Duovalve. I came across this on BW this morning. Perhaps others with the E300 TD can chime in with success in taking apart their DVs. I thought it interesting.
Courtesy of gsxr: "I didn't see this mentioned elsewhere, and it would be really helpful if this was added to the first post in this thread:
The 1997 E420 (210.072) duovalve is COMPLETELY different, and cannot be easily dis-assembled for cleaning / repair.
The same valve is also used on the 1998-1999 E300 turbodiesels (210.025) and CDI (210.026). More details in this thread:
E420 Duovalve - A Cautionary Tale - Mercedes-Benz Forum"
Main thread here
Duovalve Removal and cleaning - Page 10 - Mercedes-Benz Forum