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.

Step 1: 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. See photo...

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