Valvestud

Hi All,
For anyone interested, I did a transmission service on my Daughter’s 2011 C300, which has the same tranny as my 2010 C63. I made a couple of special adapters; one to pressurize an old 5 quart oil container, and one to do the temperature sensing and fluid fill. I also modified the top cap of the container to allow for pressure in and fluid out. At 2-3 PSIG, the container bulged but held OK. Pictures attached for all three. Since the car is under warranty I used all MB parts, but used Shell ATF 134 that I got for $5.90/quart.


The process, while not particularly difficult was very time consuming due to the requirement to make sure the temperature of the fluid was at 45 deg. C (113 F). It took forever once I got the initial fluid in before the temperature dropped below 113 so I could overfill and drain back to a dribble as per WIS procedure. I was fastidious about collecting all the fluid from the pan and torque converter. This amounted to just short of 8 liters. Having it to do over again…. and I will shortly when I do my C63, I will just put back in the amount I take out, plus a half a liter and then check and top off as required.


The temperature was measured on my Fluke DMM with a temperature module I found on surplus. I decided to put the thermocouple up through the fill fitting to get a better read on fluid temp.

Regards,
Joe

jvanbrecht

Interesting.

I just purchased the $80 pressure/vacuum pump and the 10$ adapter for the pan. As far as temp, I used a thermal IR laser type, it sucked, and since I did not do the TC last time, I am going to eat the cost and do it over in the next few weeks.

I did pickup a copy of Auto Enginuity software with Mercedes option pack and obdii adapter on ebay for $350 (retail is close to $550 I think for the base software and the mercedes option). It reads the transmission temp sensor, so I will use that over the external method.

glennhl

Valvestud, thank you so much for posting this. And you did a great job making those tools, I especially like the one with the thermocouple, very clever.

I just did my wife's C300 and I'm about to do my C63. I bought an adapter for the drain plug and put on a small globe valve along with a length of tygon tubing. I used a similar transfer method, but I used a 5 quart container that motor oil comes in and just drilled 2 holes in the cap. I inserted the tygon tubing in one hole and inserted an air gun from my air compressor in the other. Both holes were tight fitting on the tygon tubing and the air gun tip. I bled my air compressor down to 10 psi and then was careful to not blow too hard into the container. Worked like a champ.

I also wussed out, it takes a lot more effort to get to the torque converter drain plug. You have to remove a bracket to get to it and then have to rotate the engine to find it. So I used the GM method of replenishing the ATF, I only replaced 5.4 quarts out of the 9.4 quart capacity. In order to have the same effect of replacing it all, I will have to change the fluid more often, like every 24,000 miles. I probably won't go more often for my wife's car, but I will on the C63.

Other than being lazy, the other reason I didn't drain the torque converter is I know that a mistake there can be extremely expensive. It probably would not happen, but if I stripped the plug, I would be looking at pulling the tranny. I just didn't want to go there. And my experience is that every other auto tranny car I've owned has never had a torque converter drain, I just replace the fluid in the pan and I've never had trouble.

One other thing, most of the threads I saw here used 45C or 113F as the temperature you have to get to for setting the fluid level. I figured there has to be a range and I knew I wanted to shoot for the lower part of the range in order to not under-fill the tranny. I used a multimeter that has a thermocouple to determine the temp. I taped the thermocouple to the bottom of the pan. I opened the globe valve when it got to 41C, let it drain, and pulled the adapter and replaced the drain plug. Temp got to 42C as I finished up.

I did some more searching to find out what the range is and I found this thread:

https://mbworld.org/forums/clk-class...ce-thread.html

The range is 40 to 45C. So everyone that is shooting for the high end could be slightly under-filling their tranny.

Mort

Appreciate the posts and information on changing the transmission fluid. Even to the point of making some useful and imaginative tools to get the job done. MB has managed to make this service much more complicated than need be just by removing the the dipstick and fill tube. And to what purpose? Nice to see more members tackling this job.

Ingenieur

Anybody do this?
Have 11 qts
Do a change w/o converter
60% new 40% old
Run engine & shift gears
Do another change
76 new 24 old
If you did it one more time
85/15
Wastes some fluid but gets the whole system
And sounds easier than messing w/ torque convertor

jvanbrecht

Very costly too, especially if you go with OEM vs the Shell fluid (which is not actually fully synthetic).

It really is not that hard to drain the TC, as long as you have the right tools.

Merc63

TC is one Allen head bolt from the access port with a swivel.

Ingenieur

You don't have to remove any cross members or such?
Just turn the engine for access?
Thnx

motoman

The TC plug does deserve respect. Be sure to get insertion into the allen opening and square off. I did a small relief grind for the rachet driver. A lot of dirty (swarf) fluid comes out of the TC. When replacing plug "back index" (unscrew motion) until the threads drop in and align before tightening first by hand. From cold takes 45 min idling to achieve fill temp.

Ingenieur

Back index
Haven't heard that term for a while
You need to do it to seat Panerai strap screws lol

glennhl

I just did my wife's C300 and I chickened out with draining the torque converter. First off, you need to get someone to watch for the drain plug while you rotate the crank. I'd have to get one of my kids to come by, I'm pretty sure my wife won't lay under the car. Second, there is a cross member that holds connectors that needs to be removed. Third, if for some reason you did cross-thread the drain (and it is tiny), you are looking at pulling the transmission to get to the torque converter.

In the end, I decided to just drain the pan and replace the filter, that's what I've done for years with American cars. I thought about your idea to fill, drain, refill, drain, refill. That would work. Or you can just change the fluid more often. Instead of every 40,000 miles, go every 20,000 miles.

Good luck.

Goni C63

Wow I never change my tranny oil close to 80k so I guess tomorrow I'll drop the car @ my brothers shop...

jvanbrecht

Just drop a mirror and a light under the tranny, and crank the pulley from under the car and you can see inside the little TC hatch.

The rest, well that is a risk you take on any bolt and screw, just be careful not to cross thread.