"Sealed Transmission"??

I was told the other day that my 1998 C230 MB has a "sealed transmission" and almost never needs to have a fluid change. The MB dealer last year told me that it is good to change out the fluid every
50k miles. Who is correct? I changed out the fluid using the MB fluid (expensive stuff) and now wondering if I did the correct thing. The only thing I can amagine is if inert gas is pumped into the system to prevent oxidation?? Of course I did pop off the red plastic cap when I added fluid after a complete fluid drain from the pan. Please explain as I am confused. I guess I better buy a CD for service details for $300. Thanks.
Larry/ San Diego
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MB recommended Trans fluid changes at 30k miles for earlier models. I have been told that MB had to deal with a lot of problems caused by people overfilling the transmissions. They went to a sealed approach to preclude these problems and the resultant grief and aggravation.. It is a good idea to change out the fluid to get rid of the contamination that builds up. Also the filter should be replaced. 50k miles is probably appropriate unless the car is driven in extreme climates As far as trans fluid is concerned the good american stuff meets the specs for MB.
Peter

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Peter W Peternouschek wrote:

What models were those? Just about all auto manufacturers have recommended that for normal driving conditions, no transmission service was needed until 100K. The only place I've ever seen telling people to do it at 30K were the quick lube oil change places looking to make an extra buck.
I have

I've also heard plenty of stories where trannies worked perfectly fine, until people fooled around with them by doing unnecessary maintenance. It's another opportunity for someone to drop some dirt, gasket material, etc in. Or overfill it, as the foreign car repair place that I use did on mine. I've never changed tranny fluid in any car I've owned till 100K miles and never had a problem.

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Almost all mercedes transmission until the last eight years or so have reccomended service at 30,000 miles, and if you do it properly, the trans will last an extraordinarily long time.
Overfilling is a big problem with the trans service, and one has to be very careful when refilling the trans to just put the fluid level between the marks and no higher.
As for service on the newer transes, the Mercedes Benz Club of America technical adviser suggests the same maintenance schedule as the older transes be performed on the new transes since it is basically the same trans that used to be in the old cars and although the trans is "sealed" it still has a filter that has no value unless it is changed regularly at 30,000 miles.
My take on the thing is that it is a marketing ploy by mercedes. Since everyone else's transmission needs no service for 100,000 miles then neither should theirs whether or not that interval would improve or extend the service life of the trans. "Service" now is to replace the trans at 100,000 miles when it goes bad, which is a very expensive way to maintain one's car.
You did the right thing by changing the fluid, but how did you determine the proper fill level without a dipstick? The only way that I know to do it on one of these is to carefully measure the amount of fluid removed and replace with the exact same amount. Overfilling will still lead to premature transmission failure.
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O have the exact same model and year. My regular mechanic does virtually all my MB work. I asked for a fluid and filter change at 90,000 miles...no problems noted.
On another note, I am having a noise problem from the left rear quarter panel area. It sounds like something is loose, not metallic, but more of a thud. So far, my mechanic has not been able to find any problem. Anyone else experience this and have a solution? Thanks.
Sherm

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The torque converter also needs to be drained and the filter should be replaced. Peter

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Larry wrote:

Don't worry Larry. There is an amazing amount of misinformation here about this.
Basically these transmissions are a new design, unrelated to previous models that needed regular oil and filter changes. These new ones do not have brake bands fitted for a start. As for maintenance, Mercedes designed them to be used with special synthetic ATF and specified no set service interval. It turns out that the fluid manufacturer designed the fluid to remain within specification for a minimum of 100,000 miles, so it would perhaps be prudent to change the oil at that period. Only a proportion of fluid is actually changed at any one drain and this is why previous models had such regular changes. I wouldn't worry about it because ultimately you may find that the transmission fails due to something entirely unrelated to the oil or lubrication. There is no filter change either. If a filter blocks then the transmission has already failed, probably due to clutch packs delaminating or just wearing down to the metal backing. It could be argued that this type of failure could be delayed by a fresh dose of fluid now and again after 100,000 miles.
You have certainly done more than is needed as long as the correct fluid was used when it was changed.
Huw
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Thanks to Huw and all above. I am pretty certain I added back exactly what was drained. I didn't drain out of the torque converter but figure 90% clean would be pretty good. A "sealed tranny" can be confusing terms methinks..
Larry
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You figured wrong I'm afraid. It'd very important to drain the torque convertor too. Turn the engine by the crankshaft nut till you see the drain plug. Drain it.
Would you change half the oil in yur engine?
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Richard Sexton wrote:

Of course not all the oil is actually changed at an engine oil change, nevertheless..........
The transmission oil is changed for a different reason. Not because it is dirty but to keep a reasonable level of friction modifiers and other additives in the oil so the comparison is irrelevant. This is why a transmission service schedule almost never includes draining the converter or anally flushing the pipes and cooler. Do it if it makes you feel better or it puts money in your pocket by all means, but it isn't needed unless the transmission has failed and the system is full of crud and filings. In fact neither Mercedes nor ZF actually have any service schedule for these boxes except a simple [partial] oil change at 100,000 miles in heavy duty use. Driven hard they will fail at about the same point whether the oil is changed or not. In other words, failure is not generally linked to lubrication change periods in these boxes.
Huw
Huw
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No sir. I work at a MB-only dealership [over 27 years] and ALL transmission services include the torque converter draining. That IS part of the MB recommended @ every 30K trans service on all transmissions up to and including the 722.5. Things maybe different in the UK and at independant repair shops, but this is how it is done at MB dealerships in the USA. If you just do the pan and filter, you may get 3 qts of ATF. But there is another 3-4 qts in the converter.
wrote:

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Karl wrote:

How can this be true when MB do not have a service scheduled for this transmission at all at any time?
Huw
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Look... there is no such thing as" lifetime". Have you ever drained one of those "lifetime" fluid at 100,000 miles or so? I have on the BMW I own... and I'll tell you this... it is black... so full of sediments and primary reason my my tranny died... the valve body choked.
Once I replaced the valve body with a rebuilt one... everything is okay again with new fluid.
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Tiger wrote:

I am just telling you as it is. I have hinted that a change of fluid would be a 'good thing' around the 100k mark, but the fact remains that there is no actual service schedule for these things. FWIW I believe your car was very hard driven or has another fault which contaminates the oil. Even standard boxes with up to three services scheduled but missed to 100,000 miles generally don't have contaminated oil. Not the ones I am concerned with anyhow. Of course there is a hundred thousand miles and another hundred k and the duty could be completely different. All these things are subject to wear. If there is crud in the oil then please believe me that this has come from an internal source, which is where it differs substantially from an engine where the major proportion of the contamination comes from combustion and the results of combustion.
Huw
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Bullshit.
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Richard Sexton wrote:

Old Mercedes transmissions are almost unique in having a drain for the converter. There is no major difference in the principles of construction of these to any other automatic yet no other that I can think of drains the converter. Most of the others last as least as long as a Mercedes transmission on average. On all these others only about half the fluid is changed at a time and most even have longer drain intervals than 30,000 miles.
All this is not relevant to the OP because he has a modern, not antique, transmission which is of a simpler construction, less prone to wear and using synthetic fluid. It has NO scheduled oil change period, not even a level check other than a quick visual check for external leaks, but the fluid life is apparently 100,000 miles more or less. Now service geeks would love nothing more than to scare owners into more servicing of these things but they have been around now for nearly ten years and there are few complaints that I know of when just the standard servicing is carried out.
It would be nice to know how long the transmissions last on average [not a worse case] with zero servicing as per schedule. The longest I know of personally is around 180,000 and still going strong. I have no personal knowledge of early failure for any reason, let alone a lubrication failure, although I have heard of some. During a visit to the Jaguar factory in around 1997, there were a high reject rate on these Mercedes transmissions compared to the ZF before assembly for some reason. It could be to do with the quality of housings rather than internal problems because they were being rejected before installation in the vehicles [supercharged XK8].
Huw
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And when they do you damn well beter drain them.

Mine has abut 400-500K miles on it. Odo broke at 250K m about 6 years ago. I have the plastic gear to replace it but, well, you know...
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Richard: I forgot to add that I had planned to once again drain the tranny and add back new oil about 15K miles from now. This would bring "purity enriched status" of my oil back to nearly new status. Thanks for your input.
Larry Richard Sexton wrote:

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Larry wrote:

Maybe you should change it every time you change the oil, if you like doing unnecessary maintenance that makes you feel better.

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Trader4: I agree ... I just wanted a "come back" to address Richard's comment.
Larry snipped-for-privacy@optonline.net wrote:

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