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 08-05-2009, 07:05 PM
Registered User
 
Join Date: Jul 2009
Location: Black Hills of SD
Posts: 56
Trans vacuum module, keep or replace?

After searching and reading extensivly I am trying to resolve my wickid 2-3 and 3-4 shift flare. My initial check of the vacuum pot on the drivers side of the trans reveals a slow leak.

When pumped up to 15 hg it will zero out in about 12-15 sec so I know its not as new as it leaks ~1 hg/sec. Im asking beacuse I have read that a slow leak like this (if it is indeed considered slow) is not ideal but still servicable, I have also read if it does not hold vacuum its garbage and should be replaced before further adjustments and trouble shooting are performed? Which is true and if replace what do I need to know to get another (besides trans #)?

Thanks. I want to resolve this before I pull out the hyd psi gauge and set internal psi.

87 300SDL

Reply With Quote
  #2  
Old 08-06-2009, 09:22 AM
John Schroader's Avatar
Registered User
 
Join Date: Jan 2007
Location: Kentucky
Posts: 405
I'm probably not one of the more knowledgeable people who could offer an opinion, but at this point I seem to be the only one. So-----if your car has a Bowden cable, you might want to adjust it first. Last spring I bought a 300SD with a pretty pronounced 3-4 flare and a simple adjustment of the Bowden cable cleared it right up.
__________________
John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln
Reply With Quote
  #3  
Old 08-06-2009, 02:46 PM
Registered User
 
Join Date: Jul 2009
Location: Black Hills of SD
Posts: 56
My less than perfect understanding is the bowden cable alters shift points and the modulator/vacuum system status will effect shift quality. Again my understanding being less than perfect. I dont think Im going to chance it, I'll order another one, I have to keep this car for a long time.

Perhaps after I replace all the defective components I can begin dialing it in to shift correctly. I have been reading about shift correction kits to, I think its time for a call to Phil.

I have something like 3 different issues going on this car right now trying to get it roadworthy.
__________________
87 300SDL (Silver/red)
08 VW GTI (Sold)
89 F250 5sp turbo diesel
00 Triumph Sprint ST (4sale)
00 Polaris Xplorer 400 4x4
09 Kawi KLR
Reply With Quote
  #4  
Old 08-06-2009, 03:06 PM
John Schroader's Avatar
Registered User
 
Join Date: Jan 2007
Location: Kentucky
Posts: 405
Agreed --- also an adjustment on the vacuum control unit might help. I was of your same opinion about the Bowden. As stated before, my 300 SD was flaring and I suspected that I had larger project ahead than it turned out to be. A simple adjustment of the Bowden made shifting superb. On the other hand, when I bought my 300D a few years back, I wanted to tweak the shift. First I replaced the transmission modulator (it would not hold a vacuum) but no real improvement in the shift. Finally adjusted the vacuum control module (behind the injector pump on the 300D) and got the shift I wanted. Was prepared to repeat that trick on the SD but was relieved that the Bowden took care of it. Not quite what I expected, but was happy that a 5 minute job with no tools cured the flare.
__________________
John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln
Reply With Quote
  #5  
Old 08-06-2009, 03:12 PM
tbomachines's Avatar
ಠ_ಠ
 
Join Date: Mar 2009
Location: Philadelphia
Posts: 6,660
Completely unplug the vacuum line from the transmission. It should shift ultra firm with no vacuum, that would also be my assumption from a leaking modulator. Change your fluid and filter before going crazy....if that doesn't solve it plus the vacuum unplugged, then I would move on to the springs in the valve body and/or worn clutches.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth
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 10:47 AM.


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