Cylinder Head Bolt Hole Thread Repair

Special Tools 

• EN 42385-700  High Feature Thread Repair Kit
• EN 42385-2000  Thread Insert Kit

Fig 1: Identifying Cylinder Head Bolt Hole Thread Repair Special Tools

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The cylinder-head bolt hole thread-repair tools are in the kits EN 42385-2000  insert kit and EN 42385-700  kit. The cylinder head bolt hole thread repair components consist of the following:

• EN 42385-723 Drill (1)
• EN 42385-724 Tap (2)
• EN 42385-725 Installation driver (3)
• EN 42385-303 Alignment pin (4)
• EN 42385-302 Bushing (5)
• EN 42385-733 Bolts (6)
• EN 42385-401 Fixture plate (7)

Refer to SAFETY GLASSES WARNING .

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

1. Position the fixture plate (3) with the bushing (1) installed over the cylinder head bolt hole to be repaired (4).
   Fig 2: Identifying Fixture Plate, Bushing And Bolts

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2. Loosely install the fixture plate bolts (2) into the remaining cylinder head bolt holes.
3. Position the alignment pin (1) through the bushing and into the cylinder head bolt hole.
   Fig 3: Positioning Alignment Pin Into Cylinder Head Bolt Hole

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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.
6. NOTE:

   • During the drilling process, it is necessary to repeatedly remove the drill and clean chips from the hole and the flutes of the drill.
   • Drill the hole until the stop collar contacts the top of the drill bushing.

   Drill out the threads of the damaged hole.

   Fig 4: Drilling Out Threads Of Damaged Hole

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7. NOTE: All chips must be removed from the drilled hole prior to tapping.

   Using compressed air, clean out any chips.

   Fig 5: Removing Tapped Hole Chips Using Compressed Air

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8. NOTE:

   • 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.

   Using a suitable tapping wrench, tap the threads of the drilled hole by hand only.

   Fig 6: Tapping Threads Of Drilled Hole Using Tapping Wrench

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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 mark (3) on the tap aligns with the top of the drill bushing (2).
   Fig 7: Aligning Tap Mark With Top Of Drill Bushing

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10. NOTE: Remove the fixture plate prior to installing the insert with the installer tool.

    Remove the fixture plate bolts (2).

    Fig 8: Identifying Fixture Plate, Bushing And Bolts

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11. Remove the fixture plate (3) and bushing (1).
12. NOTE: All chips must be removed from the tapped hole prior to insert installation.

    Using compressed air, clean out any chips.

    Fig 9: Removing Tapped Hole Chips Using Compressed Air

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13. Spray cleaner into the tapped hole. Refer to ADHESIVES, FLUIDS, LUBRICANTS, AND SEALERS  for recommended cleaner.
    Fig 10: Spraying Cleaner Into Tapped Hole

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14. NOTE: All chips must be removed from the tapped hole prior to insert installation.

    Using compressed air, clean out any chips.

    Fig 11: Removing Tapped Hole Chips Using Compressed Air

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15. NOTE: Do not allow oil or other foreign material to contact the outside diameter (OD) of the insert.

    Lubricate the threads of the driver installation tool (2) with the EN 42385-110 (1).

    Fig 12: Lubricating Threads Of Driver Installation Tool

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16. Install the insert (2) onto the driver installation tool (1).
    Fig 13: Installing Insert Onto Driver Installation Tool

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17. Apply threadlock sealant, EN 42385-109, LOCTITE 277®; or equivalent (1) to the insert OD threads (2). Refer to ADHESIVES, FLUIDS, LUBRICANTS, AND SEALERS  for the recommended sealant.
    Fig 14: Applying Threadlock Sealant To Insert OD Threads

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18. Install the insert and installation driver (1) into the tapped hole by hand only.
    Fig 15: Installing Installation Driver Into Tapped Hole

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19. Start the insert into the threaded hole.
20. NOTE: 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.

    Install the insert until the flange of the insert contacts the counterbored surface.

21. NOTE: 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.

    Continue to rotate the driver installation tool through the insert.

22. In order to completely form the new threads in the insert, rotate the driver installation tool through the insert until the mark (1) on the driver installation tool aligns with the surface of the engine block deck (2).
    Fig 16: Rotating Driver Installation Tool On Surface Of Engine Block Deck

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23. Inspect the insert for proper installation into the tapped hole.