What are the issues with 722.6 transmission ?
 

I read several posts reporting problems with the early models of this transmission.
3 questions:

1. What problems ?
2. Can they be fixed on a preventive basis by changing selected parts instead of waiting and praying. Which ones ?
3. My transmission is 722.604 0 01022161. Do we know if there is a serial for the last affected transmissions? Am I in or out?
TIA, Jorge. (praying in the meanwhile)

Well if you already have that transmission, I would think that all you should do is service the transmission with proper MB fluid and filter. Seems like consensus is every 50 to 60K miles. That's what I did when I got my '97S320. I also preventatively replaced the part called a spacer, where the wiring plugs into the transmission. Other posts said part was prone to leakage. Cheap part.

Steve

Steve,
My car has 48K miles. 75% on highways, which are gentle to the car and the transmission in particular (low usage of low gears, low changing and cooler environment)
I already had planned to replace filter+ATF+gasket.
Your point on the spacer comes on very good time as I live in Brazil and will order the part now.
One suggestion: from my research: we may add a magnet to the pan, already present in newer models. Inexpensive and important to keep metalic debris from flowing.
There is a MB P/N for it. (two in fact. the newer is the better)
Thanks!
Jorge
PS: Read something about premature wearing of discs... ??? synchros??? (I am not sure). They were supposedly modernized in recent versions. It will be worthwhile to know if the newer can replace the originals. (on an affordable labour expense)
PS2: Will probably change ATF much sooner than the new consensus. Looks like the cheaper insurance policy one could buy.
PS3: My transmission has a serial number > 1,000,000. If that really means 1 million units I HOPE that the critical versions were left behind.

I've been doing about two .6s a month. 97,98,99. 75% of the time it's been the roller bearing failure that takes out the planetary gear. you'll hear the gravel when is starts to go. The planetary gear is so expensive, at that point it's almost a wash to rebuild or buy factory. or gamble on a used. There are updates for that trans.
Paul

This is a precious info !
 

Paul,
Thats truly VERY GOOD NEWS provided that just changing the bearing prevents the planetary (literally...) tragedy.
2 questions:
1. Would that (bearing change) be expensive? (I mean part+labour)
2. Can you provide us the current P/N ?
Many thanks ! Please think is there would be something else to be carried out preventively.
Jorge
PS: Your testimonial carries another info: the issue was NOT solved in 97 and perhaps a higher serial number means close to nothing.

Don't forget the weeping seal leading to the ECU, thats probably the most common problem I see on forums.

I'd say overall though its a very reliable transmission.


Paul, can you give an idea on how long this 'gravel' noise will be there before failure? Are we talking a few minutes, or a few weeks? Forewarned is forearmed, as they say.

Is this failure lubrication related or simply desgn defect?

The transmission would need a complete tear-down to replace the one-way rollers. It would be like re-building it now, to prevent having to re-build it later. Not exactly feasible, IMHO.

What abotu this one...

First winter and a darn cold one with my W202 and its 722.6

When its first turned on and let it warm up for 5 mins, I get to the first stoplight and sitting there for 2-3 mins...as I try to go its not fully in first...it revs but is moving but slowly..then hops into gear. Once warmed up its perfect.

Only did this in very cold temps

When did you last check the gearbox oil level?

I have builder who does mine on site. from what I can see from the sidelines is that it's a design defect.
a bearing on one end of the pitch shaft doesn't support the shaft enough to prevent the rollers from the bearing on the other end from cutting loose. I say this because the update has a support bushing instead. To my knowlege, the bearing and the whole gear set is an update. The original planetary gear is not available. So yes it would be expensive. Like someone said in an earlier post, just service them on a regular basis. In the early stages I remember hearing a slight gravel noise in reverse when backing slowly.
Paul

MB did the fluid change on mine 10,000miles ago.

Paul,
When you say the parts were updated you mean for the regular 722.6 ? (I mean: if we change the parts on OUR transmission the issue will be in the past)

The word "rebuilt" itself is scary...
I imagine that a rebuilt of a truly broken transmission, with broken parts braking other parts must be extremely expensive.
Can you give us a perspective of what would be the effort to this "soft rebuilding" - lots of tear down to reach the parts but not generalized damage as you would be acting before the real tragedy?
Let me explain why I ask: In Brazil parts are VERY expensive (but I can buy them in US as I travel frequently) . On the other hand labour is far from cheap but is AT LEAST 50% of the US. (and we do have good professionals for transmissions)
So the whole economics may be different in my case.
I plan to keep my car for a long time. So the costs are important but may be worthwhile in some situations.
TIA, Jorge

My tech does not bother to rebuild 722.6 trannies. They are available from MB for less money, and have the latest bits and a good warranty.

Mine's been standing up to abuse including regular WOT highway-speed downshifts (exercise) for 145k miles.....knock on wood

Fluid/filter every 40k.......yes all electronics and a conductor plate were done under warranty, but the basic mechanical internals are 10 years old and perform flawlessly to this day

If you have one that's defective, I think it would have been evident before now. If you've got over 50k and 5 years on a 722.6, and it hasn't grendaded, you don't have a defective tranny........if it dies at any point after this, it's because YOU didn't maintain it properly

A bit of relief to hear. Mine is all original except the fluid done at 52k when I bought it. Although now it slips once in a blue moon (when cold) from a standing start. It would do it only once a day and its when its still all cold and pulling away.

180,000 miles on mine, and nothing but a whisper from it.

No fluid change yet, Parrot?

"If you have one that's defective, I think it would have been evident before now. If you've got over 50k and 5 years on a 722.6, and it hasn't grendaded, you don't have a defective tranny........if it dies at any point after this, it's because YOU didn't maintain it properly."

I read statements like the one above, and just get this puzzled look on my face. My mind says, "Really?"

The writer's logic starts with a declaration about 50K and 5 years. Exactly where did those statistics come from? Then the assertion that the defect either exists, or does not exist. Where are the facts for this statement. Thought it was stated by the pro mechanic that it was a design defect, not a defective part. In other words, you can have a perfect part that is not up to the task and fails over time.

Finally, we get a pronouncement that death after 50K is your fault due to faulty maintenance. Maybe, but you can find some pro's on this forum who disagree.

Within this thread alone, we have professional mechanics, who actually have some real data. Even their data is very limited as a percentage of all the 722.6's out there. It has been stated that the problem bearing has been updated to a bushing. I suspect the driving environment has a lot to do with the time before failure. Highway versus City.


My '97S320 has 116K. Tranny serviced at 65K and at 109K when I got it. I would not presume to reach any global conclusions based on the my data point of precisely 1 transmission. Working fine at the moment, but who knows what will happen in the future?
My logic is as follows. I got the car cheap, $12,000, relative to any new car I would even consider. If I have to buy a factory re-manufactured transmission for another $5,000, I'm at $17,000, still cheaper than any new car I would want to drive.


Steve

This debate is getting VERY useful !
Let me add a bit of poison, addressing a taboo topic:
Is there a known "super lubricant" ATF aditive that may help us on a preventive basis ?
I know and understand that manufacturers are adamantly against this. In fact cars are supposed to work with regular off the shelf stuff. (certificating aditives and their interactions with regular brands of lubricants may become a nightmare if a manufacturer tries to do it)
Using a special aditive to minimize a design flaw would NEVER be addressed. It would mean acknowledging the flaw...
Just for a starter: I remember the Molykote (molybdenium bissulfide if I recalls correctly) revolution back 40 years. It was not a detergent, an atioxidant etc: it was LUBRICANT. It dealt directly with friction reduction.
No need to say it was very polemic. (despite being widely used in race cars)
I remember it was not accepted in Porshe gearboxes because the synchro rings would sleep and fail to synchronize)
How about this vis-a-vis the current world + auto transmission environment ?
Do we have components that cannot be overlubricated?
Jorge

An automatic transmission is different from a manual transmission. Automatics have clutches that have to have friction to engage. Thinking about preventing this potential failure by some amateur hour addition of lubricating additives is just foolish.

Stay with what the manufacturer recommends. The manufacturer has invested thousands and thousands of development manhours in this transmission. They are smarter than we are relative to this subject. Logic says you should follow their advice with one caveat. The sealed for life thing is most probably a marketing ploy. I choose to service my transmission, but that is not the same as choosing to pour in some snake oil.

Steve

My friend has 175k+/- miles on his 722.6 and it's still shifting like new. AFAIK the fluid was only changed once, by him at about 150k miles or so. It did shift better after that.

Even the old MB trans usualy die between 200k-250k, if they are good, some much younger. My 300SD for example the PO rebuilt the trans before 150k miles.

So they seem like a fine transmission to me, last pretty long, shift real nice. The only downside is last I checked rebuilts were $3k.

Steve, there is no scientific research behind my statement. I'm not an expert. My grandmother's 98 E320 had the trans grenade at 30k years ago. I've been around this board and picked the brain of my own shop foreman at the dealer (while under warranty) enough to deduce that most of these rebuilds (MBDOC, etc, correct me if I'm wrong) occurred under warranty back when the 722.6 was newer/more of an unknown, and when fluid changes were not advised. Seems now the ones that the various techs on this board talk about seeing fail (in other words, the ones that have survived several years/10s of thousands of miles) are the ones that saw no fluid changes. If all 722.6s were POS units, I would have killed mine long ago. I'm not easy on it, but I am anal about maintaining it. Again, 146k so far...

I like the anal and easy on it points. I am the same way. The computer brain learns your driving habits. I try to play off that with my throttle habits. I have enjoyed the trannies in my 124's, but I really like the 722.6 better.

Hey, at least you have a good relationship with your shop foreman. Our dealership elects to run without a shop foreman. I really pissed off the head service writer just after I got the '97S320. It had been serviced at that dealership for 4 years and I have every record.

I simply inquired about having the transmission serviced. He cut me off with the sealed for life thing. Then he said it would be $450. I asked him whether he thought I was just plain stupid. Told me the filter was $75. Then I explained that I didn't buy the sealed for life thing and that I had their own service record for a tranny service at 65K miles. All the guy had to say was, "Yes, I understand your concern. We charge $450 dollars. You might want to take it to an independent shop." I left in disgust and haven't returned.

Steve

Another thing....I drive mine like there is a glass of water on the dash. Its just the way I like to drive a Benz....I also think this benefits things like transmissions as the shifting is barely noticeable when doing that. On the highway I always open it up.

Would driving it smoothly help things out?

Frequently, the problem may is as simple as an internal seal failing. There wouldn't be any metallic debris floating around internally, causing subsequent damage. In that case, if I were a brave DIY'er, I'd take it apart and see what happened. A seal kit is cheap, so while I was in there I'd replace all the seals possible. I'd also measure and correct the clutch clearances if necessary. If they were all out-of-spec, only six snap-rings would be needed to fix it. Cheap. And don't forget, the 722.6 is not that complicated. I think it's well within the ability of many DIY'ers.

On the other hand, if I dropped the pan and found a mess, I'd just bite the bullet and replace the entire unit. I'd also flush the cooler and lines as well.

Bought the car at 163,000 and did a change at 165,000 - I don't believe it had ever been changed before that. Minor improvement in gearshifts since.

The old fluid was as black as used oil.

Steve,

Conceptually could'nt agree more. Our problem is that in OUR case those many hours led to a faulty design. It happens and may have fixes or not.
I would never go after some "snake oil" wonder thing. We are in full sync on this.
My question is broader: is there a known addictive coming from a known brand accepted to help in some circunstances?
For example: Race cars, cars used in hot boiling deserts, car with extra high mileage, extra low temps, etc.

In general manufacturers may be skeptical but even they support some of these solutions. The concept of severe usage is in the owners manuals.
I consider that the lifetime thing is part of the past. Just for reasoning lets imagine that the accepted standard is now 5 years or 50K miles, whichever comes first.
Would a 722.6 be benefited if we divide the mileage by two ? (about 250 dollars more in 5 years)
Why not making official the installation of the pan magnet present in newer versions? it is so intuitive.
How about an extra cooling pump? (it has ben done before)
And, if (only if......) some addictive is accepted for specific situations what COULD be the effect of using it in a not so good vintage of trannies?
We are in a grey area. Officially , as far as I know, the issue is not even acknowledged by MB.
We don't know the figures but so many among us say they are doing great... at much over 100K miles...
I am concerned but at 48K my transmission is wonderful. Far better than the ZF in my Audi. (not plagued as ill)
I am fighting to keep it as it is... The shifting is the best I have ever known.
I can always say: If I only divide for 2 the change interval... as an educated guess ... I am ALMOST sure I will greatly reduce my risks. For how much $$$? Close to nothing.
I have much to lose if it fails. But LOTS to gain if the lifespan is increased by 25% in exchange for a 250 dollar oil change. If it is increased by 50% the issue is over.

On my side I made, so far, a set of decisions:
- 5 years most
- every 25K mile
- magnet in the pan
- every change=new filter

I don't live in a place whose market is able to evaluate addictives to expensive german cars. You are in the best one. (well, may be except Germany itself - which BTW would be VERY nice to hear of) (I mean - equivalent newsgroups)

Well - at least we are having fun...
Best Regards and thanks, Jorge

Save money on the additive thing. Specific lubricity is required for proper function of the transmission. If you alter that part of the equation, something else will probably give.

If you are concerned, simply change your fluid more often.

As we always say on the farm, dealing with extremely high stress lubrication situations: change it hot and change it often. If it breaks, get a new one.

My 1998 E430 has 134,000 Kms on it, and the tranny fluid was changed at 100,000 Km. My tech also recommends changing the fluid in the 722.6, every 50,000 Kms. When I asked about it he didn't even hesitate. Change it, he said.

I trust my techs (have known them over 12 years) and they've yet to steer me wrong.

It makes sense to me as well.

I don't see how changing the fluid properly (with the MB fluid) can hurt the transmission. Pocketbook, yes. Tranny, no. :D

On the other hand, I can see how not changing the fuild could potentially hurt the transmission. With the heat generated, the moving parts and friction, inevitable wear, etc., there is a lot of chemical and mechanical changes occuring inside that sealed transmission. How can any lubricating oil last 'forever'? I just don't see how the oil could not get contaminated, could not change wrt its chemical properties and thus lubricating properties and hence not perform as it did when fresh.

After all - MB put a magnet in the pan for a reason, didn't they? :rolleyes:

Read this old post from Gilly (a former dealer tech), posted in 2004:

Filled for life?
The 722.6 Automatic Transmission uses a special oil and is said to be filled for life. The oil can only be purchased through the Mercedes-Benz dealer using part number 001-989-21-03-10. A 722.6 holds about 9.3 liters and the fluid is sold by the liter. Checking the fluid is accomplished by breaking off the red locking seal located at the dip stick. the lock is replaced after the oil is checked. Use part number 140-991-00-55 for a new lock. There is no dip stick to check the ATF. You need a special tool to check the fluid on all 722.6 transmissions, part number 140-589-15-21-00. The oil level is a critical factor in transmission shifting. See Service Information 27A95105 for details. When you refill, or check thetransmission fluid level make sure that you check the level with the special tool and at the correct temperature. The latest information from Germany is that we should fill the oil to the MAX line. Not overfilled, just maxed out. This is said to improve shift quality. At normal level it is possible for the oil to form air bubbles. The increased level helps to minimize this. You might want to remember to try this on customer complaints involving shift quality before you replace any component. Along with setting the adaptation you would be surprised to see how much of an improvement you will see.

The Automatic Transmission fluid is said to be filled for life. We never specified who's life. (Yes, they actually wrote that in this!-DG) The transmission control module contains a program that keeps a running count of the "calculated" cndition of the ATF oil. (Note from Gilly-I believe this was deleted from the modules right around 2001-2002, not there anymore-DG) The factors that affect the oil are time and temperature. The counter is incremented with engine running time and incremented greater with higher ATF temperatures. The Hand-Held Tester (now SDS-DG) displays a numerical value that represents the value of the calculation. At some given point in time Germany will tell us (still waiting, evidently-DG) which number means its time to change the oil. For now there is no service interval for the ATF oil. If you replace a transmission you should re-set the counter back to zero to account for the new oil. If you are doing internal work and you are replacing the oil you should also re-set the counter. It is acceptable to drain the oil out into a clean container and reuse it, provided it was collected using the MB filter funnel. Remember to flush the converter and kines before installing the new transmission. You should also replace the converter if the transmission was HEAVILY contaminated with metal. Make sure you return the converter with the transmission to warranty. Fine metal particles in the bottom of the pan are allowed. (I think what they mean here is that fine metal particles are considered an "acceptable" condition, do NOT replace transmission, as you will see if you read on:-DG)

The Color of Money:

We have been conditioned to judge the quality of the transmission fluid based solely on it's color and smell. We have no way of judging the frictional quality. The rules have changed. (didn't Iaccoca say that too?-DG) The bright red color that we are all used to seeing may not be what you see when you look at the ATF in a 722.6. The reasons that the oil looks differently are as follows:

1) The oil may appear dark red due to the graphite material that the friction discs contain. This does not change the characteristics of the oil. Do not change the oil or transmission if the oil appears dark red or even if it has a yellowish tint to it. The color will change with time and temperature. As of 10/97, the manufacturer of the oil has agreed to put more red particles in the oil.

2) If a copper color is seen in the oil pan the bushings of the front or rear planetary gear set may be in the process of wearing out. Inspect the bushings and if they are defective replace the complete transmission. If they are not defective, then the transmission is repairable.

3) If a silver color is present in the oil it may be a clutch and steels moving up and down on the hub as they are being applied. This is normal! Use your best judgement here. If the particles are fine they should not cause problems as they will be trapped in the filter. The fluid could be drained, including the torque converter, and the lines flushed and the valve body should be disassembled and cleaned, replace the filter of course. This usually takes care of the problem. If you take the time to inspect and clean each slide valve for ease of movement and base position you will have a better valve body than a new one from spare parts. In more severe cases where the particles are large, then something is in the process of self destruction and the transmission should be either replaced or repaired. Don't forget to check the electrical solenoid valves. Shine a light through the top of it and see if it "leaks". If you drop the transmission oil pan (I think they mean "remove the pan"-DG) and you find yourself feeling like a miner panning for silver, or knee deep in a graphite colored mud, then it's time for a new transmission. You may have noticed that the new pans are painted black on the inside. The metal particles show up better against a black background as opposed to the previous unpainted silver pan. You must get used to seeing some metal in the bottom of the the pan, with this transmission this is normal.

4) Smell the oil. You know by now what burnt oil smells like. If it looks burnt, and it smells burnt, then its burnt.

Example: Try looking at the adaptation values for K3. If the numbers are high, then you have a K3 problem. If the customer is complaining about shift quality going in and out of third gear, repair K3.

5) Make sure you understand the complaint before you disassemble the transmission. Use the HHT (SDS now-DG) adaptation screen values along with the shift application chart to see which shift members are applied during your customer complaint so you will know where to concentrate your efforts when you disassemble. Remember to disassemble the transmission like a surgeon, you need to observe the condition of seals, rings, c-clips and shims as well as being aware of the potential for missing parts.

Repair or Replace:

Use the transmission oil pan as an indicator when deciding to repair or replace the 722.6 transmission.

The following pictures (sorry folks, I'm transcribing the written part only, no pictures-DG) are for reference as to which transmissions should be replaced and which should be repaired.

(picture shows a black pan with some small "dots" here and there-DG) This is a normal oil pan for a 722.6. The fine particles are normal. Do not replace this transmission.

(can't tell what's "wrong" with this picture-DG) The brass colored particles may be a sign of a bushing problem. This transmission may be repaired.

(can't tell by the next picture either what the problem is supposed to be, rotten copies!-DG) The metallic sludge indicates that there is a major mechanical problem. This transmission would probably cost more to repair than to replace.

(This picture you can see obvious copious amounts of metal shavings, a pretty good coating of it-DG) This picture also indicates internal damage has been done. This transmission would be replaced (as well as the TC and flushing lines and cooler, etc-DG).

Surprising info
 

I had a long discussion with an experienced MB consultant (he owns an MB authorized service shop)
He got surprised when I tried to learn about the 722.6 issues.
He said that, for sure, that specific transmission NEVER faced specific problems.
What is odd: MBs are relatively rare in Brazil, as they are expensive (at least twice the US price. Sometimes three times) but 1997 was a very good year because of a favorable Euro Vs Real exchange rate AND a tax reduction on imports.
My conclusion: possibly this is an issue more connected to cold climates.
This may be of some help for you in the US discuss alternatives.
And, if true, is good news for the floridians.
Regards, Jorge
PS: He was not trying to hide anything. We discussed openly other issues.

I'll tell you that my 99 E320 with the 722.6xx whined quite a lot when the temp was minus 15 F. In fact, it made enough noise before warming up, that I've decided to have the fluid changed at the dealer's again. It was done one year and 25,000 miles ago. Now that the weather is warmer, there is no noise at all at start up, but fluid is cheap, why not change it?

Couldn't agree more.
Again, filter is also cheap.
And if we have one of the early 722.6 without pan magnet: it is also cheap.
In other words: cheap to protect. Expensive to fix.
The choice is quite obvious.
Jorge

Reading these had brought up a question, or two.:confused:

First, when did the bearing change to a bushing? I have read a few articles about a bushing self destructing and the residual copper like remnants being found in the pan. It is related to the planetary gear. Is this the same item?

Second, about the magnet. I have a 2000 and am planning on changing the fluid when it warms up a bit. It sounds like I will not find a magnet in there. Where and how is the magnet attached, and is there a part number for same?

Thank You,
Ron Young
2000 E320 @ 70,000K miles.

Stymied