Cylinder Head Bolt Hole Thread Repair Procedure

The cylinder head bolt thread repair kit consists of the following items:

Fig 1: Cylinder Head Bolt Thread Repair Kit Components

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• Drill (1).
• Tap (2).
• Installer (3).
• Alignment Pin (4).
• Bushing (5).
• Bolts (6).
• Fixture Plate (7).

Driver oil must be used on installer driver tool.

The tool kits are designed for use with either a suitable tap wrench or drill motor.

1. Install fixture plate, bolts, and bushing onto engine block deck.
   Fig 2: Installing Fixture Plate, Bolts, & Bushing

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2. Position fixture plate and bushing over hole that is to be repaired.
3. Position alignment pin through bushing and into hole.
   Fig 3: Positioning Alignment Pin

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4. With alignment pin in desired hole, tighten fixture retaining bolts.
5. Remove alignment pin from hole.
   NOTE: During drilling process, it is necessary to repeatedly remove drill and clean chips from hole. Install drill sleeve onto the drill if required.
6. Drill out threads of damaged hole.
   Fig 4: Drilling Out Damaged Hole Threads

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7. Using compressed air, clean out any chips.
   • M6 inserts require a minimum drill depth of 15 mm (0.59 in).
   • M8 inserts require a minimum drill depth of 20 mm (0.79 in).
   • M10 inserts require a minimum drill depth of 23.5 mm (0.93 in).
8. Using tap wrench, tap threads of drilled hole.
   Fig 5: Tapping Threads Of Drilled Hole

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9. Tap new threads to proper depth by turning tap into hole until mark on tap aligns with top of drill bushing.
   Fig 6: Turning Tap Into Hole

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10. Remove fixture plate, bushing, and bolts.
11. Using compressed air, clean out any chips.
12. Spray cleaner GM P/N 12346139, P/N 12377981, or equivalent into hole.
13. Using compressed air, clean any cutting oil and chips out of hole.
    CAUTION: Do not allow oil or other foreign material to contact Outside Diameter (OD) of insert.
14. Lubricate threads of installer tool with driver oil. See Figure .
15. Install insert onto driver tool. See Figure .
16. Apply threadlock Loctite 277(tm), J42385-109, or equivalent to insert OD threads. See Figure .
17. Install insert and driver into hole.
    Fig 7: Installing Insert & Driver

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    NOTE: Installer tool will tighten up before screwing completely through insert. This is acceptable. You are forming bottom threads of insert and mechanically locking insert to base material threads.
18. Rotate driver tool until mark on tool aligns with deck surface of engine block.