MiataMan

New owner of a pristine 2004 C240 4Matic Sedan with 138k miles. I do all my own work. I did the (oil drain plug method) 8 Qt Mobil 0w-40 oil change with MB fleece filter, replaced air filters, replaced all rear bulbs.

I would like to change the transmission fluid next but the MB parts guy said since I didn't know the history of the transmission fluid change NOT to change it or it would start leaking.

In other cars I'm on a schedule where I frequently suck out as much as fluid as possible and replace that amount exactly. I want to do that to this car too.

I plan on keeping this car a long time and not changing the transmission fluid sounds absurd. Any thoughts?

samaritrey

Do the fluid change! Look in the sticky at the top and you will find the 722.6 diy guide. I wouldent just suck fluid out and replace. I would take the pan off and clean it out and repalce the filter. You can get shell 134 ATF from your local shell suplier for under $70 for a case of 12 quarts. I would also change all other drivetrain fluids such as difs.

MiataMan

Thanks for the reply samaritrey. I've always used synthetic fluids in my other car's transmissions and differentials. Are there approved synthetic fluids for this car? What about Redline suggests D4 ATF for the transmission and 75W90 GL-5 for both diff's. Will these products work? Any thoughts?

neurodave

Did it in my C320 without issues, and that's with 106,000 miles and being the second owner (purchased car at 100,000mi.)

Take care of the diff while you're down there, I used Mobil1 75W90 without any issues. Purchased it at Advance Auto for ~$10.

Keep in mind, I am rear wheel drive. Not sure if the above would apply to the 4Matic models.

samaritrey

I would only used approved fluids in the car and I believe all the fluids except for the diff is already synthetic. I don't belie redline has any approved fluids for Mercedes while they may claim to have something that meets requirements in reality it may or may not be good enough. Getting the approved fluids is actually not that much more for everything I have done such as the Shell 134ATF which is approved and the approved rear diff fluid is only like $12 a bottle.

The rear diff in my car also had mobil1 in it for over 100,000 miles with no issues but I didn't put it in and if I had known about it I would have taken it back and had it changed out (noticed it when I was getting records together to sell car)
As you have a 4matic you may want to double check specifications for your car as it may be different.

cvx

Service the transmission imo. Also remember that if you have 5 speed 722.6 transmission it does not have the drain plug for torque converter.

You need to flush it in order to completely change fluid, there is no point to do half *** job and contaminate fluids by just draining half. About 14 quarts needed for this job.

Also replace the electrical connector at the pan/conductor area so you dont experience tranny oil leaking to the transmission control module ("capillary action" video 5 see below)

Please look at this 6 part video series and you gain a lot of information even you dont have any problems with your transmission. I found it very informative
for 722.6. Welcome to the forums

Glyn M Ruck

Changing the transmission fluid & filter will always be the best possible thing you can do & thereafter every 39K miles or 60K Km's for long service life. If a transmission gives trouble after a fluid change it would have failed anyway.

Ignore the urban myths & BS.

The WIS flush method is in the Wiki. Work cleanly.

MiataMan

Excellent advice / information. Thanks! I'm ordering the Shell 134ATL, the electrical connector, Mann filter kit, and even a dipstick! hope that electrical connector isn't too hard to do on my back. The guy in the video made it look pretty easy.

Glyn M Ruck

Electrohydraulic bush replacement: DIY

http://www.installuniversity.com/mb/...ans_oring.html

samaritrey

It is an easy job as our senior oil guy says work cleanly and you will be fine.

MiataMan

I'm the OP on this thread. My car is a 2004 C240 w/ 139k miles. This weekend I changed the transmission filter and gasket (Mann) while the car was on a lift. I replaced the fluid with exactly the amount that came out (120 oz.) using MB ATF 134 from the dealer. The pan was clean, clean, clean. Magnet had nothing on it. Later it measured exactly to the top of the 25 degree marking on the stick when running when the car was warm.

But, much to my dismay, the connector would not come out of the socket for me. I released the latch/lock OK but couldn't pull out the connector. It's not leaking at all so I'm not too worried but I'm not sure when I can use a lift again and I squandered a great opportunity to work sitting down under the car. Any tricks to removing the plug?

C230 Sport Coup

Not really other than there's either or 6 or 7mm bolt inside the connector you have to loosen. Then it will just pop out. It's a captive bolt or should be.

Putting the new one requires great care not to bend any of the pins.
Note the orientation of the old one as it comes out.

You'll need to catch any fluid that leaks out and pour it back as well, so make sure you use a clean pan, or have an extra bottle handy.
Be sure to lube the new orings up real good. Every time I do this job, it's not easy, and the potential to bend the pins is there, and then what a tedious job trying to straighten them, as it is necessary for them to be absolutely straight when the connector goes over. Fortunately I've never bent them.

Take a deep breath and don't rush.

C230 Sport Coup