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.