Hey guys - a good night finally in the garage. My couple days away from the project really paid off with renewed patience. I've got the car shifting OK now, but most importantly responding to vacuum signals. Here's how I got there:

1.) Began the night with three turns counterclockwise on the modulator T to decrease pressure (increase vacuum). Tested dashpot per Sams suggestion - it was fine. Drove, still noticed some harder shifting.
2.) Curious, disconnected my throttle linkage from the VCV, giving me a constant high vacuum. I should have done this earlier as a check. Now the trans would flare a bit upshifting at higher throttle settings. I never think I will hear a flaring transmission sound so sweet again...
3.) On the same drive as 2.), I then yanked the vacuum from the modulator, giving no vacuum. Back to really hard shifting - much harder than the in my first step 1.). Sweet!
4.) Took two more turns counter clockwise on the modulator. Better, still a little clunky.
5.) Adjusted VCV to give 14mmHg at idle. Drove again. Now we're getting there...its not too bad at all, here are some specs...

1-2 shift is very smooth and nice @ ~ 2500 rpm
2-3 is a little harsher and happens a little quick @ ~ 2000 rpm
3-4 is fine in quality but seems a little late @ ~3000 rpm

Overall I still think the shifts are a bit harsh, but very driveable. BUT, essentially I'm comparing them to my main car, a '95 camry. I need to go drive a friends 83 SD and 81 300D to get a comparison. My rear axles are also bad so I dont know if that could make things seem clunkier than they reall are.

My concerns -
1.) Why are the shift points kind of inconsistent? Two are high, one is low. what could cause this?
2.) I really am having to give the tranny a lot of vacuum to calm down - maybe I still have something going on in the valve body or somewhere else?

Next im going to adjust the modulator a little more counterclockwise and see if that yields any results. I need to check my turbo and make sure the engine is running right before I really tweak.

any thoughts?

thanks again for all of the help, encouragement and well wishes...i was losing hope on it a couple days ago. overall i am surpsied at how insensitive the adjustments are. from my reading I thought is 1/4 turn on the modulator would make radical differences. same thing so far with the bowden cable. hmmm.

-dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

It sure is amazing how many variations in shifts we can manage to come up with! I don't think I could ever get my 3-4 shift to occur at 3000rpm unless I was at full throttle.

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2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)

DD - Considering I know nothing about Bowden Cables or Turbo-Charged engines, I am a little surprised and somewhat proud that you were able to accomplish so much by making exactly my recommended 3-to-5 counterclockwise turns on your new, mid-way adjusted, vacuum modulator.

YES - there are many mechanics who will point their fingers at the tranny WHEN they are working on the engine OR mechanics that point their finger at the engine IF they are working on the tranny [that's because these are usually two different guys looking for exoneration from responsibility!]... so in a way you are at that point that not only do you need to investigate and fix some of the questionable engine issues before you can really expect the tranny to "tweak" well for ya... but as you also pointed out yourself, you have a clunking rear end that could be contributing to your bad shifting sensations.

I am no help with any turbo issues [not yet any way] but let me ask:
Q1 - Have you checked the gear oil level in the differential?
Q2 - Have you checked the rubber couplings in the drive line between the tranny and the differential?
Q3 - Have you checked the two drive axles... their CV joints?
Q4 - How is the engine's power signature?

For answers to Q2 and Q3, I wish you were here so I could get the car into my MBz Indy friend for these areas are where he really excels! Do you have one there you can trust... professionally and ethically not to rip you off ? If so, getting the car up on the hoist and having a good mechanic just go through the suspension & driveline with ya would be worth a few $(s)!

You do realize that you are left with mostly subjective symptoms [ at least as I see them ] and you might need to pick [for the FORUM group's benefit as well as yourself ]... pick one of the more important side issues that might be impacting your tranny shift sensations... and try to get a concrete handle on and maybe solve 1 or 2 of these.
Still, your last POST was GOOD NEWS!
Regards,

Sam,

To answer your questions...

No, not yet.
No, but I will. Do have any info on exactly what to check and where? The flex disc looks ok.
Yes...they're shot. I knew this when I bought the car. PO drove on em fo a while so they have to be replaced. This is project #3 after this transmission stuff and motor mounts. It will be a nice change to go to a 'brute force' project rather than a finesse one.

I thinks it's ok, but not great. Tad slow off the line, I think the turbo is not quite up to snuff. I need to do the regular adjustments on it. I did the valves, I intend to do the injector nozzles and injector timing, fuel filters, and a boost pressure adjustment. I need to compare it with a good running 300D-T to really know.

No....and I need to start looking for a good one here in metro-west Boston. The MB diesel specialty place told the PO that *nothing* was wrong with the transmission when it had no vacuum. They also wanted $300 for a valve adjust and compression check. Yikes! Thats more than the dealer!

I now feel much better about investing more time and $ into the car to get some of the other issues shored up. As promised, I will write all of this up so other can benefit from my debacles. And there are some good stories in here, especially from some of the junkyard sessions.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

You've done an admirable job getting all the components functioning as designed.

The shift points have nothing to do with the vacuum level to the modulator and checking your flex joints, differential oil, and drive axles isn't going to make one iota of difference to those shift points.

My advice, at the present time, is to leave the modulator as it is. The modulator pressure has a specification that should be met and it's not preferable to simply adjust it on the fly. If it works for you, that's fine, but don't go overboard with it.

You don't mention the position of the pedal at the various shift points. With very light throttle pressure, the shift points should be well under 2000 rpm. The SD is dialed up so that it shifts slightly late and it's currently at 1700 rpm for the 1-2 and the 2-3 at minimal throttle.

You may wish to take a stab at adjusting the Bowden cable to provide a bit more slack. Turn the plastic adjusting knob clockwise so that it adds slack to the system. Start with about three turns and then take it for a drive.

There is nothing that can be done about the inconsistency of the shift points. This is setup in the valve body of the transmission and is dependent on the stiffness of the springs and any residual varnish that prevents the pistons from sliding in their bores. If the problem presists after you adjust the Bowden cable, you may wish to add a chemical cleaner to the transmission and then after a few miles of driving, see if it frees up the valve body somewhat. There is no guarantee of success, but, it has benefitted others in the past.

Naturally, all of this discussion on shift points is heavily dependent on the condition of the engine. If the timing is off or the camshaft is late or the valves are not on spec, the driver must press deeper into the pedal to get the performance from the vehicle. This serves to delay the shift points. So, the condition of the engine is important before final adjustments are made to the shift points to lower them.

Thanks Brian.

I will try adjusting the cable tonight. Thus far I have set it to the 'default' setting described of just picking up slack at idle.

I have a full fluid and filter change in my very near future, I will add Trans-x (seems to be the drug of choice) at that time, as well as maybe some synthetic transmission fluid.

I will check my engine performance next.

At some point in the future I would like to check this and see where I stand in relation to the spec. I'd be very interested. the mbz.org article makes it sound like a little bit of a project.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

It's not all that difficult by my read. You'll need the gauge and suitable fittings to attach to the port that is present specifically for that measurement. The most difficult part might be the adaptation of the fitting to the trans.......likely Metric of some type.

... welcome back... I was near the end of being able to give meaningful, specific, suggestions on DD's car with its Bowden cable and turbo and many other admited rattles distracting him! DD - I leave you in Brian's capable hands when it comes to either of these components.

Also DD, Let me say that I think your car picked the right person to orchestrate its escape from becoming a parts car! You have come a long way in a very short while... and YES, please document on this FORUM [this, my, THREAD if you wish] as best you can so that others who are willing to read and sort through our ramblings... just as you have done so clearly thus far.

Sorry, but it's COLD here now and I'm off to get my furnace back on line.
I'm running out of wood for the fireplace insert stove!
Regards,

hey guys,

been a couple weeks since I have thought about the transmission. it seems to be shifting a little harsher now (still way better than where i began), even though I have made no further adjustments. I am in no way concerned, I am just waiting until I get through verifying the engine operation and rear axle replacement before i look at it again. but a couple things occured to me:

what color orifices do folks have in their transmission vacuum circuits? i have a blue one. I have seen red or maroon as I have seen more underhood pictures. anyone know what is stock for the 722.3? even the vac diagram doesnt give the stock, it just gives all of the sizes.

i would assume a bigger opening means more vacuum and softer shift, smaller would give less vac and harsher shifts.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I've been away to a wedding in Miami... caught the bad stomach virus running around and unable to return home as planned on Monday. At a relative's now.
As to your problem - When I ran upon this very same situation of not knowing which orifices I needed, I got all that I could get [ six ] and used a smaller orifices if I needed to decrease the vacuum that was being seen at the connection leading down to the modulator and larger orifice if I wanted it to be larger... and I think you are correct about the affect of these two.
One enterprising reader of this THREAD ["Yellit"] even made his own orifice(s) with very small openings and then drilled them out until he obtained the affect he wanted! I think these cost ~$1.50 to $3.00 for each of these gold-plated pieces of plastic at the dealer ! Not so bad if you knew for certain which you need... but I don't think they even knew when MBZ rolled them off the assembly line those many years ago. These were their way to do the final "tweak" of each and every engine/tranny combination... at least that's my theory of why there is no spec size on the diagrams!
Regards,
Sam

Thanks Sam, hope you feel better...

That makes a lot of sense, certainly the easiest place to tweak is right there.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Well, after reviewing the information in this thread and here:
http://www.mercedesdismantlers.com/722.118_transmission_adjustments.html

I've now succumbed to the realization I'm missing vacuum parts and my modulator T is missing. I've attached a couple of pictures, about which I have a couple of questions:

A) What is this on top of the FI pump? I see part# 1 427 231 001 but haven't found out what it is?
B) This, I believe, is the vacuum kill switch for keying the car off, right? A search for part# 1 427 133 091 calls this the shutoff valve.
C) What is this part? I see part# 001 545 0732 but, again, haven't found out what it is?

In the picture of the modulator, I presume my "T" handle has broken off--is this accurate? Am I able to service it?

I take it my VCV (vacuum control valve) is completely missing, as it should be mounted there on the FI pump--is this right? 1980 seems to be a bit of an odd year for vacuum setup, and there are quite a few non-stock things about this car, so I'm a bit at a loss about those things which are, well, lost.

Thanks for any help.
-noah

Attached Thumbnails

     

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1980 300D (non-turbo, 421k miles)
1984 300TD (turbo, 305k miles)
1985 Vanagon (170k miles)

noah,

you can get another T handle and try to see if the modulator still works. the T can just fall out, not break off (at least on mine). did you try and see if it held vacuum?

PM me and Ill send you the T handle of of my old modulator. its off the green one, but maybe theyre interchangeable. i dunno if you could buy one alone.


i think this is the non turbo version of the famous ALDA system. not involved in the transmission.

yes.

i think this is the cruise control unit...i think.

As to your VCV, i assume you saw the pics of one earlier in the thread. I dont know where it goes on an '80, someone else will chime in. i dont see a spot on the IP for it like there is on mine.

dd

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

In responding to your Q(s) above:
[A] I think "DD" is correct about the ALDA... and there is also the question of why there is no Vacuum Control Valve [VCV] on your IP. Well on earlier models this has puzzeled me before... but in your case, I don't see where you told us the YR/MODEL of your MBZ!!?? So take the time to take the time to put in this useful information into you signature similar to what you should see on mine below.
[B] I believe that both you and "DD" are correct in IDing the all critical vacuum shutoff valve.
[C] And YES, I agree with "DD" ID of the cruise control on these earlier models.

So IF you plan to stick with this THREAD a while, please do NOT keep us in the dark any longer... put your YR/Model in your Signature!
Regards,

Hi Sam,

Thanks for your reply--you'll find my signature does contain my year (1980) and model (300D)--perhaps you missed it since it's after the attachments. My vacuum diagram from:

http://www.peterschmid.com/vacuum/1980/617_912.jpg

clearly points out the VCV as being on the FI pump, so I can only assume it's missing on my car.

Thanks for the help.
-noah

__________________
1980 300D (non-turbo, 421k miles)
1984 300TD (turbo, 305k miles)
1985 Vanagon (170k miles)