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W211 722.6 lock up speed? experts only.

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by G-a-r-y, Oct 25, 2012.

  1. G-a-r-y

    G-a-r-y Senior Member

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    I think I've sussed out why my box doesn't feel right. Its took me a while to diagnose strange jerky gear changes and poor acceleration but I think the TC is locking up too early. 16 mph to be precise even in first gear.

    My old W210 didn't lock up at low speeds like this (same box?).
    You could put your foot down and the revs would increase and you would hear the turbo spool.

    But on this W211 once locked up (16 MPH) acceleration is slow because the engine can't rev freely. also I noticed that once over 16 mph if I let my foot off the revs do not drop in the slightest in any gear.
     
  2. OP
    G-a-r-y

    G-a-r-y Senior Member

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    Mine does and I had a new electro plate last week which I presume contains the "speed sensor" (£450) Is it the TC that locks it up?
     
  3. whitenemesis

    whitenemesis Senior Member

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  4. whitenemesis

    whitenemesis Senior Member

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  5. television

    television Always remembered RIP

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    The 722.6 never locks up completely, a simple test, drive along when holding any gear, just blip the throttle slightly and you will see a change in the engine RPM but not with the road speed
     
  6. whitenemesis

    whitenemesis Senior Member

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    Last edited: Oct 25, 2012
  7. OP
    G-a-r-y

    G-a-r-y Senior Member

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    Looking on the reciept for my electro plate the oil I was charged for is ,
    shell ATF.M1375 .4

    Searching the net I found a Mercedes site which says Shell ATF 3353.

    Does this matter?
     
  8. television

    television Always remembered RIP

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    It never locks completely, the drive would be horrible, it again it can be tested as I posted above, and many have done this test over the years. sure it locks up at times as it has to, but not in normal just driving along completely
     
  9. whitenemesis

    whitenemesis Senior Member

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    Open - Slipping - Closed

    Those are the conditions stated in the doc and shown on the graph.

    I remembered having this discussion some time back and trying as you suggested. If I blipped the throttle the car shot forward (this was on the CDI, obviously).
     
  10. television

    television Always remembered RIP

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    Then take your boots off and do it more gently,,,I have had 3 cars with the 722 box and they will all change the rpm in top by a gentle movement of the throttle.

    As the 722.6 box uses the torque converter and the same valve block and electro plate principles as the 722.9 look at page 78 http://www.mercedestechstore.com/pdfs/286_722.9/286 HO 722.9 062504.pdf

    If you understood what it would be like driving a car that locked up completely, that would help.

    It is only the fact that the boxes do not lock up that makes them slightly more uneconomical than manuals.
     
  11. whitenemesis

    whitenemesis Senior Member

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    I do know what it's like to drive a car that locks up completely.. I have driven a 203 and now the 219, both have the 722.6, which MB state quite clearly has a CLOSED clutch phase. If the clutch is closed, it's locked up!
     
  12. Miffy

    Miffy Senior Member

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    The way I understand the lockup is that it is only locked on an even throttle position and speed, as soon as you change the throttle position then the clutch slips again.

    If id didnt do this, it would feel like a manual rather than the smooth auto that it is
     
    Last edited: Oct 25, 2012
  13. television

    television Always remembered RIP

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    You really talk rubbish Peter, you grab a little info from the net, but you do not know what it is or what to do with it :shock::shock: you have read that page 78, but all your cars are different.

    This is where a little knowledge or non is a pain in the back side, if you do not know when its in the CLOSED phase its not much use is it, again you can see it in that page 78.
     
  14. television

    television Always remembered RIP

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    Thank you Mark, This is what I have been trying to get across to him, and the biggest challenge to auto box makers, some boxes from Japan do lock up completely and the drive is so hard
     
  15. V6Matty

    V6Matty Senior Member

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    Absolutly spot on Mark,

    I've noticed on my car that if I move up through the gears (actually asking the box to go up the gears) and keeping my foot down a little at 25+ mph, you can see the RPM stay static while the speed is still rising, This happens right up until the point I ease off the accelerator then both the speed and RPM level them self's out. And if I really concentrate you can feel a small change in the car as it finally locks up.

    At least thats what happens on my box, I could be totally wrong and its about to fall to pieces, but hey if feels right to me :lol:
     
  16. OP
    G-a-r-y

    G-a-r-y Senior Member

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    Mine deffo locks up completely, it's going back to the box specialist Monday.
    The biggest problem is that it lock up in 1st at about 16mph even if I'm accelerating. It then shoots forward with a jolt.
     
  17. V6Matty

    V6Matty Senior Member

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    hmm I have felt that a couple of times too now you describe it, but after i went across europe this summer i haven't felt it, possible coincidence or is there something we are missing :confused:
     
  18. television

    television Always remembered RIP

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    The engine and box must be up to temp to be really sure due to the boxes holding onto the gears when cold
     
  19. V6Matty

    V6Matty Senior Member

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    sorry should have mentioned that i had the experiance when the car was warm, was trying to find a flippin B&B in the middle of the night after an hour journey.

    Silly owner hadn't updated their website to say they had moved to the other end of the village grrr
     
    Last edited: Oct 25, 2012
  20. television

    television Always remembered RIP

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    Some of these problems can be odd, my 129 was fine for most of the time, on the odd day the changes where very hard, particularly if a bit of driving in the lower gears
     

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