Just got my shifting problems fixed when I had a mechanic checked vac lines' pressure and connection but I noticed that ever since, everytime i turn off the engine, the brake pedals now depress higher before starting the engine and slowly sinks to normal after the engine starts. I am posting a picture of my vac connections and hope somebody can help me identify and double check if I have the right connections.


















Can anyone spot what's wrong with my connections?

TIA

I won't be any help to you, sorry! I know what mine looks like and it doesn't look like yours. (Your engine bay looks pretty nice and clean!!)

I suspect this is a pretty common occurance on these older MB....by the time we get 'em, everybody has "fixed" them. I know my system has been cobbled up and glued back in place....forcing me to follow someone else's lead, right or wrong.

WE NEED TO SEE A CORRECT ORGINAL SYSTEM IN PLACE...at least I do!

Anybody got pictures of one?? The good ole Haynes (almost worth the paper it's printed on) Manual justs "many systems on the MB run off vacuum" and other "usefull" bits like "motor mounted vacuum pump"!

__________________
Mark
1983 300TD Wagon
Even a broken watch is right twice a day

Thanks for the reply Mark. I have searched other links and seen some pics but they don't seem to be the same as my engine bay.

and that is EXACTLY our problem! I would love to see a pictorial diagram...with notes for newbies...like the leg bone is connected to the kneebone or in our case vacuum lines instead of bones!

Just as an example, mine has a green dash pot installed right above the transmission vac valve just behind the alda...yours doesn't. My tranny shifts good, yours is fixed, so who/what is correct? I don't think that "missing" dash pot is gonna help your brake pedal problem.

__________________
Mark
1983 300TD Wagon
Even a broken watch is right twice a day

The proper vacuum line connections for the '82 300 SD look like this:




It's difficult to troubleshoot your system via photos because it's not possible to follow each line to determine where it leads.

However, I do have one question regarding the line from the overboost valve on the firewall to the ALDA. This line has a "T" in it. One part of the "T" goes to the ALDA. Where does the other end go? I mention this because it's definitely not proper for this line to have a "T" in it.

Compare the vacuum diagram to your own vehicle and understand it. It's possible to greatly simplify the diagram when you eliminate all the plumbing to and from the EGR. The black box on the top of the valve cover can have all of it's lines removed.

While comparing my vac lines to this image from boostbenz, i tried to make the connection descriptions clearer.









#1 I don't have a surge damper vacuum. What is the effect of this piece?

EGR Connections #2 is not connected #3 is connected behind the firewall (to brake master? i'm not sure what that round thing is.) and the other one is connected to the vacuum control valve. But it seems i lack 1 y connector there.

#4 I'm wondering of there is supposed to be vac line connected in this opening?

#4a I suppose this is my feed line. Isn't it supposed to be connected to #4 via a Y connector? If I remove and transferred this to #4, will it cause any leak or problem from where i unplugged it?

#5 I suppose connects to the transmission.

#6 connects to the over boost valve that bryan might be referring to.

#7 connects to the ALDA via the Y connector.

#8 goes to the cabin. I also noticed that I don't have the yellow thing like the one on the boostbenz pic. What is the effect of this? My vacuum doorlocks are not working anymore since the it doesn't have the a motor/vacuum located in the trunk when I got this car.

#9 I'm not sure whether this is the right connection for this link. I don't have any idea where this red line goes to.

#10 Came from the EGR. I am really wondering if this is the right connection. Maybe this is where my brake problems arise.

Whew!!! Any help on how I can make these connections right will be very much appreciated.

TIA

#1: The surge damper cuts the occillations in the system due to the changes in vacuum upstream of the VCV. It's a dealer item......not too costly.

#2: It's not connected, but, where does the other end go??

#3: This is the vent line. I does nothing more than add fresh air to the system when the vacuum drops. You can leave it.

#4: There is a vacuum line that is properly connected here. It T's into the vent line to the cabin. Since you don't need the EGR, reroute the vent line (#3) directly to this port.

#4a: This is a brown vacuum line?? I can't tell where either end of it goes.

#5: Yes, it goes to the vacuum modulator on the transmission.

#6: Yes, that's the line from the manifold to the overboost valve. This is the line that typically gets plugged with soot. You need to remove it periodically and clean it out.

#7: That's the line from the overboost valve to the ALDA.

#8: This is the main problem. If this line goes into the cabin, the only possibility is that the PO decided that he wanted a boost gauge. The line measures pressure. So, if there is no boost gauge connected inside the cabin, then you MUST remove this line and plug it........better yet........get rid of the "T" altogether.

#9: I'm not clairvoyant.......either. You need to show where the ends go. That line might simply be one of the main vacuum supplies that provide vacuum to the doors or the climate control system.

#10: If this is the vacuum supply to the EGR, you can reroute it and feed the VCV directly. All the lines from the EGR can be eliminated. HOWEVER, you MUST HAVE a vacuum restrictor in the line to the VCV. It's a small plastic piece with two nipples and it has a small orifice inside. This is critical. Without it, the entire system won't work properly.


I posted the vacuum diagram for the SD for you to specifically note and understand it. It's much better to work from a specification and return to that specification.

I tried to xfer 4a to slot #4 but my engine won't shut down.

Go back and reread what I wrote.

I already did this connection before brian's post. I test drove it and it works fine but sometimes jerks again when shifting. Already removed the EGR lines. Looked neat and simple.





I connected the "don't know" line to the #4 slot. I now know that it is the vent line from brians earlier post. I dont have a straight hose so I blocked the other end with a bb.

I'm wondering if it is safe to connect the overboost line directly to the ALDA? I just want to see if there will be any difference in performance. My 0-60mph is at 40 seconds. I don't know where to start to bring it to 20 seconds at most.

I did not connect one line to the cabin. I have observed no difference when I test drove it. Do I need to plug it, too?

Ignition line was left untouched....

Thanks for the info Col. Klink. I will check the white valve tomorrow.

My problem with the diagram is that I don't know where #62 is connected. Nor I dont think I have the right colors of the hose/wire it is saying.

Any other suggestion or comments on what I did wrong?

I'm going to make one last attempt.

You've ignored my previous posts and have connected the VCV directly to the transmission. So, there is no vaccum to the VCV. The proper setup.......per the diagram listed above.........is supply vacuum that gets a T. One end goes to the VCV and the other end goes to the transmission. You already had this setup properly before you went ahead and randomly replumbed it.

All you needed was the vacuum dampener (green and white device).

You also need a proper orifice in the line, #63 on the diagram, or the system won't work properly.

I previously advised you to remove the line from the manifold and clean it. Also clean the banjo bolt that you remove from the back of the manifold. It's plugged solid with soot. That's the reason the vehicle won't perform.

Hi Brian,

Sorry for my ignorance. Problem is I don't know which one is the supply line. I don't know where #62 on the diagram is located.

Before I replumbed it, it was connected to the EGR. I removed the connection from the black box and all was left was the transmission so I places it directly to the VCV (VCV-I hope we are referrring to the same thing here ) I hope you can describe to me the supply line based on the picture if it is there.


To answer your previous questions:
It is connected to the black box (EGR) on top of the valve cover.

I just did that. I don't have a straight hose so I plugged the other end of the T with a bb. I hope I understood it correctly. Pls, see pic.

This brown line is connected to the ignition. I also cannot see where the other end is connected but my engine doen not stop when I tried to put it to slot #4 earlier.

I have already cleaned the banjo bolt and this overboost line is newly installed only about a week ago.

I already did and placed the ALDA line directly to the overboost valve(?)

I did not connect this line anymore. My ac still works fine and I don't have the air pump thing that is located at the trunk for my power doorlocks.

I would appreciate if you can give me the part number of the vacuum restrictor and the vacuum dampener so I can ask the dealer.

Thanks for all your help... It is very much appreciated.

The supply line will terminate into the main vacuum line from the vacuum pump to the brake booster. All vacuum comes from this line. The restrictor, #62, needs to be placed in the line before the VCV. The vacuum T's into the VCV and continues on to the transmission.......like you originally had it setup.


That's correct. It had a second T that sent vacuum to the EGR. This T can be removed (is removed). But, the T for the VCV must be in place as you see in your original photo.


Don't have access to the EPC, personally. Maybe someone else will chime in. However, that's what a dealer is for. They turn the description of the item into a part number.........if they have half a brain.

Thanks for your effort. I feel so dumb at the moment. These pics might help in giving me a clearer understanding. This is the pic behind the firewall which shows the main vacuum line.




I can clearly see that #11 connects to the T on the main vac line. My problem is I can't see where #12 went. I'm afraid to pull this line as it goes underneath where I can't see it. I'm afraid I might pull the connection and I cannot see (or reach) where to put it back. If you can see the THREE lines that went out of the firewall these are 11 which went straight to the VCV, the cabin line (black) which goes inside and left unconnected, and the ignition which was connected to the vac shut off valve. Is there supposed to be a FOURTH line for the vac supply?

Thanks for your patience.

Look at this photo:






Do you see the T that is directly above the vacuum control valve? One end of the T goes to the transmission. The bull goes to the VCV. The other end of the T is the vacuum supply line.

What did you do with this line when you replumbed it.........erroneously??

Don't mess with any of the other lines that come off the main vacuum line. They feed the doors and/or the climate control unit. They are not relevant to this discussion.