[W126 Coupe] tranny fluid

[Steve Lemberg]

If you have a transmission that is being held together by sludge your problem is it can fail at any time anywhere with out notice.     I prefer to choose the time and place to affect repairs if at all possible.     Saying that dirt is what keeps an old transmission working is absurd.     The info from TCI is great for their stuff and general knowledge but TCI makes converters that are not usually in service the length of time many OEM converter are that do have the fluid drained repeatedly.   

The many hundred RPM's with no oil is just not true, as soon as the engine turns the front pump starts to develop pressure and feed the converter.    I would say the amount of time it takes for the car to move while in gear after a refill (don't ask how I know this) is around 8-10 seconds or 60 rotations at a 600RPM idle.     There is oil film on the internal parts after draining and the few seconds of minimal oil is not a factor, the oil is feed to the converter under high pressure form the start of engine rotation or very soon thereafter.    The information posted is regarding a new transmission install that has never been filled and run, the fluid drained during a service does not remove every drop of oil in the valve body and passages so the pressure is restored almost at once.

Doing a service with out following the procedures recommended by the manufacture is your right however you are doing a disservice to masses of people here who are not professional mechanics or skilled in repair and maintenance work on their cars.    There are many Mercedes with automatic transmission that have well in excess of 500K miles, very few a handful have ever needed a converter and these were due to hard failures in the transmission.     

I have been involved in operating and maintaining things that drive, fly and float for about 35 years.     The range is rather broad from a 1936 Chevy to Falcon jets and things in between like P-51 Mustangs and Cosworth DFV/DFX engine development.     Disregarding standard operating procedures negates the expected service life and quite possibly the failure mode of the item in question.    I would not want to fly an airplane that just had a C check done to some mechanics own short cut idea of an inspection and I wouldn't stand for that in my cars service either.

Steve
  ----- Original Message ----- 
  From: Richard Hogarth 
  To: 'Mercedes Coupes Mailing Lists' 
  Sent: Thursday, April 05, 2007 11:21 AM
  Subject: Re: [W126 Coupe] tranny fluid


  Bellamy, 

  That cuts to the chase, good points. 

  BTW - Volvos ain't the only cars where old fluid is a make or break difference.

   

   Now for the religious experience part:

  If you drain the torque converter, you are running it dry for many hundreds of RPMs while it fills up. The torque converter is a pressure pump, not a suction pump. Until it starts circulating fluid, nothing else gets fluid circulated and the Converter is running dry. If one were to purchase a new converter, the warranty would be voided if you don't fill the converter prior to installation.    

   

   

        Size of Converter 
       Number of Quarts 
          
        13" 
       5 
          
        12" 
       4 
          
        11" 
       3-1/2 
          
        10" 
       3 
          
        9" 
       2-1/2 
          
        8" 
       2 
          
        7" 
       2 
          
           
           
           
           

   

   

  Also, the recommended service on some newer automatics is to not even drop the pan on the tranny. Ford recommends that for the first tranny service, the fluid gets suctioned out through the dipstick tube. It's the second service where the pan gets dropped and filter screen changed. They don't drain the torque converter at all. 

  -RPH

                   

  From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Mister McGoo
  Sent: Thursday, April 05, 2007 11:04 AM
  To: Mercedes Coupes Mailing Lists
  Subject: Re: [W126 Coupe] tranny fluid

   

  Oh?  half a bath?  Look at it this way...  how often do you change your transmission fluid?  If you're only going to change half of the fluid at a time by not draining the converter (an exaggeration... you're changing considerably more than half), then change it twice as often, right?  But ALWAYS change your filter, OK? 
   
  Let's not turn changing your transmission fluid into a religious experience.  We have read how to check the oil level every which way short of while driving at 50mph.  We have even heard that the dirt in your fluid might actually be the only thing that is holding your transmission together, ('specially if you drive a Volvo).
   
  Advice:  Simply follow the Mercedes instructions.  If you don't do it yourself, take your car to a Mercedes specialist.  

  OK?

  -Bellamy


------------------------------------------------------------------------------

  From: mbzman560 at hotmail.com
  To: mbcoupes at mbcoupes.com
  Date: Wed, 4 Apr 2007 21:23:13 -0700
  Subject: Re: [W126 Coupe] tranny fluid

  Steve- I'd say amen to that.  Not draining the converter is like taking a 1/2 bath, or only draining half of your motor oil.
  Camran


   

   


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