On my 116.120, I have (3) lines at the plastic shift modulation valve (vacuum) on top the injektion pump. I marked everything when I removed the engine, but some of the tape has fallen off since then.

I have noticed there is one black line that somes off a 'Y' fitting, directly from the vacuum pump itself, (1) black line that goes into the car at the firewall and lastly, a single black line going to the transmission modulator.

How are these supposed to be routed??? Any information would be helpful. I just can't remember where they went.

If I hook them up 'logically,' the engine will not shut off. When I hook them up so the engine will shut off, shift quality is too soft to suit my tastes.

Anyone have a 116.120 / 617.950 they could take a look at for me???

I may be dealing with a vacuum leak, but I would like to make sure I have the routing correct before proceeding further.

Thanks very much...Bert

You have a W116, with a OM617; but what year is it?

A picture would help also.

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Herr Doktor Bert, how are things in the valley?
Most of my experience is on the 123 and 126 chassis, but I believe the 116 is very similar. You probably already know all this but I'll say what I know in case it helps someone else in a predicament understanding that system:
The black line going thru the firewall is a vent line (to atmosphere). If you also have a 2/3 way valve atop the valve cover it has a vent line (also black) and a couple lines for the EGR, those small valves can, if leaking, cause hard shifts, not soft ones.
A soft shift is a result of excessive vacuum, not loss of vacuum.
There is a small "splice" that has a controlled orofice and is colored brown or green (there may be other colors also). Green makes for firmer shifting than the brown one. This splice lies between 2 rubber Y's the secind of which fits on the IP transmission modulator valve on the rear of the IP. No splice (ie a regular piece of hard tubing) there would probably result in real slushy shifts but I've never tried that personally.
The modulator valve is a controlled leak that reduces vacuum gojng to the trans in accordance with the accelerator rack position, it can't be checked with just a Mity Vac BTW (BTDT)
Someone posted pics of the vacuum routing here some time back and I thought there were plans to make it a sticky.

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The black line through the firewall is a vent??? Hmm...that is interesting.

Keep in mind the 116.120 (1978) does not have any vacuum valves atop the valve cover, nor does it have any check valves in the lines as you speak of. I am interested greatly by this information.

I have a black line coming directly off the vacuum pump, a line going to the modulator valve on the transmission and the 'vent' you speak of that goes through the firewall.

I think the 'splice' you speak of was robbed off my 116 while it was in storage. Are you saying the controlled orifice goes in the vent line???

I would love to see a photo of these three lines in their correct relation...Bert

Mine has the "Y" fitting going in at the top...and the single black line coming off the side. I've only had it on adn off about 6 times in the last 2 days while I was playing musical IP's as I am turning up the full load adjustment....and fighting what I believe to be a partially airlocked IP.

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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

Bone...

Do you have the 'bleed orifice' (green or brown) that was previously mentioned???...Bert

I will look at that one when I get home also....that should be in about 2 hours....I'll get back to you then....I have a dentist appointment before I get home.

__________________
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)
---------------------
Section 609 MVAC Certified
---------------------
"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

Thanks very much...Bert

The orifices were not used in all years. I have an '81 240D, and while trying to solve my shifting/vacuum issues I tried to purchase my "missing" orifice. Came to find out they did not start appearing in 240D's until '82. So, DoKtor's W116 may never have had an orifice

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the Solid brown.......and the Green / with black stripe go to the "T"s that are feed from the small Vacume pump line..........the side of the vacume valve goes to the black line that goes through the firewall...the "T" on the top goes to the trans modulator AND the "T"s fed by the small line from the vacuum pump.

The Brown with grey strip goes to the shutoff solenoid.

Now is the right? this is how it was since I got the car and seems to work well.

Well I got the car running....first two cylinders were not being fed due to a large anount of air at the front of the pump...and it was facing uphill.

Car is seriusly overfueled now...to the point its reluctant to idle down...it does but real slow at it...also confirmed by massive black smoke accelerating...only drove it 1/2 mile but that was enough to confirm it for me.

Pump comes back off now to lean out the Full load.......by 2/3 what it was enriched.....damn....its supposed to rain tomorrw and its almost dark now.

__________________
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)
---------------------
Section 609 MVAC Certified
---------------------
"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

Would you happen to have a digital photo???...Bert

No but I will try to take one tonight and email it to you.....I can't host the photo for everyone to see however.

Incidently I found a simple cure for the airlocked IP....and I settled on 1.5 turn of the Full load internal adjustment...even with that its holding my idle at 1,000rpm right now and is a little slow returning to idle....but that thing does accelerate strong...all the way through the gears....3 was obvious overfueling it.

I have the W116 with me at work today but my camera is at home. I will try and hope the picture comes out well enough to answer your questions.

__________________
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)
---------------------
Section 609 MVAC Certified
---------------------
"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