Flexplate

Replace the flexplate (flywheel) on a 2019 Mercedes-Benz G-Class with 4.0L Turbo V8, requiring transmission removal to access the flexplate between engine and torque converter.

Warnings

Tools required

Parts

• Flexplate × 1 — Use OEM specification (Mercedes-Benz)
• Flexplate mounting bolts (new) × 8 — Use OEM specification
• Transmission-to-engine mounting bolts (new recommended) × 6 — Use OEM specification
• Torque converter-to-flexplate bolts (new) × 6 — Use OEM specification
• Transmission oil pan gasket × 1 — Use OEM specification
• Transfer case drain plug seal × 1 — Use OEM specification
• Exhaust flange gaskets × 2 — Use OEM specification

Fluids

• MB 236.17 ATF — 19 qt
• MB 236.17 ATF (transfer case) — 1.9 qt

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Disconnect battery negative terminal and wait 15 minutes for system discharge.
3. Raise vehicle on lift to working height and secure on safety locks, or raise and support on jack stands rated for vehicle weight.
4. Remove engine undertray panels and skid plates using Torx fasteners.
5. Place transmission jack under transmission and adjust to support weight without lifting.
6. Place drain pan under transmission oil pan and transfer case.

Procedure

1. 1

   Drain transmission and transfer case
   Remove transmission oil pan drain plug and drain fluid completely into appropriate container. Remove transfer case drain plug and drain fluid. Once drained, reinstall drain plugs finger-tight to prevent debris entry during remaining work. Total fluid drainage will be approximately 8-11 quarts combined (VERIFY drain capacities against MB WIS).
2. 2

   Remove exhaust system components
   Disconnect exhaust system at catalytic converter flanges using E-Torx fasteners. Support exhaust with jack stand or wire to prevent stress on downstream hangers. Remove exhaust heat shields if they obstruct transmission access. Mark oxygen sensor connectors and disconnect as needed for clearance.
3. 3

   Remove driveshafts
   Mark front driveshaft flange-to-transfer case and rear driveshaft flange-to-rear differential positions with paint pen for reassembly alignment. Remove driveshaft flange bolts using E-Torx sockets. Support driveshafts and carefully lower away from flanges. Cap transfer case output and transmission output shaft openings with clean rags or plugs to prevent contamination.
4. 4

   Disconnect transmission electrical connections and shift linkage
   Disconnect transmission range sensor connector, speed sensor connectors, and solenoid body harness connector from transmission case. Release harness clips from transmission. Disconnect shift cable from transmission lever and remove cable bracket from transmission using Torx fasteners. Disconnect transmission breather hose from vent tube.
5. 5

   Remove transmission cooler lines
   Using line wrench or appropriate tool, disconnect transmission cooler lines from transmission case fittings. Expect residual fluid loss. Cap open ports on transmission and lines immediately to prevent contamination. Remove any cooler line support brackets from transmission case.
6. 6

   Remove transmission crossmember and mounts
   Support transmission securely with transmission jack. Remove transmission mount-to-crossmember fasteners using appropriate socket. Remove crossmember-to-frame fasteners and lower crossmember away. Lower transmission jack slightly to create working clearance between engine and transmission.
7. 7

   Support engine and remove transmission mounting bolts
   Install engine support bar across engine bay or attach engine hoist to engine lift points to support engine weight once transmission is removed. Remove the 6 transmission-to-engine bell housing mounting bolts using E-Torx sockets. Note upper bolts may require extension and universal joint for access. Keep bolts organized by position as lengths may vary.
8. 8

   Separate transmission from engine
   Install torque converter holding strap or secure torque converter to transmission bell housing using wire or strap to prevent it from sliding out during removal. Verify all electrical connections, lines, and fasteners are disconnected. Carefully pull transmission straight back on transmission jack, ensuring torque converter remains fully seated in transmission pump. Move transmission rearward until input shaft clears engine block, then lower and roll transmission away from vehicle. Torque converter should remain with transmission.
9. 9

   Access and inspect flexplate
   With transmission removed, flexplate is now visible on rear of crankshaft. Inspect flexplate for cracks, damaged ring gear teeth, or elongated bolt holes. Inspect torque converter pilot bearing in crankshaft for wear or roughness. Check rear main seal for leakage. Rotate crankshaft using front crank bolt to inspect entire flexplate circumference and ring gear.
10. 10

    Remove torque converter-to-flexplate bolts
    If torque converter remained attached to flexplate (unusual but possible), mark torque converter position relative to flexplate. Remove the 6 torque converter-to-flexplate bolts by rotating crankshaft to access each bolt through starter opening or bell housing inspection cover. Use crankshaft holding tool or have assistant hold front crank bolt to prevent rotation. Keep these bolts separate as they are specific hardware.
11. 11

    Remove flexplate
    Install crankshaft holding tool or use appropriate method to prevent crankshaft rotation. Mark flexplate orientation to crankshaft with paint pen for reference (though new flexplate will have specific dowel pin alignment). Remove the 8 flexplate-to-crankshaft mounting bolts using E-Torx socket, working in cross pattern to prevent warping. Remove flexplate from crankshaft flange. Inspect crankshaft flange surface for damage or debris.
12. 12

    Clean and prepare mounting surfaces
    Thoroughly clean crankshaft flange surface with brake cleaner and lint-free cloth. Remove any oil, debris, or old thread-locker from bolt holes using compressed air and appropriate thread chaser. Inspect crankshaft flange for wear, cracks, or damage. Clean torque converter hub and pilot bearing area. Verify crankshaft end play is within specification if rear main seal area shows unusual wear.
13. 13

    Install new flexplate
    Position new flexplate onto crankshaft flange, aligning dowel pin hole or offset bolt pattern correctly. Flexplate typically has specific orientation with ring gear positioned away from engine block. Install new flexplate mounting bolts (8 bolts) finger-tight initially. Apply appropriate thread-locker to bolts if specified by manufacturer. Using crankshaft holding tool, torque flexplate bolts in cross pattern per MB WIS specification for the M176 engine (typically an initial torque stage followed by a specified angle of rotation — VERIFY exact multi-stage torque-plus-angle values against Mercedes WIS before final tightening). Verify flexplate runs true by rotating crankshaft and checking for wobble or runout.
14. 14

    Reinstall transmission
    Verify torque converter is fully seated in transmission pump (should be recessed approximately 10-15mm from bell housing face). Apply thin coat of high-temperature grease to torque converter pilot bearing. Carefully align transmission input shaft with crankshaft pilot bearing and raise transmission on transmission jack. Ensure torque converter hub enters crankshaft pilot bearing as transmission approaches engine. Slide transmission forward until bell housing contacts engine block evenly. Do not force - if resistance is encountered, lower and realign. Install transmission-to-engine mounting bolts and torque to the MB WIS-specified values for each bolt size/position in a cross pattern (VERIFY exact torque figures against Mercedes WIS — do not assume a single value for all bell housing bolts).
15. 15

    Install torque converter bolts and verify rotation
    Rotate crankshaft to access torque converter bolt holes through starter opening or inspection cover. Align torque converter bolt holes with flexplate holes. Install new torque converter-to-flexplate bolts (6 bolts) and torque to the MB WIS-specified value using appropriate socket (VERIFY exact torque against Mercedes WIS — 31 Nm appears low; confirm whether an angle stage is required). Rotate crankshaft through complete revolution to verify smooth operation and no binding. Remove torque converter holding strap if used.
16. 16

    Reinstall transmission crossmember and mounts
    Raise transmission on transmission jack to align with crossmember mounting position. Install crossmember to frame and torque frame fasteners to specification. Install transmission mount to crossmember and torque fasteners appropriately. Remove transmission jack and engine support equipment. Verify transmission is properly supported and aligned.
17. 17

    Reconnect transmission cooler lines and electrical connections
    Remove caps from transmission cooler line ports and fittings. Reconnect cooler lines to transmission case using appropriate line wrench and torque to specification if applicable. Reconnect all transmission electrical connectors including range sensor, speed sensors, and solenoid harness. Secure harness clips to transmission case. Reinstall shift cable to transmission lever and secure cable bracket with Torx fasteners. Reconnect breather hose to vent tube.
18. 18

    Reinstall driveshafts
    Remove protective caps from output shafts. Align front driveshaft to transfer case output flange using alignment marks made during disassembly. Install driveshaft flange bolts and torque to specification using E-Torx socket. Repeat process for rear driveshaft to rear differential flange. Verify marks are properly aligned to maintain driveline balance.
19. 19

    Reinstall exhaust components
    Position exhaust system to catalytic converter flanges using new gaskets. Install exhaust flange bolts and torque to specification. Reconnect oxygen sensor connectors. Reinstall exhaust heat shields if removed. Verify exhaust system has proper clearance from driveshafts and chassis components throughout suspension travel.
20. 20

    Fill transmission and transfer case with fluid
    Remove transmission fill plug and fill transmission with the correct MB-specified ATF (VERIFY spec — 725.0/9G-TRONIC typically MB 236.15 or 236.17) according to manufacturer procedure (VERIFY dry-fill capacity against MB WIS — typically approximately 9-10 quarts, not 19). Typical method involves filling until fluid reaches bottom of fill hole with transmission at operating temperature. Remove transfer case fill plug and fill with the correct MB-specified transfer case fluid (VERIFY exact spec against MB WIS — may differ from transmission ATF) to the specified capacity (VERIFY quantity) until fluid reaches bottom of fill hole. Reinstall fill plugs with new seals and torque to specification.
21. 21

    Reinstall underbody panels and final checks
    Reinstall engine undertray panels and skid plates using Torx fasteners. Reconnect battery negative terminal. Perform visual inspection underneath vehicle for any loose fasteners, disconnected sensors, or fluid leaks. Verify all tools and equipment are removed from vehicle and work area.

Reassembly

1. Torque all fasteners to specified values using torque wrench, not impact tools for final tightening.
2. Use new flexplate mounting bolts, torque converter bolts, and transmission mounting bolts as recommended.
3. Maintain driveshaft phasing by aligning marks made during disassembly.
4. Fill transmission and transfer case to proper level with correct MB 236.17 ATF specification.
5. Install new exhaust flange gaskets and transfer case drain plug seal.

Verification

• Start engine and allow to idle. Listen for any unusual noises from flexplate or transmission area.
• Check for transmission fluid leaks around cooler lines, oil pan, and rear seal area.
• With engine at idle, shift through all transmission gear ranges (P-R-N-D) and verify smooth engagement without harsh shifts or grinding.
• Road test vehicle through all gears. Monitor for vibration, noise, or abnormal transmission behavior.
• After road test, recheck transmission and transfer case fluid levels with transmission at operating temperature and adjust as needed.
• Perform final inspection underneath vehicle for any fluid leaks or loose components.
• Clear any diagnostic trouble codes and verify transmission range sensor calibration if equipped with scan tool.

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