As much as I see people mention the torque converter drain, I figured I'd try it. It was a regretful choice. There's no way to reliably get to it except with a right angle hex key. I even remove the two E14 (connects to the bell housing) and 13mm hex bolts for the exhaust hanger and it just barely cleared. You can not use the bottom port that is covered by the electric pump. I also droped the new plug INSIDE the bell housing and spent 30 minutes trying to fish it out with various picks and tools. Luckily I ended up getting it out without losing the washer. Also need a big 27mm socket to turn the crank. It made a huge mess.

I guess that’s why my mechanic said he could not do it and drained it twice , he had me take it home a few days then bring it back .

Do you recommend eventually doing it just not every single time?

I would only do a full drain if there was coolant intrusion from the radiator or transmission out/rebuild. I'm not sure if the earlier transmission has a bigger (circular) port or if the screw plug was at a different angle. The workshop instructions gives two different screw plugs torque specs. My 2015 build has the M8 screw plug. When I drained the ATF, it was pretty clean. So the magnets and filter are doing it's job.


If you do choose to tackle this endevour, I recommend a stubby 4mm right angle hex key. Depending on the brand, this can allow you to loosen the screw plug at the circular bottom port.


The estimated amount drained from the torque converter was between 2.75 liters and 3 liters. (I poured the old ATF into the new empty 1 liter bottles to check capacity)

I see, my thinking was, fluid eventually does go bad (the sealed for life transmission drain intervals backfired for MB) and eventually we should still replace the fluid in the TC.

Yes you should change it eventually, but even dealerships don't drain it on a regular basis as part of B7 service. If you really wanted to do a through drain then you would also disconnect the hard lines and take out the solenoid plate.

It is very difficult to DIY, especially without a lift. Honestly its just super risky if you lose the screw plug inside the bell housing and can't fish it out.

Thanks for this image.

Huh I just discovered the Liquimoly Top Tech 1900 is NOT approved for the 7G transmission. I just purchased it from FCPEuro's first result without really looking.

FCP shows the 1900 is approved for the 722.9. In my 2013 I put in the Liquimoli trans fluid 1900 from fcp years ago. Is this wrong ? I see the blue fluid is after 2010 in a simple google search. I am going to look at what I have left in the bottle to check color.

I just checked my 1/2 empty bottle of Liquimoly 1900, it’s blue and the proper color for a 2013. I think red is 2010 and earlier , but I’m not sure. I do believe 1900 is correct for my 13 , and is good for 2010 and later .

If your build sheet shows code A89 you need MB 236.15 spec fluid.

The liquimoly 1900 is NOTan approved item as of FEB 2025 via the official website. That's the FCPEuro kit I bought.

https://operatingfluids.mercedes-benz.com/sheet/236.15

I'm not too concerned. Blue drained out, blue goes back in. Smells and feels the same. Shifting smoothly like before. Just figured I mention it. I'll try the cheaper Fuchs TITAN ATF 7134 FE (or whatever is on sale) next time around.

Huh that is strange indeed, what does MB say?

Oh hmmm thanks for the heads up, that was the site I was about to look at as well.

Was A89 high or low resistant?

Here is a good article: https://www.fcpeuro.com/blog/how-to-...smission-fluid

Is there a mb approval certification number on the bottle itself? If so, what does it say?

?
A89 is "Reduced Friction"

whoopsie I mixed it up with something else sorry about that.

The FCP Web site says:
Approvals:
MB 236.15

Which would lead one to believe it has been approved by MB. I wonder if it really means "we say it meets the spec"?

[Edit] I see the label says "[we] recommend..." Probably OK, but...

Yeah weird. I guess in this scenario filling the transmission with the "incorrect" fluid does benefit from a full torque converter drain 🤔.

https://mbworld.org/forums/c63-amg-w...-approval.html

Somebody reached out to Mercedes-Benz and they just gave a vague response.

Thank you for the label, so "recommended" as another forum member mentioned.

Probably have to then.

So looks like 2013, 2014, 2015 have the three port housing A2222705801. Older years have the two port housing A2042710800 or A2042710501. So if you have the pre facelift GLK, you should absolutely do the torque convertor as the port is very wide.