722.9 (7-speed) transmission corrosion issue
Super Member
Joined: Apr 2010
Posts: 520
Likes: 5
From: Tromsø, 69° 41' N
2010 GLK 220CDI 4M BlueEFFICIENCY
722.9 (7-speed) transmission shift quality issue
Made aware of this thread by MBNA109 on the GLK forum, I just add a paper (which apparently has its origin from a MB bulletin?) with regard to shift quality of the 722.9, NAG2 transmission.
Super Member
Joined: Dec 2009
Posts: 541
Likes: 22
From: USA
10 speed bicycle
You are missing the first page of that bulletin which has the validity. That bulletin applies to early 722.9 transmissions. The B1 & B3 as well as there snap rings have been modified since that bulletin which dates back several years.
Newbie
Joined: Jan 2012
Posts: 5
Likes: 0
2006 Mercedes CLK500
"What's unclear about the MB document in post 28?"
I learned the hard way long ago not to attempt to interpret the applicability of tech. bulletins anymore than I self-diagnose medical needs. That's what the "experts" are well paid to do. More to the point, the issue, at least for me, is not what's in the tech. bulletin. Rather, it's why the independent and the dealer are giving me exact opposite answers on a vehicle they've both serviced. Since I practially support both of them, I'm taking the bulletin to both next week asking for an explanation. It appears that one or the other doesn't know what they're talking about. When you blithely ask for $500 to service a transmission you just serviced 10 months ago, you better know your facts.
I learned the hard way long ago not to attempt to interpret the applicability of tech. bulletins anymore than I self-diagnose medical needs. That's what the "experts" are well paid to do. More to the point, the issue, at least for me, is not what's in the tech. bulletin. Rather, it's why the independent and the dealer are giving me exact opposite answers on a vehicle they've both serviced. Since I practially support both of them, I'm taking the bulletin to both next week asking for an explanation. It appears that one or the other doesn't know what they're talking about. When you blithely ask for $500 to service a transmission you just serviced 10 months ago, you better know your facts.
MBWorld Fanatic!
Joined: Jun 2005
Posts: 1,511
Likes: 267
From: Chicago
2025 AMG E 53; 2018 GLC300 4Matic; 2003 360 Modena
I recently brought my car in for service to my local Mercedes dealer near Sacramento (Von Housens, El Dorado Hills) and discussed the issue of the "blue" transmission fluid alledgedly now being required for my 2006 CLK 500. This was based on an assertion by a local independent Mercedes shoip. I also brought a copy of the earlier discussed MB bulletin. Met with the service manager and shop foreman. Was advised that this bulletin has 1) been superceeded and 2) does not apply to my car. In short, I was advised to keep using the "red" fluid. Using this information, I wrote directly to MBUSA. Received response only recently confirming what the dealer had advised. My conclusion: the local independent tried to stiff me with a needless $500 service. While MBUSA did take a while to respond, they are a good source for guidance on such issues. Hope this helps anyone with the same concerns.
2. Where is the new bulletin? Did the dealer show it to you?
3. 09/11 is quite current and the bulletin lists all superseded bulletin information up until that point.
It seems from your post that the dealer confirmed exactly what was in the bulletin and advised as such. As did MBUSA.
I don't know how the bulletin could be more clear. Read it, determine your car / trans and use the fluid as specified. Not rocket science.
Newbie
Joined: Jan 2012
Posts: 5
Likes: 0
2006 Mercedes CLK500
Your're right - it's not "rocket science". This is more remedial. One last time -- its not about reading the bulletin. It's about exposing the misrepresentation by an "expert" independent to perform an unnecessary transmission service based on his interpretation of the aforementioned bulletin. The transmission service was irrelevant, the disreputable business practice was at issue. Got it?
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Newbie
Joined: Feb 2015
Posts: 4
Likes: 0
cls 320
Seems this thread has run off into what trans fluid to use....................
Can I ask about the root cause of the problem as I see it, Fault codes originating from failing speed sensors.
If the ECU gets corrupt information (counting ) from the sensors the ECU faults.
MY QUESTION would be, if I have my part re manufactured by one of the many refurb companies out there offering a next day turnaround. Are they replacing the speed sensors with new or just hardwiring or re soldering everything on the circuit board ?
Perhaps someone who has had a board repaired could shed some light on this ?
722.9 valve body speed sensor repair, DIY ????????????
Good utube vid of parts in question by softelectronic.com
Can I ask about the root cause of the problem as I see it, Fault codes originating from failing speed sensors.
If the ECU gets corrupt information (counting ) from the sensors the ECU faults.
MY QUESTION would be, if I have my part re manufactured by one of the many refurb companies out there offering a next day turnaround. Are they replacing the speed sensors with new or just hardwiring or re soldering everything on the circuit board ?
Perhaps someone who has had a board repaired could shed some light on this ?
722.9 valve body speed sensor repair, DIY ????????????
Good utube vid of parts in question by softelectronic.com
MBWorld Fanatic!
Joined: Dec 2011
Posts: 1,694
Likes: 489
From: Spain UTC/GMT +2 hours
W213 All-terrain
722.9 speed senzor
Till 7g+, there was 3 generation of conductor plate: 1, 2 and 3.
I own an independent repair shop in EU, specialised in 7g rebuilds.
In 5 year, I replaced arround 100 pcs of conductor plates for 722.9, 20% from first generation and 80% from second generation (vgs2).
None VGS3, red or blue ...
My opinion is that the speed sensor issue has nothing to do with the oil.
Maybe the vgs2 has a low quality soldering points or copper plates.
Maybe is safer to change from vgs2 to vgs3 ( 350-400 euro in EU) instead of using blue oil on 7g non FE.
On some cases I resolder the speed senzor on vgs2 plate and 50% still play very good after 2 year.
I notice on vgs2 something related to oxidation when the valve body is out for repair. If the valve body together with conductor plate stay out of oil, due to repair time of the gearbox the oxidation of the soldering points become visible and from our experience 60% of this die after few month.
I own an independent repair shop in EU, specialised in 7g rebuilds.
In 5 year, I replaced arround 100 pcs of conductor plates for 722.9, 20% from first generation and 80% from second generation (vgs2).
None VGS3, red or blue ...
My opinion is that the speed sensor issue has nothing to do with the oil.
Maybe the vgs2 has a low quality soldering points or copper plates.
Maybe is safer to change from vgs2 to vgs3 ( 350-400 euro in EU) instead of using blue oil on 7g non FE.
On some cases I resolder the speed senzor on vgs2 plate and 50% still play very good after 2 year.
I notice on vgs2 something related to oxidation when the valve body is out for repair. If the valve body together with conductor plate stay out of oil, due to repair time of the gearbox the oxidation of the soldering points become visible and from our experience 60% of this die after few month.
Newbie
Joined: Feb 2017
Posts: 2
Likes: 1
2006 ML 350
7G Tronic 722.9 transmission
The NHTSA has been recently notified of the systemic problems with this transmission which causes the effected vehicles to go into LIMP MODE and restricts the speed of the vehicle causing a life threatening safety issue. This defect can only be repaired at an authorized MB Dealership as the transmission control module part has restricted access and can not be purchased. The repair will cost anywhere from $1500 to $2000 at MB, like 1/3 of that the part access was not restricted. If you have this problem with your MB vehicle you must file an official complaint on line at NHTSA it is very simple and easy to file and takes no more than 3 minutes. If enough complaints are filed, the NHTSA spokesperson indicates that MB will be forced to make the needed repairs to each vehicle via recall and MB will have to fund the cost to repair.
Newbie
Joined: Jan 2022
Posts: 2
Likes: 0
E250cdi coupe 2012
722.9 transmission problems
Gents, have you guys heard about this? I heard this from a credible source and I am planning to take action to save my own trans...
There is a growing problem with the older 7-speed trannys (pre-2010 manufacture date). The red trans fluid used in the pre-2010 722.9 units causes corrosion in the electronics inside the trans. This apparently affects several manufacturers, not just MB. The electronics are made by Siemens, which supplied parts for many manufacturers. Transmissions made after sometime in 2010 use a new blue trans fluid which is not corrosive and do not have this problem.
If your car has this trans and it already has the blue fluid, then you have nothing to worry about (re: this issue). If your car has the red fluid and your car experiences no transmission problems (e.g., stuck in gear, hard to start, check engine light for trans problem,...), then you should proactively flush the old red fluid out and put the blue fluid in. If your trans is giving problems like those mentioned above, then you might be looking at a complete trans replacement! This issue can start appearing in earnest around 60k miles. Note that the red and blue fluids are not compatible, so the red fluid must be flushed out. There can be some residual red left over, the trans does not need to be wiped dry before installing the blue, but you must do a full, normal, complete flush.
I am going to have my fluid changed again within the next few days, despite the fact that my trans just had a flush (red fluid) completed a year ago and has no problem symptoms.
Comments?
There is a growing problem with the older 7-speed trannys (pre-2010 manufacture date). The red trans fluid used in the pre-2010 722.9 units causes corrosion in the electronics inside the trans. This apparently affects several manufacturers, not just MB. The electronics are made by Siemens, which supplied parts for many manufacturers. Transmissions made after sometime in 2010 use a new blue trans fluid which is not corrosive and do not have this problem.
If your car has this trans and it already has the blue fluid, then you have nothing to worry about (re: this issue). If your car has the red fluid and your car experiences no transmission problems (e.g., stuck in gear, hard to start, check engine light for trans problem,...), then you should proactively flush the old red fluid out and put the blue fluid in. If your trans is giving problems like those mentioned above, then you might be looking at a complete trans replacement! This issue can start appearing in earnest around 60k miles. Note that the red and blue fluids are not compatible, so the red fluid must be flushed out. There can be some residual red left over, the trans does not need to be wiped dry before installing the blue, but you must do a full, normal, complete flush.
I am going to have my fluid changed again within the next few days, despite the fact that my trans just had a flush (red fluid) completed a year ago and has no problem symptoms.
Comments?
I would really appreciate it if someone could help me as I'm having some shifting issues with my 722.9 transmission. I think the guy who serviced my gearbox around 6 months ago put the red transmission fluid in even though my car is a 2012 c207 250cdi. He said it doesn't matter the red transmission fluid does the same job. I've read the forum and a few people have said only use the blue transmission fluid in cars built after 2010. I'm worried the gearbox has been ruined by the imbecile who put the red transmission fluid in it. Will I need to change the tcm and valve body or will the gearbox just need a full flush and then the correct blue fluid put in it. Thank you
Newbie
Joined: Jan 2022
Posts: 2
Likes: 0
E250cdi coupe 2012
I've booked my car into mercedes benz main dealer as the garage isn't interested anymore. He said he hasn't the time to deal with my transmission issues and he isn't the only mercedes benz specialist in london. I had originally told him to use the blue transmission fluid but he never listened. He has denied the fact that the red transmission fluid he put in it has messed up my gearbox. I will get a full report from MB then take him to the cleaners after my transmission is sorted. Thank you for your help.
