Mercedes-Benz W639 automatic transmission fluid change (722.6)
How do you change the fluid in the W639's 722.6 automatic?
The best method is flushing through the return hose, which replaces all of the old fluid. The filter is replaced at the same time. The fluid temperature has to be measured, so a diagnostic tool is needed. Filling is done through the dipstick opening.
How much fluid does the W639 automatic take?
According to the manufacturer's instructions the fluid quantity is 5 litres if the torque converter is not drained and 7 litres if it is drained. Flushing usually uses about 12 litres. Use fluid of the correct specification.
Which parts should be replaced with an automatic transmission fluid change?
In addition to the fluid, a filter and a gasket are needed. Sometimes the plug grommet, the conductor plate and the torque converter lock-up solenoid are also replaced. Replacing the control unit is not necessary.
Should fault codes be read before the fluid change if the transmission is acting up?
Yes. If the gears do not shift properly, read the fault codes first. If interruptions in the speed sensor signal show up, the sensor is replaced. A fluid change alone may not fix the fault.