Update 1: Blocked off the vac lines going to the door locks (and shutoff valve incidentally) from right off the main brake booster line.

Result: Yep, locks stopped working as expected but trans problems are all still there. While I still suspect a small leak in the door lock system, I can now at least rule that out as being the cause of the transmission problems.

I'm thinking I'm going to get a hand vacuum pump this week and get to testing the trans vacuum system.

Question: the big vacuum distribution box on top of the valve cover (3/2 switch is it called?)...Ideally that should have three vacuum lines coming out, correct (84 non-CA turbodiesel)? Ok so two are coming out, and I blocked off the other one which went to the EGR. When I bought the car the line was broken anyway so I just stopped the vacuum leak.

So what about those other empty holes? Should they be plugged?

I'm beginning to think my problem is either with the green dashpot, trans modulator or the lines in between because I know the system is getting good vacuum from the pump, checked it the other day. Don't remember the number though.

Updates to follow...
Patrick

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1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Patrick,
Until you get that pump/gauge, we will be stumbling a bit... but here are some comments that correspond to the "NOTES" I have inserted above into your last POST:
[<-Note-1] - the big vacuum distribution box on top of the valve cover (3/2 switch is it called?)... well to answer your question, lets call the big box what the diagram calls it... #64a and #64b which is the designers way of telling you that this is the " switchover valve " that switches off certain thing(s) at idle and other thing(s) at full throttle... and I canNOT remember which is when. But for now let's not worry about these for until you get your pump/gauge, you will not be able to test this multi-function vacuum switching valve. You might end up abandoning this valve anyway for one of the things being shut off is the EGR and until you decide you need this needless system, I recommend it be left out or until near the END of your repair project!
[<-Note-2] - Yes, I'm all-but-positive the switchover valve has only 3 vacuum lines in/out of it... and the other "stuff" you see illustrated on the diagram to the left side of #64... these are the internal pieces of the idle and full throttle vacuum switch-off parts of #64. When I blow up this diagram here and try to look close, the line that goes down and to the EGR, appears to be labeled #1 on the SwitchOver vavle... and the line that goes down and around to the "Y" or 3-way connector to the right of the VcV, this line, this line appears to come from #2 on the SwitchOver valve... and finally the line that goes directly to the right to two 3-way connectors [with the #63 written between them (a restricted orifice - more on these later)], #63 above the VcV & DashPot, well this line appears to be coming from #3 on the SwitchOver valve. I hope I did not confuse you with the above!?
Q1 - Do you see any numbers on the SwitchOver valve?

[<-Note-3] - For now you might want to either put golf "T"s to plug up these lines that are shown going to #2 & #3 on the SwitchOver... OR if these lines are no longer there, plug up the "T"s in the 3-way connectors where these lines are shown going to [described in Note 2 above].
[<-Note-4] - No way... see my THREAD:
Try a “DashPot” on your Pre-1981 auto Mercedes... as it sort of explains the fine-tuning purpose of the green DashPot!
[<-Note-5] - No... the vacuum modulator [on the tranny] will not figure into this troubleshoot until we get the vacuum control components under the hood tested, working right, plugged off, balanced and/or working correctly with one another... and then the very last thing we will address is the vacuum modulator!

I hope all this has not confused you, but I thought I would respond to your specific question(s) and points in your last post... to get a jump on things as it were. Please expedite obtaining your vacuum pump/gauge combo!
Regards,

I'm trying to be kind here Patrick... but put plainly, it is premature to talk about the internals of the transmission before we finish troubleshooting the engine/tranny vacuum control system and then tweaking the vacuum modulator to get the tranny shifting its best with whatever improvements we make. And I might have a K1 or K2 spring kit I'll discount for you IF it turns you really need one.
Sorry IF I answered this one out of order!?
Regards,

Not a problem at all, Sam. I really appreciate your help. Taking this project on with no prior knowledge of M-B was a challenge and you and this board have helped greatly in my education.

I have read through the big "how to fix your shifting" article on mbz.org that goes through chronological steps for diagnosing shifting problems. I am going to get a vac pump hopefully this week so I can get to testing. I intend to fix anything within the engine bay first.

Speaking of engine bays, I noticed today how the W123 hood can be partially unlatched and point straight up into the sky for easier access...love it. When I discovered it I remembered my friend's S420 had that exact same feature. Why can't BMW think of that one?

Anyway, I shall keep everyone updated on the diagnosis. Currently the only things I have done are replace the crumbling vacuum hose between the green dashpot and the IP valve (which made the car turn off alot faster incidentally) and plug the EGR vacuum hole on the 3/2 valve.

Patrick

__________________
1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Patrick,
(1) To be certain that I am not misunderstood, IF you see any "crumbling" vacuum hose during the course of this troubleshoot project, you have my permission to replace it! As a matter-of-fact, you shoud go ahead and purchase a yard or two of vacuum hose... but make sure it fits the more plentiful size hard vacuum line you see under the hood!
(2) Something to keep in mind... I leave on Nov 1st for a 3-week trip out of the country and will not like have many opportunities to check my e-mail!
Regards,

Okay, here we go.

Pulled some vacuum and such. Everything seems to hold vacuum just fine except for the brown line running through the firewall...not sure what this is yet. The door lock system seems to be fine. Which is strange cause sometimes the locks are slow or nonexistant after it's been parked for a while.

Also, the car was producing proper vacuum at idle and the trans got a signal of just over 10"Hg at idle and it went down to zero at WOT. Seems fine to me.

Anyway, I disconnected and removed all the EGR and 3/2 switchover stuff and made the appropriate connections because I believe the 3/2 setup was leaking. Things pretty much remained the same except a bit less clunking on downshifts.

Then I disconnected the line going down to the transmission. Now THERE are some downshift clunks, wow. Doing that made 1-2 and 2-3 a bit harder (since it thought it was getting full throttle without vacuum), but the 3-4 flare was still there in all its glory. So looks like we have an internal trans issue

Does anyone know where I should proceed from here? I am thinking I might do a fluid/filter change this weekend. Are there any of those B1 / B2 piston kits or K1 spring kits that usually fix a 3-4 flare? The downshift clunking is pretty much nonexistant and I have traced the other clunk (I think) to a worn diff or trans mount or driveshaft coupler. So the only real problem now is the 3-4 flare.

Thoughts?

Thanks!
Patrick

__________________
1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

One more coment on vacuum. There is a black vacuum line that comes off that little white plastic thingamajig on top of the IP that goes through the firewall and connects to nothing. I coulndt figure out where it went so I plugged it. Afterwards it downshifted extremely hard making me think the differential was going bad. Later I learned this line is a vacuum release to leak off vacuum!

Interesting.

Well since I have found no serious leaks in the vacuum system even with the small leak plugged up from the brown line, and since unplugging the vacuum to the modulator didn't change the 3-4 flare at all, it's time to go internal.

I believe what I shall do next is install the Superior Shift kit and put a stronger spring on for the 3-4 shift (K2 I think) and maybe a softer one for 1-2 since it likes to fishtail a bit in the rain. In addition to this I'll change the fluid and filter at the same time.

Updates to come soon...

Once again my current situation is 1-2 hardish, 2-3 crisp but fine, 3-4 bad flare, delay and lurch into R and D.

Patrick

__________________
1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Ok. Today I changed the fluid, filter, seal, and did the Superior Shift correction for the 3-4 shift.

Well, the clunks into R and D are pretty much gone, but it still flares. So I guess its just internal wear.

Oh well. Any other suggestions before I just decide to leave it?

Thanks!
Patrick

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1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Be careful plugging those vacuum lines which seem to go nowhere. Could be just a simple vacuum vent line and needs to be left open. they usuall run inside the cabin and left open ended or as my 87 was had a filter in the line under the hood to protect the whole vacuum system from junk in the air.
Bud

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1987 300D Turbo, 175k mi., 1998 BMW 323i Convertible, 1997 F250 4x4 7.3L PSD

Hows your kickdown cable?

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91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

Would the cable cause only one gear to mess up?

Patrick

__________________
1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Did you ever get a chance to figure out what was causing the 3-4 flaring?

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

... left us hanging here. In re-reading your last few POSTs you seem determined to condem your tranny as having "internal" problems much too quickly... even after it improved after your fluid/filter service.

Bring us up-to-date and I hope that does not include your notice that you have just invested $2K or more in a rebuilt tranny [Dealer =~$4K+].

Regards,

I'm having the exact same problem with the 3/4 shift flare. It occurred after I changed the fluid/filter.

Patrick. What's the status of your problem now? What's the latest update please?

Here are the specifics of my problem. I don't want to hijack your thread, so here's the link.

3/4 flaring after fluid/filter change-'83 300d

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alimony