black_e63

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?

MB-Dude

The first question that comes to my mind is, why only the 722.9? Wouldn't the same problem occur in any transmission with internal electronics? Do we know the how the corrosion occurs and what specifically is the culprit (electronic solder points, chemical in fluid, bad karma)?

To be filed in the 'For What It's Worth' folder... I had the dealer change the fluid in my 722.6 (5-speed) in September and the fluid is red (just looked). While the transmissions are not the same, apparently dealers (as of September) are still using red transmission fluid in the 722.6.

Cheers,
Jeff

black_e63

Good questions, for which I have no definitive answers. My source, an indy MB mechanic, simply told me that the fluid has a corrosive component that attacks some "electronics" in the trans. He showed me a document from MB that discusses the problem, but I have no reference number, nor a good recall of the specifics within the document.

I was told this information just started coming out this summer; if this is a real issue, perhaps the dealer did not know or choose to act upon the information? Or possibly, if it is real, this problem is indeed unique to the 722.9 series transmissions?

Am I the only one who has heard of this? If I am, then my mechanic is either on the cutting edge, or he is reaching pretty far for an extra buck. We'll see, and I have no qualms about outing a crooked mechanic. Nor for praising someone with my best interests at heart.

MB-Dude

Chatted with my local MB dealer and there two different transmission fluids - one red called ATF 134 (p/n 001.989.68.03.13) and one blue called ATF 134FE (p/n 001.989.78.03.09). Not sure what the 'FE' stands for. The blue fluid is specified for later transmissions. However, the dealer - as of this writing - is unaware (or isn't saying) that there is any connection to older 722.9 trannys. They are poking around on my behalf and as soon as I hear more, I'll post what I can. At this point, still not sure whether the tale is true or not.
Cheers,
Jeff

tcesario

the blue fluid is not interchangable ,it is for low friction new generation trannys.,less friction = more mpg just do the 40 k fluid and filter and it should last for a long time ,,

black_e63

Thanks Jeff. I'd love to hear what they say.

Tcesario, are you saying that the later 7-speed trans is built differently inside and thus the blue fluid is not intended to be backwards compatible wth the older 7-speeds? That would be an interesting twist on the story, if that's the case.

MBtech1098

This is correct, it was done as a measure for "BlueEfficiency" and to help meet CAFE. For the most part the trans are the same, however through the course of the 722.9 transmission, there have been 3 generations of valvebodies.

You don't want to mix the fluids. There is a MB document stating this.

You can also tell what type of fluid is intended for the trans by looking at the pan. If you have circle dimples in the pan - red. If you have oval dimples in the pan - blue.

MB-Dude

Excellent information. However, the concern was internal corrosion by using red ATF in older 722.9 transmissions. At this point, the corrosion aspect seems to be legend, folklore and an indie repair guy's word on the subject. Are you saying that there is not a potential corrosion issue with older 722.9 transmissions and red fluid, or that if blue ATF is used that all the red fluid must be removed? I guess the real question is... Can older 722.9 transmissions utilize blue ATF if all the red ATF is removed? Simply seeking clarification.

For additional reference, I have attached 3 documents - the Material Safety Data Sheets for both ATF-134 and ATF-134FE, and an excellent paper produced by 4 MB Engineers discussing the latest generation 7-speed transmission. The paper is dated Dec 2010 and discusses blue ATF. I submit these for general consumption and to add supportive data to the discussion here.

Cheers,
Jeff

black_e63

Thank you, MBtech1098, I appreciate all the info you can provide, especially as it applies to corrosion issues/potential.

Jeff, you're the man!!

kjb55

Nothing in this post has provided anything substantial to support a corrosion issue. I call bunk by a misinformed independent. Red and blue fluids are discussed in the above attachments by nothing more than necessitating a new formulation (blue) to meet stringent requirements of efficiency and start/stop in an automatic trans equipped car.

The MSDS documents are meaningless for this discussion and only serve to meet OSHA requirements for hazardous storage and use of chemicals. WorldPac is only a supplier of automotive parts and supplies to the IAM market.

If this problem is credible and as systemic across manufacturers as stated - someone, somewhere would be able to produce a TSB specifically addressing this issue and probably to the extent of issuing a voluntary service campaign. Some of these cars are/would still be in warranty and the MFR's would be looking to mitigate their risk.

MBtech1098

There has been no mention of corrosion issues with ATF134. I hope this shop is not getting confused with the trans fluid used in the 164 hybrid. This fluid is non-conductive.

Note once again...I would NOT mix the two fluids. I just searched through WIS, STI, and a couple more documents. All of them state in bold lettering not to mix fluids.

MB-Dude

Neither black_e63 nor I disagree with you. Quite the contrary, black_e63 was only looking for any substantive data to either say the indie repair guy was true or off his rocker trying to make a fast buck. Agreed… if there is a TSB, we’d love to see it. My dealer has not found (as of this writing) such a document suggesting that one doesn’t exist. I provided documents to support the discussion, instead of just words. The MSDS’s are provided because they will provide clues as to what makes each fluid slightly different; nothing more. Written data is always better than verbal data.

Thanks for restatement about not mixing fluids. Much appreciated. Also good input on the possibility of confusion with a different transmission. Interesting.

Personally, I do not think there is any truth to the tale about corrosion in the 722.9 transmission using red ATF. Although it doesn’t even make sense from a logic point of view, at least we have exhausted other avenues to refute the tale.

Cheers,
Jeff

black_e63

Tomorrow (Monday) I will see the guy who told me about the problem and ask him for a copy of his source document. I'll report what I get from him.

biker349

keep us posted.
thanks

black_e63

OK guys, I just got a chance to sit down and communicate what I've learned. Hopefully I can transcribe it accurately. Please take this information as an FYI from which you may choose to take action or not.

-There are many cases of poor shift quality from 722.9 transmissions (as acknowledged in Bulletin number LI27.00-P-051451 Date: 10-03-2011).

-It comes down to particulate contamination inside the transmission which lands on valve screens on the electrical conductor plate attached to the valve body. When the screens get clogged they create speed sensor faults.

-Usually the method for fixing the speed sensor faults is to replace the electrical conductor plate or the entire valve body. However, now that there are so many failure occurrences worldwide, MB will no longer sell these sub-unit parts to independent dealers, and they are even more difficult to obtain for dealerships and are currently back-ordered for dealerships. Thus, typically the entire transmission may be replaced instead.

-Apparently there are now replacement screens available, which can be replaced, if the problem has not advanced too far (I'm not sure about that part).

MB discusses the method for fixing the problem in Bulletin LI27.20-P-051537 Date 11-18-2011:

COMPLAINT:
Vehicle jerks during gear change or has hard or slipping shifts. In some cases the torque converter lockup clutch (KuB) cannot be actuated.
CAUSE:
Torque converter lockup clutch (KuB) cannot be activated due to a clogged filter in the KuB solenoid valve. Other solenoid valve filters, e.g. K1 control solenoid valve (Y3/8y2), may also be clogged with wear debris.
REMEDY:
Removal of EHS & removal of all solenoid valves from the EHS to evaluate the contamination of the solenoid valve filters. Please observe AR27.19-P-0212A. Install repair filter A 221.227.00.00. Clean all valves with a small magnet, afterwards bathe the valves in fresh 134FE-ATF {Blue} (A 001.989.78.03.09) several times to remove debris.
AR27.55-P-0100SX: The entire transmission must be flushed with fresh oil (134FE-ATF A 001.989.78.03.09) & then filled with new oil.

The source of the metal particulates is *possibly* due to corrosion caused from the red fluid.

-Flushing out the red fluid and installing the blue fluid may stop the corrosive process and prevent an expensive failure if it is changed soon enough.

-The blue fluid is backwards compatible with most all MB auto transmissions (722.6, 722.7, 722.9)

-In Europe, MB Service Bulletins say to switch to blue ATF in ALL 7 speed transmissions. However, in the USA, EPA regulations are preventing MB from changing the fluid in older (pre 2010) 722.9 transmissions.

- Most common symptom is that the transmission intermittently won't upshift, i.e., stuck in low gear. Problem gets worse (not shifting at all) and check engine light comes on. This normally occurs around 50k to 60k miles.



Let me know what questions you guys have, I probably left some stuff out during my write-up. FYI, I am having my fluid changed to the blue fluid, and having magnets installed in my trans pan to collect metal particulates.

MBtech1098

I will do some more research tomorrow, but the information in your post does not accurately correspond with the LI number you posted. There is no mention of red fluid and only applies to vehicles that already have ATF134FE. Do you have the actual document from this shop? I am curious if he modified the document for his benefit. There have been two versions in the US and I will have to see how many documents for the world there are. But the current one for the US discusses an issue with torque convertor operation.

black_e63

Yes, you're right that the red fluid is not mentioned in that document. Actually, I do not have an official document that specifically states that the red fluid is corrosive. However, Bulletin LI27.00-P-051451 states that the clogging problem affects both 7G-tronic and 7G-tronic Plus transmissions, and the referenced Solenoid Replace and Cleaning document states only to use the blue fluid during reassembly. In the notes provided by my mechanic, the blue fluid is supposed to solve many of the 722.9 transmission problems documented by MB, but I don't have any lab tests or comments from MB. I'm still looking to see if the red fluid is discussed anywhere outside of my mechanic's notes. I believe my mechanic is earnest and not making things up, but I would like to see the red fluid implicated from a second source as the cause of the corrosion, if indeed it is...

BTW, here is a link that talks about the valve body and conductor plate issues from the viewpoint of an independent repair shop (not mine). Again, there is no mention of fluid types.

jctevere

This is very interesting as this issue is persistent in my 2009 w204 (right at 42k miles). However, I also have another related issue covered under a different TSB:
LI27.00-p-048552
Complaint: After a cold start, slippage may occur in the 2-3 shift when vehicle moves off for the first time.
Cause: Basic charge for the K1 piston is not guaranteed with a cold start. The plate pressure still has to be built up. This can cause the shift operation to slip once.

There has been talk of a software update to the transmission to fix the problem, but this TSB has been around for a while, and no update to my knowledge cures the problem yet. Also, the fact that the other TSB listed above is also present on my car (or starting to show-face) with rough upshifts, the linkage or commonality seems to be an issue in the K1 piston. The rough upshifts are present from 1-2 and 3-4, but not nearly as bad or noticeable as 2-3, which to my knowledge involved the K1 piston. I'm going to bring my vehicle in to the dealer as soon as I get an appointment and will keep you all updated with the prognosis.

MBtech1098

So I have searched all variations of LI27.20-P-051537 both US and world, and it only applies to any vehicle with a NAG2FE+ transmission in vehicles 212, 216, 221, 251, & 164. Your vehicle is not equipped with this variation of transmission. All affected vehicles were shipped from the factory with blue fluid. So once again I am quite curious as to where he got is information. I am aware of the control unit/conductor plate issues, however it is not related to the fluid.

black_e63

Jctevere, good luck with getting your transmission issues fixed. I'd like to know how this gets resolved for you.

MBtech, I don't know for sure, but I suspect that my mechanic is basing his logic about removing red fluid and replacing with blue by what Europe is doing, i.e., switching all transmissions over to the blue fluid. If it is not fluid related, does any data exist that shows what is the true cause of the metal particulates?

My car is now running the blue fluid and it seems to function properly. I will update if the health of my trans changes markedly. Otherwise, I don't have any new information at the moment.

MBtech1098

There is no documents I see that supports Europe swapping to the blue fluid. As far as metal particulates it could be from any number of things. Keep in mind the reference LI is no where near being related to your vehicle.

MB-Dude

You raise a good point here. I received a copy of LI27.20-P-051537, ver. 2, dated 11-18-2011. The TSB clearly states the validity of the document is applicable to [I quote], "BM 212, 216, 218, 221, 251 and 164 with A/T NAG2FE+ ...” If these Base Models use the 722.9 transmission, and it's the 722.9 transmission that is causing a problem, what is different between these 722.9 transmissions and black_e63's 722.9 transmission? Just curious. By the book, black-e63’s transmission is not a part of this TSB. But why? What’s different?

FWIW - The document has a title of, Vehicle jerks during gear change, hard 1-2 and 2-3 shifts, torque convertor lockup clutch (KüB) not engageable. The cause stated is, "Torque convertor lockup clutch (KüB) cannot be actuated due to a clogged filter in the KüB solenoid valve. Other solenoid valve filters, e.g. K1 control solenoid valve (Y3/8y2), may also be clogged with wear debris."

The root cause of the debris is not listed nor is it speculated upon. It only goes into the remedy that, in essence, drains the fluid (ATF color is not specified), removes the solenoid valves and seeks to “evaluate the contamination of the Solenoid valve filters. Please observe AR27.19-P-0212A”. This last document number covers the removal and installation of control solenoid valves of the electronic controller unit.

I have to agree with MBtech1098 that on the basis of TSB LI27.20-P-051537, it makes no mention of corrosion. But I am still quite curious as to the differences in the 722.9 transmission series. More troublesome to me, is that some of the symptoms listed in this document fit current problems I am having with my 722.6. Different animal, yes. But am developing clogged solenoid filters?

Cheers,
Jeff

MBtech1098

There is not really a component difference between the NAG2 and NAG2FE+, the difference is in the internal tolerances are tighter and the torque convertor. ATF134FE is a lower viscosity fluid, but is essentially the same as ATF134, for this reason this is why it is NOT reccomended for use in transmissions that were not designed for this fluid. If you have a NAG2 transmission, and you use the FE fluid you will actually shorten the life of the trans by creating more wear as the FE fluid does not provide adequate lubrication.

DerekLMartin

We were told at work that the new blue fluid is not backwards compatible and that it should never be mixed with the red fluid. We even have different filling pumps for the blue and red fluid for this specific case. Like MBTech mentioned, I would be very concerned about running the wrong fluid in such and expensive component such as the transmission.

Ausmbtech

I think you're heard a little bit or urban legand/misinformation from your local indy.

I've never seen any corrosion issues using the "red" fluid. electronics in transmissions is nothing new at all. the only corrosion I've ever seen in a benz transmission in solely due to leaking radiators causing rust.

The blue fluid is for new transmission and it primary benifit is reduced friction/power loss. It coincides with a compleatly new torque convertor too. If benz say it's not backwards compatible then thats good enough for me. They were very upfront with the last fluid change with the 722.9's in that it was backwards compatible right back to the 722.3 and .4's but the old 722.6 fluid wasn't good enough for the .9's.

Remember, they aren't new to this game.