Bob,
As the originator of this THREAD, I wish I could contribute something to your current discussion... but I must admit my almost complete lack of experience with these later model "tranny-shifter engine vacuum control systems" as well as any real experience with turbo model cars.

I will readily intrust you to the capable hands of Brian Carlton for he either personally owns or works on such models and obviously has such experience!

One day I expect to get into my In-law's '85 Calif 300SD and will likely seek a way to convert it have a Federal version "Trany-shifter Engine Vac. Ctrl Sys."

P.S. - By the way " Great Graphic" !
Regards,

samuel,

no, thank you. no need to apologize. your thread got me at least thinking about the ins and outs of the vac system and its relationship to ... well, just about everything. i thought that at least there were some universal rules that applied to both 617 and 603s, but i was wrong.

i obviously have a lot to learn, but thanks again for being so helpful to everyone.

Bob,
Early this a.m. [ the clearest time for my 65-year-old mind these days ] I did a little of one thing I think I'm really good at regards to this, our BAD MBZ habit... I did some browsing in an effort to see IF I could contribute to your project. I have also read some of your "blog" and find it to be really well written... cudos! So I will be joining your blog... at least to the extent that I see I can be useful... and my 1st contribution there will be something I found in Russia that might be useful... parts blowup diagrams and their accompanying tables of P/N(s) I thought you might find of interest IF not outright useful !
Regards,

Thanks.........but, I don't see the purpose of it when used for the
603. That trans usually doesn't suffer from the issues common to the 617.

I have the vacuum diagrams for the OM605/606 in PDF format, but the file is too large to post here and I didn't see an option to add an attachment to a PM. Thanks a TON for all your help!

BeerLover,
You are 100% correct... the way this normally works is now that I know you are volunteering the diagram, I will send you a a Direct Email via the resources on this FORUM and this will allow you to simply respond by REPLYing and attaching your file(s) to that email. Try to limit the total size of things to less than 10mb!

I will now close out this POST and email you. I sincerely thank you for this offer.
Regards,

Brian,

I took your advice and turned the control shift cable nut CCW...first one full turn, drove around, no change...then I decided to go all the way in either direction to see what the effect would be. When I turned it almost fully CCW, the shifts improved dramatically. So I knew I was close, so I turned CW a half turn at a time and now the shifts are nearly perfect. On light throttle, shifts are:

1 to 2: close to 3k
2 to 3: quick, but around 2,500
3 to 4: same

On WOT, above 3k

It really, really hauls arse on freeway speeds. I may adjust the ALDA, but for now, I'm leaving good enough alone and will start to work on putting some of the other interior pieces back on and work on my biodiesel processor.

Oh, in the morning, the first few shifts are hard. Why is that? But after a few minutes and shifts on the road, back to smooth shifting. It's amazing that this car could be resurrected from shifting h#ll and lack of power. I wonder if the previous owner just gave up. Pity b/c this is really one of the most funnest car projects I've worked on given all the manually adjustable things re shifting and engine tweaks.

Re Superior kit, I'd have to say that by installing the kit, my shifts are so much better. But then again, I'm sure its a mix of making sure that the tranny vac system was to spec too. I'm going to say though, that since i installed the kit before making major trans/vac adjustments, the springs worked as designed.

On light throttle, I have found that shifts should occur at about 2,000 or slightly less. If the setting is too late, the engine doesn't have sufficient fuel to get to the shift point and you'll find yourself pressing further into the pedal to get the engine up to the shift point. 3,000 rpm shifts should not occur unless you're at least 1/2 way into the pedal.

The system has a shift softener that will normally operate when the temperature is below 50°C. However, I've got the same problem with both of these..........the circuit doesn't work. Either the switch is NG or the solenoid is NG............I haven't sorted it yet. The solenoid is right next to the blue transducer if you want to screw with it. It should be energized below 50C. engine temperature.

Glad the kit worked for you............I haven't seen a need on any of these.

Brian,

Ok, perhaps I will try adjusting the control cable nut a little more to decrease the shift point. But i think maybe my numbers are a little more than light on the pedal. i have a heavy foot i think

On another note, after all the transmission, vac, etc. monkeying around that I've done the last 2 months or so, I finally got the best mpg on a single tank. 26 mpg! exciting for me considering i was getting low 20 to 24 mpg on 3 previous tanks. So I'm getting up there which is a good sign. My 33 mile trip to work is about 28 miles of highway driving, so I was easy on the skinny pedal. Avg speed was about 70mph. At that speed, my rpm was around 2700. Is 26 mpg good for this car? I bought it with the expectation of eeking out 28 to 30 mpg.

So if I adjusted the shift point downwards, do you think I could eek out another 1 or 2 mpg? If I can get 28 mpg on this car, I will have achieved my goal of surpassing my Toyota 4runner's avg mpg of 16.

Brian,

I just followed your directions on removing the egr vacuum lines and my car shifts nice and smooth through all gears. It was previously very harsh from 1st to 2nd. I was actually used to it and could ease off the accelerator pedal to soften the shift. Now I don't have to worry about that. It is also much more responsive now at higher speeds. This "mod" was right up there with my valve job, bosio nozzle replacements, and ALDA banjo bolt cleaning. All Essential maintenance or modification jobs in my opinion. I also live in AL where we have no emissions testing. Thanks again!!!

__________________
Scott

1983 300D Turbo

Excellent.

Help is what we do here.

My 1981 MB 240 D body style 123.123 was having a hard time shifting.
I tried to link it to motor temperature because it shifted better after the motor got up to running temperature. I tried many different things to try to correct the problem to no avail. Still looking for answers, I contacted Sam Ross.

Sam Ross suggested that I find my vacuum schematic at
http://www.peterschmid.com/vacuum/1977_1985/616_617_91/616_617_91.jpg

240D 1977-83 123.123 616.912


This diagram was similar to what I had on my Mercedes (except that I have no EGR valve)
I first purchased a vacuum gauge.
After checking the vacuum at the mechanical switchover valve located on the valve cover the problem was apparent. It was a blocked orifice in the Y in route to the transmission.

After applying CRC and using a “tip cleaner” the orifice was cleared and the transmission shifts well and the diesel runs significantly smoother.

I fear that I replaced a transmission in this car with 214, 000 miles thinking the transmission was bad when the problem was with the vacuum system. What a conundrum this orifice in the rubber Y can cause when blocked !

I have read many threads on this subject and picked up much information about these wonderful cars. Thanks to all who share info on these forums.
I can now run my grease and bio-diesel car in relative peace and wait for the next glitch to arise.

Arster... [ Jack ],
Thanks Jack... I am happy your problem was so easy that I somewhat accidently helped you find it as quickly as you did !!

By your following my request to write your POST above give as much detail as you could, I finally realized that your dirty orifice was the "in-line" orifice and/or " Y " connector supplying vacuum to the transmission vacuum modulating valve on the tranny... so the dirt was starving the "Tranny-Shifter Vacuum Control System" of vacuum thus allowing the Vacuum Control Valve [VCV] that sits on top of the IP and bleeds off vacuum according to throttle position... and this allowed the VCV to drop the vacuum level too quickly which in turn was causing early up-shifts you experienced!

A final recommendation... install cheap [ less than $2 ea ] in-line paper-medium [low friction loss ] filters to keep the dirt out of your system... on your model, install one of these on each vent line [ labeled "a" on the diagram ] and usually terminating under the dash.
One of these comes from the VCV [#65 in diag.] and for those of you with an EGR on your engine [post-1981 models!?], the other comes from the electric switchover valve [#81 in diag.] that controls the EGR incorporated as part of your Tranny-shifter Vacuum Control System on these later models. My 1980 and Jack's 1981 240D do NOT have EGR(s) system despite what these diagrams indicate!
Regards,

Folks,

I have an 81 300D and lately I have been working the vacuum system. My system appears most like http://www.peterschmid.com/vacuum/1977_1985/616_617_91/616_617_91.jpg, except that I do not have item 81 (and my car is 300D not 240D). Anyway, I have reworked the lock system and it is working fine. I have disconnected the HVAC vacuum system and plugged it off (will replace leaky under-dash actuators later). I have completely reworked the 3/2 valves on top of the valve cover, replacing them and the levers and tightening up all connections, replacing connector block as well. I have verified that all under hood connection are per the schematic above. I have replaced the green dash pot (72) and yellow orifice (63). I have also added a green orifice at 62 (since I did not know what was in the built-in tee). Flaring is the current issue as I am flaring in 2/3 adn 3/4 while also shifting at too low an RPM. I have checked the vacuum at the top of the VCV and it reads about 10 in HG and bleeds off to zero when I advance the throttle (performed with engine off). The vacuum line going to the transmission can hold a vacuum of 20 in Hg, while very slowly decreasing. Using a vaccuum tee in the transmission vacuum line and driving around, I see the reading fall from about 10 in Hg at idle to much lower levels quite quickly, not gradually over the range of throttle. So, I end up with 2-5 in Hg as the gears begin to shift. So far, I can not get the adjustment screw on the VCV to move (afraid I will break it) so I have not attempted any adjustments. Finally, I actually blocked off the vent branch of the Tee at the VCV and drove around - the situation was slightly improved. Any ideas?

Others will chime in but from what I remember in the previous posts, your vacuum readings sound reasonable.

I'm thinking next would be upgrading the springs found in the Superior shift spring kit.

__________________
Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html