Alex:

How is your oil consumption? After how many miles do you have to add a quart(if at all)? I would say if your oil consumprion is low then your cat would not get damaged.

Do a search on this site for do it yourself valve stem seal replacement on your engine and check the Fastlane for tools and parts.

I have the same problem with a 300d and found directions for valve stem replacement on this site. There is a Haynes manual for your vehicle available. Or you may want to slurge for the MB manual on CD.

__________________
David
'00 Mazda MPV Family's car
'83 300D 235,000
'84 109E 175,000
'74 280C 125,000 in garage; needs rehab or sell for parts???