Sam,

Thanks for the quick response. You are correct W123.153 and 617.952. She is from California...so I have been using the vacuum diagram you listed from Cali.

I am currently living in a rural area just outside healdsburg. There are tons of the older 300Ds still living out here...very little rust.

I will try the tests you described on Thursday morning. I was also going to get the adjusting roller to run the test on the VcV after disconnecting the VcV from the IP lever.

I can say my hopes have been fading a bit. I find it hard to believe the vacuum curve can cause the tranny to slip so much in first gear, but I will trust in the troubleshooting and see where it takes me.

Thanks again, I'll post with the results.

Brandon

__________________
'81 300TD Chassis-235K Miles, Engine 120K, Tranny 5K, Just Purchased
'84 300CD 230K Miles, Vegetable Oil Vehicle - Owned 2 Years
'82 VW Vanagon Diesel (Butter Bean), 1.9l Turbo Engine 5K, Chassis 130K, Vegetable Oil Vehicle - Owned 2 Years
'82 VW Vanagon Diesel (Marigold), 1.9l Turbo Engine 11K, Vegetable Oil Vehicle - Owned 2 Months - Not Running

Hang in there Brandon... it was Steve Brockton who said that a lot of rebuilt trannies have been sold by the lack of understanding of just how critical it is to get the proper vacuum signature being sent to your tranny's modulator BEFORE you trying to adjust the modulator... and "tweaking" the modulator is exactly what most mechanics [even experienced ones] usually try to do when they try to solve shifting problems on these automatics.

And Let's also not forget those restricted orifices in your car !

So you are unlucky to have a 1984 CA car... but at least you don't have a 1985 CA 300SD like my Father-N-Law has!
Regards

You have issues with your vacuum system due to leaks. This affects the door locks and the capability to shutdown.

However, it does not affect the ability of the transmission to move the vehicle. The only thing that vacuum does for the transmission is to soften the shifts.

Your problem with the transmission is identical, whether you have vacuum supplied or not, therefore, you have no vacuum problem with the transmission.

If the trans won't move the vehicle, it's time to change fluid and filter and pray that it makes a difference. Otherwise, it's transmission time, unfortunately.

Samuel,
I just wanted to let you know I took the part numbers you gave for the orifices to the MB dealer and his references state that these are vacuum lines that are sold by the meter. I don't know who's right or wrong, just wanted to point this out.

Also, I believe you are quoting Steve Brotherton, not Brockton.

Patman

__________________
1984 300SD 148K Gold
1979 300SD 142K Cream
2001 Audi TT Roadster 60K
2005 Chevrolet 3500 13K

Well, I'm greatful for the info I gleaned from these and related threads! I too was missing the #62 orific on my '83 300d Turbo. Out of shear curiousity I had an idea to make an orifice to see if that helped all of my symptoms. I was reading 20 in Hg at idle tapering to 2 in. At cruise speed I had 7-9 in. I had flaring, early shifts rapid repeater shifting and very soft and slow shifts. What I did was take the insulator off of a spade that you'd crimp on a stereo wire. Its round and just the right diameter. I filled it with JB Weld and waited till it was starting to cure but not totally firm. I punched a hole in it with a pin. Now I still read 15 in. Hg at idle but by half throttle or cruise I'm at 1in Hg. Shifts are now acceptably firm and flaring is gone except at very very light throttle. I still have an early shift from 2-3 but thats at light throttle too. We all know they like it rough so I'm still training my foot to go to 3/4 throttle automatically. Thanks guys! I really appreciate your knowledge.

After reading this thread all the way through, and a couple other threads about similar issues, I have finally achieved at 99% fix for the 2-3 flare I was experiencing with my 1983 300D turbo. Many thanks to all who partipicated in these threads for all the knowledge captured here. I've also learned a few things I'd like to relate...

First off, the bowden cable and modulation vacuum to the transmission have some sort of relationship where they both need to be adjusted correctly to fix the 2-3 flare. I discovered this because I've tried all four possible "combinations" and only one made any difference. In my case, the bowden cable was set such that shifts happened at extremely low RPM (~1000RPM) and the car would get into 4th by 25MPH (~40KPH). Also, the EGR and 3/2 switchover valve was dumpping all the vacuum to the transmission as soon as the throttle was cracked a little. The fix was to tighten the bowden so shifts occur around 2000RPM, and to disconnect the EGR from the car (temporary measure) to eliminate the dumpping fo the vacuum to the transmission. In my efforts I tried both adjustments alone and found that neither made any difference whatsoever to the 2-3 flare I was experiencing, but both together made a world of difference and all but fixed it (I can still get it to happen, but I have to try pretty hard to make it happen now instead of just barely being able to keep it from happening as before).

No wonder the 2-3 flare is such a common problem with these cars. Only with experience does one know that the two are related to such a degree that with either being out of adjustment so completely cancels the effect of fixing the other.

So there's my addition to this thread.. these both need to be in adjustment or the 2-3 flare may remain.

For completeness, I should also mention that I replaced the K1 spring kit earlier during some other routine maintence. It, the new filter, and the new fluid had absolutely no effect on the flare because both bowden and vacuum problems existed. The K1 may have been another critical "adjustment" that played a part in fixing my 2-3 flare, but there is no way I'm going to replace the old spring kit just to find out.

__________________
'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

Yep,
I'm having to retrain my foot/feet to drive our 240D for I just returned from a 3-week rental/use of a new Renault "Megrane" which is a "compact" size 6-speed stick 1.5L turbo-charged diesel. On the straight & level this car would cruise easily at 100 mph on the Autostrada in Italy!
Regards,

First off - Sam and Brian and everyone who has contributed...thank you...24 hours ago I had never touched a vac gauge and now Im well on my way to solving my shifting problems.

I having gotten here by reading this thread (the vac system was a *mess* yesterday) and the popular articles, here's where Im at (82 300DT, federal)

-did all of the troubleshooting up to the tranny vac line(22mmHG on main supply)), tested vac pump, main vac line, plugged door lock/HVAC line etc.
-T'ed in to the tranny vacuum line, I see 11 mmHg. I assume this is good.
-eliminated EGR per Brian's instructions. glad to hear I don't need it.

advancing the throttle, the vacuum drops a little bit (~1mmHg). Certainly not a smooth linear transition to zero.

-also notable, if I pull the dashpot at the VCV and plug the end of the dashpot with my finger, I get 22mmHG (supply line level).

So, my conclusion is that it's the VCV or the dashpot. I would think it's the VCV since if it's not bleeding vacuum then it's not doing it's job.

Is there any way to directly test the function of the VCV (or dashpot)? Can I clean the VCV at all?

When I figure this thing out I ll do a write up and some pictures to pay it forward.

thanks in advance guys -
dd

__________________
-------------------------------
'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

The dashpot is not the culprit.

There is a T above the VCV. One leg is the supply vacuum, one leg goes to the transmission and the third leg (the bull) goes to the VCV via the dashpot.

Remove the supply vacuum and connect up your Mityvac.

Pump up the Mityvac fully. See if the modulator/VCV holds vacuum. That's the first step.

If it does hold vacuum, note the reading. Report back with the reading.

Then, slowly open the rack and watch the gauge. It should slowly fall to zero when the rack is fully opened. Report back with results.

All tests are done with the engine not running.

thanks brian!

-used the Mity vac as you said to provide supply to the system - didnt hold vacuum.

-then, isolated line that goes down to the transmission, pumped that and it didnt hold a vacuum. leaked down over a few seconds.

Modulator, right?

I have to figure out where this thing is (Ill search- that line dives down onto the top of the transmission) and how to test it.

dd

__________________
-------------------------------
'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

Right.

Follow the line down to the transmission. There is a rubber cap that the line passes through. This is the first item that should be replaced. Usually that fixes the leak.

Then, once the modulator holds vacuum, we can continue with further tests.

I just went out and did the same test myself. I could not get the VCV to hold a vacuum either. I even went and isolated the VCV from the rest of the vacuum system, still wouldn't hold vacuum. Is it supposed to hold, or bleed off?

__________________
'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

im going to do the following...

1.) trace and replace rubber cap, re test.

if that doesn't work...

2.) buy and replace modulator

Is that the course i should follow, or is there an intermediate step before buying a new modulator?

__________________
-------------------------------
'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 agree with Brian... the most likely culprit, and IF you are lucky, will be either the cap or o-ring [IF it has one] on the modulator... but I would also suggest you consider these related test "intermediate steps":
[1] Put a golf tee/cap on one end of the hard vacuum line that runs to the tranny modulator and use your new pump on the other end to test this hard line by itself. It's not unheard of that these can be abraded or cracked somewhere and thus leaking.
[2] It's also a given that you should replace any associated straight-line rubber connectors at either/both ends. Buy yourself a yd/meter or two of the size [ 4mm ID?] suited for the most common [small] hard vacuum line running around the engine compartment. Also consider using small electrical ties to sinch(sp?) down and tighten any questionable soft rubber connector-to-hard vacuum line connections [see: http://www.peachparts.com/shopforum/showpost.php?p=1247118&postcount=5 which will [if the link is working] lead you to: http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG for examples of how smaller electrical ties can me useful in solving nuisance vacuum leaks. I have found these a little tricky to install but invaluable in my efforts to make for tight vacuum lines.
Regards,

thanks for the tips sam...once i get this sorted out i will replace most of the rubber components. its amazing more of them arent leaking...

i took a look and the black rubber cap on top of the green modulator was cracked for sure. i took it off, and am patching it up with superglue/silicone to see if that fixes it. a rubber cap at that harsh enviro spot is quite the weak point...

sam: how would i check the o-ring?

im guessing to do anymore work on that area other than replacing this cap i am going to need to pull the transmission pan?...it's tight up there. i can barely inspect anything, i only can whats going on with a mirror.

thanks again,
dd

__________________
-------------------------------
'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