Just wanted to share a little fix I did. I mainly followed the instructions here:
Door closing assist pump adjustment on S class

However, I did one thing a little different. I didn't mess with the spring because I personally disagree with this approach. All I had to do was put a little Ultra Black silicone gasket maker around the lip of the diaphragm and reassemble. Just smeared a thin layer on it, careful not to get any on the moving part of the diaphragm. If the diaphragm were torn I'd have tried the latex glove trick. So far this seems to have sealed it up and it works great. No further adjustment necessary.

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Jay
1998 S320

Also remember that MAVA over on the Benz 140 forum repairs these.
Anziani
'97 CL600 50K

Well OK, that's good to know I guess. I like doing stuff myself and this didn't cost me anything but about 30 minutes of my time.

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Jay
1998 S320

Good day guys,
I have a 1993 400SEL W140.
My Driver door and boot lid won't close on its own. ( vacuum suction not working) How do i fix this?
Regards
Rudy
Australia.

Rudy, you might want to look at the Benz 140 forum.
W140 S-Class - Mercedes-Benz Forum There is a lot of info there specific to our cars. And one of the moderators is an Aussie.
Anziani
'97 CL600 64K

J - the link is not working.

I just clicked on it from above and it opened .
W140 S-Class - Mercedes-Benz Forum
Anziani
'97 CL600 64K