Recently I had my engine switched out for an 83. I had a local garage do it, he spent a lot of time getting the shifting to time properly. It has never been great since I got it back but good enough.
A few weeks ago it started shifting extremely slow into both 3rd and 4th.
It'll shift well into second and then when shifting into 3rd and 4th I have to put the petal all the way to the floor.
One question is, if I still drive it what array of damage can happen.
2nd question is how do I diagnose it.
I have checked the pressure at the second barb from the brake cylinder and the vacuum is over 15.
My next plan is to check the vacuum just on the line going directly to the transmission.
If someone has the time and know how to get super thorough on what sorts of things it can be and ways for me to test one by one I would be super appreciative.
All of the switches are new.
The only vacuum tester I have requires the engine to be running-and I don't have the money to buy the other fancy one, so the tests have to be relatively free.
Thanks everyone!

You can wear out the friction surfaces on the clutches in short order...
the clamping needs to be pretty fast to keep that from happening....

check your pm's

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

What do you mean by clamping and what are pm's?

the automatic hydraulic operated clutches which do the same thing as letting out your clutch with your foot in a manual shift car...if you regularly let them out too slow.. you wear out the friction material way too fast....unnecessarily....
pm personal messages...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Loads of information here for you =>

DIY W123 Transmission Diagnose and Adjustment 722.xx OM 616-7 - Mercedes-Benz Forum

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Without using a mityvac it makes the job harder if not impossible. It sounds like you have a vacuum leak somewhere in the system. If you just check the vac line that runs to the tranny, ideally it should have 12" of vac on the mityvac guage, if its like 3-4" you get flaring, high rev shifting and a frustrating ride. When tuned right, half throttle should give you nice shifts at an easy pace. (See the shift points in the previous post link for a general idea)If you stamp on the pedal, you should get higher revs in second and third before it goes into fourth, it will noticably get up and go (as best it can) at full throttle.

Problem is, you kind of have to get vac system normalized by ensuring no leaks to then start checking vac to the modulator, 3/2 valves on the valve cover etc. Each bit of the vac system, locks, vac reservoir, ignition cut off, are consuming vacuum and if they are leaking vacuum your vac pump is working harder and stuff like the tranny is negatively affected because it isnt getting the vac it should. As much as it is a pita, you have to get familiar with the lines, where they go and what they do, the link in the prev. post has the diagrams. I started by just looking at the vac lines/hoses and replacing what was tired and crackled or spongy with new rubber hose.

Assuming you have a good 12" of vac going to the tranny, you finally have to look at the linkage on the vcv to ensure it only leaks out almost all the vac at full throttle. The cheap and cheerful method of testing that is to suck on the vcv supply line (engine off) and reach over and move the throttle linkage manually and as you just get to full throttle you can sense the leak down. On the side of the vcv you can adjust the linkage on the vcv from the throttle to achieve that effect..