Hi guys I need your help. I have a 1980 240D that I love but just today has been having horrible shifting issues. This occurred after I replaced the 3/2 valve (my mechanic's recommendation) since mine had a worn lever. Ever since then it has been shifting very late and hard but will upshift whenever I take my foot off the gas. It was shifting fine before but would already be in 4th by 25mph which seemed low to me. It also used to have a slight flare. I'm thinking it could be a vacuum leak but have no idea where to begin. I've checked all the tubes and they seem fine, my doors close without any issues, and when I unplug the tubes from the 3/2 I can hear a distinct hiss.

Any help would be greatly appreciated!!! I don't have the money right now to take it to the shop and don't want to cause any permanent damage to the tranny.

It's the modulator. Had the same problem '81 240d. There are no cables on a 240d transmission.

My S hoses turned into powder,so I don't use the valves anymore

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

The early ones have a control rod however I don't think the 1980 model did.

I'd check the vacuum line that goes to the transmission.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I just went through similar on an 84SD. The general process is to repair the vacuum leaks (all of them). Then test/adjust the Vacuum Control Valve. Measure & adjust the modulator pressure. Adjust he bowden cable.

Some of the variables interact. I didn't find all of the info in any 1 place. Send me an email if you want some pdf(s).

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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.

No bowden cable on this model I think. I believe this is the year where everything was controlled by vacuum. There are a few threads devoted just to this particular system if I'm right that it's all vacuum. But I'd start with checking the line that goes to the transmission to see if it's become disconnected somewhere. I think that's likely due to the fact that you recently worked on the lines. If it's not disconnected, you'll need to T into that transmission line and get some readings on teh vacuum levels while driving.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'm not 100% sure if the transmission has a "vacuum only" transmission or the earlier rod and adjusting screw as shown in this thread =>

http://www.peachparts.com/shopforum/diesel-discussion/304479-79-300d-upshifting-problem.html

It could be one of the first "vacuum only" ones though - 1980 seems to be a change over year

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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!

The changeover year was 1980 for the USA models, a year earlier for the Euro models.

@ OP

If the lever of the 3/2 valve was worn out, why not just replace the lever? Cheaper too.

I think your 3/2 valve isn't functioning as it should, do you have a vacuum gauge to check the vacuum going to the transmission? If not, buy one.

X2

Had this problem before ... and the symptoms were identical. The vacuum line was disconnected from the modulator on the transmission.

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1983 300CDT -- 177K

Thanks for all the suggestions. I checked the lines and they seem to be alright. If it was the modulator that went bad why would it have been working before? Someone mentioned the VCV valve needs to be adjusted. Where is that located and how do I do that?

Check the vacuum levels in the line going to the modulator before you start messing with the VCV. Without some baseline measurements, there's no way to make adjustments.

Do you have a Mity Vac? You need one to deal with this problem.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

So I went and put the old 3/2 valve back in and no change . Does this mean that somehow having the other one in permanently broke something? I also noticed a green tube coming out from the car that wasn't covered. What is that green tube?

Need a picture. Green vacuum lines typically go to the climate control system. Likelihood of breaking something is very slim. Likelihood of disturbing a line in the vacuum system is very high.

Do you have a Mity Vac?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I checked with other sources and it is indeed a climate control line. Unfortunately I do not have a mity vac. I will look into buying one. If it did connect from the transmission where would I check for that? Sorry, I'm a novice with these kinds of things.