What you will need
Checking transmission fluid level requires transmission to be at a precise temperature; take your car for a short 10-minute drive to warm it up.
- Raise the vehicle at all four wheels and make sure the vehicle is level.The easiest way to do this is on a lift. If you don’t have access to a lift, lift both the car's front and rear sides. Secure the vehicle on jack stands, making sure it is leveled and sits securely.
- Remove the whole splash guard under the transmission.You will need an 8mm socket to remove the screws.
- Locate the drain plug at the bottom of the transmission pan.Break it free using a 6mm Allen key, but don’t remove it just yet.
- Position a drain pan underneath the drain plug.
- Climb into the car, turn on the engine and check the transmission temperature using an IR thermometer by pointing it at the transmission oil pan. You can check the transmission oil temperature with an advanced diagnostic scanner as well.
- With transmission temperature at 45 °C, push the gearbox lever through P-R-D and back several times.
- Go back underneath the car and remove the drain plug.Carefully observe what happens.
- If nothing flows out - fluid level is too low - go to step 9
- If there is a strong and continuous flow - fluid level is too high - skip to step 12
- If oil drips in small quantities - fluid level is correct - skip to step 13
- If the transmission fluid level is low, fill the transfer pump with 1 liter of transmission fluid.
- Place the filler adapter into the drain plug, connect the pump hose to it, and open the valve. Pump about 0,5 quarts and then close the valve.
- Disconnect the filler adapter allow excess fluid to drain until only a small amount still drains out. If there is no transmission fluid draining out, add more, and repeat the process as needed.
- Wait until the excess transmission fluid drains until the flow is minimal.
- Reinstall the transmission drain plug and tighten it to 17 lb-ft using a torque wrench
- Reinstall all remaining parts.
Most Mercedes cars made after 2005 use a 7-speed automatic transmission, called 7G-Tronic or NAG2. The 722.9 transmissions were installed in European vehicles around 2000, while in the US, it was installed on most 2005 and newer models.
Mercedes-Benz 7-speed transmission is a superb gearbox that offers improved performance, shorter shift times, and improved fuel economy.
Many car owners find that checking the transmission fluid level inside this transmission to be troublesome, as there is no dipstick.
Mercedes-Benz 722.9 transmission was available in a few different US models as early as 2004, which in Europe was available in the C-Class as early as 2000.
- SLK (R171 starting in 09/04
- M Class W164 starting in 2005
- R Class W251 staring in 2005
- G Class X164 starting in 2006
- CLS 350 / 500 starting in 2004
- E Class starting in 2004
722.9 became the standard transmission for various chassis including 164, 171, 203, 204, 207, 209, 211, 212, 215, 216, 219, 220, 221, 230, 251, 463.
4Matic equipped vehicles were the last models to phase out the 722.6 and shift to 722.9 around 2006-2007.