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 ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-10-2002, 11:11 PM
Buzzard
Guest
 
Posts: n/a
W126 300SEL Auto Trans Mystery

Greetings to all you Mercedes Benz fanatics from New Zealand

Car is 89 W126 300SEL done 149K well serviced (and loved)

OK here we go !
Recently when the engine/trans cold no problems, however everything got hotter when say, turning at an intersection, the auto trans started to drop from 4th into neutral (instead of 3rd) then after 8/10 seconds bang (and I mean bang) into 3rd.

Had auto trans rebuilt by local MB Agent and had everything that needed replacing replaced. Normal wear, nothing visible broken.

Now the following is happening

When engine/trans cold, everthing perfect. Better than before.
As verything gets hotter the following occurs:

- trans drops from 4th to neutral instead of 3rd
- car creeps forward in neutral
- car strains in reverse, feels like brake on, trys to go forward !
-manual change from 4th to 3rd (with gas on) goes to neutral 8/10 seconds then bangs to 3rd

Line pressures to cooler OK and we have tried a another valve body from an identical trans. Trans stripped down again, all clearances etc checked...nothing !

MB (DC) stumped

Any ideas greatly appreciated

The Buzzard
Reply With Quote
  #2  
Old 01-11-2002, 12:04 AM
Registered User
 
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Here is a band apply chart. You can use this to help diagnose your problem.
(Thanks to www.transonline.com)
Attached Thumbnails
W126 300SEL Auto Trans Mystery-band_apply_mercedes.gif  
__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS
Reply With Quote
  #3  
Old 01-11-2002, 09:38 AM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Exactly what parts were replaced during the rebuild? It sounds like a band or a clutch is engaging or partially engaging when it should not be. Did you remove / replace the gasket under the aluminum plate that the valve body sits on. I could see how a leak under the plate could cause something line this.
__________________
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
  #4  
Old 01-11-2002, 04:22 PM
Mattman
Guest
 
Posts: n/a
Hi Buzzard - I am located in Wgtn NZ and contemplating a rebuild on the trans for my 560SEL. Unfortunately I don't have any info/help for you but would like to know where you went to get this rebuild done.

Cheers
Matt.
Reply With Quote
  #5  
Old 01-11-2002, 07:52 PM
MIKE FREEMAN
Guest
 
Posts: n/a
4-3 downshift

Buzzard;
The delay may be caused by the B-2 piston or a bad B-2 reaction valve.
The piston is easy and cheap to replace and can be done in the car with no special tools.
The valve is cheap but requires disassembly of the trans.,it may be venting apply pressure.
I think if I were in your shoes I would replace the piston!
M.F.
Reply With Quote
  #6  
Old 01-11-2002, 10:30 PM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Actually both the piston and reaction valve can be replaced without removing the transmission. As Mike mentioned some partial disassembly of the transmission is required, but it can be done in the car. I am assuming that it is a 722.3xx series. Let me know if you want details.

BTW I never got a response to my earlier questions.
__________________
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

Last edited by dpetryk; 01-11-2002 at 10:42 PM.
Reply With Quote
  #7  
Old 01-13-2002, 09:14 PM
Buzzard
Guest
 
Posts: n/a
Question W126 300SEL Auto Trans Mystery Contd:

Thanks for all your replies/thoughts etc...

However the saga continues....

I went back to my MB Agent (where the car still is) and he believes that the PRIMARY problem is that the car, when hot, moves off with the car in NEUTRAL. Everything else is caused by this.

In his own words:
"trans works correctly until 30 minutes of use, eg starting and stopping continually (e.g.town driving) at which time the trans temp has risen.. Then the vehicle tries to move off in NEUTRAL. The usual whine heard when in NEUTRAL is no longer apparent and it appears that the front planetary unit set stops turning. B1 clearance is correct. K1 clearance is correct. Temprature valve has been replaced."

Other items that were replaced were, the 12 Discs, 2 Bands, filter, all gaskets (including valve body) & seals, 1 bearing and a modulating valve.

Some lateral thinking required???

Thanks again
regards
John
(The Buzzard)

89 W126 300SEL (The problem !!)
80 W123 250
80 W123 280
Previous
80 280SE
72 250CE
Reply With Quote
  #8  
Old 01-13-2002, 10:43 PM
Mattman
Guest
 
Posts: n/a
Does it sound like it's in neutral or is it actually slipping? Sounds like the trans is reaching some sort of temp that is allowing it to slip somehow. Who is doing this work for you Buzzard?

Cheers
Matt.
Reply With Quote
  #9  
Old 01-14-2002, 01:22 AM
haasman's Avatar
Registered User
 
Join Date: Jun 2001
Location: San Francisco, CA
Posts: 3,097
Benzmac

Benzmac

How does one use this chart. (sorry for my ignorance, but what is a sprang?)
Reply With Quote
  #10  
Old 01-14-2002, 11:15 AM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
The transmission gear ratio is controlled by two clutches and two bands. This chart defines which clutches and bands are engaged for each of the transmission gears. A sprag is a one way clutch. Works similar to a ratchet or the gears on a 10 speed bike. It turns in one direction and freewheels in the other.

Not sure what a sprang is, possibly a southern version of a spring?
__________________
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
  #11  
Old 01-14-2002, 12:40 PM
haasman's Avatar
Registered User
 
Join Date: Jun 2001
Location: San Francisco, CA
Posts: 3,097
Thanks for the explanation Dave,

Jeff
Reply With Quote
  #12  
Old 11-09-2002, 04:19 AM
rebenz
Guest
 
Posts: n/a
check trans whine,click. Is it the same problem?

rebenz,check my thread on trans whine,click.Let me know what you find out.I am getting ready to have my 1992 500sel towed in and want a heads up.A mechanic suggested mine could be something related to a broken drum or ring.I DO NOT HAVE A CLUE.
Reply With Quote
  #13  
Old 11-10-2002, 08:01 PM
Registered User
 
Join Date: Jul 2002
Location: Devon, UK
Posts: 26
I am having identical problems with my 300TE-24v. I also get hard upshifts when hot. My problems started when I had water in the trans fluid - it was OK with the water in but started after I flushed & refilled the fluid (several times).
I've been driving it for about 9000 miles since & it hasn't got any worse.
I've been putting off a rebuild but will have to do it soon - my wife refuses to drive the car.
Please let us know the solution to your problem - especially if it doesn't involve taking the trans out of the car again!!
Good luck
Adrian
__________________
90 300TE 24v (M104 eng) 207K miles
87 300TE (M103 eng) 269K miles (and never had the head off!)
86 300TE (M103 eng) 230K+ miles (donor car)
95 Toyota Lucida diesel 4wd
86 200T 165K miles (sold)
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
AUTO TRANS for W126 380SEL woody Mercedes Used Parts For Sale & Wanted 1 02-23-2006 11:31 PM
190e 2.3 Auto Trans Shift Problem earossi Tech Help 3 09-15-2003 03:54 PM
Auto trans starts off in second Graeme Clark Tech Help 3 08-09-2003 07:01 PM
W126 auto trans...slips out of gear on upshift agara Tech Help 2 11-13-2002 04:47 PM
W126 trans leak(s) - DIY or not old blue Tech Help 2 03-01-2002 08:32 PM



All times are GMT -4. The time now is 11:29 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page