I am posting this with the objective of learning more about the vacuum system on my 1980 300 SD 116. I have battled thru the "no door lock", "no engine shut off", "no CC" and bad transmission shifting problems and now have gotten thru all these after a fashion. Now I have the usual defective CC servo which I have bypassed by way of a valve which enables me to shut the heat off in the summer(No AC). I can ,by necessity,live with this. The transmission shifting is tolerable with some slight flaring at times between 3 to 4. Depends on throttle position. Downshifting is smooth at all times.

The engine I now have came from an 82 300 D complete with transmission. The combination had less than 50K miles. I had all seals in the engine replaced and had the tranny rebuilt because they had been sitting for an extended period.

The people that replaced the engine knew less about the vacuum system than me.(I found this out after finding my way to this forum). This newer engine had the variable valves on top of the valve cover pan and they contributed to the aforementioned problems. I think it was Steve Brotherton who told me to eliminate these and that was the beginning of the solution to most of my vacuum problems. My EGR system developed a clogged vac supply line soon after I became aware that the EGR system existed.

Which brings me to here. I plan to keep this car for the duration. I have no major problems other than the usual oil leaks.Also, the usual adjusting of valve clearance a couple times a year . BUT--I know that vacuum problems are lurking in the bushes just waiting for the most inconvenient time to strike.I have not the option of taking any problems out to a shop. I am supposed to be retired and my income is based on my 1990 salary. ( I was paid weakly). Beside that is the fact that know-how about this system is,to my knowledge, not there

I have made a diagram of the engine compartment vacuum hookup as it now exists. My problem is that I have not a clue where the lines go after they enter the interior near the brake booster.I will try to post that diagram in the hope that someone might help. I have compared my diagram with the PeterSmid diagram for the 80 300 SD and find no similarity. If a different diagram or other information need be sent that is too bulky to post here my email is Tinwillie . I thank everyone in advance.

I have read all the threads I can find about this system and find that the ones by Brian and Sam are exceptional. I recognize that there is a wealth of knowledge on this forum. THANKS

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Correction on email address. it is Tinwillie SORRY!

Willie:

I'm no expert but I've purchased 15, 123's and have had my fair share of vacuum related issues. Brotherton is a genius.
My two cents worth is as follows:

1. Don't worry about this issue. If you want perfection, go to a 'get together' that features many cars like yours and configure yours like one of the other MB's.
2. Otherwise know this....of my five daily drivers (all 123's with 300D turbos), none are configured alike. They are all different.
3. Once you have the door locks and associated shut off vac's working and once you can live with your 'flaring' issues, most of the battle is won. We drove one car for a year without the flaring getting worse.
4. At first I got real obsessive about this stuff, but after having 5 daily drivers for nearly 6 years, its not as big of an issue as it first appears.

Its mostly the way it is with these cars. High maintenence at the beginning and then lots and lots of carefree miles.

My record is 22 months on a daily driver without touching it (other than oil changes and valve adjustements).

For what its worth

diesel don

__________________
DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

in the 123 the lines going in the firewall by the booster are the ones that plug into the ignition switch.... the rest of them run into the firewall under the battery,. Your mileage may vary. Get the MB manual on CD. It has full vacuum diagrams and testing directions.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Unless you like spam, I'd strongly recommend that you edit your email out of your posts. People can PM/Email you directly (by clicking on your name) to contact you.

You could also obscure your email by doing something like this: justin [at] gmail [dot] com. I'm very protective of my email and a spam-free inbox proves it works.

__________________
-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

Hey Guys Thank you for your responses. Any contribution is well appreciated. Diesel Don:As I stated initially, my objective is to improve my limited understanding of the vacuum system.I would like to get to the point where I can troubleshoot the system with some degree of intelligence. I cannot do so without knowing exactly where the lines connect inside the car. Incidentally the car is a 80 300 SD 116 body style.It was the repl engine that came from a 300 D. You are absolutely correct in that my 27 year old car is not ever going to be perfect. I am probably getting as close to that condition as I'm going to get. Thanks

Winmutt: There are 9 lines going thru the firewall near the brake booster in my 300 Sd 116. I think the lines going thru on the passenger side are related only to the climate control(servo). I am quite happy with fuel economy getting about 28 mpg average. I got the MB CD early on. The only readable vacuum diagrams are for the CC system and they do not answer the questions that I have. It appears that their mission was to get all the CC information on one page without thought to logical presentation. Thanks

Justin:Your advice about the email is well taken and I will try to edit that out. My concern was the size restriction on attatching a file. I had a 1981 Rabbit after market turbo diesel (long gone to Rabbit heaven)that ate head gaskets with great regularity. the only thing remaining is the heat control valve which is now in my MB Servo bypass system.I still have a 83 rabbit diesel pickup.233k miles still going. Also a 48 flathead Ford F6 dump truck(The handsome Devil) that sports a snow plow. Bought it in 1962.
Thanks

I am adding another diagram in order to correct,and add to the original that I posted. I would like to ask more specific questions that this brings to mind.

1.The vac line that I have designated as 1. Would this connect to the vac reservoir located in the trunk? The reason that I suspect this is that I figure that the brake booster must be a heavy consumer of vacuum(given its size and the work that it must do) and so in order to keep the vacuum nearly constant when the brake is applied let the reservoir help supply same. Anyone?

2.The vac line that I have designated as 2. I have corrected the routing and note that this goes to the intake manifold. Why? It seems to me that the only information there would be manifold pressure. Is this then a measure of turbo boost?? Right? Wrong?

3 .The vac lines 3 and 4. Line 4 is not a clear line but is in fact brown. It is, as proved by my trusty Mitivac, the engine shutoff line. I suspect that this goes directly to the keyswitch as I have indicated. Is this as I show??

I am trying to get some answers to very specific questions here rather than all questions at one time. I would like to be able to make a series of diagrams that depict the whole system--eventually.

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Willie - Your model/chassis is different from my 1980 W123 MBZ(s) but just in case, I wanted to make sure you were aware of my THREAD, diagrams and other graphic files at these hyperlinks:
W123 Vacuum InterLock Diagram
W123 Vacuum InterLock Diagram
http://ericandkat.com/mercedes/W123VacDoorLockDiag.doc
http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG
I think/hope you will find the *.doc file useful in anticipating just where the door-lock system vacuum lines run through inside your car under the dash, into the doors, and finally to the gas access door and trunk lid.
I suggest you print or have someone else print this MS Word file in color IF it looks as though it reflects how your car's lines are tun!
Regards,

... now that I have done this in more detail, I sympathize with your trying to tackle multiple vacuum systems. Hence I think the best acvice I can offer to right now is to: (a) make certain that you have a hand vacuum pump/gauge to work with, (b) continue your learning curve about these very different vacuum systems, and when you work on one next, (c) try your best to to isolate that system from the others by use of golf tees or other means to shut the others off temporarily, and finally (d) ask your questions and for help on one system at a time. IMHO this FORUM will work far better for you this way!
Vacuum Diagram - This is essential. If I remember correctly you said you car is a 1980 W117 MBZ... so if that is correct I find your diagram at:
http://www.peterschmid.com/vacuum/1980/117.jpg
If not, start at: http://www.peterschmid.com/vacuum.htm OR
http://www.peterschmid.com
Since I see you now have a 1982 300D 617 engine, you will probably need to also have and use a copy of that vacuum diagram too so start looking at:
http://www.peterschmid.com/1984.htm and then go to the specific 617 engine type that you have.
Regards,

Sam, Many thanks. Your door lock/unlock diagram is super. This is exactly what I have in mind to do for every vacuum system in the car. Unfortunately I do not have the computer skills to produce such a professional diagram as you have done. Since yours is a 1980 300 D I am wondering if the colors for the lines might not be the same for my 1980 300 SD 116. If that is so you will have already answered some questions that I have not even asked yet!
I try to learn a little more every time I get the chance,given the constraints of "yesdear" projects and cold weather. I try to read as much as I can here on the forum so that I might at least be able to ask intelligent questions
Thanks again Sam,you do good work! Regards, Willie