I got a "really" good deal on a 1999 S320 with 99K miles on it. I was in a bit of a hurry to get the deal taken care of and failed to get the car inspected in the process. After a few weeks of driving I notice some "quirks" in the transmission and suspect that I don't have long before I need a rebuild or a replacement unit.

The transmission has done some odd things some I have read in the manual are normal some are definately not normal. At first the way the car held the car in low gear when it first started freaked me out until I read in the manual the computer does that to warm up the emissions system. From there I have had a few other "oddball" encounters. One time out of the driveway when shifting from reverse to drive there was a delay. I pressed on the gas and the car lurched forward when the gear engaged. The worst one and the big confirmation for me was my experience on the interstate today. I was going about 75mph and this guy in a Lexus was going to attempt to pass me and cut me off. I accelerated and the transmission dropped down a gear and got "stuck". I was holding 4000 rpms pretty steady and the car would not shift. I removed my foot from the gas and the car still would not shift. I switched into neutral and then back into drive and still could not get the car to let go of the gear it was in. I eventually pulled over and put the car in park and shut the car off and turned it back on and everything was normal.

I talked to my mechanic this morning and they indicated that this was common on these cars and normally the onboard diagnostics would flag it and complain on the display in the car. Other than these two events the car has been almost flawless. I have noticed some odd shifts but Im not sure if its me being overly sensitive to the issues with the car. I have yet to get any display errors and wonder how long I have until this problem reaches critical mass and if I would be doing any additional damage by driving the car.

Advice is welcome especially from people who have had a rebuild done. I do intend to have the car repaired because even with the out of pocket cost of the repairs the car is still a wonderful car.

When was the trans fluid last changed? Have it done, you may find that some of those problems get a lot better.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Yes Actually my call was to schedule the transmission fluid change. The Mechanic indicated that these transmissions run synthetic and that changing the fluid probably would not solve the issues like with the older transmissions.

On a Newer Mercedes Im flying blind unfortunatly and don't have much info. The flexible service system and synthetic engine oil have already thrown me for a loop. Supposedly your supposed to get 13-15K out of an oil change.

I wouldn't wait 13k-15kes to change the oil if you want to keep the car. Also if you are going by FSS you better make sure to run Mobil 1 0w40 or something from Amsoil.

Over at MBworld they said it best:
Follow FSS on the leaser, for the keeper change every 5k+/- miles.

Also the trans is according to MB filled for life. Their is a lot of info on this site about them. You have to use the MB trans fluid. You need to buy the dipstick tool, and you also need some way to measure the fluid temp You have to check the fluid level at a specific temp, proper fluid level is critical for shifting.

My friend had his E300D done at the dealer for like $200, it shifted better with the fresh fluid.

Don't be in such a rush to rebuild it, think $3k-$5k for a rebuild.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Hmmm,

I think I will have the fluid changed. In a worst case scenerio it could buy me some time. I read that the synthetic fluid has a 100K lifetime anyway and its getting to be about that time. Ill keep you posted as to what's going on. Would you get the independant to do it or go with the dealer?

I have no experience with the W140's tranmission.

However, transmissions are usually rebuilt because their clutches or bands wear out and/or their valve bodies get contaminated and won't allow the springs and valves to move.

In your case, the transmission works flawlessly, most of the time. Every so often, given a specific set of circumstances, it fails to shift. Then, when shutdown and restarted, it performs flawlessly, yet again.

So, your problem is almost certainly one of control of the transmission via it's computer and/or various sensors. It's very unlikely that the internal components of the trans require a rebuild. If so, the "problems" would be apparent every time you drive it.

80k-100k seem to be what most people agree is the mileage that it should be changed.


As far as indi vs dealer well that depends. We have a great local dealer so my friend used them, price out a tranny fluid change $200 is a good price.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Please check this thread about changing the transmission oil, not for the faint in heart, though: 1999 S500 with 722.6 Automatic Transmission Filled for life?

The electronically controlled transmission _sometimes_ behaves strange. It is an adaptive control system which might make wrong decisions occasionally.

Just have the oil changed by a specialist and enjoy.

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S320L -97

Hmmm,

Kinda of scary about the sealed transmissions. Even with synthetic fluid a car needs new fluid in the transmission. Perhaps its a way of maximizing profits. Im sure cars like my 126 are not very profitable to them in the aftermarket for anything other than parts.

Speaking of profitable service. I was quoted $1460 by my local dealer for a 100K service on my car. A "B service" at $460 and $1000 for spark plugs. My Independant will do a B service for $200. Spark plugs I would do myself for the cost of parts. Perhaps the dealer does not want "old clunkers" like mine on their lot?

As for the electronic issues that makes a lot of sense. I also read about the downshift switch sticking in another post which might explain my 4000 rpm experience today on the interstate. I don't know a lot about this transmission but certain Volvo computer controlled transmissions have to "learn" your driving style. Perhaps its getting confused between me and the previous owner.

Im going to get the car down to the independant as soon as I can and get its service work done and get its transmission fluid changed. Ill talk to them about the transmission fluid and make sure they understand what's all involved first. I may even go and buy the correct fluid and bring it with me to save them a trip.

Do it yourself! S320's are cake to work on.

Buy the oil filter wrench from MB its only like $30. The filter is right on top and comes right out. Either drain or suck the oil out whatever you prefer.

The air filter is like right their. Also the coolant is well no different really then changing the coolant on your SD.

The spark plugs cost $2 each from the dealer and are right on top, took me about 15 minutes to change them.

Don't forget the air filters behind the glove box.

Flushing the brake fluid is just like any other car.

The serp belt looks a bit hard to change, I have not looked at it closely. Also the fuel filter I have yet to locate.

Not really all that different then your SD really.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Here are some pictures I took of a 722.6.

http://www.mbnz.org/forums/forums/thread-view.asp?tid=1256878&posts=12&fid=13

I have been reading about the operation
of 722.6 all easter, from;
http://mb.braingears.com/W210/w210/transmission7226.htm , and I also think your
problem is related to a malfunction of some
of the sensors, that will cause a error core
on the ETC. Have you error codes checked
at a dealer.

Still amazed about the complexity/simplicity
of the 722.6.

br,
syljua

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1998 CL500 W140
1984 230E W123

Thanks for the information on the transmission. It gives a LOT more information about this transmission and makes it seem a bit less scary. It seems that the "excitement" that I had on the interestate was probably due to an error code of some sort and my turning the car on and off reset it. I am going to do some more reading and get to know my new transmission.

The more and more I learn about the 140 the more and more I realize how complicated this car really is. My 126 is simple in comparison.