N14 Base Engine Troubleshooting and Repair Manual – 001-059   Cylinder Head Mounting Capscrew Holes

Inspect the capscrew bosses for cracks or porosity that extend into the coolant cavities or that have damaged threads.

Mark all cylinder head capscrew holes that are to be repaired. Refer to Procedure 001-028.

When machining work is done on an assembled block, special precautions are required to protect other engine components from contamination. To protect cam bushings, main bearings, crankshaft rod journals, and coolant passages, the areas listed below must be covered as noted:

• If the cylinder liners are removed, put chip control plugs, Part Number 3823231, into the lower liner bores to catch metal chips and dust.
• If the cylinder liners are removed, cover the coolant passages in the liner cavity, on the exhaust side, with Damtite, Part Number 3823232, or some type of formable substance such as modeling clay.
• Cover the push tube openings with masking tape.

If cylinder head capscrew threads in the cylinder block are stripped or the thread area is cracked, blocks can be repaired by using a closed end thread insert.

The following kit contains the necessary components needed to repair cylinder head capscrew holes.

Components included in the capscrew thread repair kit, Part Number 3376208, are as follows:

Burr removal is necessary for an accurate fixture location.

Remove any burrs from the top deck surface of the cylinder block.

A flat mill file is very effective for this process.

Align the fixture with the failed capscrew hole.

Install the reamer base plate and the guide bar to the cylinder block.

Position the guide bar over the capscrew hole to be repaired.

Using a tapered locator, center the guide bar and the bushing over the capscrew hole.

Tighten the guide bar and bushing assembly.

Remove the tapered locator.

Ream the failed capscrew hole to the full depth of the hole.

Use a chip removing unit to remove reamer chips from the capscrew hole.

Set the tap stop collar to the correct height, using the insert to be installed.

Tap the hole.

It can be necessary to stop, remove the tap, and remove chips from the hole several times before achieving full depth.

Remove the tap.

Use a chip removing unit to clean the capscrew hole of shavings and debris.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Clean and flush the newly cut threads with safety solvent.

Use a chip removing unit to clean the capscrew hole of shavings and debris and allow to dry.

Lightly spray the threads with Loctite® Primer-T and allow to dry.

Prepare the thread insert for installation.

Put the jam nut on a cylinder head capscrew.

Install the repair insert onto the capscrew until it contacts the jam nut.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Clean and flush the outside diameter of the repair insert with safety solvent and allow to dry.

Lightly spray with Loctite® Primer-T and allow to dry.

Apply four beads of sealant to the outside diameter of the closed end thread insert.

The beads of sealant must be approximately 8 mm [1/32 in] wide and 90 degrees apart.

Each bead must be the full length of the external threaded portion of the insert.

Install and tighten the repair insert.

Loosen the jam nut. Remove the cylinder head capscrew and jam nut arrangement.

Correct installation will provide 0.00 to 0.50 mm [0.000 to 0.020 in] protrusion above the cylinder block surface.

File the top of the thread repair insert even with the cylinder head mounting surface.

Make sure the inside portion of the repair insert is clean.

Remove any file shavings or debris.

Before tightening the cylinder head capscrews, allow the sealant to cure for three hours.