Hard shifting between 2 and 3 after transmision oil change

I changed my transmision oil and filter last week for my 91 560SEC. It took just over 7 liters to reach near the full mark. Drove the car for about a week without a problem but now I noticed the shifting between 2
and 3 is hard and noisy sometimes very hard. Any idea on what could have caused this?
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saeef wrote:

Did you fill it up to the full mark when the engine was running, or when it was stopped?
Check the level again with the engine running. If it is over the full mark you must remove some.
Regards, WS
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WS,
I filled it to just below full mark. Yes I started the engine and shift it between D and N few times, checked the level again and it was and is still just below the full mark.
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Just shifting isn't adequate. You need to drive a bit and then recheck it...
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Correct, when you fill it cold, it should be 10mm BELOW the low mark. Drive the car until the trans oil reaches operating temperature and then check it on a level surface with the engine idling. You can let the sit and idle all day and night and the trans will NEVER reach operating temperature.
said:

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Karl,
The manual says dry fill is 8 liters. I drained the oil in the pan and removed it using 13 mm socket. Uscrewed the old filter, installed new one. Put new gasket on the pan and torqued it up. Removing the oil from the torque converter requires turning it until you access to the 5 mm allen screw. I used flat head screw driver to turn the convertor anti-clockwise. Most of the oil was here. I used genuine MB fluid.
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Dry fill is when you completely disassemble and overhaul the trans. It will NEVER hold 8 liters without overfilling on a fluid and filter change.

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Not sure what manual you used...... Mercedes says: Initial charge: 7.3 liter [THAT is dry fill] Following oil change: 6.2 liter [THAT is what you did]
And you never put in what it says it takes at once, you put in slightly less, let it idle and check it. Add as needed till it is below the add mark. Then drive it. ATF EXPANDS with heat.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The new 772.9 7 speed transmissions are a nightmare to check the fluid level on. Depending on the shape of the oil pan, it depends on the EXACT temperature of the fluid. The temp figure is 30C, 35C, 40C, or 45C depending on the shape. IF the temp is higher, we have to put a fan on the trans to cool it down and that could take up to 3 hours!! Try explaining that to a customer who brings in the car after Joe Independant just did him a favor by doing a fluid/filter change!!

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Karl wrote:

Hm Karl,
This is the engineer in me talking: Wouldn't it be a good time to construct your own temp. vs fill-level charts for higher temperatures? You would then have to do this only once or twice after that to confirm the levels.
Might as well put those 3 hours to constructive use!
Regards, WS
--
change to leews to mail.

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No, they do not have dipsticks. They have a tube sticking up in the pan. You pull the drain plug and if it is overfull, ATF runs out until the level is at the top of the tube.
What's that you say? How tough is that to figure out? You have to remember, ATF has a high expansion rate due to temperature. If the trans oil temp is too high, the level below the top of the tube will drop as the oil cools. And then you are under-filled!
The 722.9 transmissions are VERY sensitive to oil amount.

the
35C,
cool
car
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Karl wrote:

However -91 560SEC does not have 722.9 transmission.
Reg: Harri
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I WAS ANSWERING WS'S QUESTION. If you open your eyes, you will see THAT is what his question was about. His question makes no mention of your car. READ first then run your mouth.

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Hi Karl,
Thanks for the enlightenment. It's almost like they don't want normal users to be checking their fluid levels, neccessitating a visit to the deal...oh, wait! ;-)
Don't be too hard on Harri, he may be posting after a long hard day's work (10:30pm EST), try posting at 2am in the morning, like I do sometimes, and see how coherent I am. :D
Cheers, WS
Karl wrote:

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Karl wrote:

So you did not even try to help with the problem in the original question.
Actually you made it only more unclear. Nice work ;-)
And there is no need to shout.
Reg: Harri
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Hi Martin: Anything wrong with not doing a complete change out of fluid in the torque converter step (for those who change out the trany fluid often enough). Furthermore if the fluid level after running and cooling is exactly at the same place before and after a change of fluid and filter, then one should be safe not to have over/under filled. I use a small diameter push rod which measures the level when cold. Seems like after 2-3 cycles (every 20,000 miles) ALL the fluid would be pretty clean.
Larry
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It's better of course to drain it all and start with fresh new stuff. The amount the torque convertor holds is significant. Still if you are changing it "frequently", and it works ok, that's probably fine.

This means you need to drive the car without being sure it's correctly filled?

Not the approved method, but still if you baby it when you are feeling out the fill level it should be ok.
Checking the transmission oil level should be done with the engine/tranny HOT and after driving a bit with the engine still runniing...
Marty
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Saeef, consider yourself lucky, last time I changed the trans fluid in my 95 s300, I lost reverse! Got a bit better over time but slips real bad on any incline and seems to grip better when cold. I'll do a full rebuild when forward gears act up.....

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Well, I decided to open the trans at a workshop. They found most clutch plates worn out including the steel plates. The gear box has 15 clutch plates, 5 are steel. The overhaul kit also includes all gaskets and o-rigs. I just pick up the car from the workshop and it is shifting very smooth. Thanks to all who provided me with feedback
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