Hello - First poster here,
Let me begin by saying this post should never have needed to be written, but I accept responsibility for it. I have owned my E320 for 8 years, and the original trans was not the best when I got it.
My original M104 722 trans had fully lost reverse, so I located a reasonable used unit (correct 1995 model) to install. It was not guaranteed, but I believe it was sound. My local mechanic suggested I use another local shop to do the swap, and could receive his shop-to-shop rate for the work. I decided to go this route instead of swapping myself, on my back.
It was swapped without apparent incident, Maxlife Dex III was used and a new filter was installed, with the plans to do another fluid change in 5,000 miles to be safe. I did not double-check how much fluid the shop filled the transmission with when they handed me the remaining fluid in its container.
The transmission worked fine, much better forward than the former unit, and had decent reverse function and engagement.
Today, reverse acted up, acting as though it was engaging both reverse and forward gears at the same time, in reverse only. I checked the fluid level, when hot, and it had been overfilled. I had to drive 90 more miles to get home (have put 1,800 on the fresh install), siphoned out perhaps 2 quarts (!?!) of overfill, topped it up to the correct level with fresh fluid and prayed. I nearly cried when I realized they had overfilled the trans that much, and I hadn't checked their work. The fluid, only 1,800 miles, did not smell burnt, or feel like it had shavings in it, but was not fresh and red, and will be completely drained and a fresh filter installed in the next few days.
The current status is: reverse engages, cool and warm both, and the car rolls backward as it should. If I apply throttle, it feels as though forward gears are also engaging/trying to engage, it halts the car from moving, and applying additional throttle does nothing except cause some slippage. One time, it sounded as though their was something grinding, so I immediately stopped that line of testing.
Please let me know if there is anyone with any experiences in this arena, and if I may be able to simply replace some seals with the trans still in the car, or if I'm staring at another removal due to my lack of oversight and trusting nature.
Thank you

My first step would be to contact the shop that installed the replacement transmission, describe your findings and ask what the shop intends to do to make things right. Presuming the shop intends to do nothing, then stop doing business with that shop immediately. Hard to believe any shop would overfill a transmission by 2 quarts. There is a standard procedure for refilling a MB transmission that the shop personnel could easily have read online. Obviously that shop's personnel lack attention-to-detail. As I tell my sons regularly ... "just because a person earns their living doing something, does not mean he/she is competent."

__________________
Fred Hoelzle

I agree, Ferdman, but I think i figured out how they arrived at that fill level. The level appeared correct on the dipstick when the stick was inserted with the cap lock flipped down so it hung up on the ring around the neck. But that's not the correct way to read it - it is supposed to be inserted fully, buried, before the lock is clamped. Either way, I had them installing an unproven, used transmission. I intend to let them know what happened, but don't see that as being productive to resolve my current state of affairs, and don't want them touching it again. My update is excellent forward response, a total loss of reverse now when hot, with a curious 'leaking' sound when attempting to engage, that stops when I engage drive then shift back to neutral. It had good response before the failure, no slippage, quick engagement forward and reverse, etc. What seals/piston do the experts think I should I start exploring first? Once again, when engaging reverse, it did engage until I applied throttle, then felt as though it was engaging both reverse and drive. It seems like this might be something that I could repair, perhaps with the trans still in the car. Or maybe I'm crazy. But I just reworked the ETA/ASR wiring harness and it was screaming without any issues and I don't want to walk away from this car based on my misplaced trust ... thank you ...

Three links on this thread lead to the trans FSM.


W124 Automatic transmision diagram ? - Mercedes-Benz Forum

Thank you, MCallahan - I have found those, and will find them quite useful should I be faced with a complete tear-down. What I'm seeking is anyone who might be familiar with the gross negligence I've experienced, and if there is a repair method that doesn't require starting over - the trans was working fine for a short period after installation, until something (likely a seal from pressure issues) let loose. I've found this bulletin and am wondering if this might be the key to my issues: http://www.europeantransmissions.com/Bulletin/DTC.merc/97-20.pdf
Any input is appreciated. Thank you ...