Originally Posted by funola

"I'll try to get a new crush washer in there on Saturday and fix the fuel leak. If that doesn't help, I'll have to continue on with diagnostics. The car still starts very quickly, so I also don't suspect any sort of compression problem. If this minor fuel leak isn't the issue, I'm wondering what to look at next. Injectors? How would I diagnose bad injectors? Could one go wonky so suddenly?"

You should not see or smell fuel anywhere, anytime so fix the leak(s) first. The best diagnostic aid for air in fuel in any diesel engine is a clear return to tank line. In your Mercedes, it is at the filter tee on top of the filter housing (where the cigar hose connects to). You should see solid fuel there without bubbles at any time, engine running or off, otherwise, air is getting into the system.