I thank you all for your inputs. I am going to get a new modulator valve and repeat tests like DieselDan suggests.

And I will be back to report my results......

I wish I had the time and I would transcribe this thread into a structured and indexed document to help the members.

If some others came up with a draft I would be happy to be an editor. I just have not got the time to do it the way it should be done.

HELP.......HELP......HELP.........
 

Does anyone know how the plunger or thrust pin assembly, or whatever it is called, is fastened to the modulator valve part#:1232700679 ???

I do NOT want to brute force it since this has to be transferred on to the new valve diaphragm.

Ok, I have partially fixed my vacuum trans issues on my 87 190DT. I had a vacuum leak so the trans moudulator did not get a signal. There is a white check valve in the drivers cowl. One side has one nipple the goes to vacuum, the other side has 2. One of the lines is a red w/silver plastic line. It does down by the m/c and cannot find where it goes. What ever is connects to is bad. Any ideas? I cannot find a W201 chassis vacuum diagram. I now have 6" vacuum going to the trans but now it is shifting too soft since I do not have a boost signal to the vacuum amplifier. I am trying to figure out if my VASV or switchover valve is bad.

I recently purchased a 1984 300TDT that has tranny problems. It suffers from a rather severe flares on the second and third shifts. It also had problems shifting into drive early in the day. I dropped the pan, changed the filter, while also draining the converter. The pan and fluid appeared to be fine. Replacing the fluid I added a qt of Marvel. The valve body problem seems to be getting noticeably better. The second and third shift flares have not. I'm trying to get a grip on the vacuum issues. BTW the AC and door locks seem to be pretty good overall. Have the feeling this is a manageable problem between potential leaks (I do have a vac gauge), the K1 spring, the modulator valve, not to mention a bunch of other stuff. Where to start

How to access Site
 

Greetings,

This is a great site - www.w124performance.com

but it has a problem in that near the very end of the URL the back-slash has been replaced with a front-slash.

Example - here is a manual page for the 124

http://www.w124performance.com/service/w124CD1/Program/main_manual.htm

From here you are offered a number of choices. Let's say I select "Adjusting injection timing - 0761"

I click on it and a new page opens with this URL -

http://www.w124performance.com/service/w124CD1/Program/Maintenance\MY81\0761.pdf

and no page appears.

Now, starting at the end of the URL replace every "\" with "/".

http://www.w124performance.com/service/w124CD1/Program/Maintenance/MY81/0761.pdf

Voila. You may now access the content.

1982 300tdt, mileage unknown, 155k on the odometer.

With vacuum system connected, wot,
1-2 no flare, shifts around 1400
2-3 medium flare, shifts around 1800
3-4 medium flare, shifts around 1800
Flare continues but is lower under partial throttle.

With no vacuum, all of the shift points are the same
1-2 no flare
2-3 flare only at wot, no flare at partial throttle
3-4 no flare at all throttle positions

The downshift from 4-3 clunks a bit no matter what the vacuum, all other downshifts are fast enough/smooth enough that I don't even notice them.

Strange.

And no matter what adjustment I make to the Bowden cable, which is connected, the shift points don't change. There might be some strangeness, I have a replacement cable waiting to be installed.

Vacuum system holds vacuum, looses it at about 1psi per second when car is off.

The vcv holds vacuum, looses it slowly, about within spec. It's adjustable. With the mityvac, car off, it goes from 10"-0" as the throttle goes from idle to wot. With the car on, it stays at 10", but at wot only drops to 5". Can't get it to go lower when the car is on.

Right now I'm driving without vacuum to the transmission, it's the most drivable and smooth is way. I'll be lifting the car soon to get numbers for you guys and to inspect the modulator. The kick down solenoid doesn't work either, I replaced the switch under the pedal, which didn't work. It's on my list of things to check under the car.

Oh, and when I got the car in April, vacuum system was a mess. I fixed it based on the same engine configuration I found online in a picture. I haven't found a vacuum diagram where I can read the parts to verify I'm doing it right. But my hvac works, shutoff works, and vacuum to the transmission is not within spec, but getting there.

My theory is that either the modulator is going bad, or was over adjusted by somebody who didn't know how to adjust the Bowden or vacuum communications.

More numbers to come, I just wanted to start to get information for other things to look for while I'm under the car!

If the system performs best with no vacuum, you're on borrowed time with the trans. Nothing further can be done with the vacuum system by adding vacuum because that will simply aggravate the flare.

You'll have to leave it as you have it............and hope for the best.

This is making me run out of reasons to keep the car. Damn.

Some folks have had success with the Superior shift kit (do a search), but with a high mileage trans, there is no assurance of success.

Although it's one tough transmission, it won't last forever.

I'm thinking of turning this car into a parts car and getting another wagon. Otherwise, I might just go back to the old Volvo 240's I drove before. They're about as indestructible.

Great Article, Thanks.
 

I've read all of the entries and have to say what a great series of very informative posts. I've simplified the 81 Federal drawing for a 1982 300 SD down to components & was wondering if I'd gotten it correct. It looks goofy with the loop in it, but if that's the way it is.......
If you all would want to take a look & let me k now if it's good, I would sure appreciate it.
Next step is eliminating the EGR to see if that helps my 1st - 2nd transmission slam-fest of a shift. The previous owner had removed some vacuum hoses, but not all, so it'll be fun to sort out.
Thanks & Best Regards,
Jon

http://i561.photobucket.com/albums/s...thoutEGR11.jpg

Answer
 

Contact me by phone when you can.

I will help as possible.

location: Detroit Metro area...



.

rcwarship
Doesn't look correct for an 82 CD 617.95 engine.
http://www.peterschmidtransmission.com/vacuum/1977_1985/617_95/1981_1984.jpg

Wow, over 100,000 views!

Great information... I'll need to walk through it if I were to attempt the process myself. My 83' 300D will not go beyond 3rd gear regardless of throttle position (pedal to the medal or other... max speed about 25mph). What is this an inidication of?

Thanks.

Low tranny fluid, old filter.

Check linkage
 

When mine did that, it was due to the worn out ball on the throttle linkage. Raise the hood and check out the linkage component attached to the firewall. It would not give full range of motion at the injection pump.

1984 300D Mechanic Rigged Orifice
 

While replacing my master cylinder, the mechanic broke the brown orifice of the check valve on the brake booster vacuum hose. Instead of replacing the hose, the mechanic took a piece of old vacuum hose and used that for an "orifice". Now my car slips through first, I can feather the accelerator through first, to second where it still slips a little then engages and then shifts better.

My trans fluid is red and smells fresh. Thought it was the filter, so replaced that, and the car still shifts the same.

I have over 20" from the hose coming from the check valve where the mechanic substituted vacuum line for the stock brown (.9mm) orifice.

Did the mechanic screw me?

Called PeachParts and spoke with Roy AAA+ experience very helpful

Answer
 

Here is a local shop that will fix it right.

MBS Motors
Near the corner of Pleasant Hill Rd. and Buford Hwy. in Duluth.
Ask for Axle or Jeff.
770-623-8280

borrowed time?
 

first off a big thank you to the moderators and posters on this thread.the entire community deserves praise for sharing their experiences,good and not so good.
i recently purchased a 82 300td with many small problems in spite of the previous owner having spent a ton of money on the brakes and front end.most notable problems being a strong smell of burnt oil in the passenger cabin and transmission slipping during shift 3 to 4.following the instructions here have finally arrived at plugging the vacuum line to the trans. and now have a fairly smooth shifting tranny.
a previous poster was informed that such a set-up was an indication of a transmission living on borrowed time.my question is would a fluid and filter change extend the time being borrowed?i am a retired millwright and our first rule is "if it aint broke dont fix it"
thanks again.

yes.
a fluid change can extend or eliminate the borrowed time. DO NOT GET A TRANS FLUSH DONE!
these cars are equipped with torque converter drains as well as pan drain plugs. both take the same 5mm allen wrench, and combined with a filter and pan gasket change will really stretch the life of your transmission.
line up the TC drain plug with the access window, I use a 27mm deep socket and a 1/2" drive ratchet turned by my brother, and I look up at the TC for the plug to come by. nearly impossible to do it by yourself. starter bumping ALWAYS spins it right past... annoying. remove the plug, drain it out, remove the plug from the pan, drain it out, then drop the pan and drain out the leftover fluid. clean out the pan, then change the gasket. remove and change the filter, and put it all back together.
fill with 5 quarts of Dexron III fluid, and start the car, and cycle through the gears. let it warm up, and top off the fluid to the fill mark.
done.

I wanted to post some of my findings. On my 87 190D 2.5L Turbo I checked my vacuum readings. I had 10 in. at idle but when I went wide open it only dropped to ~5 in. of vacuum. So I bypassed the vacuum amplifier and tried it, went to 0 in. at wide open now. The symptoms were going from rev to drive it would slip for a split second and it would slam into lower gears during a down shift. Bypassing the amp. fixed it. It downshifts better and has only done the rev to drive thing once (used to do it a lot). Not I need to smooth out the upshifts. One thing that it is still not right is the shift points and kickdown. It shifts it 4200 and will not kickdown like it should. It will if I am going well slow enough to go down a gear. I have the bowden cable adjusted full tight. Any other ideas?

clear
 

thanks for the clear instructions on transmission servicing.the pan had a small amount of brass flakes in the bottom and the filter was dark but i am hopeful she can give me a couple of years more of driving.moving over to another thread for the other problems.

Any ideas why my shift points are too low on my 87 190D Turbo? My modulator is holding a vacuum, my bowden cable is adjusted tight and my vacuum goes to 0 at full throttle. It shifts at 4200 in all gears and will not kick down correctly. I have tried to do a search but there is so much w123 mixed in the results. I know there is not much W201 love here but can anyone help?

I just did this alone by bumping the starter by touching bare wire ends while under the car staring the the torque converter opening. It took about about 2 minutes of bumping before I got the drain plug to overshoot the opening a little but still visible through the slots. I then used a screw driver to pry the drain plug back to line it up with the opening.

Another method which will work if working alone is to rig up a buzzer with a wire that shorts to the drain plug when it makes contact as you rotate the torque converter via the27 mm crankshaft bolt.

I would like to thank all those that added to this thread. Its a good long read but very useful.

Brian's pratical suggestion on post #8 solved my trans shifting issues as I have a '84 cd.

Again, thanks,

Bryan

I have been reading about this transmission issue since I first obtained the car in May 2011. The shift flared from what I believe is 3rd to 4th and the line to the modulator was just hanging, not hooked up. I hooked up the modulator and it flares from 2 to 3 and 3 to 4. Yesterday I found that that VCV was only putting 3" to the modulator and adjusting it didn't make any difference. I hooked up a gauge to the test port on the trans and it was only making about 36 or 38psi....turned the pin as far CW as possible and there was no increase in pressure. My central locking system stopped working shortly after I got the car and the center vents do not work. Today I am going to see if I can chase down the rest of leaks but in the mean time am curious about the pressure modulator....as I cant get it to make any more that 36-38ish or so psi, does that mean I have weak pump and am going to need to rebuild the trans soon anyway? Monster of an issue, I cant wait to get the car all squared away. Any info or ideas are much appreciated!

1995 E300D OM606 adjustment how to?
 

Has anybody been able to successfully adjust their modulation pressure for an E300D? If so, would you mind giving me some pointers?

I've read through the entire post, but I'm still none the wiser as most of this post seems to be for earlier vehicles.

And I went to the w124performance site and was unable to find a vacuum schematic for this car.

Waiting for my vacuum guage to arrive but would like to have some notes ready.
Thanks

Pressures up to spec - flares are gone!
 

FYI Everyone following...

While my modulator WAS holding vac, I couldnt get more than 25 psi with the pin cranked all the way in. So I ordered one. I pulled the modulator to see if the pin was broken, it wasnt. It was oozing a rust colored liquid from under the black cap.

http://img32.imageshack.us/img32/749...acement001.jpg

I installed a new modulator (febi/biltstien) and pin which had a longer base as well as overall length.
http://img337.imageshack.us/img337/1...acement002.jpg
http://img217.imageshack.us/img217/6...acement003.jpg
http://img534.imageshack.us/img534/2...acement004.jpg
Then I hooked up the pressure rig, and it was (miraculously) reading at 42 psi at idle, dead on. Quite amazed I didnt have to adjust it.
http://img402.imageshack.us/img402/4...acement005.jpg

I test drove it and the 3 to 4 flare is gone, still a slight on the 2 to 3...so I adjusted the VCV to put only 10" to the modulator at idle. Still a slight flare, which went away when the car warmed up.

BTW the modulator (from Fastlane, came with the o-ring seal and the rubber cap, no need to buy extras)

At this point the 2 to 3 is firm, clunks a little and I cant feel 3 to 4 at all.

I plan on tinkering with the VCV a little more but am quite happy that the problem is "resolved" and I dont need to rebuild the trans.

I'm debating on if I should install the "Superior Transmissions Shift Correction" spring kit I bought now or maybe at next fluid change or maybe sell it?

As always your thoughts, comments and ideas are appreciated!

bumpity...

Need Help with Up/Down Vacuum - '81 300D Non-turbo
 

I installed a new brake booster line because the old one had a cracked T that resulted in a 5-20 second shut-down time. Before replacing, the tranny shifted fine, maybe a little early and the kick-down worked. Now, shut-down is instant but the tranny has a 2-3 flare, shifts early, and there is no kick-down. Following the advice in this thread I ran a vacuum line into the cockpit with a vacuum gauge to monitor vacuum while driving. I learned three things and one strange occurrence:

1. The vacuum load at idle was not steady. The gauge needle bounced erratically between 10 and 15 pounds. With just a little throttle the needle settled nicely at just under 15 pounds.
2. The vacuum moved from 15 pounds to just 9 pounds under full throttle.
   
3. I found I could improve shifting (eliminate the flare, improve shift timing, and get kick-down to work) if I removed the gauge and just let the vacuum line "leak".

The strange occurrence happened after a few days of monitoring with the vacuum gauge. With the gauge plugged in (no self-induced vacuum leak) the vacuum began ranging from 12 pounds to 2 pounds under full throttle, just like it should. Shifting improved and kick-down started working. When I stopped and let the engine idle, the needle did not bounce around but instead registered right at 13 pounds, like one would expect. After stopping for the night, the erratic vacuum reading at idle and the 15-9 range under throttle are back.

Other things I know:

• The EGR and 3/2 valve have been bypassed. There are 5 hoses coming from the 3/2 valve, one of which goes to the side of the VCV but that is no longer functioning. Any concern here given my make and model?
• The center climate control pod is leaking, but no difference in vacuum readings when that system is isolated from the VCV/tranny system.
• The new brake booster line did not seem to have the built in orifice restriction at the T, as indicated by my crude test of blowing through the old T and the new T to see if there was a difference.
• There is a vacuum pod (green) and a yellow (2.0mm) orifice in the line just before it enters the VCV.

Next steps?

1. Introduce a smaller vacuum line orifice to restrict vacuum getting to the VCV?
2. Try to adjust the VCV so the range drops to near 0 at full throttle?
3. Pull the vacuum pump to see if it is failing? I don’t remember if I isolated the vacuum pump and tested it with the vacuum gauge. I’ll try that before pulling.
4. Try to reconnect the 3/2 valve but keep the EGR offline?

Thanks and any suggestions are appreciated.
VM

Orifices Make the Difference - Beta Testing Adjustable Orifice
 

Either this thread is dead or you all where silently encouraging me to find my own solution. Well I did find the solution to my fluttering vacuum gauge needle and 15-9 vacuum range at full throttle (see post 731). No surprise to some of you who pioneered this thread, there was a need for an additional orifice in the tranny/vcv line as too much vacuum was entering (exiting?) that system.

I found this easily by watching the vacuum gauge while I pinched the rubber vacuum line right where it T’ed off from the main brake booster line. Pinching the line about half way stabilized the needle at 13 pounds and resulted in a 13-1 vacuum range at full throttle. I knew now that I needed to put in an orifice to control the amount of vacuum in that system. The dealer wanted $22 per orifice, which could have cost more than $100 not knowing which size I needed.

Thinking about what I might use instead had me rummaging in my drip-irrigation supplies until I found a ¼ inch veri-flow valve used to control water pressure on stake sprinklers. This $0.62 valve fit perfectly in the vacuum line and has allowed me to adjust my vacuum in that system to just the right amount. I now have near perfect vacuum readings in that system, my shifts are in the right place, and my kick-down is working. I can now make adjustments at the tranny modulator to smooth things out for perfect shifts. This veri-flow valve is, of course, in beta testing as I need to find out if it will handle the heat of the engine and is able to keep its setting against all the vibrations. Anyone see any other potential downfalls? For those interested in what this valve looks like, here is a link to one, except the one I used was barbed, not threaded like in this picture: 1/4" Fittings - Dripworks 1/4" Vari-Flow Valve. Possible hardware store purchase.

I’ll keep you all posted…:)

Marked.

Would the 1977 300d have this kind of vacuum set up?

Answer
 

MZF-Bayer Transmissions


.

Can anyone point me to some info on how vacuum is supplied to the modulator on an M-pump equipped car? I recently snagged one from the local p/p and it does not have a VCV on it,like the MW-pumps do. None of the gear on top of the valve cover was present, BUT the trans DID have a modulator of course...

I lost that link. Thanks for re-posting it!

Custom Vacuum System
 

I'll confess that I came to this thread late and didn't read quite all of it so this may have been addressed - but is so, I missed it.

Anyhow, I'm putting an '84 300SD drivetrain in an '82 S10 Chevy PU to be used as a Land Speed Racing vehicle. It will never see street duty and is trailered to the track. I posted a couple of threads in the "Diesel Performance" section if anyone's curious. I won't be using much of the vacuum system (no PB, no heat/air system, etc.) but I am retaining the MB transmission, the vacuum engine shutoff, and any other bits that you guys tell me are critical.

So -
- How do I plumb this monster?
- What vacuum readings should I see at the shutoff, transmission vacuum modulator, etc?
- Can I skip the pile of stuff on top of the valve cover or is that critical to transmission operation? (Sure would look better w/o that mess!)
- Any other input? I'm new to MB but a pretty experienced automotive professional (retired).

Thanks for whatever input you can provide.

Dan

I'm pretty sure, all you'll really need is to get vac supply to the vcv, properly, 13-15 in/hg....and have the vcv connected to the modulator thru an orifice restriction fitting.

http://imageshack.us/a/img20/8785/19811984.jpg

That will depend on the car. Can you specify?

The VCV of a MRSF pump has an input (vacuum supply) and an output (regulated vacuum). It also has a vent line on the side.

I dont understand, there doesn't appear to be anywhere to connect vac lines to the pump itself

I see the two bolt holes where a VCV would go, I guess thats how I would hook this up... this is an M pump isnt it?

http://imageshack.us/a/img824/483/boschmpump.jpg

Thanks for the diagram. That helps a lot!

Dan

That is a MW pump.

Any time Dan, I'm happy to help if I can. As far as the pump types, I guess I had to re-read on how to tell the difference.

without VCV ;)

.

The stock transmission doesn't have a locking torque converter...you will always be seeing a loss between the engine and transmission. I'd recommended swapping in a different transmission if you're building a race car.

You can ditch the pile of stuff on the valve cover.

Dang. The vacuum diagrams only go to 1985 on his site

Thanks so much for the great info