Tips for Changing ATF in the 722.6 Transmission

[RuthHimmic]

A filter, gasket, and fluid change on the 722.6 should be performed shortly. The car is 23 years old and has never had the necessary maintenance, making it significantly overdue for service. Merely 38,000 miles, however.
I will utilise exclusively authentic components from Mercedes. No need to drain the torque converter; just the pan requires attention, as the gasket appears to be leaking somewhat.


I intend to refrain from manipulating the drain plug on the sump, opting instead to syphon as much fluid as possible from the top using a vacuum pump, which facilitates a cleaner process and mitigates the risk of future leaks. I will remove the six Torx T30 screws, clean the pan, replace the filter and gasket, then re-torque each to 8 Nm before reinserting approximately the same volume of fluid that was extracted. First, measure the cold levels accurately; adjust as necessary, then take it for a drive and add more as required.
I possess a digital thermometer that is quite useful for measuring the temperature of the sump. Additionally, a dipstick is available for level assessment.
The pilot bush has already been completed.

I understand that safety is paramount; I consistently utilise stands on the sills. However, for this task, I will procure an additional set of stands to provide supplementary security beneath.

Does anyone have any recommendations regarding this job?

Thank you

[MercedesMan98]

The suction pump will not extract all the ATF, so anticipate some leakage when you detach the sump for removal.
After suctioning the oil, you may introduce around 3 to 3.5 litres of clean ATF and operate the engine briefly before suctioning again, which will facilitate achieving a 75% oil change.
Utilise new bolts for the sump pan.

Utilise lint-free cloths to clean the sump pan; I additionally apply brake cleaner to eliminate all residues.I am uncertain whether this constitutes good practice, but I have performed it on each vehicle three times.

[RuthHimmic]

Thank you for the advice. I will take that into account, thank you.

Is it vital to substitute the six bolts?
I believe Mercedes has transitioned from T30 screws to reverse Torx (E12 or a similar variant).

[SteveRulz23]

A thread exists here authored by one of the Independents. Conduct a search for it.

[SteveRulz23]

[MercedesMan98]

They are 23 years old, my friend; for a small amount of money, I would. At such age, individuals may exhibit unpredictable behaviour.

[RuthHimmic]

Indeed, I will ensure they exercise caution.

It is hoped that no bolts have fractured. I am aware of that issue; however, it typically occurs in models with exhausts situated near the sump, which might cause the heat to melt the bolts. My C240 is not constructed in that manner, since the exhausts are adequately distanced and shielded. I will also use ample penetrant as per usual practice. There is no rust on the automobile, and the location has previously seen an oil leak; therefore, it is anticipated that the 8Nm bolts will be removed without difficulty.

[MercedesMan98]

Replace the large electrical connector on the side of the gearbox as well, my friend.