Engine Mounts - All

Complete replacement of all engine and transmission mounts on the 2007-2013 Mercedes-Benz S65 AMG with M275 6.0L V12 BiTurbo engine, requiring engine support and lifting to access all mounting points.

Warnings

Tools required

Parts

• Left engine mount (driver side) × 1 — A 221 240 20 17
• Right engine mount (passenger side) × 1 — A 221 240 21 17
• Front engine mount × 1 — A 221 240 24 17
• Rear engine mount × 1 — A 221 240 25 17
• Transmission mount × 1 — A 221 240 26 17

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal and wait 10 minutes for system discharge
3. Remove engine cover by releasing quick-release fasteners
4. Remove front undertray and lower engine splash shields
5. Drain coolant if accessing front engine mount interferes with coolant hoses
6. Mark or photograph engine position relative to frame for alignment reference
7. Install engine support fixture across engine bay or attach overhead hoist with load leveler to engine lifting points

Procedure

1. 1

   Support the engine and transmission
   Attach engine support fixture to the engine lifting eyes or use overhead hoist with proper rigging. Take up slack until the engine weight is just beginning to transfer to the support equipment, but do not lift the engine yet. Support the transmission with a hydraulic transmission jack positioned under the transmission pan with a wood block to distribute load.
2. 2

   Remove left engine mount
   Raise engine slightly (approximately 5-10mm) using support fixture to unload the left mount. Remove the mount through-bolt first, then remove the engine mount-to-block bolts (typically 3 bolts). Finally, remove the mount-to-frame bolts and extract the mount. Inspect the mounting surface on both engine block and frame for damage or corrosion.
   ⚠Raise engine only enough to unload the mount. Excessive lifting can damage coolant hoses, wiring harnesses, or exhaust components.
   Torque spec

   Mount Through Bolt119 Nm (88 lb-ft)

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

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
3. 3

   Remove right engine mount
   Adjust engine support to take weight off right side mount. Remove the through-bolt, then remove the engine mount-to-block bolts. Remove the mount-to-frame bolts and withdraw the mount assembly. On V12 models, clearance is extremely tight on the right side due to turbocharger proximity; carefully maneuver the mount out.
   ⚠Right side mount is close to turbocharger components. Ensure engine is cool and avoid contact with exhaust manifolds.
   Torque spec

   Through-Bolt85 Nm (63 lb-ft)

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

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
4. 4

   Remove front engine mount
   The front mount is typically accessed from below. Remove any interfering coolant or vacuum lines by disconnecting quick-connects (mark positions for reassembly). Remove the mounting bolts securing the mount to the engine, then remove the mount-to-frame bolts. Lower the mount assembly downward for removal.
   Torque spec

   Mounting Bolts64 Nm (47 lb-ft)

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
5. 5

   Remove rear engine mount
   Raise transmission jack slightly to unload the rear engine mount. Remove the mounting bolts from the engine block side first. Then remove the mount-to-frame bolts. The rear mount may be integrated with transmission mount support; carefully note configuration before removal.
   Torque spec

   Mounting Bolts64 Nm (47 lb-ft)

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
6. 6

   Remove transmission mount
   With transmission properly supported on hydraulic jack, remove the transmission mount bolts connecting the mount to the transmission. Then remove the mount-to-frame bolts. Lower the transmission slightly (5-10mm maximum) if needed to clear the mount for removal. Inspect transmission mount bracket for cracks or damage.
   ⚠Do not allow transmission to hang unsupported or sag excessively, as this can damage the output shaft seal or torque converter.
   Torque spec

   Transmission Mount Bolts65 Nm (48 lb-ft)

   Engine Mount-to-Frame Bolts75 Nm (55 lb-ft)
7. 7

   Clean and inspect mounting surfaces
   Clean all mounting surfaces on the engine block, transmission, and frame rails with brake cleaner and a wire brush. Inspect threaded holes for damage and chase threads with appropriate tap if necessary. Check frame rail mounting points for cracks, corrosion, or elongated bolt holes that would indicate previous movement or stress.
8. 8

   Install new transmission mount
   Position the new transmission mount on the frame rail and start the mount-to-frame bolts finger-tight. Raise transmission with hydraulic jack to align with mount, then install transmission mount bolts finger-tight. Torque mount-to-frame bolts first, then torque transmission mount bolts to specification.
   Torque spec

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

   Transmission Mount Bolts65 Nm (48 lb-ft)
9. 9

   Install new rear engine mount
   Position rear engine mount onto frame rail and start mount-to-frame bolts finger-tight. Adjust engine height with support fixture to align engine mounting points with new mount. Install mounting bolts finger-tight. Torque mount-to-frame bolts first, then torque mounting bolts to engine block.
   Torque spec

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

   Mounting Bolts64 Nm (47 lb-ft)
10. 10

    Install new front engine mount
    Lift front engine mount into position from below. Start mount-to-frame bolts finger-tight. Adjust engine position as needed to align mounting holes on engine side. Install mounting bolts finger-tight, then torque mount-to-frame bolts followed by mounting bolts to engine. Reconnect any coolant or vacuum lines that were disconnected.
    Torque spec

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

    Mounting Bolts64 Nm (47 lb-ft)
11. 11

    Install new right engine mount
    Position right engine mount on frame rail and start mount-to-frame bolts finger-tight. Carefully maneuver mount into position near turbocharger area. Adjust engine support to align engine mounting holes with mount. Install engine mount-to-block bolts finger-tight, then install through-bolt finger-tight. Torque engine mount-to-frame bolts first, then engine mount-to-block bolts, and finally the through-bolt.
    Torque spec

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

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

    Through-Bolt85 Nm (63 lb-ft)
12. 12

    Install new left engine mount
    Position left engine mount on frame and start mount-to-frame bolts finger-tight. Adjust engine support fixture to align engine with mount. Install engine mount-to-block bolts finger-tight, then install mount through-bolt finger-tight. Torque mount-to-frame bolts first, then engine mount-to-block bolts, and finally the mount through-bolt to specification.
    Torque spec

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

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

    Mount Through Bolt119 Nm (88 lb-ft)
13. 13

    Release engine support and verify alignment
    Slowly and evenly release tension on engine support fixture and transmission jack, allowing engine and transmission to settle onto new mounts. Verify engine sits level and centered in engine bay using reference marks from preparation. Check clearances around engine to firewall, frame rails, and steering components. Rock engine gently by hand to confirm all mounts are properly seated and loaded.
    ℹ️Engine may not settle into exact original position immediately. A brief test drive may be needed for mounts to fully seat.
14. 14

    Reinstall covers and components
    Reinstall engine undertray and splash shields. Reinstall engine cover and secure all quick-release fasteners. If coolant was drained, refill cooling system with Mercedes-Benz Blue coolant and bleed air from system. Reconnect battery negative terminal.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

Reassembly

1. Verify all mount bolts are torqued to specification in the correct sequence (frame bolts first, then block bolts, then through-bolts)
2. Ensure all electrical connectors, coolant hoses, and vacuum lines are properly reconnected
3. Double-check that no tools or parts were left in the engine bay
4. If coolant was drained, ensure system is properly filled and bled of air according to Mercedes-Benz bleeding procedure

Verification

• Start engine and observe for excessive vibration or movement; mounts should limit engine movement to minimal displacement
• With engine running, shift transmission through all gear ranges and verify no harsh engagement or clunking from powertrain movement
• Perform a test drive and verify smooth acceleration and deceleration with no abnormal vibrations or harshness through the chassis
• Check engine bay after test drive to confirm engine remains centered and no contact marks appear on firewall, frame, or hoses
• Use diagnostic scanner to check for and clear any fault codes related to engine position sensors or alignment
• Verify no fluid leaks have developed from disturbed hoses or connections during mount replacement

Related trouble codes on this vehicle

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