Hi all

My 98-E320 has about 50,000 miles on it. As I search through the forum, I realize that the transmission is sealed and the T. oil is for life. However, I went ahead a have my mechanic change the T. oil anyway for peace of mind. I don't believe he drained it out of the torque converter but at least there are about 70-80% new T. oil in there which may work for another 50K. He was careful enough to add the same amount of T. oil that was drained so it seems OK. Here are my questions though:

1. Where is the torque converter drain plug?

2. There is no T. dipstick, how can I check the T. oil level? Where can I get one?

3. What is the proper procedure for checking T. level? If there are overfilled, how can I drain some?

Thanks in advance,
JeffreyP

When changing the fluid on a 722.6 you should use the SDS to set the fluid level at the operating temp of 80C. This tranny is sensitive to fluid level and should not be "topped off." That is why there is no dipstick.

You can buy the dipstick at the dealer, but make sure that the fluid is at 80C when checking, or you'll be off.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

Torque converter drain plug is on the torque converter. It needs to be rotated until it is at the bottom and visible through the window. As always, use only the MB specific 722.6 tranny fluid in 722.6 trannys.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Thanks,

About the torque converter's drain plug - where is the approximate location of the torque converter?

JeffreyP

It is a round dougnut looking piece that is bolted to the flywheel and connected to the transmission's input shaft. The housing rotates with the engine, therefore the engine and thus the torque converter must be rotated to locate the drain plug to the bottom.

__________________
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

I bought the AT dipstick and after several checks the AT level seems too high. I checked it after driving the car for about 20 min., the AT fluid seems very warm so I suppose it was close to 80 degree. Couple more questions though:

1. Do you suppose to check the AT fluid when the engine is off or still running? I did it when it was off.
2. What would be the negative effect of having too much AT fluid?

Thanks,
JeffreyP

Check the AT fluid level with engine on and warm - at idle, car in park position.
Should be between the marks on the stick.
Too much is not good - Nor is too little...
Some say too much puts you in a better position than not enough.That gets you into a philosophical
thing.

"...What would be the negative effect of having too much AT fluid..?"

Just guessing the transmission was engineered "not" to vent/blow extra fluid to the atmosphere because of environmental concerns...

Also every dealership enjoys selling/installing new or rebuilt transmissions...

They are in the business to rake in the money however they do it...

Pre-syntheticaly engineered trannys just vented/blew out extra fluid if they did not go into self destruct mode first...

Let me rephrase my question:

2. If the AT fluid level is too high, would it in any way hurts the transmission and how? Thanks,

JeffreyP

low fluid I can understand being a problem. But high fluid.. I've heard is bad..

foaming/cavitation/ATF breakdown.. which of course leads to more serious problems.

But I've never really seen a good explaination as to why that would happen.

To be honest I'm just a step past the "Automatic Transmission as a Magic Box" phase.

__________________
'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

Overfull trans fluid will become foamy [aeroated= implying the fluid becomes saturated with gas/air bubbles]...

Foamy fluid destroys clutch packs...

Pressure sensitive valves get all out of whack...

Interesting what knowledge can be obtained by digging deep into the website archives...

Next thing an individual will become a self proclaimed know-it-all lol talking about myself no doubt lol

Actually well over half of the fluid is in the torque converter.

You can't check the transmission fluid without monitoring the transmission temperature. Just driving 20 minutes is NOT close enough.

The transmission fluid will not "blow out" as has been suggested, the transmission is sealed.

The transmission case is a "scavanging" design, too much fluid and it can't scavange properly and too much fluid is retained in the case. This is bad. You need to get it to a place where the transmission oil temp can be monitored, such as a dealer where the computer can be hooked up to it to use the integral temp sensor.

Did he use the fluid MB specifies for this transmission?

Gilly

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Thanks all, it was very informative

Hi Gilly

The reason I said 70-80% was that my mechanic replaced about 6 quart of transmission fluid. Thinking the case has 8-8.5 quarts, so 70-80% is about right.
My mechanic did use the MB Transmission fluid. So far I haven't any problem.

I cann't believe it's that difficult to check the AFT level. There must be a more scientific way to check its level hot or cold. For example: (again this is my opinion hypothetically)
- cold: engine is not even on - torque converter say keeps 50% (this number could be any) of the ATF, so the level should be check for at 1/2 way mark.
- hot: torque converter may "blow out" and only keep 10% ATF, so the the level should be check at 90% mark + oil volume expansion - so maybe at top of the stick is the right level.

I don't think oil expand/compress that much between 60-80C, now would the different in temp. cause the converter to blow out more ATF?

Just my thought

Regards,
Jeffrey