Great, thank you! Ill check that out asap. in the mean time, would you know where the line from the transmission is supposed to go? This is the one I'm holding in my hand in the first picture of the first post.

It comes directly from behind the engine between it and the firewall. It was one that I found disconnected for some reason. Ive put it back into a 4-way connector that has one green line entering it but nothing seemed to change.

One of the other holes in the 4-way was also open with no apparent line to be connected to it. I plugged it up with a golf tee for now.

OK so I have here 2 diagrams that should be for this model (i hope) if its correct it should answer my question about where the transmission line goes to.

It should go to the vacuum transducer while passing through the green vacuum damper. The part you were mentioning to me must be the switchover valve vacuum transducer (#125)

I'm now wondering what 63 and 63a are? and I see there is a 4-way connector near the check valve that has "c" indicating "residual consumer" should these be open then? I think this may be the 2 holes I plugged up.

Also where the diagram shows line "a" ending it says its the line from passenger compartment. Is this a line simply loose in the passenger compartment somewhere?

Thank you all for the help so far!

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Not sure what is what in the diagram since it's kind of small to read on my computer. There is a vent that terminates in the passenger compartment. 125 could be the part I was referring to, although I'm under the impression the switchover valve is the valve to the right of the brake booster.
It's too dark for me to see anything on my car now.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

This is my '84 CD. The yellow check valve is open because there is a vac leak in the door lock system. I used a connector (distributor in MB speak) with one fewer orifices so there isn't a plugged off line. I have also taken the egr system out of the loop.
The black line coming from the top of the green damper goes over to the passenger side, down to the transmission. The other black line that T's off, is the vent that goes to the cabin.
You'll note an opening on my turbo over boost switchover valve. The line is connected from the manifold and a PO just used a single "U" connector to bring it to the ALDA.

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83 SD

84 CD

The device pictured in 1 looks quite different than the device I have in the same location on my car. Yours looks like the one on toomanymbz's CD. Mine includes an electrical component and is a square larger device. So any advice I have given may be inapplicable to your system, which is odd since we both have 85TD's.

Given toomanymbz's picture it looks like the line from the banjo bolt on the back of the intake manifold should attached to the top of the device in picture 1. Mine does not attach there.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

What's that clear plastic filter on top of the fender liner in picture 1? Is that in the window washer fluid line?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yes, when I replaced everything in the system, I went ahead and put that filter in. I mistakenly thought a pice of $hit got in there and clogged up one of the nozzles. Seriously overboard.

The switchover valve on my SD looks quite different than the one in the CD.

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83 SD

84 CD

I need to edit myself.
The above sentence SHOULD say "The other black line that T's off goes to the forward most nipple on the main vac line."
The line coming from the bottom of the Vacuum Control Valve is the vent line.
Sorry for any confusion.

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83 SD

84 CD

I believe its like mine, and I followed all the hoses and they are all connected. Including the one you thought might be disconnected that is supposed to go under the Blue Vacuum transducer part downstream.
Its a clearish line with a green stripe for mine.

I also hooked up th transmission line to the line that was disconnected with the small green damper on it. Now teh car hesitates for quite some time before it shuts off. After turning the key it probably takes 5 or 6 seconds to shut off.

Does anyone know of any more thorogh diagrams. The two I posted are the ones Ive found on the sticky for vacuum diagrams and theres another for the lock system but not an up close or part by part diagram. Im seeing parts connected with several vacuum lines that aren accounted for in any diagram Ive been able to locate.

Which one is the main Vac line?

The one from the vac pump to the booster. It has two nipples on it.

You have a leak somewhere, as the engine doesn't want to shut off as before. Start with the pump itself. Plug off the nipple closest to the cabin, hook up a gauge to the first one, check the reading, should be over 20 in Hg.

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83 SD

84 CD

IM slowly figuring this thing out. Thanks for all the help.

I started replacing many of the rubber hose connectors as most of them are getting pretty crusty. However I noticed leakage from lines still even when I simply block off the line on one end and test it with a mityvac on the other.

I found that the rubber tubing Im using, although seems a tight enough fit, is still allowing some air to leak in. Im having a hard time trying to find hose thats small enough. What size should the smallest of the vacuum lines be. Im sure it could stretch onto the larger vacuum lines too so even if I got a length of the smallest needed I would be good to go.

I just dont know what size to ask for when searching. is there a size in SAE that will fit very snug on these lines?

Question number 2 is,
I found a small rubber cap on the green plastic part that connects the vacuum line directly to the transmission, in bad shape. Its crumbling and old. I tried to see if it was interfering with the vacuum going to the transmission but it didn't seem to make a difference weather it was on there or not, however its hard to say.
It looks like a pretty specific size and shape of cap so as not to be able to find some generic match. Would anyone know if this should cause a leak in the transmission vac line?

and if this isnt the cause of the air leak, and the line itself is in good shape, what to do about the transmission not holding a vacuum. It may be the replacement rubber hose thats causing the leak but Im not sure yet, Have to do some more testing and replacing of lines.

Click on the buy parts button at the top, if you can't find what you need, call Phil, there's a number.
I'm currently checking vacuum on my modulator.

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83 SD

84 CD

we just bring the rpm up for a second and shut off the key, then let off the fuel. it shuts right down. 79 300 td 300000 and going.