It’s great to see you engaging with the Mercedes-Benz community! When it comes to maintaining your Mercedes, especially tasks like transmission fluid changes, accuracy is key. We noticed you mentioned replacing the pump, and wanted to clarify – perhaps you were referring to the transmission filter instead? It’s a common point of confusion. Getting the fluid level correct in your 722.9 transmission is crucial for its longevity and performance. Forget about just observing drips from the plug; the Mercedes 722.9 transmission requires a specific procedure involving overfilling and temperature monitoring to ensure the correct fluid level.
The proper method for checking and setting the transmission fluid level on your Mercedes 722.9 transmission involves a precise overfill technique. Instead of simply filling until fluid barely drips, you need to initially overfill the transmission pan. For a standard drain and refill, without draining the torque converter, you’ll typically need around 5 quarts of fluid. If you’ve also drained the torque converter, then approximately 10 quarts will be necessary for the initial overfill.
This overfilling is not an arbitrary step; it’s essential for ensuring the accurate fluid level. The next step is to heat the transmission fluid to a specific temperature. This is achieved by running the engine and shifting through the gears to circulate the fluid. Once the fluid reaches the correct temperature, you then open the drain plug. Because of the overfill, you should observe a steady stream of fluid initially draining out. As the excess fluid drains, the flow will naturally reduce to a dribble. It’s at this point, when the fluid is just dribbling, that you should replace the drain plug. This ensures the fluid level is precisely correct.
This entire procedure must be performed with your Mercedes safely lifted and the transmission pan perfectly level. The correct transmission fluid temperature for checking the level depends on your transmission pan type. For the older style pan (without a sloped end), the temperature should be 95°F (35°C). If you have the newer style pan (with a sloped end), the target temperature is 113°F (45°C).
For detailed instructions and visual aids, you can refer to this resource: https://benzbits.com/722_9/FillFluid.pdf
Ensuring the correct transmission fluid level using this temperature-sensitive overfill method is vital for the smooth operation and longevity of your Mercedes-Benz 722.9 transmission.
