Couldnt come up with a better way to clarify the title. My new '91 350SD holds vacuum wonderfully. And all vacuum items work. Ive got two beautiful w123s that I think are supposed to lock and unlock all doors from the trunk, but dont... This one works perfectly even with that.

So my left rear door "works", i.e. the little knob rises and falls with the vacuum actuation. But accidentally I found out that it doesnt actually lock. With the knob in the lowered position, the door will still open.

Has anyone experienced this? Id assume that there is some connecting rod mechanism that perhaps is not connected for some reason.

Any ideas?

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Take the door card off and follow the linkages. Chances are good that you have a plastic retainer that's fallen off or one of the metal rods has come detached.

The 126's don't hold vacuum for the locks, they have an electric pump to operate the locks. If you're in a quiet area, you can just barely hear it whirr when you lock and unlock the doors.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Thanks - yes I feared a door card removal was in the works. Not a bad job but not one of my favorite... At least I can spray some rustproofing oil in there when open...

I wondered about that noise. That would explain it...

Here I thought I had the world's best vacuum system!

Thanks!

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Removing the rear door cards isn't too bad. Take off the bob on the lock lever, remove the 3 screws holding in the trim in the rear 1/4 window and then remove the trim, remove the window switch, the courtesy light in the bottom of the door, the trim around the latch, the trim behind the door pull, then the screw holding in the door pull trim, and the arm rest. The panel then lifts straight up and off. Typing out the process probably took longer than actually doing it!

Once you're in there, you can see the linkages for the locking mechanism, there are several steel rods running around in there.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]