In this case, this guy is on one of the younger ones. He's second generation. His dad was also a MB mechanic... and sounds like the type you're referring to. Being Silicon Valley, I don't think he's fixed many diesels. (There are many more SL500s than diesels here.) I'm in the computer field, and he's impressed me a number of times with his in-depth knowledge of how the whole system works. However, this problem has stumped him, which is why I'm here (frustrating folks like yourself).