped (off the car) from 1/8NPT and up, including M10 used by Mercedes' temperature sensors/switches.
The 78-79 W116 300SD used a 100*c switch to control the front A/C fan. A feature they removed from .95x engine starting in 1980.