On most of the engines covered by this manual the flywheel and the ring gear are machined from one piece of metal and cannot be separated. On some of the 4.3L engines the ring gear is a separate piece and can be driven from the flywheel once the gear is heated using a torch.
Removal & Installation
Remove the transmission.
NOTENote the position and the direction of the engine flywheel before removal.
- Remove the flywheel bolts.
- Remove the flywheel.
- Clean and Inspect the flywheel.
Add threadlock to the new flywheel bolts.
Install the flywheel and secure the flywheel with the new bolts. Tighten the bolts in sequence, as follows:
- First pass: 18 ft. lbs. (25 Nm)
- Final pass: An additional 50 degrees, with a torque angle meter
- Install the transmission.
- Remove the transmission assembly from the vehicle.
- If equipped with a manual transmission, remove the clutch and pressure plate assembly.
- If equipped, remove the flywheel cover.
Remove the flywheel-to-crankshaft bolts, then remove the flywheel and spacer (if used) from the engine.
- Inspect the flywheel for cracks, and inspect the ring gear for burrs or worn teeth. Replace the flywheel if any damage is apparent. Remove burrs with a mill file. Remove ant thread sealer from the flywheel bolts.
- Install the spacer (if used) and the flywheel. Most flywheels will only attach to the crankshaft in one position, as the bolt holes are unevenly spaced and/or the crankshaft is fitted with a dowel pin.
- Install the bolts and tighten to 74 ft. lbs. (100 Nm) using a crisscross pattern.
- If equipped, install the clutch and pressure plate assembly.
- Install the transmission assembly.
- Remove the transmission.
- Note the position and direction of the engine flywheel before removal.
- Remove the engine flywheel bolts.
- Remove the engine flywheel.
- Clean and inspect the engine flywheel.
- Install the engine flywheel to the crankshaft.
Apply threadlock GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the threads of the flywheel bolts.
Install the engine flywheel bolts. Tighten, in sequence, as follows:
- First pass: 15 ft. lbs. (20 Nm)
- Second pass: 37 ft. lbs. (50 Nm)
- Final pass: 74 ft. lbs. (100 Nm)
- Install the transmission.
Ring Gear Replacement
- Remove the flywheel from the vehicle. Refer to the procedure outlined in this section.
- Make certain that the ring gear is a separate piece, then using a torch, uniformly heat it around the entire circumference. DO NOT heat the gear until it is red hot as this will change the metal structure.
- When the ring gear is hot enough, drive it off the flywheel using a hammer.
Using a torch, heat the ring gear uniformly until it expands enough to be installed on the flywheel.
CAUTIONNever heat the ring gear to a temperature above 400°F (204°C) as this will weaken the structure of the metal.
- When the ring gear and flywheel have cooled sufficiently, install the flywheel on the vehicle.