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Discussion Starter · #1 ·
Whats Up Guys I am New To the site I hope your knowledge and experience can help me out.
I have a 2008 s550 and it just recently started slipping on every gear, or speed, it will slip as it shifts to the next gear on every single gear,
its my daily driving car so I been driving it like that.
so what Ive been doing is , let it catch some speed and let go of the gas pedal and wait few seconds until the next gear engages then I push the gas pedal once again
gear after gear until it reaches normal driving speed.
Does anyone have any idea of what the problem could be? ive heard of this cars having valve body problems but im not sure if thats what im having any help
will be much appreciated.
thank you in advanced.
 

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Hard to say. Could have started off being a valve body/conductor plate but driving it like that could have worn the clutches. I would recommend having your mechanic drop the transmission pan and check the condition of the fluid and check for metallic shavings in the pan.
 

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Discussion Starter · #3 ·
Thank you for repling I already Checked the oil level and it seems good, i being drivin g it like that for few days like i said i let go of the gas so it can engage, not to cause more damage. to it
 

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Change the fluid immediately. Do you know when it was done last? When you drop the pan, check for metal pieces/chips . If there are none, the fluid may be shot. I had that happen to my 722.6 5 speed and the fluid change was all that was needed. Make sure you get as much of the 9 quarts as possible. Just droppping the pan only gets 3.5 quarts. CTA makes an air purge tool that gets 90% or more.
 

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Discussion Starter · #5 ·
when i checked the oil level the oil seemed a bit dark, i got the car with 136k miles in it, i added anothother 30k
I havent done any transmission oil change my self, would you happen to have a link? where i can get this tool you mentioned?
thank you for your info.
 

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when i checked the oil level the oil seemed a bit dark, i got the car with 136k miles in it, i added anothother 30k
I havent done any transmission oil change my self, would you happen to have a link? where i can get this tool you mentioned?
thank you for your info.
I posted the video for you. Dark fluid is a no go. Get that out of there and see if that resolves your issue. I was shocked at the difference it made in my S600. Apparently, the shop I paid to change the fluid, only dropped the pan. The old stuff was left in there. This tool from CTA (CTA7650) helps quite a bit.
 

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Discussion Starter · #8 ·
I posted the video for you. Dark fluid is a no go. Get that out of there and see if that resolves your issue. I was shocked at the difference it made in my S600. Apparently, the shop I paid to change the fluid, only dropped the pan. The old stuff was left in there. This tool from CTA (CTA7650) helps quite a bit.
Im surprised they only charged you for oil job, specially at a shop, its hard to find a honest shop this days, they will get you for anything.
thank you for your time and for sharing your experience and knowledge.
 

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I posted the video for you. Dark fluid is a no go. Get that out of there and see if that resolves your issue. I was shocked at the difference it made in my S600. Apparently, the shop I paid to change the fluid, only dropped the pan. The old stuff was left in there. This tool from CTA (CTA7650) helps quite a bit.
Was the S600 a biturbo? Was it modified and tuned? I rarely hear of the 722.6 V12 models turning into slush boxes unless the fluid I missed never changed and it is not maintained perhaps by the PO.
 

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Discussion Starter · #10 ·
Was the S600 a biturbo? Was it modified and tuned? I rarely hear of the 722.6 V12 models turning into slush boxes unless the fluid I missed never changed and it is not maintained perhaps by the PO.

Good morning:
I have an update , I changed my transmission fluid the original oil it had seemed a bit dark but once I pulled it out it wasn’t as bad as it seemed I was expecting a bunch of clutch residue but there wasn’t much the oil pan seemed okay
I drained the transmission applying to release most of internal oil
I added new oil but there was no change
In fact I got a message
That went away almost right away
It said.
Do not shift any gears Maintenance due
Then it went away and I had the same problem for a while
I had to stop to get something on the way to my house,
But I didn’t turn it off fearing it would get stuck in park
I came back and started driving it a below normal speed and if seeMed to shift a bit better but the problem still persist
Any suggestions?
 

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I am sure I am not telling you anything you don't already know, but it is obviously mechanical or electronic/software. If you make sure the TCU has the current software and perform the adaptions in DAS a it instructs you to do, I feel unfortunately you will need to go to a transmission shop for proper diagnosis.
 

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Discussion Starter · #13 ·
I called a shop and he asked if was it every year and reverse. He said it could be your oil pump,
And I recalled previous to this problem it sounded like if it was wining when I would catch high rpms
Almost as if it was supercharged “type of sound”
I also have seen this transmissions are notorious for having the problem on the oil pump,
I think I’m just going to get a used transmission if it’s going to cost me an arm and a leg along with few thousand dollars
 

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Discussion Starter · #14 ·
Good afternoon gentleman’s
I have an update this morning I went to see a friend of mine who he worked on transmissions for the last 30 years he is telling me my valve body seems to be the problem.
He will open up my transmission maybe by next week and let me know if that’s the problem but from what it seems, it’s most likely to be the problem
He discarded the possibility of being the oil pump, he said it seems it’s an over pressure problem , apparently something in the valve body worn out and it causes the oil pressure to leak,
I’ll keep you guys posted and take pictures and info for future help to others
 

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Good afternoon gentleman’s

I have an update this morning I went to see a friend of mine who he worked on transmissions for the last 30 years he is telling me my valve body seems to be the problem.

He will open up my transmission maybe by next week and let me know if that’s the problem but from what it seems, it’s most likely to be the problem

He discarded the possibility of being the oil pump, he said it seems it’s an over pressure problem , apparently something in the valve body worn out and it causes the oil pressure to leak,

I’ll keep you guys posted and take pictures and info for future help to others
I am a bit new on working on the Mercedes transmissions but I am pretty sure yours has the 722.9 (I'd need the Vin but want to say it is), if you do go down the route of taking it apart (so more than just the valve body), upgrade the oil pump/pan etc. Here's my thread, towards the end I mentioned everything I did I think on page 2, mine was in limp mode though- Ml500 / Transmission 722.9



With that said, you can easily flush these removing the return line after the cooler and pumping new fluid in from bottom or other ways this way you're going to be able to get even more fluid replaced, there's various ways if you'd like to discuss, but I'd recommend fluid/filter upgraded/pan upgraded, and possibly upgraded magnets, and definitely consider the other stuff I did on mine if you go further. You don't want to have the oil pump or torque converter issue later because if you do... It's going to be bad.



I also agree with your transmission guy that this isn't the actual oil pump, but most likely the valve body, they're not too bad to overhaul (as long as nothing serious). But again the upgraded oil pump is a lot better, so if going further just replace it.



Also, do you have any check engine/other warnings other than what you listed?



Lastly from everything I've learned on these you basically want to flush or replace the transmission fluid (5qts or even more if you can drain the Torque Converter) - so drop the pan replace filter, clean the magnets, replace the seal and the one time use bolts every 40k miles, these transmissions run very dirty vs other transmissions (so as long as it isn't burnt it's normal). With that said you definitely want to get it all cleaned up for sure, now that the pan will be open again. And I'm not saying you need to go further but since I was doing all my own work and repairing the conductor plate myself, I figured I might as well avoid the more serious issues.
 

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Have you tried to reset the transmission to learning mode? It won't cost you anything and it might work. Just search on YouTube
"Reset automatic transmission Mercedes"
The procedure is the same for all Mercedes.
 

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Discussion Starter · #17 ·
Hello guys thank you for the support, tips and for sharing your knowledge,
Someone here advise me to flush my transmission which I did I got most of oil out and replaced the filter along with the gasket
The oil once outside the vehicle did not seem much dark but I replaced it anyway,
According to my friend we will re-bore
Something I’m not sure what it is exactly but he said it’s very easy,
A company called sonnax sells the complete kits for this jobs
So that’s what we are doing
He did mentioned since they sell the complete kit they are expensive but not sure how expensive ,
If they turn out to be too expensive I think I will just buy the rebuilt valve body and use the same conductor plate so I don’t have to worry about programming.
I love my car but I have had enough of it
I have replaced Starter, left air strut, right strut, air compressor, Air valve body, fuel pump, fuel filter , gas cap, radiator, oil coolant seal, coolant reservoir, cam shaft sensors , outside temperature sensor, both day light running lights, left motor mount, both batteries, the worse part is that it’s not even mine yet, I still owe almost 5k
I kind of just want to get it up and running and trade it for a newer Mercedes.
And only reason it’s because since it belongs to them they might give me a better deal in another if they’re cars.
 

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Discussion Starter · #18 ·
By the way I’m getting a code secondary air pump
And multiple cylinders misfire I looked it up and someone is saying it’s a bad intake manifold I guess Mercedes is notorious for faulty intake manifolds and to top it of my low beam lights went out left side 1st and the left shortly after now I’m driving with high beams,
 

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Gee sounds like you've replaced a lot of stuff on this car, I hope mine has better luck!!!!!!!
 

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Discussion Starter · #20 ·
whats up guys new update on this thread, I ended up Replacing my transmission i swapped the conductor plate as well i drove it from california to arizona about 600 miles round trip and it was working fine.
i had it sitting for almost a month i decided to drive it few days ago and my rear battery was dead so I got a new one,
replaced it, I took it for a spin and its doing the same thing its slipping on every gear I got a New Transmission new torque converter.
my old transmission did had a bunch of clutch pieces so I assumed it was the clutches, but! now its doing the sane thing, I have a feeling it wasnt my transmission but something else, I do not have a limp mode nor any codes.
to pin it on the conductor plate. transmission level is good I of course got a new gasket and filter.
any suggestions?
 
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