Gentle Warning - Service your 722.9 Transmission every 39K miles 60K Km's
 

Guys and gals. This is not intended to cause alarm but to respectfully suggest that you service your 722.9 transmission every 39K miles or 60K Km's as in ROW. We are seeing an increased number of TC et al failures as mileage increases & feel it prudent to inform you while we try to fully understand the failure mode. I should also state that forums such as these concentrate problems as many only post when they have a problem.

https://mbworld.org/forums/c-class-w...need-help.html

thanks glyn. Any other info like how much is an expected service would run?

The services vary from $300-500 from what I've seen.

See Johnand's excellent service thread here.

https://mbworld.org/forums/c-class-w...ce-thread.html

I think someone local should comment on typical pricing.

Matt is pretty close on pricing. With a PROPER service the parts alone are close to $200. When I had my 1st one done at the dealer it was ~$350, and they did NOT drain the torque converter.

Thanks Matt - your post was not visible when I posted :D

I agree 100%. Based on all the information we have to date, this will go a LONG way in possibly saving your $Thousands.

With that said, I want to add some points based on my research, and actually servicing quite a few of these transmissions now.

1)It is IMPERATIVE that when doing the service follow the updated WIS instructions to drain the torque converter. There is another 2-3 liters of fluid that comes out of there when drained. A few recent posts show that some dealers are not even following the official documents and skipping this step.

2)If you want your 7G to last long term, I would consider an even shorter interval. Every change I have done (Even one at 30K), had noticeable discoloration of the ATF. I personally had my 1st done at 35K, second at 72K. I plan on my next one at 102K. I am going to do mine every 30K. I will try and get a sample of the ATF on my next change and have oil analysis done for some important data. Think about the small cost of early changes vs. the potential for $1000's for repairs. It really is cheap insurance.

3)Based on my observations on #2 above. I recommend transmission up/down adaptations AND torque converter lockup adaptations be reset at EVERY service. These transmissions adapt to the characteristics of the fluid over time. When fresh ATF fluid is added at a service the adaptation data is no longer valid IMO. Yes, the transmission will slowly adapt over time, but I believe it is imperative to have to keep the adaptations up to date. Every single one of these I have serviced had significantly improved shift characteristics after a complete adaptation reset and learning cycle. Just a word of caution. When you reset adaptation data the shifts can be a little abrupt for the 1st few drives. This is because the clutches are engaged at default pressures for the adaptation reset. This is perfectly normal, and after a few drives the transmission will settle into it's normal behavior. Which should be buttery smooth shifting under all conditions, other than when cold. It is well know that when cold these transmissions shifts are more abrupt. This is normal behavior and is designed to get the catalyst up to temp quickly.

4)Read my 7G transmission service thread. There is a wealth of information in that thread. Even if you are not mechanically inclined enough to service the transmission yourself, the information is invaluable to being an educated car owner. This will allow you to have intelligent conversation with your indy or dealer, and make sure they or doing things correctly.

Good info & advice.

:word: Our 722.9 guru has spoken.

My postulations on the above failure thread are just that & not proven. My logic may be flawed but time & more info will tell.

I'm pleased John intends an oil sample - it is the way I tend to tackle things due to my backgound. I have seen a couple of samples at 60,000 Km's using the 236.14 generation fluids which I regrettably tossed.:smash: You do these things when you have evaluated 1000's of oil samples. Previous samples I had seen were during the fluid development days & not real world. Rather accelerated testing.

The 60K Km samples I have seen were certainly deteriorated, oxidised & contaminated & while not awful they were certainly not fit for further service. This is why from my early days on the forum I've encouraged regular servicing & was concerned at US "filled for life" recommendations in those days.

Thanks Glyn and Johnand! I am at 37k right now and have read about this issue, it's really scary. I no longer have warranty and wouldn't want this happening to my car. Will be doing the service asap.

Good man :y

Recently did the service
 

I had a thread awhile back about my experience doing this with the dealer. If I could do it again I'd would definitely go with a trusted Indy. Here are the cost quotes I got:

dealer 1: $375
dealer 2: $350
Indy 1 - Merc specialist $325
Indy 2: - Euro specialist $400

Prices are in USD This is in the Seattle, USA metro area.

I went with dealer 2, and they immediately tried to charge me $400 upon bringing it in. Fortunately I had the quote in e-mail so they honored the price. When I asked them to drain the torque converter they said it was impossibile due to no drain plug. Not only was this false, but Mercedes says then should do it, and draining the torque converter is important to the longevity of these trannmissions. I ended up complaining to Mercedes, and they redid it only after a lot of complaining.

After the second service the car shifted a little better, but not that much. After a month of readapting itself the transmission shifts better with the occaisonal rough shift now. I need to reset the adaptions manually following a thread in the tech section on this site.

You cannot trust a dealer to do anything right, so by all means print out the documentation in JohnAnd's thread and make sure they the book. This would apply to an Indy mechanic also.

One more thing - I asked the dealer what a new valve body costs, and they quoted $975 plus 2 additional hours over the tranny service They did require diagnostics and extensive paperwork before they would sell one though. My guess is that Mercedes is selling them at cost.

Truer words have never, ever been spoken. If you're going to take any advice on this forum then let this be it. Don't make the mistake of assuming that just because you always service at your MBUSA dealer, you're safe. Our collective experiences on this forum have revealed that in addition to over-charging, dealers in the states also cut corners, lie, and often lack even basic knowledge of the cars they service.

Personally I always approach issues with the assumption that the people, even at my trusted indy, will not know exactly what to do. I don't like to leave things to chance. At first I felt like a douchebag giving them such specific instructions but since I have became a valued and very regular customer, they follow my orders strictly. You may have to do the same and short of doing it yourself this may be the only way to ensure it is done correctly.

There is something wrong there. I'll bet if you asked them to do the job the quote would suddenly be +- $3000

Have no compunction. Tell them what to do. It's your money.

I had one dealer tell me that the 722.6 had no drain plug. I said "you mean the TC". They said "No - the pan" :crazy: Needless to say I don't go there anymore.

Indeed
 

:) Absolutely! They would try, but I have it in writing.:y Mind you I would never go back there anyways, and they have many other ways to get their money. I believe they tried to switch the price of the tranny service, and deliberately didn't drain the torque converter to pad their profits.

This brings up a good point - use e-mail and get everything in writing when dealing with MB. It seems that dealers are dishonest and greedy as well as incompetent. I'm sure there must be an honest dealer out there somewhere.:rolf:

Sadly I don't think so.. not in the USA anyway.

Approved fluid update