HELP!!! Transmission Oil Change: Torque Converter Drain Plug Access Problem
MBWorld Fanatic!
Joined: May 2017
Posts: 1,234
Likes: 155
From: Montreal/Cape Coral FL
2012 X6 35i Sport, 2013 ML 350 BT, 2019 4Runner TRD Pro, 2020 CRV-AWD
I've got only 20k miles on mine, so no need to worry about flushing the tranny just yet. I'll flush at 60k miles, curious to see what the oil looks like then
Super Member
Joined: Mar 2009
Posts: 561
Likes: 72
From: Las Colinas (Irving, Texas)
2024 GLE 63 S AMG SUV
The Maintenance Book says to change the Automatic transmission fluid and filter at 70k miles 
2013 M Class Maintenance Manual
2013 M Class Maintenance Manual
Junior Member
Joined: Mar 2014
Posts: 25
Likes: 2
From: Renton, WA
'11 Merc C300 4M, '15 ML350 4M
CTA-7650 722.9 Flush Tool
Did anybody tried this CTA-7650 tool for flushing transmission oil from 722.9 on W166 (Since TC plug is hard to access)?
http://www.ctatools.com/index.php?ro...roduct_id=1687
I think their tool plugs into trans filter port and use pressurized air to push out fluid from
T.C. and cooling lines... Anybody?
Last edited by Szelas73; Jun 18, 2019 at 03:05 PM.
Super Moderator
Joined: Dec 2006
Posts: 2,403
Likes: 64
From: Camas, WA
2007 C230SS; 2014 ML350 BT
I did the transmission service on my 2014 ML 350 Bluetec a couple of months ago, and it was very straightforward. I have done my W203 many times, so I am familiar with the process (I wrote one of the early guides to servicing the 722.9 on the W203 forum.) The W166 was essentially the same. It just had two minor issues that I didn't have with the W203. First, the two rearmost pan bolts are a little difficult to access and get at with a torque wrench when replacing. Second, is the crossmember is in the way and ATF covers said crossmember and runs all the way to both ends, making a rather large mess of ATF. But, the torque converter drain plug was relatively easy to access and replace during service with a long hex bit on ratchet.
Junior Member
Joined: Jan 2016
Posts: 22
Likes: 0
2011 GLK 350 4Matic
Peter,
Coincidentally I am changing the filter and fluid in the transmission of my W204 C63 AMG tomorrow and looked up the procedure in the MB WIS Service manual. There is a flushing procedure exactly as you stated. Good job!!
The service manual "WIS - Workshop Information System" for the W166 does not list a way to flush the transmission without using the transmission rinsing device.
I find this kind of strange because the service manual for my W204 C63 AMG lists a way to flush it the way you stated and it also shows using the transmission rinsing device which is the exact same procedure for the W166.
When you use the transmission rinsing device per the service manual, on either vehicle, it does not mention changing the filter which is again weird.
The transmissions are similar but not the exact same model since my C63 has an MCT Multi Clutch Transmission which is a wet clutch setup instead of a torque converter. They are both listed as 722.9 transmissions.
I have attached the .PDF files for the procedures for the W166 and W204 so you can see the different procedures they list.
I do not see any reason you could not flush the transmission on the W166 the way it is described in the .PDF file for the W204, which is the way you suggested.
Coincidentally I am changing the filter and fluid in the transmission of my W204 C63 AMG tomorrow and looked up the procedure in the MB WIS Service manual. There is a flushing procedure exactly as you stated. Good job!!
The service manual "WIS - Workshop Information System" for the W166 does not list a way to flush the transmission without using the transmission rinsing device.
I find this kind of strange because the service manual for my W204 C63 AMG lists a way to flush it the way you stated and it also shows using the transmission rinsing device which is the exact same procedure for the W166.
When you use the transmission rinsing device per the service manual, on either vehicle, it does not mention changing the filter which is again weird.
The transmissions are similar but not the exact same model since my C63 has an MCT Multi Clutch Transmission which is a wet clutch setup instead of a torque converter. They are both listed as 722.9 transmissions.
I have attached the .PDF files for the procedures for the W166 and W204 so you can see the different procedures they list.
I do not see any reason you could not flush the transmission on the W166 the way it is described in the .PDF file for the W204, which is the way you suggested.
I just want to know if the procedure can be apply on a GLK 350 2011 - 4 matic,
in 2015 they change oil in the transmission so i'm pretty sure i have RED ATF fluid and the white overflow plug.
But i'm not sure how to remove oil from cooler and the TC, So the x204 and the W204 procedure is the same ??
and i want to know also what is this item : 129 589 00 91 00
Do you have the Part number for the overflow refil adapter ?
Thank you master !
Newbie
Joined: Sep 2019
Posts: 12
Likes: 1
From: Wisconsin
2015 ML350 W166 and 2006 SLK 350 R171
where you got your replacement parts?
I did the transmission service on my 2014 ML 350 Bluetec a couple of months ago, and it was very straightforward. I have done my W203 many times, so I am familiar with the process (I wrote one of the early guides to servicing the 722.9 on the W203 forum.) The W166 was essentially the same. It just had two minor issues that I didn't have with the W203. First, the two rearmost pan bolts are a little difficult to access and get at with a torque wrench when replacing. Second, is the crossmember is in the way and ATF covers said crossmember and runs all the way to both ends, making a rather large mess of ATF. But, the torque converter drain plug was relatively easy to access and replace during service with a long hex bit on ratchet.
Also would you say these steps represent the same process I can follow to replace the fluids: https://www.rmeuropean.com/mercedes-...placement.aspx
In many videos I see this same process and I don't see any issues with the TC drain plug. Not sure why there is so much confusion.
Senior Member
Joined: Feb 2018
Posts: 482
Likes: 140
GLK250 ML350
Hi, I have a '15 ML350 I haven't find a site to get the torque converter plug. Could you share the part number or link to the place you can get it?
Also would you say these steps represent the same process I can follow to replace the fluids: https://www.rmeuropean.com/mercedes-...placement.aspx
In many videos I see this same process and I don't see any issues with the TC drain plug. Not sure why there is so much confusion.
Also would you say these steps represent the same process I can follow to replace the fluids: https://www.rmeuropean.com/mercedes-...placement.aspx
In many videos I see this same process and I don't see any issues with the TC drain plug. Not sure why there is so much confusion.
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Newbie
Joined: Dec 2021
Posts: 3
Likes: 0
2013 ML350 4matic
Thank you for posting. After hours of searching the internet I stumbled upon this. Did you ever drain the TC? Getting the drain out I might be able to do but getting it back and torqueing is not happening so I have move on. What about draining the cooler hose???
Member
Joined: Dec 2019
Posts: 140
Likes: 25
Mercedes 2013 E350 4matic, 2013 ML350
It is possible to open that tc bolt. But you have to use drill to enlarge hole directly close to bolt. I did it for w212 2013 e350 4matic. But when i did for w166 2013 ml350 it torqued so strong and maybe the thread lock used is strong so it cause the etorque hole damage so i stop and just do transmission replace without opening tc bolt. actually the procedure put more oil so it do flush it in some way
Newbie
Joined: Dec 2021
Posts: 3
Likes: 0
2013 ML350 4matic
It is possible to open that tc bolt. But you have to use drill to enlarge hole directly close to bolt. I did it for w212 2013 e350 4matic. But when i did for w166 2013 ml350 it torqued so strong and maybe the thread lock used is strong so it cause the etorque hole damage so i stop and just do transmission replace without opening tc bolt. actually the procedure put more oil so it do flush it in some way
Newbie
Joined: Dec 2021
Posts: 3
Likes: 0
2013 ML350 4matic
[QUOTE=pete87;6743684]
That's correct but I still haven't been able to access the drain plug. It's at a very bad angle and no tools will fit the hole. I can't imagine putting the bolt back in if I was to successfully remove it.
Other posts mentioned that dealerships required taking out the transmission in order to drain the torque converter and charge over $1000 to do a full transmission oil drain.
Did you ever find a solution??
That's correct but I still haven't been able to access the drain plug. It's at a very bad angle and no tools will fit the hole. I can't imagine putting the bolt back in if I was to successfully remove it.
Other posts mentioned that dealerships required taking out the transmission in order to drain the torque converter and charge over $1000 to do a full transmission oil drain.
Member
Joined: Dec 2019
Posts: 140
Likes: 25
Mercedes 2013 E350 4matic, 2013 ML350
I mean the procedure in WIS when filling the new oil it is 2 quart more than the volume release from trans. So it is already flush the old oil because it replace the old oil until it drip before close the drain plug. I think the reason MB didn't recommend open tc drain plug to avoid damage that very small drain plug and avoid if not tighten properly it leaking and can damage transmission if low in trans oil. So the procedure if you follow you will put more oil than needed so it will push the old oil partially.
follow this youtube how to enlarge hole under tc drain plug
https://youtu.be/M6QQ6El-G1k
I have to do same for my e350 2013 ang ml 350 2013. So you can open tc drain plug and tighten from same hole in bottom.
follow this youtube how to enlarge hole under tc drain plug
https://youtu.be/M6QQ6El-G1k
I have to do same for my e350 2013 ang ml 350 2013. So you can open tc drain plug and tighten from same hole in bottom.
Last edited by andynmaas; Dec 4, 2021 at 08:18 PM.
