- Engine:
- G3606 (S/N: 3XF1-UP; 4ZS1-UP)
- G3608 (S/N: 4WF1-UP; BEN1-UP)
- G3612 (S/N: 1YG1-UP; BKE1-UP)
- G3616 (S/N: 4CG1-UP; BLB1-UP)
Description of Change: New prechamber groups and new cylinder head groups are being released in order to change to larger hold down bolts for the prechamber assembly. The previous prechamber assembly used 3/8-16 standard bolts as hold down bolts. The new prechamber assembly uses 1/2-13 standard bolts as hold down bolts. The new design is expected to eliminate coolant leaks past the joints that have gaskets.
Adaptable To: The part numbers of the new cylinder head groups and of the new prechamber groups are listed below.
| Part Number | Application | Prechamber Group |
| 219-2955 Cylinder Head Gp | 9:1 Compression Ratio | 218-3893 Prechamber Group (1) |
| 219-2956 Cylinder Head Gp | 10.5:1 Compression Ratio | 218-3902 Prechamber Group (1) |
| 219-2957 Cylinder Head Gp | Low British Thermal Units (BTU) | 218-3907 Prechamber Group (1) |
| ( 1 ) | This part number is not serviceable at this level. The parts within the group are serviceable. |
Note: This procedure is only for the 1/2-13 standard bolts.
- Use the hold down bolts in order to ensure that the entire prechamber assembly is properly seated.
- Torque each bolt to 30 N·m (22 lb ft).
- Loosen the hold down bolts.
- Alternate from one bolt to the other bolt. Torque each bolt to 30 ± 5 N·m (22 ± 4 lb ft).
- Turn each bolt 30° in the clockwise direction.
- Turn each bolt for an additional 30° in the clockwise direction.
- Turn each bolt for an additional 60° in the clockwise direction.
Note: The total degrees of turn from the initial torque of 30 ± 5 N·m (22 ± 4 lb ft) should be 120° ± 5°. Turning the bolt too far may shorten the life of the bolt. Turning the bolt not far enough can lead to an inadequate load on the gasket. This may result in coolant leaks into the combustion chamber.