So as the title states.

I have two w123's. Both are US spec, 1983 year models.

One is a 300d Turbo, one is a 240d

Both have automatic transmissions.

Here they are- the 300d is the (faded) silverblue one, the 240d is the (faded) light ivory one.




Here's the deal- i bought the 300d around a year ago for $400. I have been gradually repairing things here and there.

First line of order was making it mechanically sound- done

Then fixing up parts of the thrashed interior- done

Now i want to repair some of the vacuum system.

My transmission shifts great (at least i think so)

My door locks dont work (explained below)

My air only blows from the defrost and side vents. I have tried other ac switch panels.

Other than these issues, i do not notice any other vacuum related problems

My green/yellow vacuum line coming out of the firewall (HVAC?) is ended by a dirty piece of duct tape. no connection to the system.

My yellow check valve (door locks?) is also open to the air. I tested it with my mouth- it works.

One door lock line is severed in the door jam due to a missing door check strap. Obviously this must be repaired.

Is it possible the prev owner rigged it up like this to avoid fixing the leaks?

On to pics- since this thread is useless without them.



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Now on to the 240d.


I bought this car around 3 months ago. $150. Flood car. Has not been cranked in ~14 years. Supposedly parked due to owner not wanting to drive it anymore, it was running fine when parked, or so i was told.

I installed a glow plug relay, flushed the fluids, ran fuel out of a separate tank, changed fuel filters, and it lives. It sounds very healthy.

The bad- it doesn't want to come out of first gear. I think it did once, because it randomly slammed down back down into first, but other than that, its somewhat not drive-able due to this. Im leaning towards a vacuum issue

I believe someone had a field day on the vacuum system- alot of the connections on the valve cover are missing. See here-










My question to you all is- does anyone have one of these cars with a perfectly functioning vacuum system that they could snap me a picture of?

Or, can anyone tell me what i am missing on these two cars?

Also- where does one locate the correct lines and fittings for these?

Sorry for being such a newbie on these cars- the one i got last year is my first old Mercedes ever. I've never dealt with attempting to repair a vacuum system

Thanks in advance

Go crazy.

__________________
'80 300SD - '83 240D - '00 E55 AMG - '02 G500

It’s my experience and understanding that even with zero vacuum gong to trans, it should still shift through the gears. You’d have some rougher downshifts, and the final one into 1 will clunk. Not shifting out of first is not likely a vac issue.

I figured out a leaky vac lock system on mine. First off, i’d close off the hvac green line near the south in engine compartment, and leave that stuff for later. Diagnosing those leaks is way more of a pita than locks - and you’ll likely need the dash out.

The locks you just have to methodically go though each door and the tank in trunk - testing with mityvac. Take out the removable floor carpets, learn how to disassemble the door cards so you can get inside the doors to inspect each vac element. This is pain but after doing it like 8 times I became an expert. The vac diagrams are helpful but I will say that our friend Kent at the “source” does have a very helpful booklet on the lock system that I found key in my diagnosis.

thank you very much. Going to try and tackle this soon. The 300d is actually registered and running, the 240d has a long way to go so ill probably sort the 300 first

If anyone has a picture of their engine bay that would still be much appreciated

Great deals on great cars. The 240D looks fantastic in the photo. I'd put a bumper sticker on the back showing off what I paid, so new cross-over owners can sulk over their car payments while sitting behind you in traffic.

If like my 300D's, the vacuum stuff on the valve cover is only for the EGR system. Unlikely that Rube Goldberg system still works, and even in CA one is not required to maintain it, which would be almost impossible anyway. Rollguy here sells an EGR block-off plate set, to allow removing the EGR valve. Several posts show the EGR vacuum components you can remove, which is about half in the diagram.

For a quick stab, the usual suspect in door lock system leaks is the trunk lock. You can easily cap off those 2 tubes (behind plastic cover in trunk). Another culprit is the fuel door lock. You can cap off that and the trunk at the feed under the front passenger's carpet, outer side. That will degrade you to having to use the key to open the trunk, as do 99% of U.S. cars thru ~2000, plus you need the key anyway unless you always remember which way to remove the key to leave in auto-lock mode.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Yes. The 240d supposedly had new seats ordered new from Germany before it was left to die. The interior is mint, minus the console wood and some dash cracks.

Now that you mention that on the trunk lock, my trunk lock is literally drilled out because the previous owner lost the key and couldn't figure out how to get another one

I actually dont mind it, because the latch to open it is way back and off to the right, so its nearly impossible to open unless you know what you are feeling for. Noone has been able to figure it out, even with me trying to explain where it is.

If it is messing with my vacuum system, i will replace it.

My fuel door is also sort of "sunk" into the body, i suppose due to some sort of rubber bushing of some kind that has been swept away due to the neglect of the car in it's past.

So i doubt the fuel door locking pin could even lock it. IF that is how it works. I know that is how it is on my w212.

Trying to decide what is more important. Repairing my vacuum system, getting the 240d to shift out of first, or repairing my A/C in my 300d.

Being in Louisiana, with the summer approaching, logical me says- fix the A/C

Many posts on testing and fixing the AC. If the clutch isn't actuating, you can do so directly by removing the relay and jumpering terminals 30 to 87 w/ a 14 awg wire. The relay is on the driver's inner fender under a plastic cover, the fwd one (other is for radiator fan). Low (or too high) refrigerant pressure will prevent the clutch from actuating. That pressure switch is on the filter/drier passenger side. Remove the connector and jumper to bypass it and verify.

If not those, it gets tougher since the automatic climate control is erratic and trouble-prone. 3 boxes control that - pushbutton box and 2 boxes above glove-box liner. Good luck.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I too would address the AC first, the green pipe with the duct tape is for the HVAC and until it's connected to the larger vacuum port it's never going to work properly, fix that before doing other HVAC repairs .

The vacuum door locks are actually prettyy simple, you do need the $30 MityVac tool or it's cheaper Harbor Freight cousin and some bits of vacuum hose o use in the testing .

You don't need any more pictures, just the diagram above will do the trick .

ANY vacuum connection that pulls apart without needing to twist it, leaks and needs replacement .

Expect to find lots of very slow leaks, fix them all by replacing the hose or 'Y' connectors, NEVER trim an old hose end .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better