Captain Carling

I just went down to my friends garage for a service on my 2012 C63 Coupe.
I had bought all the parts needed for the tranny from my local Merc dealers including the tranny oil.
This was the first time we have attempted this on my car (don't worry, these guys work on GTRs, Mclarens, Lambos etc so they are well respected).
We followed the procedures for removing the oil and sump, but we were surprised that we only drained off a measured 4.5 litres of fluid.
The car has only done 19000 miles and has never had the tranny fluid changed from new.
My question is, how come the Dealership sold me 8 litres of fluid when I only needed 4.5?
Am I missing something?

Vladds

With the previous 7 speed, a good portion of the oil is drained from the torque converter, in a separate step of the procedure.
I can't see in the WIS anything that reads clutch pack oil draining, but the same step of draining the oil from the 7-g tronic is still there.


BTW, every article, every comment about the MCT cautiously reproduces, word by word the same phrase, regarding the differences between it and the 7g TRONIC.
It is a bit confusing how this phrase references a single "compact wet start up clutch", while the name of the transmission is multi-clutch-technology.
In the video about MCT, I see several clutches inside of a housing, the back of which looks like a torque converter back.
So that's what shows through the transmission porthole, the back of the converter and that's where the drain plug would be.
Maybe this has a drain plug too.
If the procedure is the same and Mercedes did not bother to change the steps in the WIS, by renaming the Drain the converter into drain the compact clutch pack, then this means that the compact clutch pack is fed the same oil as the transmission, in the same quantity as a torque converter.


So the following is up to you:


See if there is a port hole at the back of the bellousing of the transmission and if there's a rubber plug over it. If so, remove it.
If what you see afterwards is looking like the back of a torque converter, turn the engine in the normal rotation direction and look for a drain plug.
Then open it and collect the oil.
If this oil was to be different than the rest of the MCT transmission, there would have to be a separate "fill the clutch pack" procedure, possibly even more complicated than filling the transmission and there would have to be a "clutch pack oil" that you'd have to buy, as well as a change clutch pack oil maintenance line item.
If you can't find any of these, it probably means the clutch pack runs transmission oil and you are safe to drain it.


Good luck, post your findings.

roadkillrob

You definitely only got about half of it out, so it is somewhere, I looked over the docs also and in the 7G you would get half out of the pan half out of the torque converter, so would seem the other half in the MCT would have to be in the wet clutch packs somewhere, but don't see any reference to how to drain.

nobbyv

You should get about 5.5 litres for the TC-less MCT on your '12. The dealership sold you too much. My bigger concern would be did they sell you the blue fluid or the red, since they sold you the amount of fluid needed for the TC MCT? You want the blue.

EDIT: posted wrong fluid color.

Captain Carling

They sold me blue, and it was blue what we got out

nobbyv

Hmm, maybe the TC-MCT stuck around longer in the UK? Here in the US, all 2012's got the converter-less MCT, and it takes red fluid (did it myself). If your car DOES still have the TC, then the others are right, you need to drain the TC to get the remainder of the fluid. There is a separate drain for that; you have to remove a rubber bung to get access to the view window, then have someone but a breaker bar on the crankshaft bolt and turn the engine until you see the TC drain plug. Think it's a ~5mm hex bolt.

quaalude

Blue is what you want. Red is for the older TC 7G transmissions. Here is the MB part number for the ATF fluid: 001989780309.

nobbyv

You're right, I was mis-remembering. The non-TC cars take the blue.

Captain Carling

Thank you for clearing that up for us

ilovemybenz

Does this transmission call for removal of the transmission assembly for service? Prior to my ownership, my car had a transmission service done that involved removal of the unit. I’m curious.

Mort

No, but it does require removal of the pan.

Panzerbiscuit

Not to Hijack the thread, but can Ceratec be used in the transmission as well as in the engine oil?

Catchyname

You dont want to modify the friction in a gearbox.

Panzerbiscuit

I thought that was the case. I read on the back of the Ceratec box that it was suitable for gearbox and engine oils, just thought I'd check.

BLKROKT

I could be wrong, but I thought I saw a recent Tasos video where he had to physically puncture the filter in order to get the full capacity of fluid out of the trans.

Catchyname

Possible fine in a dry clutch manual, definitely wouldn’t use in an auto or wet clutch box.