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 10-15-2006, 12:36 PM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
Try a “DashPot” on your Pre-1981 Mercedes...

Before using the abreviation “ VcV ” let me define it as " Vacuum Control Valve ", the vacuum bleeding component that is so crucial to creating the artificial throttle vacuum signal sent to the vacuum modulator on your MBZ’s automatic transmissions. I have also included “Pre-1981” in my title because that’s when “DashPots” [aka= “ surge damper ” ] were apparently first made a part of the vacuum control system on these diesel engine MBZs.

Several months ago I was struggling to gain a better understanding of these vintage MBZ’s vacuum control systems and came to believe that understanding them was “ Critical ” for us DIYer’s ability to resolve the frequent shift problems many on this forum experience with our 20+ year-old MBZs… and I speculated as whether I would experiment with using a “DashPot” to see if it would take away some of the “ kick-in-the-pants ” rough 1-2 shifting I found objectionable with my 1980 240D MBZ... and then later with the 1980 300D.

Well this is to report that the answer is a resounding YES, these cheap [~$5.00] empty plastic chambers do help these earlier automatic tranny MBZs that have a “ VcV ” but do NOT have a “ DashPot ”. Both of our 1980 models benefited noticeably, especially the 240D which I suspect tends to rev a bit higher before shifting due to it’s lower H.P…. and there is also an improvement [ albeit less noticeable ] in the 2-3 and 3-4 shifts in that they do not occur quite so soon or easily, particularly the 3-4 shifts.

I therefore can wholeheartedly recommend you try a “ DashPot ” IF your MBZ has a “ VcV ” but lacks this little green vacuum control chamber that apparently became standard ~1981. Heck on my father-N-law’s 1985 CA W126 300SD… it has two “ DashPots ” [aka = “ Vacuum damper ” ] and “SwitchOver valves”. Don’t you just LUV the wacky engineering prowess of the California legislators !?


Last edited by Samuel M. Ross; 12-22-2006 at 01:06 AM. Reason: correction in title
Reply With Quote
  #2  
Old 10-18-2006, 03:02 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
A solution for hard 1-2 shifts... I thought this THREAD would surely get responses!?

Boy was I wrong.
Oh well, those cheap little green empty plastic chambers will just have to be my little secret !
Out of here,
Reply With Quote
  #3  
Old 10-18-2006, 10:25 AM
Rashakor's Avatar
Darth Diesel
 
Join Date: Apr 2006
Location: Philly PA
Posts: 676
I actually never had problems with the 1-2 shift. i have problems with the 3-4.

Would your dash pot be useful in a 116d?
__________________
------------------------------------------
Aquilae non capunt muscas! (Eagles don't hunt flies!)


1979 300SD Black/Black MBtex239000mi
1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco
1983 240D Labrador Blue/Blue MBtex 161000mi
Reply With Quote
  #4  
Old 10-18-2006, 11:00 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
By 116D...

Quote:
Originally Posted by Rashakor View Post
I actually never had problems with the 1-2 shift. i have problems with the 3-4. Would your dash pot be useful in a 116d?
... by "116D" you must be refering to your 1979 300SD TurboDiesel W116.120 with M617.950 engine... hmmm... let me see... double hmmm...

When I try to match up the above vehicle specs on my favorite WebSite [ http://www.peterschmid.com/ ] in order to find an Engine/Tranny Vacuum Control diagram this WebSite is coming up short. Take a look for yourself at:
http://www.peterschmid.com/vacuum.htm and I think you too will be more than a bit confused as I am. The closest diagram I eventually find is for a 1980 300SD with 617.950 and it is shown at: http://www.peterschmid.com/vacuum/1980/617_950.jpg

So as you can see these earlier models did NOT come with these little green plastic chambers and I'm guessing that this diagram is pretty much what you have as well.

So IF you have the Vacuum Control Valve [VcV] as shown in this diagram [#65], I recommend you get yourself one of these less than $5 air chambers and install it betwee the VcV and the 3-way connector that is shown above the VcV.

While you are at it, can you tell me if you have the item shown as #63 [the small restricted orifice] and IF so, what color it is?

Regards,

Last edited by Samuel M. Ross; 12-22-2006 at 01:09 AM. Reason: a correction of course!!
Reply With Quote
  #5  
Old 10-18-2006, 12:06 PM
Registered User
 
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Sam, perhaps you have got a few people thinking give it a little time. In a way it is a retrofit or update to the earlier models, pre 1981, you are discussing. Sounds reasonable as well. Keep digging into things. Your experience and findings are always informative. I have been somewhat occupied myself building power supplies out of old microwave ovens electrical/electronic components to produce power supplies for ion guns to melt metal in very small quantities. Son in law is going to replate headlight reflectors under my supervision part time. Perhaps even a few mercedes? Commercial equipment even if used is just too expensive to aquire. Finally got a chance to get the road kill mercedes I purchased about 1 1/2 years ago running last night. Got title from court and car delivered this early summer. Total cost to repair it was 1.90 + used primer pump and about three hours time. Garage had told previous owner car needs new starter and probably injection pump. He purchased a new car and continued his trip leaving the mercedes behind. I had replaced the wire from solinoid to starter motor a distance of about 2-3 inches as it was burnt open. It had a rotten wire appearance as well. May have been from overcycling the starter on vegatable oil. Found tank vent originally was the reason car quit on the previous owner far less than midway on his trip.. Also drained vegatable oil out of it months ago in case it went bad sitting and did not get back to it till last night. Put some diesel in the tank, Put a good used new type primer pump on to replace the one that leaked like a sieve when I went to use it. Car started up and ran like a 1984 300d with 156k real uncranked or changed out odometer miles should that was in good shape. You win some you loose some I guess. Son in law missed a really good low milage 85 123 gas sedan the other day with only an idle problem. He knew it was there for some time. His next door neighbour in fact. Lady sold it for 200.00 to a stranger about an hour or so before he went over. My son in law had noticed that she did not take it out of the garage for the once a week run to the grocery store anymore. She mentioned that five hundred dollars quoted to replace an idle module by a local garage was too much to spend on her old car to him. What I find a little upsetting is that he told me about it's non use a few weeks ago and I suggested he drop over and talk to her as soon as possible. She did live just next door to him after all. She might be selling it and might not but you have to ask. Just find out. Well now he has found out. Just another long rambling post Sam. Hope people can consider what you have been working on to improve their transmission shifts. Should be lots of debate regarding improvement versus actual faults. Good thread in my opinion. People will learn a lot I think. I know I will.

Last edited by barry123400; 10-18-2006 at 12:29 PM.
Reply With Quote
  #6  
Old 10-18-2006, 01:17 PM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
Barry you have a way of...

... of showing up in the most unexpected places. Good to hear from ya!
Regards,

Last edited by Samuel M. Ross; 12-06-2006 at 08:45 PM. Reason: correct something!!?
Reply With Quote
  #7  
Old 10-18-2006, 10:42 PM
Registered User
 
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Sam, the time is coming when all these posts will have substantual meaning and value. They already have to some extent. We are not too far from the period when 123s will be treated as antique vehicles. If I where to engage in a true vaccum circuit rebuild your threads and posts would be my guidance. Especially anything to do with transmission control. Only can hope that all the information presented on this site is preserved for others in the future as well. Those people will probably have even more passion for the 123s than us. I find that hard to imagine but quite possible. Keep well.
Reply With Quote
  #8  
Old 10-19-2006, 12:58 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
If you get yourself a 1985 300SD W126 from California...

Quote:
Originally Posted by barry123400 View Post
Sam... If I where to engage in a true vaccum circuit rebuild your threads and posts would be my guidance. Especially anything to do with transmission control. ...
... don't you dare ask me for help! I rue the day that I have to troubleshoot the vacuum control system on this, my Father-N-Law's car:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1985_cal.jpg
Regards

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 02:45 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, 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