Cylinder Head Bolt Hole Thread Repair

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

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The cylinder head bolt hole thread repair kit consists of the following items:
- EN-42385 - 51 The drill (1)
- EN-42385 - 52 The tap (2)
- EN-42385 - 53 The installer (3)
- EN-42385 - 57 The sleeve (4)
- EN-42385 - 55 The alignment pin (5)
- EN-42385 - 54 The bushing (6)
- EN-42385 - 56 The bolts (7)
- J-42385 - 301 The fixture plate (8) (Part of J-42385 - 300 Fixtures and Hardware Kit
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WARNING:
Refer to Safety Glasses Warning .
NOTE:
- The use of a cutting type fluid GM P/N 1052864 (Canadian P/N 992881), WD 40®, or equivalent, is recommended when performing the drilling and tapping procedures.
- Driver oil MUST be used on the installer driver tool.
- The tool kits are designed for use with either a suitable tap wrench or drill motor.
Install the fixture plate (3), bolts (1), and bushing (2) onto the engine block deck.

Position the fixture plate and bushing over the hole that is to be repaired (4).
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Position the alignment pin (1) through the bushing and into the hole.
With the alignment pin in the desired hole, tighten the fixture retaining bolts (2).
Remove the alignment pin from the hole.
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NOTE:
During the reaming process, it is necessary to repeatedly remove the drill and clean the chips from the hole.

Drill out the threads of the damaged hole.

Drill the hole until the stop collar of the drill bit contacts the bushing.
Using compressed air, clean out any chips.
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Using a tap wrench, tap the threads of the drilled hole.
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In order to tap the new threads to the proper depth, rotate the tap into the hole until the mark (4) on the tap aligns with the top of the drill bushing (3).
Remove the fixture plate (2), bushing (3), and bolts.
Using compressed air, clean out any chips.
Spray cleaner GM P/N 12346139, GM P/N 12377981 (Canadian P/N 10953463), or equivalent, into the hole.
Using compressed air, clean any cutting oil and chips out of the hole.
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NOTE:
Do not allow oil or foreign material to contact the OD of the insert.

Lubricate the threads of the installer tool (2) with the driver oil (1).
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Install the insert (2) onto the driver tool (1).
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Apply threadlock LOCTITE™ 277, J 42385-109 (1), or equivalent, to the insert OD threads (2).
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Install the insert and driver (1) into the hole.

Rotate the driver tool until the upper mark on the driver tool aligns with the deck surface of the engine block.

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.