I know there are several posts concerning this but I have yet to find one that could help me so I decided to start a new thread. First a little background, this is my 1979 Mercedes 300d, 87k miles that my grandfather owned and willed it to me. It had been worked on a few years ago with the a/c system (which was never fixed) but I believe they have messed with the vacuum system as well since the door locks quit after that. Not realizing they ran off vacuum it would have been an easier fix at the time but oh well. I have changed the 4 way connector and both check valves due to leaks and have hooked it back up the same way but I feel it is not correct. Please someone take a look and tell me what is wrong. I'll post the pics and below will try to name the color on the line and where it's going to currently.

http://i779.photobucket.com/albums/y...o/324180fc.jpg
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I am working on a picture with labels but I am having issues uploading but when I get that fixed ill post the link.

Anyways I ran into some issues. After making some changes that left me one line left out. Should I have another connector somewhere? Let's start at the beginning of the source and work back.

I have coming off the brake line connecting to a 4way connector. One is the brown line going to the ignition which in turn off the ignition the brown/purple line goes to the IP (on the back). The other two lines off the 4way are the check valves.

One check valve has the resevoir tank in the trunk (yellow/gray) and the other is the cruise control (black/yellow). The other check valve has the climate control (green) and climate control resevoir (red/black)

Last is the door lock yellow attached to the top of the pump which I am not sure what this is called but what you are saying is this should just be vented. First thing is I have to connect the yellow somewhere so that should be where? I suspect the check valve but I would have to disconnect one of the others. I feel like musical chairs here ha ha. Should I have some t line in here or something? Also I took the cruise control (black/white) off and hooked the door locks (yellow) instead.... I obviously have a leak in the door lock system but now I cannot shut off the vehicle unless manually. Could the leak in the door locks cause the engine to not shut off? That's one issue and the extra vacuum hose is another. Sorry I know there is stuff out there on this but they all seem different and newer than mine.

 

Upload it to Photobucket and post a link. This would be super useful for folks like me who have pre-1980 cars with vacuum issues.

Absolutely, and it's one of the most common causes of shutoff failure. Trying to diagnose a shutoff problem in my 1978 300D. Mercedes Source has videos on the subject.

 

I have lost patience in fixing the problem ha ha.... The more I tore into it the more I started breaking vacuum lines in te hardest places to fix back.... My leak must have been substantial considering this has not worked for at least 15 years.... I am currently putting everything back together and hopefully I can fix the shut off problem, you just need a good vacuum source and of memory serves me correctly you must completely disconnect the door look vacuum from the system or it will bleed the air off and there will not be enough vacuum to the shutoff to work..... That is why mine was originally attached to the pump but did not effect anything because of the substantial leaks in the system it was the same as venting to the atmosphere.... I will keep you posted though.

 

Did you ever manage to fix the shutoff? Based on the age of your car, I would suspect the vacuum pump. I'm helping my friend fix the shutoff in his 1978 300D, just ordered both of the vac pump rebuild kits -- there is one for the diaphragm and another for the pump check valves, plus the vac pump to engine gasket. Less than $25 from AutoHausAZ. Good luck.

 

Oh yea I got it to shut off. There was to many leaks in the door lock system and it was losing vacuum that way. When I unhooked that and plugged it off it would shut off then. If you are having problems with yours I would start with unhooking everything and then hook up the startup and shutoff first. If that works then you know the problem is elsewhere and not your diaphragm.

 

Tried that already. Disconnected the door lock and climate control check valves and plugged them off, leaving only the shutoff. I think this leaves only the vacuum pump and the brake booster. I also ordered a Mityvac, which will be here tomorrow, so I can do a proper diagnosis. Glad yours was an easy fix.

 

Yea you should be able to tell if you are getting vacuum or not when the car is running by sticking your finger over the hole. You have already ordered it so it probably doesn't matter now but worth a shot before you tear into fixing the pump. If the booster is leaking on the brakes then you can really lose vacuum that way quickly.