Mercedes-Benz 722.3 4-Speed Automatic Transmission · Mercedes-Benz · Expert rebuild service since 1987. Lifetime warranty. Free diagnostic.
1972–1989 Mercedes-Benz W115/W116/W123/W126 (4-cylinder and V8 variants), 1984–1992 Mercedes-Benz W124 (early)
| Configuration | 4-speed automatic RWD transmission (torque converter with hydraulic control) |
|---|---|
| Gear Ratios | 1st 3.98:1 · 2nd 2.39:1 · 3rd 1.46:1 · 4th 1.00:1 · Rev 5.48:1 |
| Fluid Type | Dexron II/III ATF |
| Fluid Capacity | 7.0 qts total, 3.2 qts service refill |
The vacuum modulator valve controls shift timing based on engine load. The diaphragm ruptures, allowing ATF to be drawn into the intake manifold and burned.
Symptoms: Blue smoke from exhaust, strong ATF burn smell, ATF consumption without visible leaks, DTC not available (pre-OBD)
The centrifugal governor valve sticks or wears, causing incorrect shift timing — either late upshifts (high RPM) or early upshifts (low RPM).
Symptoms: Erratic shift timing, transmission revving very high before upshift, early shift at low RPM with cold engine
The front (kickdown) band requires periodic adjustment. Over time it slips on 2nd and 3rd gear engagement.
Symptoms: Slip during 2nd gear acceleration, delayed engagement, RPM flare on 2-3 upshift
722.3 rebuild replaces the vacuum modulator, governor valve assembly, front and rear band sets, all clutch packs, and all seals. Valve body is cleaned and inspected. Torque converter is serviced. Dexron III fluid is used.
Dexron III ATF every 40,000 miles. Check the vacuum modulator hose condition annually — a cracked hose causes the same ATF-burning symptoms as a failed diaphragm. Adjust front band every 60,000 miles on high-mileage units.
W115, W116, W123, W126, and early W124 series from 1972–1992 with 4-speed automatic.
The vacuum modulator diaphragm has likely failed. ATF is drawn through the vacuum line into the intake manifold and burned. The repair is a modulator replacement.
A full rebuild ranges $1,600–$2,100 at Chicago Transmission.
Dexron II or III ATF.
Absolutely — we regularly rebuild these for classic Mercedes restorations and have parts availability for all major components.
Free diagnostic, written estimate, lifetime warranty. Chicago's 722.3 rebuild specialists since 1987.
