Re: no forward gears...
 

Brian, thank you so much!!
Dmitri just came in to see what I was so excited about; I told him the story and showed him the posts and the link to repair, and he is amazed and also very thankful!! It's kind of a miracle; very serendipitous, and it's hard to express just how grateful we both are. He will go ahead with the inspection and repair. He did mention that I got the year wrong; his car is actually an '81, but I figured that the information probably still applies.

Thank you again!!
Dave
:):):)!!!

Well, don't get too excited. It does sound like the B2 piston, but without an investigation, nothing is assured.

Be very careful with the cleanliness of everything that touches or goes into that transmission. It's highly intolerant of any foreign material. Don't do the job on a windy day. Let us know how you make out.

Hello Brian:

One of the 3/2 valves was shot. Replaced both. Got vacuum. Shifting still too firm on 1-2 and too late on 2-3 (redline). Adjusted linkage on side of VCV and backed off modulator. Shifting very well now -- never this good in the past. Thank you for your help and advice.

Jonathan

Good job.

Had you previously adjusted the modulator to increase the pressure while you were chasing the issue?

modulator
 

Yes. It was turned almost all the way in. JM

modulator part 2
 

I forgot to mention that it was backed off in the last adjustment. In reading the Brotherton article again this morning, I can see that I should start with the modulator adjustment first then follow up with the fine tuning methods. Sometimes on fuller throttle, the 2-3 shift is too long, the 3-2 downshift around 90deg corners is off and there's slippage in the 3-4 shift after full throttle through the 2-3 shift. It's getting there.

Now that I've spent the last several days reading all 44 pages of this very informative thread, I have one question:

Why have all of Sams posts been edited by the webmaster with no reason noted for the editing?

In talking to my son's friends familiar with vBulletin, it could be that the webmaster had undeleted posts that were deleted by another?

On one of my airplane building forums, everyone left when it was found out that a moderator edited someones post. And I mean EVERYONE. The owner of the forum is really the only one there now, and this was just for changing a few words in a single post. It was understood by all forum members that all posts would remain as written and they took it very, very seriously.

Anyway, it's nice to have them (the posts) back. Sam has been very helpful in educating me in regards to the vacuum operation of the transmission in my diesels.

Thanks Sam! (wherever you are)

Just an observation, under his name it says "Banned". Now that could be a custom title that he gave himself, but if he did he has an odd sense of humor.

'Course, my wife says the same thing about me....

I believe "Banned" means what it says. I think our buddy Sam either went over a line too many times or once too far. If you look at the right side of the header you will see the infraction numbers.

Sam decided to deface every single one of his posts on this thread because he was annoyed with my moderation of the thread. I deleted one of his posts that was OT and abusive and he wasn't satisfied with that.

It took the Webmaster two hours to resurrect the thread from the backup software...........one post at a time. That's why every one of Sam's posts are edited by the Webmaster.

Accordingly, Sam is no longer welcome here.

It looks as if he had one infraction worth 5 points. Must have pissed off someone bad.

Anywho, I've read almost everything he's posted and he seems to be a knowledgeable friendly A1 kind of guy. I'd be happy to see him come back after his 6 months suspension is over.

Unfortunately, your conclusion is erroneous on all counts.

He will not be returning.

That's kind of rude and uncalled for. I find no basis for your conclusion.

What's uncalled for is an ongoing OT discussion on a technical thread regarding a banned member. If you have any additional burning desires to discuss Samuel Ross, please take it to PM.

Been reading
 

Brian and others

I've been reading this forum and this thread for a while and re-reading it.
I just wanted to pass on my success after reading this thread.

I've got a 83 300sd that I got for almost nothing - Im slowly turning this car into my daily driver.

I had slipping/flaring from 2-3 and 3-4 .... after following all the suggestions here I've fixed all my slipping and flaring.... it shifts like a brand new car...

I had one question ?? Have you noticed how much more firm the throttle pedal is after tightening the VCV on the IP??? Mine seemed sloppy before - now its tight. Which makes sense - since you are overcoming the internal flat spring of the VCV...

Thanks for all the info !!!

The internal spring inside the VCV is negligible in terms of overall friction in the throttle linkage. The pedal is never "sloppy" unless there are loose linkage components. What I find is the pedal gets "sticky"........cannot move it a small fraction.......it jumps. That's a sign of needed lubrication in the ball joints. This lubrication is necessary every oil change if you want the throttle to respond appropriately.

Additionally, removal of the 3-2 valves will allow the throttle to operate a bit easier........no friction from the cam to push the valves.

Thank you all!
 

:)To all who have added to this thread over the years I would like to thank you.

I don't usually comment on threads except when necessary but By reading this thread the past couple of days I have been able to do miracles with my NTM 84 300sd turbo!

I purchased this car a month ago and have been looking to solve the PO problem that "the transmission is bad and they are way to much to replace". As I have glanced at the thread in the past I knew that all it needed was adjustment. so I paid the $700.00 for the 205,000 mile no rust car and brought it home. The PO was right it didn't shift right and was flaring so bad I wouldn't drive her.

I then started reading the thread from beginning to end. I put the knowledge I got here to use today to diagnose and repair the problem. After a couple of hours with the mytvac(SP) I was able to get the car shifting like a knife through butter!

This site has been an invaluable asset to me in repairing my 77 300D with my donor 84 230 EURO. I replaced the HVAC to manual, redid (with the floaty things) the seats and many other amazing (to me) things. It now resides as my daily driver.

Again this is through all of the knowledgeable people like Brian, dedicating there time and talent to help us keep our beloved BENZ running forever.:)

PS: I know that I will be following some other threads now that I have two big D's to keep running. Now on to the next problem the wipers don't work :mad: to name but one on a long list LOL:)

Dump the RESTRICTED ORIFICES idea and install a 1/4 " needle valve in place of the orifice. Minuscule adjustments can be made to attain smooth shifting.

I found I had a vacuum leak in the VCV. I found this by odd coincidence by troubleshooting an inconsistent center vent. It wouldn't open because the vacuum getting to the vacuum pod was an inch or two too low. It needed 6 inches to open and it was getting 5. The leak that caused the low vacuum to the climate control was the vacuum control valve on the the side of the IP.

Once fixed, the transmission shifted wonderfully, until the the head gasket blew a wek later.

Brian - clarification pls.
". It'll be the Mityvac on one side, the transmission modulator on the opposite side and the VCV on the bull (via the damper). Pump up the mityvac and confirm the 12.5" at idle. It should hold vacuum reasonably well..........bleed down in 20 seconds or more."
Engine running at idle with the rod VCV to fuel injection pump connected?

The engine is not running. The Mityvac provides all the vacuum necessary for the test.

The linkage is connected normally per the FSM.

BTW, 12.5" isn't a magical figure. It can be less than this value if the shifts are too soft for your own requirements. The SD is currently at 8" and I still get no banging.

RogerB34...
 

RogerB34,
Brian is 100% correct about 12.5 NOT being gospel. I have just set up early two 1980(s) models, a 240D & a 300D, and found that 7.5-to-8.0" Hg. worked out best for me. Age and condition of your VCV could be a factor as could the internal condition of your tranny and the vac. modulator that sits on the tranny!?

For my adjustment, I have devised a way to make such VCV adjustments while the engine is running at idel. To help me do this I use a more accurate liquid-filled vacuum gauge that has 0.5" Hg. increments.

Once I made these and was happy with the results mainly for the up-shifts using such low idle vacuum setting, I have found that I can install and use a very small model airplane needle valve on the "T" coming off the main Vac.pmp-to-brake line.

Adjusting this tiny valve to tweak/adjust the vacuum going into the vacuum shifting system further now allows me to control the downshifts some. I think this is mainly the 4-to-3 downshift and to a lesser degree the 3-to2 down shifts. These earlier model MB(s) have very few compontents on their vac. control shifting systems so they have benefited from these needle valves. Later model W123(s) probably would not need such add-ons.

Roger - What model/Year is your car?

Brian - As a new member to this forum I have found this THREAD to be very helpful to me in refining my adjustment method. Is there any chance that Samuel M. Ross will ever be invited back to participate?

SteveR

Ive been investigating my harsh shifts on my new Wagon over the last week or so...

My initial fault was the main vac source at the brake-booster-line. This has a white tagged side-barb, which according to earlier posts is for a 0.8mm orifice. It was blocked--well, nearly. Cleared it through with some 0.6mm Mig wire, and forced some WD40 through it for good measure...

I think my VCV is not operating correctly...

I have 11 ins Hg at the outlet to the trans, but the VCV is acting more like a switch than proportional. It will go from 11" to approx 7" from Idle to full WOT.--The change in Vac. happens in a small range of VCV shaft-movement.

--Adjusting it makes no difference, apart from where in the throttle arm range the vac. change takes place...

--Is this the usual 'mode-of-failure' for a VCV...?

BTW, Been looking for a MityVac here in UK--I know they are available, Somewhere....

Had some luck finding summit similar made by Sealy..

But, they want near 300 dollars for it...:eek:

How much are you guys finding MityVac in the 'States for...?

tooldiscounter.com
 

About $28.00 USD

Would this be something like you are talking about? I am going to try and get one and fine tune my own if this is what you are talking about:
http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=+OSMG7164&search=Go

VCV faulty....
 

Well, just for the record, Ive replaced that VCV which had a 'switch' like action.

I fitted the same type, (which isnt the 'usual' seen on US models) and have a fully proportional control of the Vac, right down to 0, so I guess the first one with the switch-like action must be faulty.

Shifts are much better and more predictable now, Before-they were either harsh or flary, neither which I liked much....;)

I think I may crack the faulty VCV open and take a look see as to whats gone wrong, and If it could be renovated....:D

1982 MB 300 CDT 125K mi
Eng 617.952
Tranny 722.315
Cleaned intake banjo and line. Mostly blocked.
Also the switchover valve.
Replaced fingers and 135 dashpot.
Clean and lube rod ends.

Adjusted the VCV stop to 0.5 mm.
Required turning in the injection body stop
Adjusting the rod length was difficult as I couldn't make
the adjustment with the VCV in place. Remove,
adjust, check, remove ...
Tested vacuum lines for integrity and vac.
Adjusted VCV to 8 in vac for ok 1-2 shift and reduced 3-4 flare.
Piece of info I don't have is tranny hyd pressure.
Still working the problem. Car belongs to a friend.

Modulator Valve
 

1983 MB CDT, 125K miles, 722.315 tranny
The modulator was adjusted at 99k miles from 44 lbs to the correct 42 lbs.
Does anyone have experience of the effect on shift performance of:
1. Replacing the modulator.
2. Increasing modulator pressure slightly for higher mileage transmissions.
3. A combination new modulator and increasing pressure slightly.

What issues are your trying to resolve?

1980 300D Is the VCV Adjustable ??......
 

This is a large thread. I am discovering the transmission vac control. The VCV is acting like a switch. There is no nice linear ramp of inverse inches of Hg v acc pedal position as I monitor line to the transmission modulator.

I pulled the VCV and opened it. 2 screws and the top comes off. There is a coil spring on the throttle input shaft which displaces a brass slug. There is a nut on a long sided nut. My question is can I adjust this to restore the linearity of control. Is there any data out there as to what the right performance curve (inverted In Hg V pedal depression %age) should be. If this has been discussed on here where is it at.

Any help much appreciated.

I have a slight issue with my 87 190D and drive engagement. Going from either park or neutral to drive there is a hesitation. As soon as I go into drive there is a pause, then what feels like a slight engagement, slight pause then full engaement. Is that something that is controlled by vacuum?

Well, I DID crack open the one I had with a switch like action....

Inside, there is a spiral-spring that the throttle-shaft 'winds up. The outer end is attached to a diaphragm and a valve.
--The assembly was sticking, the spring was 'winding up' then suddenly the movement was transferred to the diaphragm...

Dismantling the whole thing, cleaning everything including the tiny metering orafice inside the diaphragm restored smooth operation and I was able to re-fit and set the VCV correctly. It has been working faultlessly since....

--I would not adjust anything, as we're not sure exactly what does what. Just dismantle the whole thing clean it all and make sure nothing is broken or sticking when the device is operated....

Faulty VCV valve
 

Well after reading for two hours and thinking in the middle I could probably just install my 240D's standard faster than I could get through this thread :D

I pushed through ! This resulted in a wealth of info. If you start at the end or the middle the full effect of it will not be realized.

The 81 300SD I just transplanted the 83' motor into would break your neck and chirp the tires when shifting through the gears. Thus I found this thread.

The new engine had a brand new VCV valve on it nothing wrong with that right ??? Wrong !!!!

I removed the EGR valves ..... no difference
Changed the green dash pot......... no difference
Checked for bleed down on the modulator........it Held vacuum
Changed the new VCV valve for the old ugly one (original to the 81's trans ).............. OH WHAT A FEELING !!!!!!!
Who ever installed it "adjusted " it . Vise grip marks on adjuster screw!! There's your theory of just a little adjustment is possible Brian. Spring was tweaked and never shut down the bleed valve

May be what killed the trans in the 83' ???


The car shifts better than my 2003 4runner !!!!!

On a side note I did not find one orifice fitting on any vacuum line on this car. All vacuum systems work flawless.
Therefore I agree with Brian as for the tuning of the VCV valve being the Key here . Even the original Steve Brotherton paper states Mercedes went through numerous changes. They finally settled on the amplifier "to reduce the sensitivity of the final signal to small changes in the proportional signal ". ( VCV valve is the proportional control )

I wonder if the newer 85' system can be incorporated into the older cars ? Cost effectively ? If not keep tuning !!!

Thanks to all who contributed to this thread ! Thanks Brian for sticking with this thread I appreciate the time and energy it took ! Also for passing on the knowledge to those of us new to Mercedes autos.

The wife says a big thanks as well !!!! ( its her car ) :D

The saga of a very interesting 722.118 tranny......HELP HELP
 

I bought a 1981 300D at very low cost which had a massively flaring transmission. This was my first venture into this type of problem. I carefully studied this thread plus read and read for some four plus weeks. Great info on here.

Here is where I am at. Removed the 3/2-valve and rerouted the plumbing. This did have a leak. It is a useless appendix on this car never to be recalled. Tested diaphragm on modulator valve on transmission. It is holding indefinitely so appeared fine. I have a MityVac. Next I removed the VCV and opened it. I understand its function.....it emulates the vacuum of a gas engine by controlled vacuum leak in proportion to pedal position. This was set incorrectly. It had a totally non-linear response. I cleaned it ,and calibrated it and I got a fine curve with 8 in Hg at idle and 0 in Hg at WOT. The system has two orifices, black at main vac source and yellow further on. All looks fine and original. Trans was now no longer flaring but I could discern 2 things that were not right. The 1-2 shift was too harsh and there was a stacked 2-3 3-4 shifting and it was downshifting too much. I disconnected the elec cable at foot of pedal. No difference. Next I tooled up and placed a 150 psi meter on the tranny test port, plugged the vacuum, started engine and voila.....the meter pegged. Next I extended the T handle on the mod valve and cranked it out. No change was happening to pressure until almost at the end and pressure went very jittery and was still up at 120 in Hg. Way too high. My trans is a 722.118 and it is supposed to read 3.0 Bar or 43.5 psi. Next I removed the modulator valve which is red and I believe the replacement part should be 1232700679 from my web research. I brought it to my kitchen table to study it. Based on what I see it is reacting when I suck on it by retracting the pin which is obviously attached to the diaphragm. The external condition looks like new. No rust or damage visible.

Why can I not adjust my pressure down to 43.5 psi??? Is it a calibration issue due to a spring in this valve having gone way out of spec??? If I purchase a new modulator valve will it make things work??? Is there some other problem possible and if so what is it?? The trans fluid is pristine....the color of a good rose wine when placed on a kleenex and pas de burnt odor. Also the valve pictured for replacement does not have the pin assembly on it. Is this a transferrable piece??

Please help me if you can and I will be tojours grateful........

Does that vehicle have a Bowden cable?

Brian,

I do not believe it has. I am not 100% sure what it is....is it a mechanical linkage to the tranny?? If so I do not believe it has. Is there a check I can make for you??

This is a bit critical to determine.

You must determine if it has a cable from the throttle linkage down to the transmission. If it doesn't.........the vacuum levels remain absolutely critical for both the timing and the duration of the shifts. Removing those 3-2 valves may not have been the best solution in that case.

No it does not. The throttle does move the VCV valve on the rear of the IP and that is it.

Then, vacuum plays the entire role in the quality and timing of the shifts. If they are not flaring, I'd increase the vacuum level from the VCV.

The issue I am chasing is not vacuum. I have disconnected the vacuum in fact for this test. Please re-read what my issue is.....sorry if I have not been clear.

I am checking the modulator valve per DieselDan writeup. It is the fact that the modulator valve on the transmission is not able to control the transmission hydraulic pressure.

Cannot help you with the modulator pressure as I've never had to bother with it.

If you decide to leave it alone and chase the vacuum, let me know.

Modulator Valve under test.....not VCV......
 

Thanks for your input.

The issue is that the hydraulic pressure which should be settable to 43.5 psi (3 bar ) for this 722.118 transmission is not doable.

I guess I will go and install a new modulator valve to see if this is the problem. Like I said the valve looks like new and reacts when I suck on it. Of course I have no way of verifying its calibration so I am stuck.

To all out there.....Are modulator valves known to go out of cal and react like this??

The "valve" is a simple piston. I do not see how it can affect the modulator pressure in any way.

Brian,

This is the test I am doing......

Here is the link. It is procedure from DieselDan44 dated June '07. I know you must be familiar with it.

http://www.peachparts.com/Wikka/Trans722VacMod

Check to see if there is a washer Under the valve on the trans....

Not so long ago a friend had issues with a trans that had been re-built that would not kick down...

There was a copper-washer under that valve causing insufficient movement of the plunger in the trans...

Alastair,

Are you asking if there is a washer causing standoff between modulator valve and trans body?? Answer is no.

I understand the test, however have not done it personally and cannot provide any feedback of why it won't behave for you.

Dionysius,

Read through your post about testing the modulator valve pressure. My experience is with the 722.315 and later transmissions, but your sounds very similar.

When making the adjustments with the T handle, the gauge movements are very smooth. Based on your description, this was not your experience...

This leads me to think you have a bad modulator valve. Perhaps, as Alastair suggested, it was installed incorrectly.

Either way, if it were me, id buy a new modulator valve (and modulator valve seal), and re-install and re-test. If you get the same results, then maybe your test fixture is faulty, or something is going on in the valve-body of the transmission (I have no experience going in deeper to one of these things)

I ran all over making vacuum adjustments on my fix. But it wasn't until I got my modulator pressure right that the vacuum adjustments worked like they were supposed to.

Good luck, its frustrating...but gratifying if you are able to bring back one of these transmissions back 'from the dead'.

dd

This is an awesome thread! I just picked up a vacuum tester yesterday and will begin working through the solutions here this afternoon. I have an 83 240d with all shifts done by 20mph and no kickdown. I'll bet the answer is in this thread.:)

Thanks to all who have contributed to make this a great forum:D

BTW, I tried approaching my local MB stealership for info about the car(which I imported from the USA) and as soon as they eyballed the VIN, I was politely but very firmly told "contact MB USA" as they had no info whatsoever. Is that just a miserable local dealer or a MB Canada policy of being awkward about imports? Makes me not wanna give them any business....:(