On a similar topic, my new-to-me 350 SDL was shifting way to late, with very hard shifts. After about 6 turns of the bowden cable (in), it shifts fantastic! They must not have set it properly when the engine was replaced.

-J

Found my Vacuum Problem!!
 

I hooked the Mighty Vac to the vac port on the Flying Saucer and NO VACUUM!. traced it back to the inline filter, just before the H connector, comming out of the vacuum pump. Replaced with a straight piece of vacuum hose (1 1/2"). and now there is 20" at the Flying Saucer and the trans shifts great!

Also the center vents on the acc work again!

Joe

Usually, the leaks are on the right side of the engine.........near the inline filter. The filter is on a separate line but it can dump all the vacuum in the system if it leaks or the EGR system leaks.

This little filter is right off the vacuum pump. There are two lines from the pump. One to the Brake Booster and one that goes to the vacuum modulator/alda area. On the latter the filter is before the H connector. I think it is #62 in the 124 vacuum drawing.


Joe

Filter Question
 

Does that mean the filter was leaking or plugged? It serves as a safeguard to keep oil from entering the vacuun system. On an older system like this, I would not replace it permanently with a straight tube.
Charles

It was plugged. I will get a new one from the dealer.

Brian, I would like to thank you for all of your information and help. You have saved me an enormous amount of time in troubleshooting.

To answer my own question; No 5” Hg was not low enough. I have adjusted the VCV and the results are quite pleasing. I still have some tweaking to do to get it to shift to my liking but I’m close.

Also, I don’t know if this is anything to be concerned of, but with the VCV adjusted down to anything below 10” Hg it starts to make a distinct audible buzz and when you lay your hand on it you can feel it vibrating rather violently. Doesn’t seem to me that this part will last too long under this condition.

On a side note; I nearly put the ‘old girl’ in the grave on the test drive. From now on my test gauges will be above the instrument panel and not down on the center console. I was running her pretty hard, doing a 0-60…looked down at the boost gauge I hooked up also……….let’s just say I’m still picking the deer hair out of my teeth as I type this.

Thanks again,
Chris

Anytime........glad to help.

That's interesting about the vibration of the VCV. I didn't observe any issues with this one when I lowered the vacuum to 8". At this level, I get very crisp 1-2 and 3-4 shifts and a decent 2-3 (but a bit slower).

Damn........be careful out there.........we've lost too many SD's to deer in the last couple of years.:eek:

Just got my car back from the mechanic. I had it in because the trans had always tended to shift a little rough on 1-2 and 2-3, and was now starting to flare on 3-4.

Well, they said they fixed a small vacuum leak and adjusted the modulator, and now things were the best they could be without opening up the transmission. Basically now the 1-2 and 2-3 shifts are very hard and 3-4 is normal. The 1-2 shift point is also noticeably higher than it was before.

I'm slightly bummed because it was actually more pleasant to drive the other way. More significantly, I'm left with the conclusion that the trans is worn out and needs to be rebuilt or replaced. I don't really live in a place where I feel comfortable trying to open up the trans myself so I'm stuck dealing with garages (and have been underwhelmed with the ones I've tried--not really inclined to explain anything or even talk much). I might be willing to try if I were confident that I knew what the issue was and I'd definitely be able to fix it.

It's definitely not short on fluid. And it never slips at all (once it's in a gear).

Any other things I can try? If I do decide to pour yet more money into having this car drive normally, what's a good price to pay for a trans and how many hours of labor should I expect for someone to replace it?

I found this one for $1,200:
http://usedautoparts.everdrive.com/PartDetails.aspx?sku=310042&searchid=4453032

Might I be better off going to a generic trans place (Aamco or whatever) and seeing if they could do anything with the current trans--I mean if it is shot already?

[edit]
Just wanted to add that the vacuum line to the passenger compartment (doors, trunk, fuel lid) is capped off in the engine compartment.

... We need more information... let's NOT go off the deep end just yet !
 

Herring,
You need to give us more information before we will agree to condem your 300K+ 240D:
[1] How long have you had your relationship with your 1982 240D?
[2] Do you have a Vacuum pump/gauge?
[3] Can you give us the car's " VIN " and the complete # off the right side of the transmission?
Regards,

Since January.
No, but it looks like that's set to change ;) Do I really need a pump or can I just get a gauge? I am reading the Steve Brotherton article and the VCV test linked to on page 1 of this thread and it seems only a gauge is necessary. Silly me thought I would eliminate any vacuum issues if I capped off the door/trunk/filler line.

VIN: WDBAB23A9CB342701

Trans code: 123 2706301 722 117 01 068252

The VCV test at http://peterschmidtransmission.com/
specifically refers to trans models
722 303
722 315
722 416

and not my 722 117.

I guess when I get time I can get the vacuum gauge and go over the engine with the vacuum diagram and see if I can find something wrong.

Herring... trust me, a combo hand pump with gauge is best........
 

Herring,
At the following WebSite: http://old.mbclub.ru/mb/vin/?lng=eng , you can input your 240D's VIN: " WDBAB23A9CB342701" and ask for the " [x] Full Version " report on your car... and although the information in these reports are NOT always perfectly accurate, I think it's still worth a " look see " !

I just looked and verified your original :
Chassis # was: 12312312342701
Engine # was: 616912 12 074212
Transmission # was: 722117 02 068252 so it looks as though the # you gave me is different by 1 digit...
...............................722117 01 068252 ... but not sure just now what significance this might mean to us!?
THERE IS A LOT MORE IN THE REPORT, SO BE SURE TO TAKE A LOOK!

From the www.PeterSchmidTransmissions.Com WebSite I conclude that the most likely correct tranny shifter vacuum diagram for your 1982 240D is at: http://www.peterschmidtransmission.com/vacuum/1977_1985/616_617_91/616_617_91.jpg

For now, the main worthwhile information in that 7-page VCV Test on the PeterSchmid WebSite... the main thing of worth is the adjustment of the mechanical linkage between the throttle and the VCV! You could check that against what your 240D is set up at and let us know what you find.

Right now I'm drawing a blank as to what further to advise you to do... until you have a hand vacuum pump/gauge.

To "Anyone else" [ Brian Carlton?]... please jump in IF you have something to add!

Regards

You should compare what your car has...........
 

Herring,
Oh yes, you might want to compare the components on your car's Tranny-Shifter Vacuum Control system with what is shown on the PeterSchmid WebSite diagram I just referenced you to:
... and let us know IF there are any obvious differences... and PLEASE note the existence of the two restricted orifices [ #62 & #63 in diagram]... and let us know what color these orifices are for your car.
Regards,

Ok, thank you very much for your help with this. I printed out the pages from the website for my car. I will have to let this sit for a while as I'm going on vacation this weekend and won't have time to get the gauge and line and work on it before then.

Sidebar........... on the same subject as this THREAD!
 

For those of you who have interest in this THREAD's subject, please take a look at this recent THREAD and contribute there as another of the MercedesShopForum's readers struggles with the abstract nature of this Vacuum Control System on these automatic shift diesels !
http://www.peachparts.com/shopforum/newreply.php?do=postreply&t=224090
Thanks,

Following that link doesn't work for me.

Ok, back from vacation, haven't gotten a vacuum gauge yet but printed out this vacuum diagram and looked under my hood:
http://home.comcast.net/~phantoms/vacuum/fuel_egr_240d_auto.jpg

On the diagram, looking at part 71, lines 1, 4 and 5 are disconnected...short pieces of line are attached that are not attached to anything at the other end.

Part 72, the green cylinder on top of the vacuum control valve, is NOT attached to line 5 from the central plug but rather to a line coming straight from what I assume is the vacuum pump (Haynes manual basically ignores the vacuum system). I have no colored orifice (63) at all.

It appears the point of these mods was to bypass the switchover valve (64).

So:
1. What is the function of the switchover valve? Is it common for this to fail and be bypassed? The Brotherton article states that this is to prevent overboost but 240Ds don't have a turbo. It also says that "the valve is often sooted closed"--should I try blowing it out with a can of compressed air?
2. Should I try just reattaching lines as in the diagram and see what happens? What color orifice should I get?
3. The Brotherton article says to attach the vacuum gauge at the "case pressure port"--where's that?

Explanation of the Throttle Switchover Valve...
 

======================================================
Let me first try to answer your Q1(a) above with this far too long answer... and first trace the vacuum from it's source down to the switchover valve:

[1] The main Vacuum source is the engine driven pump (#67)…
[2] The bulk of this vacuum is for the vacuum assist power brake system…
[3] Thus orifice #62 acts as a restrictor to prevent loss of braking power in event of a complete rupture of the vacuum shifter control system...
[4] After passing through orifice #62, this higher strength vacuum [vac#62] splits at the “ T ” connector…
[5] One branch passes through orifice restrictor #63 to further reduce the vacuum [vac#63] before it goes via the " Y " connector on to port #4 of the Mech.Switchover Valve ( #64/64a [" MSOV "] ) as well as goes on to the tranny vacuum modulator via “ b ”…
[6] The other branch of vac#62 goes on to port #1 of the MSOV…
[7] The VCV (#65) connects via the surge damper (#72) and then to port #5 on the MSOV…
[8] The vent side of the VCV splits and in addition to venting under the dash, it also connects to port #2 of the MSOV…
[9] and to round things out, the EGR system is connected to the MSOV via port #3.

Finally an answer to your Q1(a)...What does the MSOV do?

In short it does mostly the same thing the much simpler 2x3 vacuum valve on our earlier 1980 models does... so take a look at this much more obvious system at: http://www.peterschmidtransmission.com/vacuum/1980/617_912.jpg

So now for what the MSOV does:

[A] The MSOV is actuated by movement of the throttle and at idle closes off the VCV from being connected to (via port #4 ) and thus bleeding off vac#63 being sent to the tranny’s vacuum modulator valve…
[B] As you open the throttle, ports #4 & #5 are opened to each other and allows the VCV to begin bleeding off vac#63 that is being fed to the tranny’s vacuum modulator.
[C] Similar to [A] and [B] above but separately, the MSOV also acts as a switch for the high vac#62 to be fed to the EGR system via ports #1 and #3… and I speculate that this too is closed off at idle and opened as you increase throttle. You might even find that it closes off at some position of high throttle. I would guess that you could ascertain this by using your vacuum pump or just blowing air through port #3 and see if it comes out at port #1 as you manually simulate throttle changes by moving the MSOV linkage!
[D] The one thing I canNOT tell you for certain is why port #2 on the MSOV feeds back to the vent side of the VCV. You are on your own regarding this port and what it’s function is !??

[E] Otherwise this MSOV mostly adds the additional sophistication to how the EGR system functions… just as the electric switchover valve (#81) does. In later models, especially on the infamous “California cars”, they went hog-wild, adding 5+ additional components mostly in an attempt to reduce the engine’s pollutants!

Answer to Q1(b) - I think it's common to find failures in this double vacuum switching arrangement and the fact that both vacuum switches are encased in the same housing probable causes more confusion and thus people abandoning these functions that are only adding small improvements in performance. The Brotherton article can be confusing because I suspect he wrote the article [out of necessity] trying to make it applicable to as many cars as practicable!

Answer to Q2(a) - I would first do some "puffing" and verify that I am correct about the 5 numbered ports on the MSOV and see IF you can figure out port #2 which appears to be a vent function... and once you feel you understand how it is suppose to function... I would try to repair it to function OEM... with one possible exception... the EGR system which I would disconnect and plug up unless your state does smog inspections on these cars!

Answer to Q2(b) - I have found very few MBZ diagrams that show the actual color code for these restricted orifices... and for me I found it easier to have a complete set of these somewhat cheap orifices on hand and to install them by trial and error! These serve as "fine-tuning" tools for the tranny shifter system and thus I could readily understand that identical cars coming off the assembly line might end up with different orifices!

Note... for me writing out something in such detail as in the above... this helps me to think out such systems and controls and I come away with a better understanding that IF I did NOT do this! Let me know IF you figure out what the line to MSOV port #2 is all about!

Thanks for the much clearer vacuum diagram for your car !
Regards,
Sam

Ok, sounds like I will be paying a visit to the dealer for some vacuum line, a y-connector (to make my vacuum tester) and a set of orifices. I really appreciate your help with this stuff. I couldn't own a car like this without the resources of this board.

Question: how exactly do I "plug up" the EGR system--what am I plugging, and what's the standard way of doing it? Is there a step-by-step anywhere?

Plugging up the EGR
 

One simple way is to make a solid "gasket" from a piece of sheet metal (even a Coke can will work) and place it in between the EGR valve and the intake manifold. That will retain the car's appearance while defeating the EGR function. The intake manifold will no longer see carbon-loaded exhaust and, if you remove and clean the intake, will stay clean.

Another simple way is to block the vacuum line to the EGR valve, thus preventing it from operating. Blocking the vacuum line is as simple as inserting a 'BB' in the rubber jumper that connects the plastic vacuum line to the metal nipple on the EGR valve.

Both of the above procedures are unobtrusive and might even pass an inspection. Caveat: my state does not inspect so you should get an opinion from forum members in states where inspections are performed.

A more extensive removal involves a kit that one of the forum members sells. It allows you to remove the EGR valve from the engine and cover the holes in the intake manifold and the exhaust pipe.

Finally, you can remove the vacuum valves from their place (usually on the left inner fender) in the engine bay and plug/remove the various vacuum and vent lines. It goes a long way towards cleaning up the look under the hood.

I recommend labeling all of the parts and pieces and documenting your work so that you can reverse it if it ever became necessary.

I don't know if there is a one-size-fits-all DIY since there are so many versions of the EGR system. There are many threads talking about EGR removal. I suggest searching for them and seeing what information and pictures are available.

Jeremy

... Shutting off an EGR system... and testing the MVSO valve!
 

Jeremy- I agree with your advice... especially IF exhaust is leaking through the EGR valve when NO vacuum is applied to it... but IF it is holding and NO exhaust gasses are coming through to the intake manifold... well then I recommend the following:

Herring - IF there is no exhaust-to-intake " leak-through ", then I would simply use golf tees and/or appropriate rubber caps on the vacuum source side of the EGR line... this to plug up the vacuum!

IF you have to be concerned about the vehicle ever being subject to a smog inspection in your state, you could use the "ol beebee instide the vacuum line trick" !! This way externally things visually look OEM!

Also at one time Brian Carlton put together a limited production kit [~$30] that allows you to remove the EGR valve and then blank off both exhaust and intake manifolds using bolt-on stainless steel [<--I think] flanges!

Finally, I think the easiest way to sort out the routing of the multiple ports [ #1 thru #5] on the mechanical switchover valve is with the engine off to just hook up a piece of clean hose to what I eariler ID'd [ports #4 & #1] as the two inlet ports [ shifter subsystem & EGR subsystem]... and the blow into these ports [one at a time] while your rotate the throttle... and look for where the air is coming out at another port. Once you know the port-to-port switiching arrangement, then you can test things with your hand vacuum pump and know more concretely which need repairs. I was able to get parts for my 2 1980 models [~$20] so hopefully you can do the same for your 1982. I believe you will find either one double vacuum valve or two single valves under the black cover!?
Regards,

Did it!
 

Ok, I bought some vacuum line, some Y-adapters and a Mityvac. First, I attached the Mityvac and drove around. 11 inches of vacuum at idle, down to zero at full throttle. I thought that was odd, that's pretty much in-spec, and the way the trans drives is definitely not.

I had called the dealer for orifices and they told me they are all unavailable except for the largest (yellow, 2mm) and the smallest (green, 0.8mm). I bought one of each. (Kudos to Larry at Mercedes Benz of Fort Washington, PA for his patience with me and also for mailing me the orifices when they came in.) After pulling things apart, I noticed that my car DID already have a yellow orifice installed. So, I replaced it with the green one.

Shazam! Shift points are where they should be, shifting is smooth. I can't believe it, and all with a $4 part. It's like a whole new car. Thanks for everyone's help, even though this turned out to be simple I'd never have been able to tackle it (or even know the part number for the green orifice) without your help! :D

... it's a miracle...........!!!
 

Herring,
I'd like for my very specifically titled THREAD to take credit for your $4 miracle... but the engineer in me is more than a bit skeptical of your miraculous result!

Let me speculate some…
(1) first off the 11 inches seems a bit low to me,
(2) you started out with what was probably a dirty 2mm orifice, and
(3) you replaced with a new 0.8mm orifice.

Something just does not quite jell here...

PLEASE measure and report back to us what the vacuum now is at idle and what it drops to when you put “the pedal to the metal” ?

Also... I think the full range of 6+ orifices are still available !

Proud originator of this THREAD,

I know it should be a tad bit higher. What specifically would I do to raise vacuum at idle?

I just compared the orifice from the car with the new 2mm orifice I bought. Other than one being a bit dirty, they're identical. That is, the old one does not appear to be constricted by dirt at all.

Keep in mind that the PO had cut out big chunks of the vacuum system. The vacuum goes directly from the supply line, through the spaceship and into the VCV.
That is, on this diagram:
http://home.comcast.net/%7Ephantoms/vacuum/fuel_egr_240d_auto.jpg
I replaced the orifice at 62 (yellow to green) and the line out of 62 is going directly into 72.

You can see in the attached picture what I'm talking about. The yellow stripe in the line just above the green spaceship is the old orifice.

Would all of this make any difference in the expected result of the replacement I made?

OK, will do.

Well, not according to the parts guy at the Benz dealer nearest me. I read him the list of part numbers (which I got here) and all but those come back as unavailable in the computer system.

The orifice is usually inserted in the Y connector. Did you also replace the Y?

Sam's point is very valid - what are the vacuum numbers now?

....... Now that we are getting specific as to which orifice...!
 

Herring... and Charles,
Yes, now your situation is beginning to make more sense... the 2mm larger orifice was originally necessary for it was supplying vacuum to both the Tranny-shifter system as well as the EGR system so more was needed then. But then I believe you said the EGR was disconnected... so this left too much vacuum and the double switchover valves were played with so the VCV was/is probably hooked up such that the VCV bleeds down the vacuum even at idle when normally the switchover valve would NOT be open to the VCV and allow it to bleed off the vacuum.

Assuming I am correct that you are no longer using the EGR, I would try to figure what ports connect to what other ports at idle and at higher throttle positions. What I'm getting at, is that I think you should try to restore the switchover valve or valves necessary to restore the switching ON/OFF of the bleeding action of the VCV. There are subtle reasons for this action that is based upon throttle position... e.g. possibly to prevent the car from down shifting too soon... or too late! So using the "puff/blow" method I described earlier, try to figure out basically which of the 5 ports connects are interconnected at idle and higher positions of throttle. I think you will find that #1 & #3 connect and that #2, #4, & #5 interconnect. You need to first confirm my speculation... and then work on restoring those that control the shifting [ #2,#4, & #5 I think]... making them vacuum tight. These switchover valves are not too expensive [ ~$20 to $30]. Then IF the vacuum level being sent to the tranny vacuum modulator is too high or low, then we can get into how best to adjust this... including adjusting the VCV!

Keep in mind that on our 1980 models, we have a simpler switchover configuration... especially when you take the EGR system out of the picture... these cars only have the one valve that simply turns ON/OFF the VCR bleeding action. Take a look at: http://www.peterschmidtransmission.com/vacuum/1980/617_912.jpg
We are working toward such a simpler system for you too IF I'm correct that you too have abandoned your EGR!??
Regards,

Ok, first I have to say I was a little overoptimistic on my "cure". While it certainly did help things, the 1-2 and 2-3 shifts are still not smooth. The best I can say is that if I accelerate "just so" I can get them to be smooth...which is an improvement. And they're always smoother than before.

To recap, I've got a line coming directly off a large-diameter trunk line, which goes through a "Y" connector. One branch goes to the VCV (through the flying saucer), the other goes to the transmission. Where the 2mm orifice was (and where the 0.8mm orifice is now) is past the "Y" going to the VCV. So this has the effect of "diverting" more vacuum to the transmission.

I played around a bit today, putting the orifice on the "input" side of the "Y" (reducing flow to both the VCV and the trans). It made things slightly worse. I then removed the orifice altogether and capped off the line to the VCV, so 100% of the vacuum went to the trans. Very smooth, but no power due to being always in too high a gear, and slow shifts. Stupid me left the Mityvac behind so I didn't measure vacuum but now I have a sense of what's going on. Ideally, the trans needs more vacuum than it gets now, but not all that the pump can put out. IOW, an even-smaller orifice (if such a thing existed) to the VCV would be ideal.

I will still probably work on restoring the flow to the switchover valves on top of the engine. I did the puff test today, as far as I could. Again referring to the above diagram, this is part # 71.

Air blown in hole 1 comes out hole 3.
Air blown in hole 5 comes out hole 4.

This is at idle.

Hole 2 on my vehicle is broken off at the connector and capped off with a bolt on the hose side. This could be the reason my system was so "hacked".

Question: If I don't want the EGR valve anyway, it seems like there wouldn't be any reason to restore the hole 1/3 flow (which just goes to the EGR valve). Am I right on this? So what else does the switchover valve do?

Mine is an 83 300D so it may be a little different. I got the best results by changing the Y connectors that go to and from the EGR with straight hose (preserving the orifices). That effectively removed the EGR and the black box valves from the system.

Herring... I'm getting "befuddled" over what you have there !?
 

Herring - I'm sorry but as much as I would like to follow along with your situation, I'm really having trouble and the thing that really frustrates me is that I know that IF you could take the vacuum diagram and edit it graphically as I would do [IF in your situation]... I know this block I'm having would NOT be there!!? IF you have the skills to edit "JPG" graphics files... especially using colors to show more closely how your Tranny-Shifter Vacuum control system has been modified and presently exists... please do so!! IF NOT, in the future, please refer to components by their number designation on the diagram!!

But in the mean time let me try to get some clarity with these Q(s):
(a) I think by large-diameter trunk line you are referring to the large vacuum line between the vacuum pump and the brake booster reservoir?
(b) Im just not surce as to what you are calling the flying saucer) !??

I'll let you chew on these 2 Q(s) and I'll come back in a separate POST to try and address the last part of your last POST!
Regards,

Herring... I'm getting "befuddled" over what you have there !?
 

Herring - I'm sorry but as much as I would like to follow along with your situation, I'm really having trouble and the thing that really frustrates me is that I know that IF you could take the vacuum diagram and edit it graphically as I would do [IF in your situation]... I know this block I'm having would NOT be there!!? IF you have the skills to edit "JPG" graphics files... especially using colors to show more closely how your Tranny-Shifter Vacuum control system has been modified and presently exists... please do so!! IF NOT, in the future, please refer to components by their number designation on the diagram!!

But in the mean time let me try to get some clarity with these Q(s):
(a) I think by large-diameter trunk line you are referring to the large vacuum line between the vacuum pump and the brake booster reservoir?
(b) Im just not sure as to what you are calling the flying saucer) !??

I'll let you chew on these 2 Q(s) and I'll come back in a separate POST to try and address the last part of your last POST!
Regards,

Herring... OK... now to your numbered vacuum port "blow/puff" test results...
 

Herring,
Switchover Valve ports #1 & #3:
So on the double mechanical "switchover valves" inside the black box that is controlled by linkage to the throttle [#64/#64a]... so I basically guessed correctly that at idle at least ports #1 & #3 interconnect and thus these provide a simple ON/OFF vacuum signal for the EGR system so it is OFF at idle. Just in case you decide to restore your EGR system to full operation, I'm thinking this vacuum signal might also be present at a higher throttle position!
Switchover Valve ports #4 & #5:
Once again it looks like I am at least partially correct. As to the #2 port, I admit that I must NOT claim to fully understand why there is such a feedback line from what I call the "bleeder" side of the VCV [#65]. My best speculation is that at certain throttle possitions, this line provides a moderate-to-strong vacuum via this line as a means to nullify the VCV's bleeding effect through the line that vents under the dash... and thus nullifies a tranny shift under certain load/throttle conditions.

The later models muddy my understanding of such " stuff " even further... and the 1985 CA cars also add another 5 components to the system that are in or related to and accomplish a much more precide tranny-shifter control and feel of luxury!

Your Question now:
Blocking OFF the EGR system - Yes, so long as the #1 & #3 ports are serving only the EGR system and as long as your STATE dose not arrest you and drag you off to jail for not having it hooked up, I would simplify things [at least for now] by putting golf tee(s) in the line that goes to #1 & #3 [just in case] and also the rubber "T-connector" that supplies vacuum to #1.

Closing Sidebar - On both our much simplier 1980 models, I have learned to use the throttle to help me control shifting... and have found with a little practice I can do quite well at this... basically by backing off on the throttle just enough to make for a smoother shift between:
(a) 1st & 2nd gear..................... by feel
(b) 2nd & 3rd............... @ just before 25 mph........... and
(c) 3rd & 4th............... @ ~30 mph and above !
I feel that doing this (1) minimizes wear on the tranny and (2) allows me to drive more for economy by keeping the RPMs down!
For economy, I'm even running 35 psi "all the way round" in the tires!
It's too soon to give a report on any favorable results!
Regards,

Vacuum systems... they are " Static " or " Dynamic ", or a combo of these...
 

Herring,
No, actually the restricted orifice causes your modulator to receive a "weaker STATIC vacuum"... one that can more easily be modulated. Let me try to explain !

When I re-read the above parts of you last POST, I sense that I should explain my somewhat different way of thinking of vacuum control systems... a way that seems to help some better diagnose these systems.
Static Vacuum Systems - These are systems in/through which very little air actually moves except when the vacuum force momentarily actuates a diaphragm to perform some mechanical motion... door, fuel door, and trunk lock elements or "PODS". The vacuum modulator on the transmission is also an example... as is the EGR valve. IMHO orifices in a static only vacuum control system would accomplish very little!
Dynamic Vacuum Systems - These systems actually have air flowing through them either all or much of the time and the air flowing into and towards the vacuum source (our pump on the engine)... this provides the means to vary or "modulate" the strenght of the vacuum force in the system... or often thought of as " bleeding-off " the vacuum. For most of us the best example of this is the " bleeding " effect that the VCV introduces into our Tranny-Shifter Vacuum Control Systems. Your YR/model MB also has another dynamic vacuum component that is part of your EGR. Usually the "Dynamic" portion of a vacuum control system has a port that " Vents the vacuum " which is really backwards terminology... for the air actually enters into or through these "vents" which are usually terminated under the dash so as to better assure a cleaner source of air that otherwise (if in the engine compartment) would cause the system to clog up far more quickly. NOTE that the diagram for your car shows two such "vents"... both with an "a" label... one on the Shifter system's VCV and one on the EGR system's electric actuated switchover valve #81! Orifices I would think are primarily in and to my knowledge only in " dynamic " vacuum control systems.

Combo Static/Dynamic Systems - Yes, our Tranny-Shifter Vacuum Control System is a combination of multiple systems... the shifting part and the EGR part... and further it can be said that both of these systems have both static and dynamic components as I tried to explain above. The vacuum modulator that is physically on the transmission and the EGR valve itself are the static components... and the VCV and #81 electric Switchover Valve that is part of the EGR control system!

So let me now try to relate my thinking of how these two types of Vacuum Control Systems combine to give us proper transmission shifting. Let us first think of the vacuum modulator diaphragm that controls a hydraulic valve inside the transmission. As a " static " vacuum component, it it is "dumb" and IF it were connected up by itself as you tried, then its going to go to the fully actuated position and stay there... which would NOT help up much. These transmissions were designed to be hooked up to a gas engine with an intake manifold in which the vacuum level fluctuated wildely as the throttle and engine speed varies up/down. This is where our " dynamic " component (VCV) comes in for it's job is to translate the mechanical position of the throttle and use this to modulate the vacuum being sent to the Vacuum Modulator which in turn modulates the hydraulic valve inside the tranny.

So the VCV starts out NOT bleeding off any vacuum at all because it is shut out of the system by the switchover valve(s) that are also connected to the throttle linkages. When the VCV is first opened to the system, think of it as having a minimum " bleed " effect on the main vacuum (the power source) for the vacuum modulator on the tranny... but as you increase throttle, the mechanical linkage connected to the VCV causes an internal valve in the VCV to open more and more causing a greater and greater "bleed-off" of the vacuum being sent to the transmission vacuum modulator.

So the " main " or stronger vacuum is really that being initially sent to the modulator on the tranny... and it is the "dynamic" VCV component that is working as sort of a side-bar component to interpret throttle position and help modify or create a more appropriate vacuum signature being seen by the tranny vacuum modulator that thinks your car has a gas engine! This, IMHO, is why the German engineers devised the set of 6+ plastic orifices as a means to create what I think of as multiple vacuum pressure zones... and thus the need for the smaller size orifice in the line going to the tranny. Without this smaller opening, the vacuum being sent to the modulator would be too strong for VCV’s bleed-off effect to work (remember “dynamic” means there is air continuously flowing in there as long as the throttle is depressed). By using more than one orifice in your “combo vacuum system” allows the designers to create a strong initial 1st stage vacuum zone initially near the main vacuum line ( between pump and brake reservoir tank), and this is sent on via the switchover valves to power the EGR system… so the 2nd orifice is used to reduce the vacuum so that the VCV can properly modulate the vacuum signature. The VCV is adjustable but coming off the assembly line I’m sure that the orifices are far easier to use in making the final tuning of the vacuum level they want it to have.

So think about how air is flowing in these dynamic and/or combo vacuum control systems and you should be able to more readily diagnose problems! Oh yes, dirty orifices is why we put cheap in-line paper fuel filters on these vacuum vents or inlet openings under the dash! Once you get things working the way you want, then you put on these filters.
Regards... out of here!

Ok, so much to learn. I am going away but will get back to this next week, measure the vacuum going into the trans, and report what I find. It's really not as smooth as I'd like.

I'm back. Measured the vacuum today. The green 0.8 mm orifice is really not doing the job. Vacuum readings going into the trans are:
Idle: 10.5-11
"Gentle" acceleration: 2-4
Floored: actually goes slightly beyond where it goes when not hooked up to anything. Is it possible to get positive pressure in there somehow (I'd say +1 to +2). It's still within the "zero" zone on the gauge, though.

A couple of weeks ago I was at the salvage yard and pulled a thing off a W123 gasser. It's the blue-and-black thing on the line leading to the VCV in the attached pic. I know I need some more vacuum so I stuck it in the line. I noticed that it vibrates slightly when the vacuum is flowing through it.

This had the effect of boosting vacuum levels by about 2. That is:
Idle: 13
Gentle acceleration: 5
Floored: 1

I notice that when I suddenly let off the accelerator, the vacuum builds more gradually (takes a second or two to get back to 13 instead of building instantly).

So, I think this thing was worth the 50 cents I paid for it. However, it still leaves me with the same situation: more vacuum means that all shifts are softer. That's good for 1-2 and 2-3, which were too harsh and are now better. But 3-4 is now too soft and flares a bit.

Do you think there's some adjustment that can be made with the VCV, or is it a sign that the transmission's going to need to get opened up at some point? Is there a chance that the 3-4 flare can be repaired by replacing a spring inside the trans? I seem to remember something about replacing a spring on here somewhere a long time ago.
If not, should I just drive it with the flare until it turns into slipping (is that what'll happen next?) or should I look at getting a rebuild done now?

I am kind of bummed about this.

What's the vacuum reading at the main line...
 

Herring,
I went back and looked at your previous POSTS and did NOT find where you took and/or reported what the vacuum reading is directly on the main/large vacuum line that goes from the vacuum pump to the power brake booster reservoir? I'm hoping that it is 15 or more inches of Hg. Take this reading by disconnecting the line going to your tranny shifter/EGR system and connect your hand pump/gauge to this same connection. Get the reading at idle... and they see how much it rises when you race the engine in short bursts. While you are there, spray some WD40 or such into the "T" connection where it takes off to the tranny shifter/EGR system... this to make sure this restricted orifice is not clogged! Softening up whatever might be inside the "T" should allow it to be sucked out by the vacuum pump! Also, after spraying things with the WD40, take a small diameter needle and poke it down into the opening while your are running the engine to help loosen whatever MIGHT be in there!

IF you have a much stronger vacuum reading there than what you have been are seeing at idle on the line leading down to the tranny's vacuum modulator and we are assured that you don't have leaks that are causing this... well then we can talk about adjusting the VCV which could be bleeding off the vacuum too much and needs to be reset/adjusted.

Do this and report back!
Regards,

Sam and Herring,
Sam, Good advice and the numbers will tell a lot.

I'm a little confused. Several months ago, I read all the posts in this thread and finished with the conclusion that the idle vacuum should be less than 10" in the transmission line. That would suggest the adjustment Herring needs should be to produce less, not more, vacuum at idle. Mine is now shifting a good as when it was new and my idle vacuum is 8-9 and bleeds off quickly to 0 under acceleration. Did I miss something?

Ok, just connected the vacuum gauge/pump directly off (i.e. using a new Y-connector) the connection from the large diameter line. Readings are:
Idle: 13.5
Gentle acceleration: 6
Floored: 1


Or in other words, basically the same as I measured at the line to the transmission. Note that the orifice and the additional restrictor (blue doohickey in the photo above) only restrict the flow to the VCV. The line to the trans is a straight shot.

This might well be the ideal case. The story goes:

This car had always been a bit abrupt on 1-2 and 2-3, and "normal" on 3-4 since I bought it in January. Round about May, the 3-4 shift started to get slower. It was in the garage anyway for no glow light. I'd measured the plugs' resistance and found 2 bad and 2 good, and left the mechanic a note about that. When I called, I was told he'd replaced all 4 plugs. I guess there was a bit of annoyance in my voice or something when I told him to take a look at the trans.

I picked it up on a Saturday (no mechanic around) and I guess he'd spent an hour (what I was billed for) adjusting the modulator to its "hardest" setting. Now it revved way too high in gears 1 and 2 and slammed the shifts. But 3-4 was pretty normal. I called back on Monday and they said it was all they could do. The implication I got was that I was a cheap bastard and I guess they thought I'd have fun with my "fixed" car.

So, by adding the smaller orifice and restrictor to the VCV, I'm basically compensating for the "aggressively-adjusted" modulator. What I should really do is get down underneath and adjust it back, but I'd rather actually improve things first.

So, in one sentence, yes, my vacuum might be a bit "too high" but there's a reason for it, and fixing the reason won't fix my trans problem.

Thanks for your brain-teaser questions...
 

Thanks to both Herring's and Charles' [Cr from Texas], I have had to refresh my memory and thinking on this subject... and actually had to do some homework.

Yes, a new vacuum pump can generate well over 20" of Hg. vacuum... keeping in mind that when we say "vacuum" we are really talking about any absolute pressure that is less than atmospheric... which is typically ~30" at sea level. IF you read the MBZ manual section on these pumps, you will see that the Germans devised a way for you to quantify both level and the strength of the vacuum being generated by the pump. If anyone is interested in reading such, I can send you the PDF file!

As to what is the proper level at idle, the MBZ manual does not really address this... but I now think this is going to be basically a function of several things:
(a) just how new and/or effective your vacuum pump still is,
(b) how many leaks you have in any of the systems using this pump as a vacuum source, and
(c) the adjustment and condition of the vacuum control valve [VCV].

So how do you know what the proper vacuum should be at idle being supplied to your "Auto Tranny-Shifter Control System"... before you apply throttle. Well my current belief is that you want this to be the maximum vacuum reading that still allows you to reach zero at full throttle while driving down the road in fourth gear. IF you are NOT able to get it down to zero, then you need to either:
(1) make the restriction smaller or
(2) adjust the VCV so that it bleeds off more vacuum... AND
in most cases it's a lot easier to use the orifices.
Or you can do as "yellit" did... install the smallest brass icemaker control valve he could find in this line to allow him to effectively adjust the amount of restriction. I still want to try this so I can more easily experiment more on this subject, but I want something less than the 1/4 inch ice-maker plumbing valves... and I want one that uses a metal-on-metal "needle" type valve rather than the typical rubber-tipped valves that press against a valve seat!

Then I will be able to more easily test my hypothisis [sp? <--- professor Charles]... first with a long, large diameter, vacuum supply line run from and back to the engine compartment with the restriction-valve in it. I say "large diameter" for you see a long line that was too small would itself introduce friction losses and thus effectively become a part of the restriction but would be lost when you removed it from hanging out the window!

I hope these thoughts are of interest to you herring... and to others who read this THREAD!
Regards,

I downloaded a long list of things to check from a site that was posted earlier in this thread (I'll post the address, I left the list out in the car...something with mbz in the address).

First step was vacuum pump. I connected the mityvac directly to the orifice off the main (large-diameter) vacuum hose, with nothing else attached to that orifice. I got 20.5", which is about their spec (21"-23") so I think I'm good there. I tried putting vacuum into the system with the engine off. A squeeze would get it up to somewhere around 5" and that would bleed off fairly quickly (2 seconds or so), hope that's normal.

I'll begin going down their long list of things to do. Again, my frustration is that the 1-2 and 2-3 shifts are pretty much fine (or a tad harsh if I want to be picky) , while the 3-4 shift is kind of slow/mushy. Reducing the restriction further improves 1-2 and 2-3 and worsens 3-4 so "more vacuum" isn't the answer I'm looking for. Sometimes I wonder if I've set my expectations too high for a car of this age, but people claim to be able to get theirs silky-smooth in all 3 shifts so I want to achieve that or become convinced that it's not possible on mine. No one's indicated that subpar shifting is a result of mechanical wear inside the trans, which propels the car forward just fine once it's in gear, so I'll keep going with the hope that it's a vacuum issue.

And yes, Samuel, I do really appreciate your input on all of this.

The best offer I can now make is a renewed step-by-step approach...
 

Herring ,
Earlier you POSTed:
These pressure drops you reported struck me as od unless the tranny-shifter control system was connected via the “Y-connector” you used!?
------------------------------------------
------------------------------------------
Now at (A) above, you reported 21-23 inches (of Hg) vacuum readings on your 1982 240D… and this tells me that it appears that your other vacuum using components/systems are reasonably tight and not leaking badly. My 240D starts out with about 20” and the needle vibrating… and as you increase throttle, the needle steadies and rises just slightly. Even so, as hopefully you continue to try and make further improvements in your Tranny-Shftr.Vac.CtrlSys [aka = T-SVCS]. I would suggest that while parked and doing this work that you use golf tees or other means to disconnect and plug/cap-off these other vacuum systems [but NOT the power brake booster reservoir]. Report back any differences you see reading the vacuum directly and only off one of the Tee connections on the large, main, vacuum line.

At (B) above, I think you are saying that you tried to use your hand pump/gauge to see IF you could manually pump down the T-SVCS !? Personally I commend you for your inquisitive interest… but since this system is a combination of both “dynamic” as well static components, this will not show you much. The Vac.Ctrl.Valv [VCV] works by allowing air to enter the T-SVCS and thus the vacuum loss and the confusing term “bleeding”. Normally this term is used when referring to “bleeding off” air pressure stored inside something… but in this instance always remember that these VCV(s) are air to enter the T-SVCS… try to think of this air traveling along the lines and thus reducing the level of vacuum on the other side of the VCV that “TeeD” into the line going down to the TrannyCtr.lModulator [TCM]. This “dynamic” side of this T-SVCS system makes hand vacuum pump evacuation pretty much impractical ! The vacuum pump is mostly to test static vacuum components… EGR(s), TCM(s) Door-Lock Elements [aka “PODs”] etc. Yes you can use the hand vacuum pump to test the tightness of sections of the T-SVCS dynamic system when the engine is shut down… and you can monitor the vacuum level of the T-SVCS system while the engine is running, but the hand pump is pretty much for static components with no air flowing though them!

At (C ) above I’m not sure what you list you are referring to but yes, get the link address and I’ll take a look!

In closing let me try a step-by-step approach to your troubleshooting efforts… and that means more Q(s):

[1] Isolate the vacuum systems... such that only the Brake Booster is connected to the large, main, vacuum line.

Q1 – What vacuum readings do you see at one of the T(s) coming off the large, main, vacuum line?-------------------------------------
[2] NEXT connect the T-SVCS to the main vacuum line via one of the T(s) … then plug and/or Cap off the connection between the T-SVCS and the VCV for we want to see IF you can hand pump down a measurable vacuum in the remaining STATIC components and lines of the system.

Q2 – Are you able to do [2] and does the vacuum hold?

Let’s NOT get too far along with this step-by-step approach… and these were mostly to test the STATIC side of the T-SVCS system.
Soon, maybe even next we will add in and delve into the dynamic [VCV] part of the system.
Sam

A: at idle, if I have the transmission connected to the vacuum line, and test the vacuum near the large-diameter line via a Y-connector, I get 13.5". If I disconnect the transmission and plug the mityvac directly into the large-diameter line, I get 20.5".

B: If I leave the mityvac plugged directly into the large-diameter line and turn the engine off, vacuum drops steadily to near-zero fairly quickly (less than 5 seconds). If I then use the mityvac to pump vacuum into (from) the system, it falls off quickly. So, my conclusion is that the system is designed to hold only a small (but slightly greater than zero) amount of vacuum when the pump is not operating.

C. Ok, I will try vacuum-pumping the VCV/trans side of things when I next get to work on the car.

Response... & revision to my part [2] and Q2... !
 

OK Herring... let me revise my instructions for [2] above... and to NOT connect the T-SVCS to the main vacuum line for you will connect your hand vacuum pump to the T-SVCS as modified by the remainder of my instructions in [2] above! Be sure to … plug and/or Cap off the connection between the T-SVCS and the VCV... for we want to see IF you can hand pump down a measurable vacuum in the remaining STATIC components and lines of the system.

I hope my responses as done above, interspersed inside your previous quotes makes it easier to follow in this THREAD!??

Maybe some day we can do this with streaming, live, video!
Regards,

Very strange issue today. Drove the car for the first time in 6 days. When I first accelerated, I thought the trans was suddenly starting to slip. Acceleration seemed slow, and the 3-4 shift was very flare-y.

Fortunately I had my mityvac in the car and hooked it up on the way home. The "slipping" was just the 1-2 shift, happening immediately on me tapping the gas. The reason why is my vacuum has suddenly soared.

Vacuum on the transmission line is now 16.5 at idle and 10 floored. This is from 13.5 at idle and 1 floored. I took off the blue thing (pictured in post 483) I'd put in the line to the VCV and vacuum fell to 14 idle/9 floored.

What on earth can cause a sudden, huge shift in vacuum like that? Particularly the fact that vacuum is barely falling under acceleration? Did my VCV just croak?

... we need to have some rules here IF we are to really HELP ya...!
 

Herring,
Sincerely, it's difficult enough to diagnose problems with these systems "remotely" based upon another's observations! I'm afraid that your introduction of parts from a "gasser" might just make some of us become reluctant to try and help you further! For me personally, I'm inclined to say remove any and all such "gasser" or other parts that are NOT OEM to your model... and lets take inventory of just what your systems looks like. I will be glad to help you further IF you agree to do this... and will take the inventory you tell and/or show me with any photos and graphically edit a vacuum diagram and post the diagram where it will be available 24/7 elsewhere [NOT on this FORUM]. This way we will not be restricted by the 65K file size limit. Given such a diagram as a reference that I can rely upon I think we can work through your symptoms and give you good advice.

We need rules or we will be spinning our wheels bouncing vagaries off each other for ever. I for one need clarity as to just what your car's system has on it ! So IF my memory serves me well, your's is a 1982 240D... so IF this is correct, I suggest that we start with the diagram at: http://www.peterschmidtransmission.com/vacuum/1977_1985/616_617_91/616_617_91.jpg . Take this diagram and describe exactly what you have actually connected up on your car's "Auto Tranny-Shifter Vacuum Control System on yur car. You can do this OFF-Line by sending me an email [direct please... NOT this FORUM's email system] and I'll start editing the diagram using color and we will then have clarity as to what we are talking about ! Again, I am prepared to post this where we can open the diagram in a separate window and follow along with what the other is saying in their POST. To get the ball rolling you can also give me your telephone numbers and I can call you using my unlimited internet VOIP telephone line and we can chat to give me the information I need to edit the diagram. Sorry I didn't see this coming and establish "rules" sooner!

Regards,

New Owner
 

I have an 83 240D with tranny problems, I believe it is the vacum system. I think I have narrowed it down to the White Bleed Valve on back of Injector Pump but I can not find it any suggestions greatly appreciated. Maybe I have the wrong name.

Thanks GM

GM... welcome to the THREAD !
 

GM,
Welcome to the THREAD on a very popular subject for owners of W123, W124, and W126 Benz(s)!
Yes, it helps to know the proper name of any components and secondly to be able to access the correct vacuum diagram for your AutoTrannyVac-Shifter System. I believe yours is the same as in my previous POST... but here it is again on a popular tranny rebuilder's WebSite here in the San Francisco Bay Area: http://www.peterschmidtransmission.com/vacuum/1977_1985/616_617_91/616_617_91.jpg.
I think you will find your "white bleed thingie" to be the Vacuum Control Valve... #65 in this diagram. I recommend you save a copy of the diagram as best you can and print out a legible copy so that in your POSTs you can refer to components by their proper names and/or # from this diagram along with a reference to the diagrams's http address!
You also might want to go backwards in this THREAD and read some of my discussions of STATIC and DYNAMIC vacuum control systems and try to understand the point I have made that these Tranny-Shifter Vacuum Control Systems are a combination of both STATIC & DYNAMIC.
Also tell us something about your car...
Q1 - miles on car?
Q2 - miles on your current tranny?
Q3 - how long have you had the car?
Q4 - daily driver or not?
Q5 - also what are your tranny's shift symptoms?
Also even a meager digital camera that has a Macro mode for closeups can be a Godsend when trying to describe something!

IF you have no idea about Q1 & Q2... then you might want to POST your VIN next time and we will look up whatever information we can on the car using a popular Russian WebSite for such. This will give us your engine & tranny's S/N(s) which you can compare and maybe learn something more about your piece of fine German engineering.
There is a lot of information in this lengthy THREAD so browse through it and see what you can pick up... but first download your diagram, take an inventory to see what you might have missing or extra... and start becoming familiar with the various components... and count your blessings that you don't have a 1985 California Benz!
Regards,

Still trouble shooting
 

Sam

After looking further I found a vacum line shoved in firewall, which leads me to needing the diagram because I have always thought things did not look factory (if you know what I mean). Anyway the Benz and the web site is all new to me and hopefully I will get the hang of both of them. I have always had VW's and the Benz was given to me so being German made I knew I could not go wrong, I just need to learn more about the vacum system and I am sure this will be as good as my VW's. I will provide more details next time.

Thanks GM

Still learnig
 

After seeing diagram the line vents to passenger compartments:confused:
still learning.

GM's Project --- The vent line... !
 

GM,
I was fully aware that you were a "newbie"... at least to this particular FORUM... however don't feel put off as you are neither the first... nor will you be the last who gets thrown by and puzzles over the vent line that runs through the firewall and just stops open to the atmosphere! Going back to your diagram [ yu will see that there is another vent line [labeled "a" ] that is part of the EGR subsystem that is part of this Tranny-Shifter Vac. Ctrl. system. It is possible that these two vent lines [both labeled "a" in the diag.] come together before passing through firewall. I will eventually share with you ideas about using cheap paper medium see-thru in-line fuel filters on these vent lines and other lines in the Tranny-Shifter Vac. Ctrl. System
Again... welcome!
P.S. - IF you do NOT yet have a hand vacuum pump with vac. gauge, you should spend the ~$20 OnLine at Harbor Freight [or more for a quality one] for one of these is a MUST in order to work on this system!
P.P.S. - In your future POSTs, please start your "Title" with "GM's Project -..." . This way there is less confusion IF someone else continues or starts a new project for their car on this same THREAD!
Regards,

dannyf's '84 300 SD tranny question
 

Hello Sam and others,

Just noticed this extensive thread and am in the midst of dealing with a thudding 2-1 downshift on my 84 300 SD (with around 225 K ) that keeps me from wanting to drive my car..

I started trying to follow Brian Carlton's advice (post #8 in this thread) but I do not see any black box. Must it be on my car or might it not be there? So, besides looking for rotten rubber connectors on vacuum lines (and they seem OK to me) I am not sure what to do first.

One other aside is that since I have a 300 SD, my door locks are controlled by an auxiliary pump, so they are not part of this vacuum system (and that pump is dead, so those don't work presently).

Thank you!