Cylinder Head Bolt Hole Thread Repair

Courtesy of GENERAL MOTORS COMPANY

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

• EN-42385-51  Drill (1)
• EN-42385-52  Tap (2)
• EN-42385-53  Driver (3)
• EN-42385-54  Bushing (6)
• EN-42385-55  Alignment Pin (5)
• EN-42385-56  Bolt (7)
• EN-42385-57  Sleeve (4)
• EN-42385-300  Fixtures and Hardware Kit
• J-42385-301  Fixture Plate (8)

1. Courtesy of GENERAL MOTORS COMPANY

   NOTE:

   • The use of a cutting type fluid or equivalent, is recommended when performing the drilling and tapping procedures. Adhesives, Fluids, Lubricants, and Sealers
   • Driver oil MUST be used on the installer driver tool. Adhesives, Fluids, Lubricants, and Sealers
   • The tool kits are designed for use with either a suitable tap wrench or drill motor.

   Install the J-42385-301  Fixture Plate (3), EN-42385-56  Bolts (1), and EN-42385-54  Bushing (2) onto the engine block deck.

   Position the J-42385-301  Fixture Plate (3) and EN-42385-54  Bushing (2) over the hole that is to be repaired (4).

2. Courtesy of GENERAL MOTORS COMPANY

   Position the EN-42385-55  Alignment Pin (1) through the EN-42385-54  Bushing (2) and into the hole.

3. With the EN-42385-55  Alignment Pin (1) in the desired hole, tighten the EN-42385-56  Bolts (2).
4. Remove the EN-42385-55  Alignment Pin (1) from the hole.

5. Courtesy of GENERAL MOTORS COMPANY

   CAUTION:

   For the hole on the upper front corner of cylinder #1 (Left Cylinder Bank), install EN-42385-57 sleeve onto the drill. The depth of this hole is shallower than the others. If the sleeve is not used, damage to the engine block will occur.

   Install the EN-42385-57  Sleeve (2) onto the EN-42385-51  Drill (1).

6. Courtesy of GENERAL MOTORS COMPANY

   NOTE:

   During the reaming process, it is necessary to repeatedly remove the EN-42385-51  Drill and clean the chips from the hole.

   Drill out the threads of the damaged hole until the stop collar of the EN-42385-51  Drill or the EN-42385-57  Sleeve contacts the EN-42385-54  Bushing.

7. Using compressed air, clean out any chips.

8. Courtesy of GENERAL MOTORS COMPANY

   Using a tap wrench, and EN-42385-52  Tap, tap the threads of the drilled hole.

9. Courtesy of GENERAL MOTORS COMPANY

   For the hole on the upper front corner of left cylinder bank, rotate the EN-42385-52  Tap into the hole until the first mark (1) on the EN-42385-52  Tap aligns with the top of the EN-42385-54  Bushing (3).

   For all other cylinder head bolt holes, rotate the EN-42385-52  Tap into the hole until the second mark (4) on the EN-42385-52  Tap aligns with the top of the EN-42385-54  Bushing (3).

10. Remove the J-42385-301  Fixture Plate (2), EN-42385-54  Bushing (3) and EN-42385-56  Bolts.
11. Using compressed air, clean out any chips.
12. Spray cleaner into the hole. Adhesives, Fluids, Lubricants, and Sealers
13. Using compressed air, clean any cutting oil and chips out of the hole.

14. Courtesy of GENERAL MOTORS COMPANY

    NOTE:

    Do not allow oil or foreign material to contact the OD of the insert.

    Lubricate the threads of the EN-42385-53  Driver (2) with the driver oil (1). Adhesives, Fluids, Lubricants, and Sealers

15. Courtesy of GENERAL MOTORS COMPANY

    Install the insert (2) onto the EN-42385-53  Driver (1).

16. Courtesy of GENERAL MOTORS COMPANY

    Apply threadlock to the insert OD threads (2). Adhesives, Fluids, Lubricants, and Sealers

17. Courtesy of GENERAL MOTORS COMPANY

    Install the insert and EN-42385-53  Driver (1) into the hole.

    • For the hole on the upper front corner of the left cylinder bank, rotate the EN-42385-53  Driver until the lower mark on the EN-42385-53  Driver aligns with the deck surface of the engine block.
    • For all other cylinder head bolt holes, rotate the EN-42385-53  Driver until the upper mark on the EN-42385-53  Driver aligns with the deck surface of the engine block.
18. Rotate the EN-42385-53  Driver until the upper mark on the EN-42385-53  Driver aligns with the deck surface of the engine block.
19. The EN-42385-53  Driver will tighten up before screwing completely through the insert. This is acceptable. You are forming the bottom threads of the insert and mechanically locking the insert to the base material threads.