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  #46  
Old 08-25-2006, 11:34 PM
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Originally Posted by RML View Post
OK. If I am reading this diagram correctly, it looks like I am eliminating a vacuum signal to the EGR system. I read references to the 3/2 switches before. Is this referring to a switch that signals a shift from 3rd to 2nd gear or am I way off. Does it all have to do with emissions controls?

I also read references to BB's. I am assumig this means literally BB's that you use in a BB gun because they are the right size.

Yep, the 3/2 valves in the black box serve only to control the EGR system. It has nothing to do with the shifts. But, if it's leaking, the shifts will be affected and will be firmer than desired.

The BB is the perfect size to plug a vacuum line. But, in your case, if you eliminate the T's and connect the remaining lines with a short section of vacuum hose, you'll have a much cleaner setup.

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  #47  
Old 08-25-2006, 11:40 PM
RML RML is offline
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I'll give this a try and see what happens. Thanks for the advise.
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  #48  
Old 08-25-2006, 11:47 PM
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Richard, Brian and I are in agreement here...

(1) Vacuum Testing Equip - A combination gauge/hand vacuum pump that is metal and thus more durable is in order and I do believe the MityVac fits the bill,
(2) Obtaining the Clearest Diagrams from PeterSchmid.Com - Back to your obtaining the Vacuum Diagram for your '84 300D and it turing out to be a BIT "fuzzy". I too have had this in the past, so I just completed an experiement to test the two different ways I know of that results in a file that you can use to make a quantative judgement of the resolution... namely the "Copy" and the "Save" methods and found that although the easiest way might be the "Copy" method, however for me this resulted in a file of only 45KB size for example the " 616_617_91.jpg " which I believe is for your car [it depends upon what engine you have... the 617.91... or the 617.95 ] and the "Save" method resulted in a file size of 113KB. So unless you used the "Save" method, you might not have the best clarity possible from the PeterSchmid.Com resource.
So here is the SAVE method:
(a) Go through the menu/pop-up windows until you have the diagram you want... and if your engine is a 617.95, you will also need to know if it is a CA car [I hope not] or a "Federal" car,
(b) Initially left click on your graph selection while it is still small on the screen... this will expand the graph until it mostly fills up the screen,
(c) Right-Click on the graph and you will see several possible selection choices: "Save" "Copy" "Print" etc.
(d) I recommend you "Save" this file to your hard drive... and later use the file to print later. Make sure you are using the higher resolution options that most printer "driver software" offers... and if this still does not quite give you the needed clarity, you might want try a special "photo" paper to squeez out a little more.

I don't trust the print resolution you obtain from printing something via an OnLine link. Don't ask me for a technical reason why... I just don't. This suggestion is purely based upon the different file sizes I obtained a short time ago while experimenting with these two methods. Give this "Save" method a try, print it, and let us all know if you think there is a significant improvement. If there is, many of us will benefit the next time we download a vacuum diagram from PeterSchmid.Com.

Regards,
Sam
P.S. - To all who have read my all-too-often lengthy POSTs... my excuse is that I type at ~100 words/minute! This is not to brag... just an explanation of my affliction that I'm happy to have for it has also helped me tremendously over the years !

Last edited by Samuel M. Ross; 03-17-2009 at 02:32 AM.
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  #49  
Old 08-25-2006, 11:58 PM
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Richard, I'd love to know for certain which diagram...

you are using and the best, most definitive, way is to obtain and pass this along to us on this THREAD is to:
(1) Right-Click on the enlarged diagram,
(2) select the "Properties" in the pop-up window and then you will see the "URL address" in the middle of the next pop-up window you get,
(3) triple-click with your cursor somewhere on this URL address and this will highlight/block the entire address,
(4) then it's the normal copy and past

For e.g. - http://www.peterschmid.com/vacuum/1977_1985/617_95/1984_1985.jpg

This way I can follow along with this lesson... and maybe even contribute.

Sam

Last edited by Samuel M. Ross; 03-17-2009 at 02:33 AM.
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  #50  
Old 08-26-2006, 01:22 AM
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Pardon me gents but I find myself playing catchup here...

Brian,
I now see the diagram you posted earlier that appears to come from a file with the HTML address of: http://home.comcast.net/~phantoms/vacuum/egr_82_300d.jpg that I'm guessing is a personal WebSite of some sort... and although Brian's diagram is named as though it is for a 1982 300D "EGR" system, it appears to be all but identical [except for how the text legend is formatted ] to the one at:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg. This latter diagram is for 1984 "Federal" and 1983 CA cars with 617.95 engines and is labeled as such right in the graphic. Brian's diagram has no application lable on the file's graphic.

Most important, I notice that Brian's diagram has considerably higher resolution which gives better clarity.

Brian - can you tell me the original source for your diagram?... also I'm puzzled as to how you were able include such a high resolution graphic right in the body of your POST? That must be the "Attachment Management" feature that is titled "Upload file from a URL"??

Sam

Last edited by Samuel M. Ross; 03-17-2009 at 02:33 AM.
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  #51  
Old 08-26-2006, 10:02 AM
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Originally Posted by Samuel M. Ross View Post

Brian - can you tell me the original source for your diagram?... also I'm puzzled as to how you were able include such a high resolution graphic right in the body of your POST? That must be the "Attachment Management" feature that is titled "Upload file from a URL"??

Sam
Sam, the diagrams live under the "General Information" forum right here on M-Shop.

Vacuum Diagrams

One of our members, "Phantoms" was kind enough to post all of the diagrams and they reside in a single thread.
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  #52  
Old 08-28-2006, 08:45 PM
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I have a 1981 300SD, I disabled the EGR by removing the 2 vac lines to the black box and plugging/replacing the Ts. Is this right? Or have I done something bad by removing the black box? The trans seems a bit smoother now. This vacuum system is confusing!
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  #53  
Old 08-28-2006, 09:53 PM
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Hey Brian & Sam: I had a chance to inspect the vacuum system in my '84 300D yesterday between rain showers. The first thing I noticed was that orifices 4 & 5 in the central plug (71 on the diagram) were open. It shows it this way in the diagram so I assume this is OK, but I decided to plug them anyway. I figured it could not hurt anything, unless of course they are designed to expell or take in small amounts of air. I hope not. Not owning a BB gun or BB's, I found that a 16p nail cut off about 1/2" form the head works nicely. The flare at the base of the head makes a nice seal and the guage of the nail is sufficiently large to offer a bit of resistance and therefore some staying power in the rubber vacuum tubing.

As I followed the lines I found that the rubber vacuum connecting line between the the Thermo-vacuum valve (36a in the diagram) and the wh/pu/br line was broken and wide open. My assumption is that this valve is not open until it senses 40 degrees C so I was not losing vacuum until this point was reached. I found enough spare hose on another connection to cut a piece off and repair this one, along with the wh/br vacuum line to valve connection which was looking pretty rotted as well. I had the car out on the highway today and it felt like it had more power at highway speeds.

This brings me to my main question, which is, if I want to cut out the EGR system, where do I do it? It looks like perhaps I should pull the white line running from the T to the Central Plug and put a plug in the T. But does this leave the black line running from the Central Plug to the Fuel injection pump (66 in the diagram) open? Now that I re-read your instructions, I think you are saying to pull the black line as well and put a plug in the T near the Fuel injection pump. What happens to the line going to the Thermo-vacuum valve. It would seem that I just would put a plug in the #1 orifice in Central plug.

Another question - I assume the rubber vacuum tubing is pretty standard stuff available at any auto parts store, but are the T's and various colored vacuum lines proprietary to MB?

Thanks for you valued help.

Richard
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  #54  
Old 08-28-2006, 10:02 PM
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Originally Posted by RML View Post
Hey Brian & Sam: I had a chance to inspect the vacuum system in my '84 300D yesterday between rain showers. The first thing I noticed was that orifices 4 & 5 in the central plug (71 on the diagram) were open. It shows it this way in the diagram so I assume this is OK, but I decided to plug them anyway. I figured it could not hurt anything, unless of course they are designed to expell or take in small amounts of air. I hope not. Not owning a BB gun or BB's, I found that a 16p nail cut off about 1/2" form the head works nicely. The flare at the base of the head makes a nice seal and the guage of the nail is sufficiently large to offer a bit of resistance and therefore some staying power in the rubber vacuum tubing.

As I followed the lines I found that the rubber vacuum connecting line between the the Thermo-vacuum valve (36a in the diagram) and the wh/pu/br line was broken and wide open. My assumption is that this valve is not open until it senses 40 degrees C so I was not losing vacuum until this point was reached. I found enough spare hose on another connection to cut a piece off and repair this one, along with the wh/br vacuum line to valve connection which was looking pretty rotted as well. I had the car out on the highway today and it felt like it had more power at highway speeds.

This brings me to my main question, which is, if I want to cut out the EGR system, where do I do it? It looks like perhaps I should pull the white line running from the T to the Central Plug and put a plug in the T. But does this leave the black line running from the Central Plug to the Fuel injection pump (66 in the diagram) open? Now that I re-read your instructions, I think you are saying to pull the black line as well and put a plug in the T near the Fuel injection pump. What happens to the line going to the Thermo-vacuum valve. It would seem that I just would put a plug in the #1 orifice in Central plug.

Another question - I assume the rubber vacuum tubing is pretty standard stuff available at any auto parts store, but are the T's and various colored vacuum lines proprietary to MB?

Thanks for you valued help.

Richard
The openings in the central plug, #4 and #5 do absolutely nothing. When we get done, all five openings will do absolutely nothing.

Pull the white line and plug the T. Or get rid of the T and connect the two remaining ends with a short piece of hose.

Pull the black line and plug the T. Or get rid of the T and connect the two remaining ends with a short piece of hose.


Pull the line out of the central plug that goes to the thermo-vacuum valve and throw it away.

Leave the central plug wide open.........plug nothing.

The hose is 4mm hose.........it's a bit smaller than the "standard stuff". The existing hard Tecalan lines won't fit the "standard stuff". You need the metric hose.
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  #55  
Old 08-29-2006, 02:24 AM
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I leave you RML in Brian's more than capable hands....

for I'm off early in the a.m. on at 2-week trip to be with extended family in TN, MS, and LA. I am not that familar with the 84(s) anyhow and would have to sort out which diagram to use and then go from there. In any event I would not start making major changes in the engine vacuum lines unless I first made a diagram or obtained the proper diagram which I then used to document the current state and then whatever changes I made along the way. This way you can return to a former state if needed. I'd love to following along with ya on this one but will likely have to wait until I return and read about what will be history by then.

See you in a couple of weeks!
Sam

Last edited by Samuel M. Ross; 03-17-2009 at 02:34 AM.
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  #56  
Old 08-30-2006, 07:54 AM
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300sd81...

Quote:
Originally Posted by 300SD81 View Post
I have a 1981 300SD, I disabled the EGR by removing the 2 vac lines to the black box and plugging/replacing the Ts. Is this right? Or have I done something bad by removing the black box? The trans seems a bit smoother now. This vacuum system is confusing!
So you think the vacuum system is confusing... well count your blessings your MBZ is an 81 model!

I think your POST above might have been missed by Brian Carlton and others who watch and often respond to this subject... so hang there and someone will see ya and help out. I'm away from my cars on a road trip and canNOT be of much help. If you have not discovered it, check out the website: http://peterschmid.com/ as a source of engine/tranny vacuum diagrams... follow the "Vacuum Schematics" links !

It can be difficult for some models to find the correct vacuum diagram and your year might be missing... but see if you can tell if the diagram at this weblink is for your car: http://peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg

Give this THREAD a chance for it might take a while for others to discover your plight [whatever it is] and the more specific your question, the more impression you leave that you have done some homework... and thus the more likely someone is to pitch in and try to help you out... especially if your car is the likely automatic tranny model.

I'm out of here for now... suffering Jet Lag in TN,
Sam

Last edited by Samuel M. Ross; 03-17-2009 at 02:34 AM.
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  #57  
Old 08-30-2006, 10:05 PM
RML RML is offline
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Thumbs up Wow - More power

OK - I pulled the line from the central plug to the thermo valve, removed the black line and the white line and plugged the T's. On the way to work this morning the shift from 2nd to 3rd was much smoother. 1st to 2nd was still abrupt. There also seemed to be more power and response when I was going above 35 or 40. So far so good. The car seems to fly at highway speeds now with less labor.

I was thinking that I might temporarily pull off and plug the line going to my climate control system and see if it makes a difference. I have some kind of problem there in that I have to first press the a/c button (the one with the white arrows pointing both up and down) to engage the system and then I can choose the button to the right with the white arrow pointing down, or the economy button. Choosing one of the other buttons first will not turn anything on. I don't know if this is vacuum related or not, but from some other posts regarding climate control it seems like it could be a culprit.

I certainly am enjoying working on this car. It is a fine piece of engineering.
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  #58  
Old 08-30-2006, 10:31 PM
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Quote:
Originally Posted by Samuel M. Ross View Post
So you think the vacuum system is confusing... well count your blessings your MBZ is an 81 model!

I think your POST above might have been missed by Brian Carlton and others who watch and often respond to this subject... so hang there and someone will see ya and help out. I'm away from my cars on a road trip and canNOT be of much help. If you have not discovered it, check out the website: http://peterschmid.com/ as a source of engine/tranny vacuum diagrams... follow the "Vacuum Schematics" links !

It can be difficult for some models to find the correct vacuum diagram and your year might be missing... but see if you can tell if the diagram at this weblink is for your car: http://peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg

Give this THREAD a chance for it might take a while for others to discover your plight [whatever it is] and the more specific your question, the more impression you leave that you have done some homework... and thus the more likely someone is to pitch in and try to help you out... especially if your car is the likely automatic tranny model.

I'm out of here for now... suffering Jet Lag in TN,
Sam

From the 5 threads I read on the subject, I'm pretty sure I did it right, since it was mentioned that the black box controls only the EGR. But somewhere else I read that it also had something to do with the trans, o now I'm worried, since I broke the black box while trying to remove it.

Almost all of my car experience working on more than brakes and changing tires comes from my [now, my moms] 2000 Oldsmobile Alero. I love the easy access and relatively easy repair on the benz, but some of the old systems are far more confusing to me than stuff like connecting my laptop to the car computer and reprogramming the transmission shift points. I still keep 3 different profiles, normal, gas saving, and performance... An it only takes a few minutes to hook up and change them, faster when I had a car-pc mounted in the trunk. I still have not figured out now the exact shift points are set on the benz.
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  #59  
Old 08-31-2006, 01:14 AM
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300SD81... have we definitely found your vacuum diagram...

Quote:
Originally Posted by 300SD81 View Post
I still have not figured out now the exact shift points are set on the benz.
That will come in time... but I will most likely wait until I get back home where I can hopefully be of more help. Have you gone to the PeterSchmid.Com website to try and locate your vacuum diagram. You will likely need to know your engine nubmer.

Sam

Last edited by Samuel M. Ross; 03-17-2009 at 02:34 AM.
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  #60  
Old 08-31-2006, 08:11 AM
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Originally Posted by 300SD81 View Post
From the 5 threads I read on the subject, I'm pretty sure I did it right, since it was mentioned that the black box controls only the EGR. But somewhere else I read that it also had something to do with the trans, o now I'm worried, since I broke the black box while trying to remove it.
The black box does have something to do with the trans. When vacuum leaks from the box due to the bad 3/2 switches, the trans will see lowered vacuum levels and the vehicle will shift harsh.

Getting rid of the function of the black box is precisely what is required to improve the shifts.

Note that the black box may have some direct control of the transmission on older W123 vehicles, therefore the ensuing arguments on the forum. On the SD, however, this is not the case. The black box controls only EGR for all models of the W126 from '81 to '84.

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