Hi,
I recently have been having some really rough shifting on my 1980 240D. I believe this is caused by the fact that my vacuum line going to my transmission is either loose or has falled off. I can see it going into the back of the car from under the hood but have no idea how to access it in order to fix this problem. I'm a novice when it comes to working on cars and some help in access the nozzle would be great. Thanks again.

If your transmission has a vacuum dashpot you can find that at the back of the transmission on the right hand side of the vehicle.



This picture is taken from this thread (which has some links at the start of it to help people find information about their transmissions)

722.118 Automatic transmission rebuild (Monster DIY)

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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!

You need some understanding before you start just messing with things. Professor Google turns up some "how tos". Combined with some actual tech data you can get it adjusted. Roy has some links also. These 2 were helpful.

Automatic Transmission Troubleshooting

Mercedes-Benz Transmission, Steve Brotherton, ImportCar, February 2002

Also, look around on ATSG's site for a trans pdf.

Mitchell has an accessible file also. I don't remember how i accessed, perhaps with google search "mercedes 722 site:mitchell_or_whatever.com".

I'd buy an actual manual if rebuilding but you can learn to adjust vacuum & bowden and change easy to access parts from the free stuff.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Your transmission is of the vacuum-only type. A loose or damaged vacuum line to the transmission can certainly cause rough shifting, but vacuum leakage elsewhere can cause the same problems. Common fail points: central locking, 3/2 valve on top of the valve cover, worn-out lever of the 3/2 valve.

Question(s): I read on one of the transmission sites that 722 was 1st used in 1980. Is this correct?

"Vacuum Only" what is the adjustment process? ie eliminate leaks, measure/adjust VCV, measure/adjust modulator?

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

722 is a number for a whole range of automatic transmissions. After the 722 you get three numbers which indicate the specific model. The first number after 722 indicates the model range. So you can have a 722.1 transmission, but that model range came in different guises and adjustments depending on the car on which it was installed and year of production. So a 300D N/A has a 722.118 transmission, that came as a rod-controlled transmission and as a vacuum-only controlled transmission.

The vacuum-controlled transmissions on the W123 diesels were introduced in MY 1980 (1979 on Euro models). The 722.1 transmission is older.

Your description of the adjustment of vacuum-only transmission is more or less correct, before or after measuring and adjusting the VCV I would place measuring/checking/reparing the 3/2 valve on top of the valve cover.