DIY 722.9 7G-tronic 7-speed automatic transmission service thread
 

So, I just completed the 2nd 722.9 7G transmission service, so I have decided to start a thread and post a DIY write-up.

As most of you know the 722.9 transmission does NOT have a dipstick tube, so checking fluid level via a dipstick is not possible. But, with a few quality tools a moderately competent person can service their own 722.9 transmission and check the level themselves.

The fluid level is checked via an overflow method using a MB STAR Diagnostic system at a specified fluid temperature. If you have access to one, great. If you don't, that is OK, all that is needed is a quality infrared thermometer. I have a MB STAR clone system and have verified that a Fluke 62 infrared thermometer read within 1-2 degrees of what the STAR system does.

Attached are the following documents:

1)722.9 Transmission Service - This is my write-up of how to properly service the 722.9 transmission including all parts and tool needed.

2)Automatic Transmission Oil and Filter Change - This is the latest up to date MB WIS document on how to service the transmission.

3)Automatic Transmission Fluids (ATF sheet 236) - This is the latest up to date MB WIS document on approved ATF.

4)Drain Transmission Fluid from Torque Converter - This is the latest up to date MB WIS document on how to drain the torque converter, which is now required as part of the transmission service.

5)Filling Automatic Transmission with Fluid - This is the latest up to date MB WIS document on filling the transmission and checking fluid level.

6)Oil Pan and Overflow Tube Modified - This is the latest up to date MB WIS document explaining the new updated pan and overflow tube that is required if you have the old out of date pan.

I also have 2 files that are extensively detailed on the design, operation, software, and maintenance. They are posted in the MBWorld Wiki here:

722.9 Study Guide
722.9 Tech Guide

I did not take pictures of the procedure, but took video. I am still trying to process the video. The video portion is just fine, but the sound is horrible and barely legible. I may record a new audio track. I will post the video up when complete. I should be able to add still shots from the video to the write-up at least.

Another thing of note. The WIS document for servicing the transmission floating around on here on MB World is from the STAR DVD's that are available from MB. They are not updated like the WIS documents. So, if you look at the WIS document I posted, you can see MB changed a few things on the service. 1)They added shifting the car into neutral before servicing. 2)A new gasket is required now and can NOT be reused. 3)Draining the torque converter is required as part of the service now.

When I went to replace my fuel filter this weekend, I noticed my transmission pan was leaking. So, I have been talking to Glyn via PM about it. I am pretty sure, it is because I didn't clean the new gasket, and I used disposable shop towel, even though I used compressed air to blow them off.

I can't stress enough, that all sealing surfaces must be SPOTLESSLY CLEAN. MB WIS recommends using chamois leather to clean the surfaces. I would follow that recommendation.

how many miles do you have?

Excellent post John. This should be a reference for the entire board.

Hey, how come you got a TC drain screw and I don't? :(
I see you put the pdf's I sent you long ago to good use.:zoom:

Because the TC drain plug was removed from the 722.6 in mid 1999. First 722.9 tranny's did not have one. It was reintroduced later I am informed.

Because I am special and have a 7G transmission :p:

Todd, yes I did put the PDF's to good use. But, now I am spoiled with WIS.net, because I have the updated PDF's and not the old ones that are on the MB STAR DVD's :p: Let me know if I can return the favor by getting you any updated documents you want.

75K. I had the dealer do the 1st service at 36K.

I change mine around every 36K as is the recommended interval for ROW. I plan on keeping my car for several 100K miles.

Ooooo! Well, if you could find me something on wheel bearing packing and replacing, front and rear, and the type of gease needed, well, that would be helpful.
I have some bearing issues I need t deal with,
and hadn't found just the right info yet.
2002 203.747 on WIS.

John, thanks brother. I'm at 48k and will definetly need an Oil and filter change soon.

Thanks again


:bow::bow::bow::bow::bow: John Anderson

You are more than welcome bud. New job keeping you busy huh? Haven't heard from you here much lately.

Hey John, good post!!!:y

When I chenged my ATF, I barely lubricated the transmission surface, so the gasket would sits better(as I say "will find its own place"), just barely, like oil dust, no more. So far, few mounths later no leaks. and did the same way on my C230 with 722.6 a while ago,- looks clean. And I followed the same WIS instructions. :nix:
Thanks for the contribution to this forum:y

A perfect situation for the application of Yamabond 5. Note: Benz specifically recommend against this so be warned!

In the racing community we have used the Yamabond series of products for sealing gasket free casings where vibration is present for years. Works a treat.

Don't even dream of using crap like Formagasket. It will fail.

Thanks viku_st for the information. Since my pan has a tendency to leak, (Had it in twice to the dealer under warranty for leaking.) I ordered a new pan, new gasket, standoff pipe, drain plug, drain plug washer, and pan bolts from parts.com for just over $50.

My current pan is the updated beveled pan with white standoff part number A2202700912. But, EPC says that part is replaced by A2212701212. So, it appears the pan was updated again, so I figured, I would get the latest pan. Maybe there was a defect with my pan.

Also, my gasket came unpacked from RM European and was sitting on my bench for a few weeks. I failed to clean it at all before installing on the pan. I bet is had some dirt/debris on it.

Excellent DIY, johnand. Appreciate you sharing your expertise.

Extremely busy, so busy that I worked today on Labor Day :crazy:

Hows the home projects going? I saw your remodeling now :y By the way the backyard came along nicely (my comment is a little late :smash:). You got great skills :)

OUTSTANDING writeup! I just finished my fluid change following your step by step process with no issues except letting the temperature get past me. Had to wait for it to cool down and start over. Other than that everything went smoothly. It ended up taking about eight liters with only a small amount rejected.

Thanks!

Awesome! Glad I could help :cheers:

The fluid does heat up fast if it hasn't sat overnight.

So, I just got done draining the fluid and dropping the pan. Again, I made a nice ATF mess. Even with the drain plug and standoff removed there is over a liter of fluid in the pan, and you have to tip it away from the rear slightly to remove it. So, once again, I have a nice mess off ATF :smash:

I cleaned the NEW pan, NEW gasket, and transmission housing with a new microfiber cloth. Tried the leather chamois, and it left a bunch of lint behind :slap: So, after cleaning with the microfiber I blew everything off with compressed air. I then proceeded to bolt up the pan. Here is where I think I screwed up last time. There was 2 sprags, that weren't quite touching the transmission housing on the outside edge before I pulled the pan. This time I was VERY careful in making sure all the sprags were correctly seated on the pan. I did this by putting the 2 center sprags and bolts on loose enough just to hold the pan in place. Then I had to wiggle and push the pan toward the rear of the car to get the pan and sprags to seat correctly. The rear of the pan gasket touches the bracket for the transmission mount, and the gasket needs to be compressed slightly against it. I noticed this the 1st time I put the pan up, but didn't push the pan toward the rear while putting the sprags and bolts in, and remember the front 2 were a little difficult to hand tighten the bolts. By pushing the pan toward the rear while hand tightening the bolts seemed to work much better this time.

Now I just need to fill with fluid and adjust the level. Then I will report back on if that worked to stop the leak.

Gild did you have that interference problem with the pan and trans mount?

No, on the GL there is plenty of room all around the pan to work and visually inspect. It did make a huge mess though because there was so much fluid left in the pan after draining. I was able to change my W211 5-speed fluid without hardly a drip.

Nice that the GL has more room the W203 is very tight in the rear area.

I am convinced my car hates me. So, I crawled under the car yesterday after a drive to and from work and there was some ATF on front part of the pan and seal :smash::smash::smash:

Though, it appears it is not the pan that is leaking :rolleyes: When I changed the fluid, I drained the torque converter as is recommended now by MB. The problem with draining it is the torque converter drain plug is at and angle in relation to the access hole. So, when you pull the drain plug, the ATF drips down into the bell housing. There is little to no clearance to get rags in there to clean it up. So, what is leaking, is the fluid that got trapped in the bell housing while draining the torque converter. I would recommend when people drain the torque converter, to make some kind on shield, or just rags to soak up the ATF before it pools in the bell housing.

Wish I could edit my 1st post, so I could update the PDF with these observations.

But this is always a desirable trait... :rolf:

:rolf: Was wondering when someone would take that out of context.

Karo & Patrick - :naughty::D