GM Service Manual Online
For 1990-2009 cars only

Engine Flywheel Replacement Except LS9 and LSA

Removal Procedure

Caution: Failure to follow the proper removal and installation procedures may result in damage to the engine crankshaft thrust bearing.

Caution: When tilting down the rear of the driveline, observe the clearance between the rear of the engine and the composite dash panel. Do not allow the engine to rest unsupported against the composite dash panel, or vehicle damage may result.

Caution: When lowering and removing the rear of the driveline, observe the clearance between the rear of the transaxle assembly and the underbody to prevent damage.

Note: 

   • For manual transmission applications, note the position and direction of the engine flywheel before removal. The flywheel does not use a locating pin for alignment. Mark or scribe the end of the crankshaft and the flywheel before component removal. The engine flywheel must be reinstalled to the original position and direction. The engine flywheel will not initially seat against the crankshaft flange, but will be pulled onto the crankshaft by the engine flywheel bolts. This procedure requires a 3 stage tightening process.
   • DO NOT remove the prop shaft hub or flex plate from the automatic transmission engine flywheel. The flywheel, prop shaft hub, and flex plate are balanced as an assembly. If service is required, the entire flywheel assembly should be replaced.


    Object Number: 506140  Size: SH
  1. Remove the catalytic converters. Refer to Catalytic Converter Replacement - Left Side and Catalytic Converter Replacement - Right Side.
  2. Remove the driveline support, if equipped with a automatic transmission. Refer to Driveline Support Assembly Replacement.
  3. Remove the clutch assembly, if equipped with a manual transmission. Refer to Clutch Assembly Replacement.
  4. Mark or scribe the end of the crankshaft and the manual transmission flywheel. Refer to Engine Balancing.

  5. Object Number: 651889  Size: SH
  6. If equipped with an automatic transmission, remove the engine flywheel bolts.

  7. Object Number: 156166  Size: SH
  8. If equipped with a manual transmission, remove the engine flywheel bolts.
  9. Remove the engine flywheel.

Installation Procedure

Note: For manual transmission applications, note the position and direction of the engine flywheel before removal. The flywheel does not use a locating pin for alignment. Mark or scribe the end of the crankshaft and the flywheel before component removal. The engine flywheel must be reinstalled to the original position and direction. The engine flywheel will not initially seat against the crankshaft flange, but will be pulled onto the crankshaft by the engine flywheel bolts. This procedure requires a 3 stage tightening process.

DO NOT remove the prop shaft hub or flex plate from the automatic transmission engine flywheel. The flywheel, prop shaft hub, and flex plate are balanced as an assembly. If service is required, the entire flywheel assembly should be replaced.


    Object Number: 156166  Size: SH
  1. If equipped with a manual transmission, align the mark or scribe on the crankshaft with the mark or scribe on the existing flywheel. Refer to Engine Balancing.

  2. Object Number: 651889  Size: SH
  3. Install the engine flywheel.

  4. Object Number: 63174  Size: SH
  5. Apply threadlock to the threads of the flywheel bolts. Refer to Adhesives, Fluids, Lubricants, and Sealers for the correct part number.
  6. Caution: Refer to Fastener Caution in the Preface section.

  7. Install the engine flywheel bolts until snug.
  8. Tighten

    1. Tighten the engine flywheel bolts a first pass in sequence to 20 N·m (15 lb ft).
    2. Tighten the engine flywheel bolts a second pass in sequence to 50 N·m (37 lb ft).
    3. Tighten the engine flywheel bolts a final pass in sequence to 100 N·m (74 lb ft).
  9. Install the driveline support, if equipped with a automatic transmission. Refer to Driveline Support Assembly Replacement.
  10. Install the clutch assembly, if equipped with a manual transmission. Refer to Clutch Assembly Replacement.
  11. Install the catalytic converter. Refer to Catalytic Converter Replacement - Left Side and Catalytic Converter Replacement - Right Side.

Engine Flywheel Replacement LS9 and LSA

Special Tools

    • J 42386-A Flywheel Holding Tool
    • J 45059 Angle Meter

Removal Procedure

Caution: Failure to follow the proper removal and installation procedures may result in damage to the engine crankshaft thrust bearing.

Caution: When tilting down the rear of the driveline, observe the clearance between the rear of the engine and the composite dash panel. Do not allow the engine to rest unsupported against the composite dash panel, or vehicle damage may result.

Caution: When lowering and removing the rear of the driveline, observe the clearance between the rear of the transaxle assembly and the underbody to prevent damage.

Note: 

   • For manual transmission applications, note the position and direction of the engine flywheel before removal. The flywheel does not use a locating pin for alignment. Mark or scribe the end of the crankshaft and the flywheel before component removal. The engine flywheel must be reinstalled to the original position and direction. The engine flywheel will not initially seat against the crankshaft flange, but will be pulled onto the crankshaft by the engine flywheel bolts. This procedure requires a 3 stage tightening process.
   • DO NOT remove the prop shaft hub or flex plate from the automatic transmission engine flywheel. The flywheel, prop shaft hub, and flex plate are balanced as an assembly. If service is required, the entire flywheel assembly should be replaced.


    Object Number: 506140  Size: SH
  1. Remove the catalytic converters. Refer to Catalytic Converter Replacement - Left Side and Catalytic Converter Replacement - Right Side.
  2. Remove the driveline support, if equipped with an automatic transmission. Refer to Driveline Support Assembly Replacement.
  3. Remove the clutch assembly, if equipped with a manual transmission. Refer to Clutch Assembly Replacement.
  4. Mark or scribe the end of the crankshaft and the manual transmission flywheel. Refer to Engine Balancing.

  5. Object Number: 651889  Size: SH
  6. If equipped with an automatic transmission, remove the engine flywheel bolts.

  7. Object Number: 156166  Size: SH
  8. If equipped with a manual transmission, remove the engine flywheel bolts.
  9. Remove the engine flywheel.

Installation Procedure

Note: For manual transmission applications, note the position and direction of the engine flywheel before removal. The flywheel does not use a locating pin for alignment. Mark or scribe the end of the crankshaft and the flywheel before component removal. The engine flywheel must be reinstalled to the original position and direction. The engine flywheel will not initially seat against the crankshaft flange, but will be pulled onto the crankshaft by the engine flywheel bolts. This procedure requires a 3 stage tightening process.

DO NOT remove the prop shaft hub or flex plate from the automatic transmission engine flywheel. The flywheel, prop shaft hub, and flex plate are balanced as an assembly. If service is required, the entire flywheel assembly should be replaced.


    Object Number: 2054034  Size: SH
  1. Install the flywheel (2) to the crankshaft.
  2. Apply threadlock GM P/N 12345382 (Canadian P/N 10953489), or equivalent, to the threads of the flywheel bolts (1).
  3. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 2054464  Size: SH
  4. Install the J 42386-A and bolts. Use one M10 - 1.5 x 120 mm and one M10 - 1.5 x 45 mm bolt for proper tool operation. Tighten the J 42386-A bolts to 50 N·m (37 lb ft).

  5. Object Number: 2054465  Size: SH
  6. Install the engine flywheel bolts.
  7. 4.1. Tighten the engine flywheel bolts (1-9) a first pass in sequence to 20 N·m (15 lb ft).
    4.2. Tighten the engine flywheel bolts (1-9) a second pass in sequence to 30 N·m (20 lb ft).
    4.3. Tighten the engine flywheel bolts (1-9) a final pass in sequence to 40 degrees using the J 45059 .
  8. Install the driveline support, if equipped with an automatic transmission. Refer to Driveline Support Assembly Replacement.
  9. Install the clutch assembly, if equipped with a manual transmission. Refer to Clutch Assembly Replacement.
  10. Install the catalytic converter. Refer to Catalytic Converter Replacement - Left Side and Catalytic Converter Replacement - Right Side.