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722.3
The Mercedes-Benz 4G-Tronic transmission was produced from 1981 to 1996 in 722.3 and 722.4 variants. It was a hydraulically operated non-lockup four speed automatic that replaced the similarly designed 722.2 four speed automatic transmisison in 1981. The 4G-Tronic was used until mid-1996 in some vehicles when it was replaced by the Mercedes-Benz 722.5 which is basically the same transmission with an additional electrically controlled 5th gear for overdrive. This was in turn replaced with the more modern 722.6 5G-Tronic transmission that features a torque converter lockup and fully electronic control. 1)
Applications
The 4G-Tronic has been used in a plethora of Mercedes-Benz cars. It is considered by enthusiasts to be one of the most reliable transmissions ever built by Mercedes-Benz with some examples exceeding 300,000 miles of service. 2)
- 1981-1991 Mercedes-Benz W126 722.3
- 1992-1996 Mercedes-Benz W140 722.3
- 1982-1985 Mercedes-Benz W123 722.4
- 1981-1985 Mercedes-Benz W123 722.3
- 1986-1996 Mercedes-Benz W124 722.3
- 1986-1996 Mercedes-Benz W124 722.4
- 1996 Mercedes-Benz W210 722.4
- 1996 Mercedes-Benz W210 722.3
- 1982-1993 Mercedes-Benz W201 722.4
- 1993-1996 Mercedes-Benz W202 722.4
- 1981 Mercedes-Benz C107 722.3
- 1981-1989 Mercedes-Benz R107 722.3
- 1989-1995 Mercedes-Benz R129 722.3
Transmission Oil
Mobil 1 Synthetic ATF
A popular choice for fluid is Mobil 1 Synthetic ATF
Drain
- Remove oil pan drain plug and collect old fluid, 5mm allen screw
- Use a 27mm hex socket on the crankshaft bolt to turn the engine until the torque converter drain plug can be visible and removed, 5mm allen screw
- Replace transmission pan gasket
- Replace with part number: 126 271 10 80
- Reinstall transmission oil pan
- Consider replacing drain plugs with part number: N 000000 000648 and N 007603 010112
Fill and Level Check
- Initially fill with approximately 4L of ATF through the transmission oil dipstick
- Start the engine and run the gear selector through P→R→N→D→N→R→P while pausing in each gear for a few seconds
- Gradually add more fluid after each gear selector cycle until reaching fill capacity.
- At operating temperature of 80C, the dipstick should be at the max mark
- The difference between the min and max marks is approximately 0.3L of ATF.
Transmission Oil Filter
See also: Oil Filter (126 277 02 95)
Vacuum Modulator
See also: Vacuum Box (126 270 91 79)
Removal
Installation
- Clean the surface area on transmission case where vacuum modulator is installed
- Assemble vacuum modulator pieces
- Thrust pin
- Turn key and cap
- Mounting bracket
- O-ring
- Insert vacuum modulator assembly
- Tighten 2x 5mm allen screws
- Reattach vacuum line from intake manifold
- Replace old vacuum line parts if necessary
- 117 997 09 82 - Rubber vacuum connector
- 117 078 05 81 - Vacuum elbow
- 116 276 06 30 - Plastic vacuum line (black)
Adjustment
- Disconnect vacuum line from modulator
- Plug the intake manifold line to prevent leak during testing
- Locate tester port near bottom right of vacuum modulator on transmission case. Remove 12mm hex screw cover.
- Thread pitch for this hole is M8x1.0. Use an engine oil pressure tester kit and connect the gauge to this port.
- Drive vehicle at 30mph with selector in D and read pressure value off gauge
- Although the proper procedure is to perform measurements while car is moving, the same pressure could be measured by idling in D at a complete stop.
- Adjust pressure by removing the turn key cap and turning the key clockwise or counter-clockwise
- Clockwise rotation increases pressure by approximately 6psi
- Counter-clockwise rotation decreases pressure by approximately 6psi
- When complete, remove testing gauges and reconnect vacuum line
K1/K2 Spring
Valve body springs
Part number | Description |
---|---|
126 270 03 35 | K1 Spring Kit |
126 270 44 77 | K1 Spring Kit (springs only) |
126 270 05 35 126 270 04 35 | K2 Spring Kit |
K1 Spring
The K1 spring kit can be purchased and used to replace an existing part to help alleviate shift flares between gears 2 and 3. The part number 126 270 44 77 can be used at a Mercedes-Benz dealer for ordering a replacement kit.
Procedure
- Drain transmission fluid
- Remove transmission oil pan
- Locate K1 spring cover on valve body towards front of transmission
- Loosen the bottom left or right flat-head screw and remove the other 3
- Rotate cover and remove spring and bore
- Assemble new K1 spring into existing bore
- Place smallest diameter spring over white plastic thrust pin
- Place plastic thrust pin assembly inside one end of the largest coil spring
- Place black cap on the other end of the largest coil spring
- Compress the springs together until white thrust pin is inserted into black cap
- Short large coil spring goes on top of black cap
- Insert K1 spring and close cover