Transmission R&R - Automatic

Complete removal and reinstallation of the 5-speed automatic transmission (722.9 NAG2) from the 2007-2013 Mercedes-Benz S65 AMG with M275 6.0L V12 BiTurbo engine.

Warnings

Tools required

Parts

• Transmission oil pan gasket × 1 — Use OEM specification
• Transmission drain plug crush washer × 1 — Use OEM specification
• Torque converter seals (front pump seal) × 1 — Use OEM specification
• Transmission mount hardware kit × 1 — Use OEM specification
• Exhaust flange gaskets × 2 — Use OEM specification
• Selector shaft seal × 1 — Use OEM specification

Fluids

• Mercedes-Benz ATF 134 — 10 qt

Preparation

1. Connect Mercedes-Benz Star Diagnostic tool and record any transmission-related fault codes for reference
2. Ensure vehicle is on a level surface and raise vehicle on lift to working height
3. Disconnect negative battery terminal and wait 5 minutes for SRS system discharge
4. Remove engine undertrays and belly pans for access
5. Install engine support fixture across engine compartment or attach overhead hoist to certified engine lift points
6. Place transmission jack under transmission oil pan with wood block to distribute load
7. Mark driveshaft-to-transmission flange orientation for correct reassembly alignment

Procedure

1. 1

   Drain transmission fluid
   Position drain pan under transmission. Remove transmission oil pan drain plug and allow all fluid to drain completely (approximately 9-10 quarts). Inspect drained fluid for metal particles or burning smell indicating internal damage. Remove transmission oil pan bolts in criss-cross pattern and lower pan to drain residual fluid. Inspect pan for debris and magnets for metal shavings.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)

   Pan Bolts22 Nm (16 lb-ft)
2. 2

   Disconnect electrical connections and sensors
   Disconnect transmission range selector connector on driver side of transmission. Remove conductor plate connector from transmission case (large multi-pin connector on passenger side). Disconnect speed sensors (input and output) from transmission housing. Label all connectors with tape for correct reinstallation. Remove wiring harness clips from transmission case.
   Torque spec

   Sensor Bolts15 Nm (11 lb-ft)
3. 3

   Remove exhaust system components
   Disconnect oxygen sensors for rear catalytic converters. Remove exhaust clamps and hangers from rear mufflers. Lower complete exhaust system from transmission crossmember to catalytic converters. Support exhaust on stands. On S65 AMG, the dual exhaust routes very close to transmission - ensure complete clearance before lowering transmission.
4. 4

   Remove driveshaft and rear components
   Mark driveshaft-to-transmission flange and driveshaft-to-rear differential flange for alignment reference. Remove driveshaft center bearing support bolts (2 bolts to chassis). Remove front driveshaft flange bolts at transmission. Carefully slide driveshaft rearward and lower from vehicle. Cap transmission output shaft to prevent fluid leakage and contamination entry.
5. 5

   Disconnect transmission cooler lines and shifter linkage
   Place drain pan under transmission cooler line connections on front passenger side of transmission. Using line wrench, disconnect both transmission cooler lines from case. Cap lines immediately to prevent contamination. Disconnect transmission shifter linkage from selector shaft on driver side of transmission. Remove linkage bracket if necessary for clearance.
6. 6

   Remove torque converter access cover and torque converter bolts
   Remove torque converter access cover from bottom of bellhousing (multiple bolts). Rotate crankshaft using 27mm socket on front crankshaft bolt to access each torque converter-to-flexplate bolt through access window. Remove all torque converter bolts (typically 6 bolts). Push torque converter fully into transmission and verify it is seated on pump - there should be approximately 10-15mm gap between flexplate and torque converter.
   ⚠Mark torque converter position before removal if reusing. Torque converter must be fully seated in transmission pump before installation or pump damage will occur.
   Torque spec

   Cover Screws15 Nm (11 lb-ft)

   Flywheel Bolts95 Nm (70 lb-ft)
7. 7

   Support transmission and remove crossmember
   Verify transmission jack is securely positioned under transmission pan with weight supported. Remove transmission crossmember-to-chassis bolts (4 bolts total, 2 per side). Remove transmission mount-to-crossmember bolts. Carefully lower crossmember from vehicle. The S65 AMG uses heavy-duty transmission mounts due to V12 torque - ensure jack has adequate capacity.
   ⚠️Transmission weight is now fully on transmission jack. Ensure jack is secure and stable before proceeding.
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)
8. 8

   Remove bellhousing-to-engine bolts
   Remove all bellhousing-to-engine block bolts. On the M275 V12, there are typically 8-10 bolts of varying lengths around the bellhousing perimeter. Note bolt locations and lengths for correct reinstallation. Upper bolts may require flexible extensions for access between cylinder banks. Remove starter motor if it interferes with transmission removal (2 bolts plus electrical connections).
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)
9. 9

   Separate and lower transmission
   With assistant helping guide transmission, carefully pull transmission straight back away from engine. Ensure torque converter remains fully seated in transmission and does not fall forward. Clear all wiring harnesses and cooler lines from transmission path. Once clear of engine dowel pins, carefully lower transmission on jack while monitoring clearance around exhaust tunnel, frame rails, and steering components. Tilt transmission nose-up slightly to clear crossmember area. Lower transmission completely and remove from under vehicle.
   ⚠️Transmission must move straight back to clear engine dowel pins. Angling transmission during removal can damage bellhousing or engine block.

Reassembly

1. Verify torque converter is fully seated in transmission pump before installation - should spin freely and have proper depth measurement from bellhousing face
2. Clean all mounting surfaces on engine block and bellhousing thoroughly
3. Install new transmission oil pan gasket and torque pan bolts in criss-cross pattern
4. Apply small amount of high-temp grease to torque converter hub splines
5. Ensure all bellhousing-to-engine bolts are installed in correct locations - different lengths are used in specific positions
6. Torque all fasteners to specification in order listed: bellhousing bolts first, then crossmember, then torque converter to flexplate
7. Replace transmission drain plug crush washer and torque to specification
8. Verify driveshaft alignment marks match before final torque of flange bolts
9. Reconnect all electrical connectors with positive engagement clicks - verify conductor plate connector is fully seated
10. Fill transmission with Mercedes-Benz ATF 134 fluid through dipstick tube using fluid pump
11. Perform transmission adaptation using Star Diagnostic tool before test drive

Verification

• Check all electrical connectors are secure and wiring harness is properly routed away from exhaust
• Verify no fluid leaks from pan, cooler lines, drain plug, or front pump seal with engine running
• Using Star Diagnostic tool, verify transmission communication and clear any stored codes from battery disconnect
• Perform transmission fluid level check at operating temperature (80°C) in Park position - level should be in hot range on dipstick
• Test drive vehicle through all gear ranges (P, R, N, D, Manual mode) and verify smooth shifts with no slipping or harsh engagement
• Perform transmission adaptation reset using Star Diagnostic - critical for proper shift quality after R&R
• Recheck fluid level after test drive and top off if necessary - transmission may consume additional fluid after initial operation
• Verify no fault codes present after test drive and adaptation complete

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