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 > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-15-2006, 03:18 AM
Registered User
 
Join Date: Nov 2006
Posts: 6
Tranny Question From A New Owner

Just brought home a 1992 300E from Texas. 56,000 verified miles with all the stamps in the service book. The car looks and feels new. Drove it home 2100 miles without a hitch except for a tranny that started to shift harder as the temperature dropped as I headed north.


Cold morning starts produce delayed and very abrupt shifts. This condition smooths out after warm up but there's still a pop in the shifts as compared with the silky smooth shifts while driving down south.


Trans fluid looks normal,the level is good and given the mileage I'm not suspecting mechanical wear. I've search the problem and am suffering info overload. Could the more experienced and technically advanced members please check my thinking on the problem.


1) Electronic warm up cycle induces long shift duration and in my case hard shifts. I understand it's function is to get the cat to operating temp as quickly as possible but it annoys the he11 out of me. Can I disable this feature by disconnecting the single pin connector at the tranny without damaging anything?


2)Before I try to fiddle with the modulator valve on the tranny I should first check the quality of the vacuum going to the valve. Do I disconnect the line just before the valve to test and what values are considered normal vacuum? What values do I look for under what conditions.

3) How do I test the modulator valve. What condition is considered faulty?


4) If proper values are found for the vacuum source and the modulator is good do I then attempt to adjust the modulator valve and, if so, how is this done?


Is this a sound plan of attack or am I over simplifying? Please help. Sorry for the long posting.

Reply With Quote
  #2  
Old 12-15-2006, 08:02 AM
Moderator
 
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
If the car is a "federal" version?? the system doesn't care if the up-shift delay is disconnected.
California cars will turn the check engine lamp on if that is done.

I would start with fresh ATF & filter in the trans. Then see if a modulator adjustment is needed.
__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator
Reply With Quote
  #3  
Old 12-15-2006, 08:19 AM
Gilly's Avatar
Registered User
 
Join Date: Mar 2001
Location: Evansville WI
Posts: 9,616
I would inspect the throttle valve cable to make sure it isn't adjusted too tight, and that all the linkage is freely working, sometimes these get so badly neglected that you need to take the linkage apart and clean and lube everything. If it's not adjusted correctly the warm-up mode will be even harder than normal. I'd discourage trying to disable that. It's only slightly harder, for just a few miles, barely noticeable normally.
Edit: The modulator is adjusted by removing the rubber cap and there is a small "T" key that is rotated. CCW is softer, CW is harder. Go for the linkage first, and if that doesn't fix it, then I'd try just small CCW adjustments (no more than 1/4 turn at a time) of the modulator.
Gilly
Reply With Quote
  #4  
Old 12-15-2006, 10:24 PM
Registered User
 
Join Date: Oct 2004
Location: Baton Rouge La
Posts: 2,632
when was the last time the fluid was changed... filter could be clogged..

i would change the filter and put mobil one in it first...
__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]
Reply With Quote
  #5  
Old 12-16-2006, 08:22 AM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,072
Heat and age cause the O rings and other seals in the tranny to slowly get hard. They dont seal well and things begin to change. Your observation about the problem getting worse as the temps went down would support this idea. Even though you dont have a lot of miles on the car it is possible that the tranny needs to be overhauled. Fresh rubber pieces make a big difference in the shifting qualities of that tranny.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #6  
Old 12-16-2006, 10:49 AM
Registered User
 
Join Date: Jan 2006
Posts: 77
I've got a similar problem. When cold, the 3-4 shift is hard and annoying. It goes away once the car warms up. The dealer adjusted the Bowden cable but it still does it. I'm tempted to put 6 oz. of Auto-Rx into it to see what happens. The car is a 93 300E with 92,000 miles.

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 05:03 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