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  #1  
Old 02-15-2006, 09:58 AM
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722.6 transmission issue

Every once in awhile my transmission will go into neutral by itself. I lose all forward gears for sure. I think I also lose reverse, but I can't swear to that. This has happened the last three times when I have slowed to a stop very quickly and made a hard right hand turn. I can move the shifter through all the gears and it will not engage. If I shut the engine down and start it back up all is well again.

Transmission fluid was changed at 48,000 miles and I have also changed the electrical connector plug and O rings due to ATF leaking into it.

Any ideas? Is this a common occurrence? No check engine light comes on either.

Len
'99 E300TD 87,000 miles
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Old 02-15-2006, 02:27 PM
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Mine has been doing something similar letely also. If I stop quickly and then take off again soon, the car briefly acts as though the torque converter is not kicking in right away. I can imagine that the fluid is sloshing to the front and then settling again. However this is pure speculation. I don't even know if that is possible. Of course I have no way to check the fluid level without the 6 Million Dollar Bionic Dipstick. But it doesn't seem to be leaking any that I know of. Has only happened a few times.

Mike
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1988 F150 144,000 miles (leaks all the colors of the rainbow)
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Old 02-15-2006, 03:44 PM
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Yeah, I was thinking fluid level too. I don't have the measuring tool either, but I really guess I ought to get one. I know that when I replaced the electrical plug unit that I lost about a half quart of fluid. I replaced some fluid and did a best guess estimation of how much I needed.

Len
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Old 02-15-2006, 10:57 PM
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I remember one post from one of the Tech Masters on this forum about how the 722.6 transmission has to be fully filled to the top to operate at its best. There was even a link to a M.B. tech warning on the issue.

My 722.6 started to bump slighty when engaging first after a sudden stop. It did it maybe 3 out of 5 times.

I took the car to the dealer and its level was just a little bit under the top mark. Without even telling the mechanic anything about it he proceeded to fill the transmission to the top mark. When he finished, he commented: "that is where it should be".

The bump when engaging first after a sudden stop COMPLETELY dissapeared!
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Old 02-16-2006, 12:54 PM
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Filled to the top of what?

Mike
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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra
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Old 02-16-2006, 08:50 PM
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To the TOP mark of the special dipstick used for 722.6s

This special measurement device have, as with any oil dipstick, a LOW and FULL level mark. In most cases it is recommend to fill the oil to the point BETWEEN the low and full markings. Many techs advise that filling oil to the top would create oil leaks through overflow valves or gaskets.

What I am talking about on my previous post is that M.B. had found out that the oil level on the 722.6 transmission has to be always at the TOP mark, not on the middle, for the transmission to operate properly.

Be advised that the lecture of the oil on the 722.6 has to be taken at a precise oil temperature! (or it will provide erroneous readings).
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  #7  
Old 02-17-2006, 08:46 AM
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722.6 Trans. ALL TAKE SYNTHETIC FLUILD. Low fluid level could be a problem. I have replace a lot of soleniod plates in the 722.6 Trans. It is the board that all of the shift soleniod connect to on top of the valve body. It also is where the input and output shaft speed sensors are located. If the board is losing contact with a speed sensor it will shift out of gear or go into what we call "limp home mode" second gear and will not shift up. If this is the case a code will be store in the ETC, the trans. control module.
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Old 02-17-2006, 08:29 PM
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Buy the dipstick...

It's only about $40 at the dealer then you'll know if the level is the problem. I'm sure if you paid the dealer to check it they would charge you $40 so you might as well buy the tool...don't forget to buy the locking pin for the cap too! Those are only a buck or so.
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  #9  
Old 02-21-2006, 02:14 PM
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How do you then determine the exact temperature to read the stick?

Mike
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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra
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  #10  
Old 02-21-2006, 02:25 PM
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Read temperature with thermocouple

I have taped a wire thermocouple to the dip stick plastic part and when I insert it it reads the temperature and then I pull it and read the correct level based on the temperature of the fluid. But usually you do not need the teperature if you are checking it in the morning before driving then it is cold and when you have been driving for a while then check the level it it will be hot.
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