[W126 Coupe] Transmission Changing Gears with a Bang

[Ernie Stephens]

Dick,

Thank you very much! No wonder I couldn't find the dang thing.  Well, at least I got a lot of cleaning and detailing done while looking for it.  I'm going to try to use the original connection point. While under the engine those few hours that I've spent, the engine impresses me as more of a piece of art than most engines that I've had the pleasure of owning.  I recently asked rhetorically why we revere the W126 and it seems clear to me now that there is a comparison to made to that of a Rolex and a Timex; one is jewelry and a time piece and the other a good time piece.   I guess I like a little a art and jewelry in my life too.

Ernie



--- Original Message ----- 
  From: Dick Spellman<mailto:dick.spellman at gmail.com> 
  To: Mercedes Coupes Mailing Lists<mailto:mbcoupes at mbcoupes.com> 
  Sent: Saturday, November 20, 2010 11:49 AM
  Subject: Re: [W126 Coupe] Transmission Changing Gears with a Bang


  Ernie,

  EPC calls the part out as a 'hollow screw' that screws into the back side of the intake manifold.  This location is the same on the 380, 500 and 560.  So, use my previous description to locate that screw.  It looks like a stud with a nut to lock it to the manifold so it will not back out.  The end of the stud is hollow and that is where the transmission vacuum modulator line attaches.  With the US model the exhaust cross-over pipe will limit the space and visibility in this area.  I was able to find it on the 380 in one minute with a strong flashlight aimed straight down at the back of the motor.  You will see the spiral wound cross-over pipe running horizontal to the motor.  Look between motor and this pipe.  I f you find no stud then it could well have fallen out or broken off.  The threaded hole in the manifold will be there in any case and needs to be closed up if you choose to connect elsewhere on the manifold.

  -\Dick

  .On 11/19/2010 9:49 PM, Ernie Stephens wrote: 
    Dick, 
    Is it in-between the firewall or above somewhere closer to the carb?  I've  cleaned the area up with cleaning fluid looking for a shining post or that black rubber connector but I am somewhat vision challenged . . .I wear glasses and the spray mist from the compressed air blasted solvent on the eye glass lens doesn't help matters if you know what I mean. 

    Sent from my iPad

    On Nov 19, 2010, at 6:56 PM, Dick Spellman <dick.spellman at gmail.com<mailto:dick.spellman at gmail.com>> wrote:


      Ernie,

      The vacuum hose with black rubber adapter will connect to a metal tube stubbed out on the driver's side intake manifold.  So, if you have the tube in hand without the black rubber connector, look for it with an open end on the manifold.  It will either be a single or T rubber adapter.  If the rubber is on the vac tube in your hand, look for the metal stub that will be bare and sucking air on the driver's manifold.

      Now you know what the function of the transmission vacuum modulator is...smooth shifting vs. the hard bang at shift points.

      Regards,

      Dick

       oter it willOn 11/19/2010 8:06 PM, Ernie Stephens wrote: 
        Hey Michael,


        You are right!  Found the connection point at the tranny but not the engine . . can you tell me where they hid the connection point at engine?
        Thanks,
        Ernie

        Sent from my iPad

        On Nov 19, 2010, at 5:09 AM, Michael Ramay <mike.ramay at gmail.com<mailto:mike.ramay at gmail.com>> wrote:


          Check the vacuum line from the back of the engine to the driver's side of the transmission. Betcha it's loose.


          On Thu, Nov 18, 2010 at 10:48 PM, Mister McGoo <eelploot at hotmail.com<mailto:eelploot at hotmail.com>> wrote:

            Did you accidently disconnect a vacuum hose to the transmission?  - Bellamy
             

--------------------------------------------------------------------
            From: stevetsg at msn.com<mailto:stevetsg at msn.com>
            To: mbcoupes at mbcoupes.com<mailto:mbcoupes at mbcoupes.com>
            Date: Thu, 18 Nov 2010 21:26:05 -0700
            Subject: [W126 Coupe] Transmission Changing Gears with a Bang 



            Ladies and gentlemen,

            Wouldn't you know it; a couple of hours ago I had just finished changing the oil pan gasket, replaced the neutral lockout switch, tightened what I think is the oil pressure switch to keep it from leaking oil, and replaced the steering damper.  So, I clean up the mess, get in the car to take it for a spin and the first thing out of the driveway "bang" as it shifts into 2nd gear, and bang again as it goes through each shift..  I did feel a bit of a hard shift before I put the car up on jacks but something happened dramatically in the course of a few hours on the jacks; did I break something when I jacked the car up or did I disconnect something unknowingly?.  I only lowered the transmission enough to remove and replace the neutral switch!  Any ideas? I had this transmission rebuilt at 99k and it is now at 214k.

            Ernie




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