Engine Mount - Strut

This procedure replaces the engine mount strut (torque strut) on the 2019 Mercedes-Benz G-Class with the 4.0L Turbo V8 engine, which limits engine movement and absorbs torque during acceleration.

Warnings

Tools required

Parts

• Engine mount strut (torque strut) × 1 — Use OEM specification (MB part A2902400200 or equivalent)
• Engine mount strut fastener kit (if fasteners are corroded) × 1 — Use OEM specification

Preparation

1. Park vehicle on level, solid ground and engage parking brake.
2. Turn ignition off and remove key. Allow engine to cool completely if recently operated.
3. Disconnect negative battery terminal and wait 10 minutes for system capacitors to discharge.
4. Raise front of vehicle using jack and support securely on jack stands rated for vehicle weight at manufacturer-specified jacking points.
5. Remove engine cover by lifting upward - it is retained by rubber grommets.
6. Inspect the engine mount strut location: it typically connects from the front of the engine block to the front subframe/crossmember.
7. Apply penetrating oil to all mount strut fasteners and allow to soak while preparing engine support equipment.

Procedure

1. 1

   Install engine support system
   Position engine support fixture across the engine bay fender rails or attach overhead engine hoist to designated engine lift points. The M177 engine has lift eyes on both cylinder banks. Apply minimal upward tension to just take weight off the mounts - do not lift the engine. Verify the engine is stable and secure before proceeding.
2. 2

   Access the engine mount strut from below
   Working from underneath the vehicle, locate the engine mount strut. It connects from the lower front of the engine to the front subframe. Remove the lower engine splash shield/undertray by removing the perimeter fasteners (verify fastener type/size against the vehicle; these may be Torx, hex-head bolts, or plastic clips). Set aside the undertray.
3. 3

   Document strut orientation and position
   Before removal, carefully note the orientation of the engine mount strut, including any alignment marks, shims, or spacers. Take photos if possible. The strut may have specific clocking or orientation that must be replicated during installation. Check for any washers or spacers at both mounting points.
4. 4

   Remove strut-to-engine fasteners
   Locate the upper mounting point where the strut attaches to the engine block or front timing cover. Remove the 2-3 fasteners securing the strut to the engine. Fastener size and type must be verified against Mercedes-Benz service data for this engine before removal. Support the strut with one hand as you remove the final fastener to prevent it from dropping.
5. 5

   Remove strut-to-subframe fasteners
   Locate the lower mounting point where the strut attaches to the front subframe or crossmember. Remove the 2-3 fasteners securing the strut bracket to the subframe. These may be accessed from below; verify the exact fastener size and type against Mercedes-Benz service data before removal. The strut may be under slight tension - control it as you remove the final fastener.
6. 6

   Remove engine mount strut assembly
   With all fasteners removed, carefully maneuver the engine mount strut out of the engine bay. It may need to be rotated or angled to clear surrounding components. Inspect the mounting points on both the engine and subframe for damage, cracks, or thread wear. Clean both mounting surfaces thoroughly with a wire brush.
7. 7

   Prepare new engine mount strut
   Unpack the new engine mount strut and verify it matches the old part exactly, including mounting hole positions, overall length, and bracket orientation. Transfer any shims, spacers, or hardware from the old strut if they are not included with the new part and are in good condition. Apply a small amount of medium-strength thread locker to the fastener threads.
8. 8

   Position new strut
   Position the new engine mount strut between the engine and subframe, aligning it in the same orientation as documented during removal. The strut should fit without forcing - if excessive force is needed, the engine may need slight repositioning using the support fixture. Ensure any alignment marks or reference points match the original installation.
9. 9

   Install strut-to-engine fasteners
   Install the upper mounting fasteners that secure the strut to the engine block or timing cover. Start all fasteners by hand to ensure proper thread engagement. Snug the fasteners in an alternating pattern but do not torque to final specification yet - the mount needs to be loaded with the engine at rest position first.
10. 10

    Install strut-to-subframe fasteners
    Install the lower mounting fasteners that secure the strut bracket to the subframe. Start all fasteners by hand to ensure proper thread engagement. Snug the fasteners in an alternating pattern but do not torque to final specification yet.
11. 11

    Set engine to rest position and torque fasteners
    Carefully adjust the engine support fixture to lower the engine to its natural rest position - remove all support tension so the engine weight is fully on the mounts. With the engine at rest, torque all engine mount strut fasteners to the exact Mercedes-Benz specification for this application (verify torque and any torque-angle requirement against MB WIS service data before final tightening). Torque in an alternating pattern if multiple fasteners are present at each location. Note: Exact torque specifications should be verified against Mercedes-Benz service data for this specific application.
12. 12

    Remove engine support and reinstall shields
    Carefully remove the engine support fixture or hoist. Verify the engine sits level and the strut is properly seated with no binding or misalignment. Reinstall the lower engine splash shield/undertray using the original Torx or E-Torx fasteners. Reinstall the engine cover by pressing down firmly to seat the rubber grommets.

Reassembly

1. Reconnect the negative battery terminal.
2. Lower the vehicle from jack stands.
3. Double-check that all fasteners are torqued and no tools or parts have been left in the engine bay.
4. The engine mount strut must be torqued with the engine at rest position (no support tension) to prevent premature failure.

Verification

• Start the engine and observe for any unusual vibration, movement, or noise from the engine bay.
• With the engine idling, have an assistant shift between Park, Reverse, and Drive while you observe engine movement from outside the vehicle. Movement should be minimal and controlled.
• Perform a test drive including gentle acceleration, braking, and turning. Engine vibration should be normal with no clunking or excessive movement.
• Re-inspect all mount strut fasteners after the first 50 miles of operation to verify they remain tight.
• Check for any contact between the engine and surrounding components that would indicate improper mount installation or failure.

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