240D door lock/vacuum issue - PeachParts Mercedes-Benz Forum

sokoloff · #1 04-30-2012, 10:25 AM

After working on my 240D, i.e. oil change, motor mounts and steering shock, I find that my left rear door will not unlock. When something "breaks" after I just worked on the car, I try to retrace my steps to find out what I screwed up. I'm not so sure though that I caused this one? All of the vacuum lines around the oil filter canister look okay. All of my other door locks work fine as does the trunk and fuel door lock. The left rear door remains locked no matter what, although the locking button does move a little when I lock/unlock the car. I cannot pull it up manually either to unlock the door. I would have thought that if I screwed up a vacuum line somewhere that I'd have more issues than just this one door lock. I've got a Miti-vac, so I can go through the testing procedure, but does it sound more like an issue within the door itself?

tangofox007 · #2 04-30-2012, 10:28 AM

Quote:

Originally Posted by sokoloff

I would have thought that if I screwed up a vacuum line somewhere that I'd have more issues than just this one door lock.

Agreed.

Quote:

Originally Posted by sokoloff

I cannot pull it up manually either to unlock the door.

That sounds more like a linkage issue that a vacuum problem. I would be removing an interior door panel for a look.

TnBob · #3 04-30-2012, 01:27 PM

The vacuum source for the drivers side rear door is on the floor right in front of the drivers seat. Lift the carpet and the black plastic channel next to the body. You will find 2 sets of yellow/red and yellow/green lines. One pair heads to the passenger side, one set goes to the left rear door.

ID the left rear door set and use your mityvac on those two lines. Yellow/red locks the door and yellow/green unlocks it. A working vacuum actuator pod holds vacuum in either location.

Stevo · #4 04-30-2012, 02:08 PM

I would go directly to the door and take the panel off and then check the pod. Testing the lines under the carpet is great for finding where the problem is but chances are its in that back door and its the pod.

sokoloff · #5 05-16-2012, 05:17 PM

Got as far as walking up to the car and thinking about removing the door panel. Then it hit me that in order to remove the door panel, I need to open the door right? So assuming it is a linkage problem and my Mity-vac won't unlock the door, what are my options?

Stevo · #6 05-16-2012, 10:55 PM

So you cant open the door from either side?

sokoloff · #7 05-17-2012, 12:26 PM

Quote:

Originally Posted by Stevo

So you cant open the door from either side?

Correct - door will not open from inside or outside.

hschickel · #8 05-18-2012, 01:22 PM

Oddly, I am having the exact same problem while working on a 1987 300d. Rear DS door stuck locked with no way to open to remove the panel. Are the lines for this car in the same place?

Stevo · #9 05-18-2012, 04:45 PM

I dont know about the 87, but just pull the carpet up where I described and have a look. I would guess "yes".

sokoloff · #10 05-19-2012, 01:50 PM

Those of you who guessed that the linkage was the issue, give yourself a gold star. Took the door panel off today and found that the linkage had slipped out of the plastic clip that the lock works. It looks like a piece of it broke off. It looks to me like it will easily happen again unless I change the part. It is part #003 988 50 78. Hard to tell from the EPC how big that slit in the side of it is supposed to be. Anyone know?

See attached.

tangofox007 · #11 05-19-2012, 02:48 PM

Quote:

Originally Posted by sokoloff

Those of you who guessed that the linkage was the issue, give yourself a gold star.

Guess - Definition and More from the Free Merriam-Webster Dictionary

sokoloff · #12 05-19-2012, 08:10 PM

Correction - make that "suggested" or "surmised" and not "guessed." Nobody here guesses.

sokoloff · #13 06-23-2012, 06:35 PM

Just wanted to wrap this thread up. The part number I gave above is the correct part, is still available and costs about two bucks. It fixed the problem. When I took the old plastic clip off, it was cracked in a couple of places and the opening had gotten bigger too. Those things were a little hard to see until I removed it.

So I now have a functioning rear door again. Thanks for the help and for those of you who offered to ship me some used clips. I just figured that used ones after 30 years might have a shorter life span than fresh new ones.

gastropodus · #14 06-23-2012, 07:57 PM

Sokoloff, there may be one last thing to be said, however... although it is true that the clip may have simply failed, I wonder if there might be an issue with the lock mechanism itself. I had the experience of a rear door lock which virtually seized up with dried lubricant, making it very sticky and difficult to operate. If you haven't put it all together yet, or if you don't mind taking the panel off another time, I would evaluate how easily the mechanism moves in response to the vacuum pod.

Kurt

sokoloff · #15 06-24-2012, 12:02 AM

Thanks Kurt - good suggestion. In hindsight I probably should have lubed everything. However, I watched the mechanism work several times with the door panel off and everything worked smoothly and easily. Everything also looked nice and clean and corrosion free in there. I think I'm good.