The injection pump on my 190D-2.2 (OM601) had a minor oil leak from around the stop lever. I hate the idea of having something leak, so I decided to try to fix it after another forum member (sixto) suggested that it could be an o-ring that needs replacement. I documented the process in case anyone else has a similar problem... (this probably applies to the 602/603 as well but I can't be certain). In total it took less than an hour to do.
Remove the air filter, then remove the air filter box. It comes off with four 10mm nuts, two on each side. The four rubber couplers between the filter box and the intake tubes are just held in place by friction.
The oil leak is easy to see! The blue arrow is pointing to the stop lever.
Step 3: When the engine is completely cold,
clean with 'simple green' degreaser and a toothbrush. Gently rinse with clean water sprayed through an old windex spray bottle. The result:
The stop lever can be removed by taking off the nut shown in the photo. Unscrew the nut, then pull the bolt out from above, then slide the stop lever off.
On the stop lever shaft, you'll find a crescent ring clip, a washer, and then an o-ring. To remove the clip, rotate it so the gap faces up, then press down on each side of the gap. Don't lose it if it pops off suddenly. Slide the washer out, then pry the o-ring out. Clean any excess oil from the shaft.
The o-ring is about 12mm across (outside diameter) and about 2mm thick. The inside diameter is 8mm. When I replaced my spin-on fuel filter on the weekend, I was lucky enough to forget to install the new o-rings that came with the new filter. It turned out that one of those O-rings was exactly the one I needed here!
Reinstall the stop lever (New
o-ring first, washer second, clip third, then the stop lever, then the nut and bolt). Then put the air filter box back in. All done!