douglas_scott

I have a 2011 Mercedes E550 Coupe that i bought 4 years ago and have really enjoyed. It only has ~60k miles on it but the local dealer (which is high volume and in Dallas) has informed me that the transmission has been ruined by some coolant from the radiator leaking and making its way into the transmission. There was no warning or progression - it went from driving fine to trembling on every up-shift. Anyway, the dealer quoted price to replace the transmission and couple other things that were part of this malfunction is over $10,000. The worth of the vehicle is probably not a whole lot more than that, so that is not an option.

My questions are:

1. For many other makes and models, it is common to just repair or rebuild transmissions, as opposed to replacing with a new one. Is this true with the transmission paired up with the 5.5L engine in the E and S classes?
2. If this rebuild or repair of the transmission is an option, does anyone know of any shops in the Dallas area that are known to have experience in this kind of work for Mercedes transmissions?

Thanks for any input you may have.

chassis

Coolant contaminated the transmission? Is that the root cause? What is the reason for recommending transmission replacement? Seems like it could be more than is necessary.

What about a fluid flush and filter replacement, as a first step?

douglas_scott

@Chassis, Thanks for the sanity check on this. It does tremble pretty bad on the up-shifts, but does shift. It happened abruptly, totally fine on Thursday but started doing this on Friday. It's only been driven to the dealership for diagnosis since then. Calling around to some non-dealer Mercedes shops inn the last couple days has led me to believe that this may well be overkill is very possible.

While I do trust the dealer to provide a correct diagnosis of root cause, I think the allure of making repair costs so large that a new car purchase seems the only real option is too tempting for them. I've always been told most dealerships of all makes are more interested in replacing than attempting to repair.

They were leading me around the lot to show me new cars before I even received the diagnosis and estimated repair costs.

chassis

Red flag-showing you new vehicles. Go to another dealer or an independent shop.

Fluid drain and flush, plus filter replacement, would be my next step.

douglas_scott

@chassis, Thank you very much for the advice. It is appreciated.

exhaustgases

Coolant not a good thing in a transmission. First thing if it is true and they aren't just bluffing, is to replace the radiator, because the transmission cooler is the only way for coolant to get in the transmission.
You could try just a good fluid change but if the torque converter has no drain then its not worth trying. It is the Remove and Reinstall of the transmission that adds to the cost to overhaul or rebuild of your transmission, the cost of parts etc. The low cost route is to find some transmission moon lighter guy, and carrying it in will be the cheaper way to go. But then someone does the R and R as mentioned above.

chassis

Do you DIY? It would be a fun project IMO if the vehicle is not a daily driver.

The high volume dealer in a large metro will have less appetite for a lengthy rebuild or repair, compared with possibly hungrier independent shops or an MB dealer in a smaller community.

douglas_scott

Thanks for the feedback. It turns out transmission shops will not touch the 722.9 transmission due to the locking codes and whatever programming it requires, I have it in a local independent shop that specializes in Mercedes and they seemed confident in their ability to put a rebuilt one in. I did have to authenticate myself as the owner with my DL and registration, as well as sign a couple forms to get this part of it completed. It's still expensive, but several thousand less than the dealer price for the same work.

chassis

Sounds like progress. Please post an update when you have the car back on the road.

bigpapaporsche

I am a retired Diesel Mechanic (50 years) and have been trained in both Diesel/Gas engines as well as AutoTrans. Currently we have a 2010 ML 350 and a 2017 Sprinter RV Chassis. From what I understand of the situation, it seems the original problem was the A/T Cooler Leaking Coolant into the fluid, thus contaminating the A/T Fluid. This needs to be corrected first, probably with a rebuilt/new Radiator. Or, if you wanted to try something a little cheaper you could install an Air to Oil Cooler. This option however wouldn't be worthy of a MB, but it could sever as a TEST. I would then recommend a thorough A/T Fluid & Filter Service, paying particular attention to the old fluid and any material inside the A/T. Note, there is a very good video on Youtube showing how to Flush the fluid even though there may not be a Torque Convertor Drain Plug. Note, be aware that any present of Coolant inside the A/T can be very bad news depending how long it was there. It is very corrosive and can lead to bearing failure! If you experience improved Shifting Quality after this exercise I would flush the fluid again without the filter. I would put a 75% on it working.