Engine R&R

Complete removal and reinstallation of the M275 6.0L V12 BiTurbo engine from a 2007-2013 Mercedes-Benz S65 AMG, including disconnection of all auxiliary systems, transmission separation, and engine mount removal.

Warnings

Tools required

Parts

• Engine oil filter × 1 — Use OEM specification
• Engine coolant thermostat and housing gasket × 1 — Use OEM specification
• Transmission-to-engine alignment dowels × 2 — Inspect and replace if damaged
• Engine mount-to-block gaskets/seals × 2 — Use OEM specification
• Exhaust manifold gaskets (left and right banks) × 2 — Use OEM specification
• Oil drain plug crush washer × 1 — A0009831944
• Coolant hose clamps (assorted sizes) × 12 — OEM constant-tension type
• Engine wiring harness protective tape × 1 — Use OEM specification
• Power steering reservoir fluid × 1 — Use OEM specification
• AC refrigerant R134a × 1 — Recharge to specification
• Serpentine belt × 1 — Use OEM specification

Fluids

• Mercedes-Benz 229.5 5W-40 — 8.5 qt
• Mercedes-Benz Coolant (Blue) — 18 qt
• Pentosin CHF 11S — 1 qt
• Mercedes-Benz ATF 134 — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Use wheel chocks on rear wheels.
2. Connect Mercedes-Benz Star Diagnostic tool and deactivate ABC system. Allow vehicle to settle to lowest ride height.
3. Disconnect negative battery terminal, then positive terminal. Remove battery from vehicle.
4. Remove engine cover and both underbody splash shields.
5. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stalls.
6. Have AC system professionally evacuated and document refrigerant quantity for recharge.
7. Drain engine coolant into appropriate container by opening radiator drain and engine block drain plugs.
8. Drain engine oil and remove oil filter.
9. Remove front bumper cover for access to radiator support and AC condenser.
10. Remove radiator grille assembly and front cooling fan assemblies.
11. Label all electrical connectors, vacuum lines, and hoses with numbered tags and photograph connections.

Procedure

1. 1

   Remove intake and airbox assembly
   Remove both air filter housings and intake ducting. Disconnect mass airflow sensors from both banks. Remove the complete intake manifold assembly by disconnecting all vacuum lines, EVAP lines, and throttle body connectors. The M275 uses a complex intake plenum that must be unbolted from both cylinder banks. Remove intake manifold mounting bolts and carefully lift assembly away.
2. 2

   Disconnect engine electrical systems
   Disconnect all engine harness connectors including: both ignition coil harnesses (12 coils total), both camshaft position sensors, crankshaft position sensor, all oxygen sensors (4 total), knock sensors, engine coolant temperature sensors, oil pressure sender, and turbocharger control solenoids. Disconnect main engine control module connectors (2 large connectors on each ECU, there are two ECUs for the V12). Unbolt and move both ECUs aside without fully removing. Disconnect alternator wiring and starter motor connections.
3. 3

   Remove cooling system components
   Disconnect upper and lower radiator hoses, both turbocharger coolant feed and return lines, heater hoses at firewall, and coolant expansion tank hoses. Remove both electric coolant pumps from engine block. Remove radiator support bolts and carefully extract radiator and AC condenser assembly forward. Support with wire to prevent damage. Disconnect and remove thermostat housing if obstructing engine removal.
   Torque spec

   Gasket Bolts27 Nm (20 lb-ft)
4. 4

   Disconnect AC and power steering systems
   Disconnect AC compressor electrical connector. Unbolt AC compressor from mounting bracket but leave refrigerant lines attached (system already evacuated). Secure compressor to frame with wire. Disconnect power steering reservoir and drain fluid. Unbolt power steering pump and secure aside with hoses still attached to prevent fluid loss.
   Torque spec

   AC Compressor Bolts25 Nm (18 lb-ft)

   Power Steering Pump Bolts25 Nm (18 lb-ft)
5. 5

   Remove exhaust system connections
   Working from underneath, disconnect both catalytic converters from exhaust manifolds. The M275 has a dual exhaust system with one manifold per cylinder bank. Support exhaust system with jack stands. Remove exhaust manifold heat shields. Unbolt both exhaust manifolds from cylinder heads, working from hot (center) to cold (outer) bolts. Apply penetrating oil and allow time to soak if necessary. Set manifolds and gaskets aside.
   ⚠Exhaust manifold studs are prone to breaking on high-mileage engines. Use penetrating oil and heat if necessary.
   Torque spec

   Exhaust Manifold Nuts30 Nm (22 lb-ft)
6. 6

   Disconnect turbocharger systems
   Disconnect both turbocharger oil feed lines from engine block and oil drain lines to oil pan. Remove turbocharger intake ducting and intercooler piping. Disconnect wastegate vacuum lines and boost control solenoids. The turbos will remain attached to exhaust manifolds during engine removal. Cap all oil and coolant ports to prevent contamination.
7. 7

   Disconnect fuel system
   Verify fuel pressure is fully relieved. Disconnect fuel supply and return lines at fuel rail connections on both cylinder banks using proper fuel line disconnect tools. The M275 uses quick-disconnect fittings. Cap all fuel lines immediately to prevent contamination and fuel spillage. Disconnect fuel pressure regulator vacuum line.
   ⚠️Even after pressure relief, residual fuel will drain from lines. Have absorbent materials ready and ensure adequate ventilation.
8. 8

   Separate transmission from engine
   Support transmission securely with transmission jack. Remove transmission bellhousing inspection covers. Remove starter motor mounting bolts and extract starter. Mark torque converter to flexplate relationship with paint marker. Remove torque converter to flexplate bolts by rotating engine via crankshaft bolt (access through lower opening). Remove all transmission-to-engine mounting bolts. There are typically 8-10 bolts of varying lengths - document locations. Carefully separate transmission from engine by sliding straight back to disengage torque converter. Lower transmission slightly and secure on jack.
   ⚠The torque converter must remain fully seated in transmission during separation. Mark depth before removal and verify full engagement on reinstallation.
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)
9. 9

   Disconnect engine mounts and ground straps
   Disconnect all engine ground straps from engine block to frame (typically 3-4 locations). Remove engine mount through-bolts on both left and right engine mounts. The M275 uses hydraulic engine mounts. Unbolt engine mount brackets from engine block on both sides. Support engine weight with hoist before removing final mount connections.
   ⚠️Ensure engine hoist is supporting full engine weight before removing last mount connections. Engine will shift when mounts are disconnected.
   Torque spec

   Engine Mount-to-Block Bolts65 Nm (48 lb-ft)

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
10. 10

    Final disconnections and engine extraction
    Perform final inspection to verify all hoses, wiring, and mechanical connections are disconnected. Attach engine hoist chains to factory lifting eyes on cylinder heads (one per bank). Use engine leveler to balance load. Slowly raise engine while monitoring clearance around transmission input shaft, firewall, and frame rails. Angle engine slightly nose-up to clear transmission tunnel and ABC components. Once clear of engine bay, raise to safe working height and move to engine stand. Secure engine to stand using transmission mounting bolt holes.
    ⚠️Monitor engine position constantly during extraction. The V12 is extremely heavy and any shift can damage surrounding components or cause hoist failure.

Reassembly

1. Clean all mounting surfaces on frame rails and engine mount locations before reinstallation.
2. Inspect and replace transmission input shaft seal if any leakage is evident.
3. Install new exhaust manifold gaskets with high-temperature anti-seize on studs.
4. Verify torque converter is fully seated in transmission (measure depth and compare to original measurement) before mating engine to transmission.
5. Torque all fasteners in reverse order of removal, following specified sequences for critical components.
6. Replace all single-use fasteners including flywheel bolts if TTY type.
7. Refill engine oil, coolant, and power steering fluid to proper levels.
8. Have AC system professionally recharged to original documented quantity.
9. Before starting engine, rotate crankshaft by hand two full revolutions to verify no interference.
10. Prime oil system by cranking engine with fuel pump fuse removed until oil pressure is indicated.

Verification

• Connect Star Diagnostic tool and clear any stored fault codes from engine removal.
• Start engine and verify stable idle with no unusual noises or vibrations.
• Check for coolant, oil, fuel, and power steering leaks at all connection points.
• Verify proper operation of both turbochargers with no boost leaks or abnormal noises.
• Test drive vehicle and verify smooth acceleration, proper boost levels, and transmission shifting.
• Verify all warning lights are extinguished and no new fault codes are stored.
• Recheck all fluid levels after test drive and top off as necessary.
• Verify ABC system operates correctly after reactivation via Star Diagnostic.
• Inspect engine bay for any tools or parts left behind during reassembly.

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle