Cylinder Head Bolt Hole Thread Repair: Notes

Fig 1: View Of Cylinder Head Bolt Hole Required Tools

Courtesy of GENERAL MOTORS CORP.

The cylinder head bolt hole required tools consist of the following:

• Drill (1) J 42385-402
• Tap (2) J 42385-403
• Installation driver (3) J 42385-404
• Alignment pin (4) J 42385-303
• Bushing (5) J 42385-302
• Bolts (6) J 42385-421
• Fixture plate (7) J 42385-401

When installed to the proper depth, the flange of the insert will be seated against the counterbore of the drilled/tapped hole.

Fig 2: View Of Bushing, Fixture Plate, Bolts & Bolt Hole
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1. Position the fixture plate (3) with the bushing (1) installed over the cylinder head bolt hole to be repaired (4).
2. Loosely install the fixture plate bolts (2) into the remaining cylinder head bolt holes.
Fig 3: View Of Alignment Pin & Fixture Retaining Bolts
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3. Position the alignment pin (1) through the bushing and into the cylinder head bolt hole.
4. With the alignment pin in the desired cylinder head bolt hole, tighten the fixture retaining bolts (2).
5. Remove the alignment pin (1) from the cylinder head bolt hole.
Fig 4: Drilling Out Threads Of Damaged Hole
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IMPORTANT: During the drilling process, it is necessary to repeatedly remove the drill and clean chips from the hole and the flutes of the drill.
6. Drill out the threads of the damaged hole.
Fig 5: Cleaning Out Metal Chips
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IMPORTANT: All chips must be removed from the drilled hole prior to tapping.
7. Using compressed air, clean out any chips.
Fig 6: Tapping Out Threads Of Drilled Hole
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IMPORTANT:
• During the tapping process, it is necessary to repeatedly remove the tap and clean chips from the hole and the flutes of the tap.
• Ensure the tap has created full threads at least to the depth equal to the insert length.
8. Using a suitable tapping wrench, tap the threads of the drilled hole.
Fig 7: View Of Tap Upper & Lower Marks, Fixture Plate & Bushing
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9. In order to tap the new threads for the insert to the proper depth, rotate the tap into the cylinder head bolt hole until the first mark (1) on the tap aligns with the top of the drill bushing (3).
Fig 8: View Of Bushing, Fixture Plate, Bolts & Bolt Hole
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IMPORTANT: Remove the fixture plate prior to installing the insert with the installer tool.
10. Remove the fixture plate bolts (2).
11. Remove the fixture plate (3) and bushing (1).
Fig 9: Cleaning Out Metal Chips
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IMPORTANT: All chips must be removed from the tapped hole prior to insert installation.
12. Using compressed air, clean out any chips.
Fig 10: Spraying Cleaner Into Tapped Hole
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13. Spray cleaner GM P/N 12377981 (Canadian P/N 10953463) or equivalent into the tapped hole.
Fig 11: Cleaning Out Metal Chips
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IMPORTANT: All chips must be removed from the tapped hole prior to insert installation.
14. Using compressed air, clean out any chips.
Fig 12: Lubricating Installer Tool Using Driver Oil
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IMPORTANT: Do not allow oil or other foreign material to contact the outside diameter (OD) of the insert.
15. Lubricate the threads of the driver installation tool (2) with the driver oil (1) J 42385-110.
Fig 13: View of Bushing Type Insert
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16. Install the insert (2) onto the driver installation tool (1).
Fig 14: Applying Threadlock To Insert
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17. Apply threadlock sealant GM P/N 12345493 (Canadian P/N 10953488), J 42385-109, LOCTITE 277®, or equivalent (1) to the insert OD threads (2).
Fig 15: View Of Installation Driver
Courtesy of GENERAL MOTORS CORP.
18. Install the insert and installation driver (1) into the tapped hole.
19. Start the insert into the threaded hole.
IMPORTANT: If the insert will not thread down until the flange contacts the counterbored surface remove the insert immediately with a screw extracting tool and inspect the tapped hole for any remaining chips and/or improper tapping.
20. Install the insert until the flange of the insert contacts the counterbored surface.
IMPORTANT: The driver installation tool will tighten up before screwing completely through the insert. This is acceptable. The threads at the bottom of the insert are being formed and the insert is mechanically locking the insert into the base material threads.
21. Continue to rotate the driver installation tool through the insert.
22. Inspect the insert for proper installation into the tapped hole.