Good Grief.
I am going nuts trying to figure this one out.
My mityvac tells me there are leaks throughout my vacuum system. I replaced the IP shutoff, and blocked every other line in the engine compartment.
I connected the tranny line directly to the main vacuum, still unreasonable hard shift.
So I decided to include the 3/2 way on the valve cover, and the vacuum modulating valve on the IP.

Can anyone tell me what the line on the side that I have plugged on the vacuum modulating valve is? The diagram says "vent"
- the other top line goes to a 3-way, this side one went to a pod on the left side of the counsel.
Should I just leave it open or plugged? (see pic)

This may all seem confusing because I don't know what the heck all that stuff is for. Why do they make it so confusing?
Is there a simple way to just plumb only the tranny?
I have read forum after forum, and it still is a mystery...
This being that wonderful year, 1980, no turbo, no functioning alda..

If anyone could help me, I would be forever in your debt.

I called the repair shops, but at $95 an hour, with all my vacuum problems, I would get seriously spanked. I just can't afford it.

Attached Thumbnails

 

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Thats what happens when an obsesive/compulsive goes to engineering school and gets fascinated by vacume. Someone designes a vacume monstrosity like this.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

isnt that the alda riight there in the left of your picture? you like to golf?
will

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'73 VW camper
'80 300td wagon

That line on the side there that you have plugged is just a vent. On my 1980 a black vacuum line leads from it, through the firewall, and into the cabin, right there underneath the steering wheel. It goes to nothing. It is attached to nothing. So you can leave it open, not plugged.

I think that you still had bad shifting with the main vacuum attached directly to the transmission's vacuum line is because it doesn't always have full vacuum going to it constantly.

You said that you have a lot of stuff plugged in the engine compartment. I can't really tell you what to do except keep on trying/troubleshooting, but try putting everything back to normal unless you know that something is leaking (and should be disconnected).

For example, it would probably be good to disconnect and plug the line that goes through the firewall to all the door locks, fuel flap lock and trunk lock, etc, and just use the locks manually for now. It might also be a good idea to disconnect and plug the line going through the firewall to the ACC (should be green w/ yellow stripe).

Again, from here I can't really help you too much as it is all just troubleshooting. Do you know if the transmission fluid/filter have been changed? Maybe that could be a cause of your shifting problems.

Oh, and if you haven't already, try sticking a bb (ball bearing) or some other type of plug in the rubber portion of the hose that attaches to the EGR valve (under the air cleaner). That way, you can be sure that if the EGR valve is bad, you aren't loosing vacuum from there (and you might also pick up some more power and MPG's ). Although I'd recommend you get your shifting straightened out before you plug the EGR.

Yes, that's the ALDA, but we don't have the associated turbo + plumbing

Thank you so much MBwD for your thoughtful reply.
The tranny was actually rebuilt right before I got it, the fluid looks new, so it seems the filter should be fine.
For now, I just have the brown line for IP shutoff connected, and I will reconnect the vent, which was interestingly enough connected to a "t" inder the dash, now I see incorrectly.
The blue line going through the firewall leaks vacuum, I don't know what that is and it is plugged. The yellow lines (one solid, one with black stripe) both leak as well, I don't know what those are either, they are plugged. The green you mentioned leaks and is plugged. Lots of leaks, just replaced the IP shutoff.

I love this car. I am just really worried about the tranny, I couldn't afford a new one. It shifts so hard it throws me in the seat, really.

I sure do appreciate your thoughtful reply, maybe with the vent not having vacuum on it will help.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

The yellow plastic gizmo in your picture, whose vent you plugged, is there to vary the amount of vacuum to the transmission based on throttle position. When you step on the throttle, the vent opens more and more, and the transmission gets less vacuum (which, if I remember correctly, results in smoother shifts). So definitely restore the vent...

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'81 300TD Wagon 355k (Miss Diesel)
'83 300SD 180k
'84 500SEL 190k (Parting it out)

take off the little plastic cover directly to the left of your plugged line (which you can unplug) in there there should be an adjuster , turn clockwise to increase vac to the tranny (softer shifting) or counterclockwise to make less vac (harder shifts).it is very sensitive so make small adjustments and test drive.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

I have restored the vent, and it shifts hard still.
I have left the EGR, 3/2 valve, and the yellow gizmo (now vented) in the original configuration (I think) with the vacuum and trans line hooked up to it. All lines to pass compartment are plugged, so the system is tight. I wonder if the modulator on the trans could hold solid vacuum, yet still be bad?

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Hey, thanks for the tip 84300DT, and everyone else,
it's getting dark so I am giving it up till tomorrow.
I am looking forward to that vac adj.
I sure do appreciate all your help.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)