NOTE - Updated Notes - The 5th POST on this THREAD is where to go in order to download my fancy W123 Vacuum Door-Lock Diagram in living color: W123 Vacuum InterLock Diagram
Original Post from here on...!
I recently cut my teeth on this system by working on my Son's car we purchased a few months ago.
The interlock system was in pitiful condition and since there were electric window issues present, I decided to first go through all the doors cleaning and lubricating everything that looked like it had something to do with these two systems… and as I got into the project I also found rust problems at the bottom of the doors just above the inside weather/sound seals on these doors.

I ended up replacing 3 of the 4 door seals and in this effort think I found a way to reduce the rusting problem along the bottoms of the doors, so first my opinion on this. Inevitably the new foam rubber seals ended up with excess rubber bunched up at wherever you ended up… so I found that if I planned ahead for this to be in the center of the bottom of the door I could cut out the excess seal rubber here where it is not readily visible and also end up with a place water to drain down and out of the car. The water that apparently collects on top of the seal down there must be from condensation and when it is just allowed to sit there, the inevitable [rust] must happen!

Back to my Vacuum InterLock Diagram which is a short story for once.
What I did was look around for diagrams that might be helpful to me in learning about and repairing this system and YES, there was some diagrams on this WebSite’s FORUM’s but they really didn’t help too much for they were difficult to read with no color to aid in following the different vacuum lines. So after I finished, I put my knowledge [ limited as I consider it to be ]…
I put it all down in a CAD drawing [ AutoSketch ]. I then found a way to convert the CAD drawing to "wmf" and then “Jpg” file formats with tolerable loss of resolution so that I could at least post a copy with this POST
[ I hope ] for you to peruse. Yes, I borrowed some of the vacuum component graphics from diagrams that I'm sure you will recognized.

IF any of you would like a much better copy of this drawing in a MS Word format file that is just under 100K in size, please let me know by sending me your E-mail address. I'm presuming there is a limit on attached files in this WebSite's e-mail system!?

What I’m really looking for is the benefit of your experience and suggestions as to how I might improve this drawing effort… and then maybe it will be good enough that someone will decide to have the higher quality file also available somewhere here on the WebSite.

Regards,
Sam

Hi,

I used your diagram to help find my vacuum problem (passanger door actuater does not unlock) Thanks, it is great. I have an 84 300D and there was a couple of differences in my system then your diagram showed.

Under the front passenger floor panel where the 2 - 4 way junctions are, my far right holes (both green and red stripe) actuate the gas and trunk lock and the center hole (both green and red stripe) actuates the rear passenger door. I'm sure it doesn't matter which of the holes they use I just pointed out the difference in my syatem.

One mistake I found, is your diagram has the right hole red stripe locking back door, gas and trunk. The back passenger door lock should probably go from the center hole to the door to be consistant with the unlock.

Thanks again for your drawing. It's the easiest diagram to understand I've seen so far.

__________________
Mitch
1984 300D Turbo Diesel 265,000 miles
Previously Owned
1969 280SE 4.5 (what a great car!)
1979 450SL (was fun but a real gas guzzler - bought and sold on eBay)

for it led to my takking a fresh look at my diagram again. And yes your comments helped me to find an error in how I show the red vacuum line running from beneath the front passenger's seat to the right read door. This is the kind of help I need... for I have been too close to see such obvious mistakes.
I will make this and other improvements and the final result eventually will likely be re-POSTED as a THREAD in the " General Information " FORUM under the grouping titled " Do It Yourself Links & Resources ". I am referring to the link/http address: http://www.peachparts.com/shopforum/

I have received other responses directly from those seeking a higher resolution copy of the diagram...
but I would like to also see more responses directly on this THREAD so that all readers might benefit.

ANY and ALL comments and suggestions are welcome and WILL help me to improve and finalize this diagram.

Sam Ross

It was nice of you to share that with us. I was wondering yesterday how the vacuum systems work and was planning to look for this information specifically. Your contribution was quite timely for me. I appreciate it.

__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

Thanks to "Eric" we now have my files available OnLine for the taking. I drew my diagram on a CAD program after working on and repairing two 1980, W123 chassis, MBZs that are shown in my signature below.

You can view these and/or print them "OnLine" or download and save them to your owm computer... enjoy and do with as you wish:

(1) MS Word File - This first file below is the one most will probably want... as it is in MS Word format. http://ericandkat.com/mercedes/W123VacDoorLockDiag.doc

(2) This file is a useful "Jpeg" Photo of Vacuum Lines Near Brake Booster near where they pass through the FireWall http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG

(3) Windows Meta File - This last, much larger " WMF " graphic file I was able eventually to convert my CAD diagram into MS Word format and shrink the graphic file size without sacraficing quality very much... and yes it also gives us much more vivid colored lines in the final drawings... much better than the CAD file printouts. " WMF " is a special Microsoft graphics format that some of you will be able to access directly after downloading it by " double left clicking " or " right clicking " on it... and using either Internet Explorer AND/OR another common Windows program titled " Windows Picture and Fax Viewer ". So if your PC is set up to send/receive FAXes, then there is a good chance you will be able to just double click on and directly view this " WMF " file using this FAX program. An advantage of this is that the graphics you should see with this file are even better than with the MS Word file and you can more freely zoom in/out ! http://ericandkat.com/mercedes/W123VacDoorLockDiag.WMF

Attached Thumbnails

   

Nice job on the vacuum diagram. Is this diagram just for the 80 model? You have a check valve on the vacuum supply to the drivers door. I havent seen mine.. Where is this located at? Seems a good idea to have one there.

__________________
'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

... I think it too should have the check valve. On both of our 1980 W123(s) we found this single check valve on the Door Lock System under the dash up high just above the steering column where the yellow Door Lock System solid Yellow vacuum line turns toward the driver's door side. I just checked my favorite on-line parts source [because of their graphical part blow up interface] and for your car they show such a check valve although theirs seems to be in the engine compartment. They also show it to be blue & white plastic colors. I don't remember what color mine is.
Take another look under the dash and trace the hard solid yellow plastic vacuum line as it passes through and turns toward the driver's door and I think you should find it.

What are your symptoms? I'm doubtful this check valve will prove to be your problem unless someone has pulled it loose. This is a protected area so I think it should still be in good condition... and there are so many other more likely problem areas... especially the reservoir tank in the trunk and the many 4-way and 3-way rubber connectors.

I eventually want to put together a page or two of text describing these trouble areas and innovative fixes!
Regards

Wow great job on the diagrams, you just saved me removing all four door panels to find out all i had to do was put the hose back on the trunk lock! Very nice!

Back when I was working on my first W123 Vacuum Door-Lock system I just knew in my "gut" that a lot of DIYers would benefit from a higher resolution, logically laid out, diagram THAT WAS IN COLOR... for the color makes it so much easier to follow the functional vacuum lines. So thus was my motivation.

Now I need to work on the 1980 240D's lock system and would like to develop and include many more helpful hints on my diagram as footnote flags and then possibly a 2nd page with text explanations as to how one can more easily diagnose which component is causing the leak.
Stay tuned DIYers!... maybe even a " wacky " " WIKI " article on this subject next time !
Regards

hopefully you vacuum gurus still pay attention to this thread. i have just tracked down a leak behind my climate control pod - which is a huge relief that it was that simple - BUT in the process noticed that the ALL BLACK rigid vacuum line going through the firewall doesn't connect to anything inside the cabin. any ideas on that one?

much thanks
Dane
1980 300TD

That is a vent line, it's supposed to be like that.

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83 SD

84 CD

awesome. thank you.

Hello All. I am working on my what appears to be a ACC YELLOW Check Valve - the two end prongs are connected but the neck is NOT...I cannot seem to see where it goes? Any Ideas?

Welcome.
Please fill out your avatar or signature with your vehicle info, as different models have different set ups.

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83 SD

84 CD

Whoops! Sorry about that....

1985 300 Turbo D - Sedan

Federal model - Built 10/84 (per door)

Yellow Check Valve has two sockets on rear - currently connected to a SOLID YELLOW and then what looks like YELLOW with Black Stripe....The single nozzle on the front is not connected to anything.

Door Locks nor Cruise work and now the AC will not open any vents...I changed my plugs no too long ago - so I may have knocked something loose...