Main Cap Bolt Hole Thread Repair

The main cap bolt hole thread repair kit consists of the following items:
- The drill (1)
- The tap (2)
- The installer (3)
- The fixture plate (4)
- The long bolts (5)
- The short bolts (6)
- The alignment pin (7)
- The bushing (8)
Fig 1: Exploded View Of Main Cap Bolt Hole Thread Repair Kit
Courtesy of GENERAL MOTORS CORP.
Install the fixture plate, bolt, and bushing, onto the engine block.
Position the fixture plate and bushing over the hole that is to be repaired.
Position the alignment pin in the desired hole and tighten the fixture retaining bolts.

Fig 2: Installing Fixture Plate, Bolt & Bushing Onto Engine Block
Courtesy of GENERAL MOTORS CORP.
Drill out the damaged hole.
The outer bolt hole locations (11-20) have the shallower counterbores. Use sleeve J 42385-316 with the drill.

Drill until the stop collar of the drill bit or the sleeve contacts the bushing.
Using compressed air, clean out any chips.

Fig 3: Identifying Deep & Shallow Main Cap Bolt Holes
Courtesy of GENERAL MOTORS CORP.
Using a tap wrench, tap the threads of the drilled hole.
In order to tap the new threads to the proper depth, rotate the tap into the hole until the mark on the tap aligns with the top of the bushing.

For the deeper main cap holes (1-10), rotate the tap until the upper mark (4) on the tap aligns with the top of the bushing (3).

For the shallower main cap holes (11-20), rotate the tap until the lower mark (1) on the tap aligns with top of the bushing (3).
Using compressed air, clean out any chips.
Spray cleaner GM P/N United States 12346139, GM P/N Canada 10953463 or equivalent into the hole.
Using compressed air, clean any cutting oil and chips out of the hole.

Fig 4: Identifying Alignment Marks On Tap
Courtesy of GENERAL MOTORS CORP.

Important: Do not allow oil or other foreign material to contact the outside diameter (OD) of the insert.
Lubricate the threads of the installer tool (2) with the driver oil (1).

Fig 5: Applying Driver Oil On Installer Tool Threads
Courtesy of GENERAL MOTORS CORP.
Install the insert (2) onto the driver tool (1).

Fig 6: Installing Insert Onto Driver Tool
Courtesy of GENERAL MOTORS CORP.
Apply threadlock LOCTITE® 277, J 42385-109 (1), or equivalent to the insert OD threads (2).

Fig 7: Applying Threadlock Onto Insert OD Threads
Courtesy of GENERAL MOTORS CORP.

Important: The fixture plate and bushing remains installed onto the engine block during the insert installation procedure.
Install the insert and driver (1) through the fixture plate and bushing and into the hole.
Rotate the driver tool until the mark on the tool (3) aligns with the top of the bushing (2).

The installer tool 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.

Fig 8: Identifying Alignment Marks On Driver Tool
Courtesy of GENERAL MOTORS CORP.