Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-24-2012, 11:37 PM
Registered User
 
Join Date: Nov 2012
Posts: 28
Very hard late shifting on 1980 240D

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.

Reply With Quote
  #2  
Old 11-25-2012, 06:55 AM
Registered User
 
Join Date: Jun 2006
Location: Cowlesville NY
Posts: 129
It's the modulator. Had the same problem '81 240d. There are no cables on a 240d transmission.
Reply With Quote
  #3  
Old 11-25-2012, 07:21 AM
oldsinner111's Avatar
once a happy man
 
Join Date: Nov 2008
Location: bristol,tn
Posts: 5,826
My S hoses turned into powder,so I don't use the valves anymore
__________________
plant, and animal life matter. human's had their chance.
Reply With Quote
  #4  
Old 11-25-2012, 07:45 AM
gatorblue92's Avatar
Save the manuals!
 
Join Date: Jan 2006
Location: Delaware
Posts: 3,394
Quote:
Originally Posted by gregszustak View Post
It's the modulator. Had the same problem '81 240d. There are no cables on a 240d transmission.
The early ones have a control rod however I don't think the 1980 model did.
__________________
1977 MB 240D 4 speed 145K - Nearly Perfect
1995 MB E420 197K - Weekend Toy
2018 Ford F150 5.slow 23K - My DD
2020 Subaru Ascent 10k - Wife's DD

1979 MB 280E 90K - Sold
1983 MB 240D 238K - Scrapped
1984 MB 300D 347K? - Sold
1984 MB 300TD Wagon - 188k - Sold
1987 MB 300E 5 speed 258K - Scrapped
1991 MB 300TE 5 speed 276K - Sold
1993 MB 400E 218K - Sold
1993 MB 400E 130K - Sold
1995 MB E320 Wagon 190k - Sold
Reply With Quote
  #5  
Old 11-25-2012, 08:57 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
I'd check the vacuum line that goes to the transmission.
__________________
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
Reply With Quote
  #6  
Old 11-25-2012, 10:59 AM
Registered User
 
Join Date: Sep 2006
Location: Middle TN
Posts: 3,827
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).
__________________
85SD 240K & stopped counting getting paint. 84SD 180,000. Probably up for sale in the fall 2020. 85TD beginning to repair to DD status.
Reply With Quote
  #7  
Old 11-25-2012, 11:06 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
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.
__________________
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
Reply With Quote
  #8  
Old 11-25-2012, 12:57 PM
Stretch's Avatar
...like a shield of steel
 
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,461
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 =>

79 300D upshifting problem

It could be one of the first "vacuum only" ones though - 1980 seems to be a change over year
__________________
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!
Reply With Quote
  #9  
Old 11-25-2012, 03:45 PM
Registered User
 
Join Date: Jan 2012
Location: Leiden, Netherlands
Posts: 614
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.
Reply With Quote
  #10  
Old 11-25-2012, 05:33 PM
DIY OCD
 
Join Date: Jan 2012
Location: Columbia, MO
Posts: 120
Quote:
Originally Posted by kerry View Post
I'd check the vacuum line that goes to the transmission.
X2

Had this problem before ... and the symptoms were identical. The vacuum line was disconnected from the modulator on the transmission.
__________________
1983 300CDT -- 177K
Reply With Quote
  #11  
Old 11-25-2012, 06:46 PM
Registered User
 
Join Date: Nov 2012
Posts: 28
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?
Reply With Quote
  #12  
Old 11-25-2012, 07:06 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
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.
__________________
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
Reply With Quote
  #13  
Old 11-25-2012, 07:41 PM
Registered User
 
Join Date: Nov 2012
Posts: 28
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?
Reply With Quote
  #14  
Old 11-25-2012, 07:44 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
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?
__________________
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
Reply With Quote
  #15  
Old 11-25-2012, 07:48 PM
Registered User
 
Join Date: Nov 2012
Posts: 28
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.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page