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Caterpillar 3406 Bolt Hole Thread Insert Procedure: LS-8704 Professional Guide

Detailed thread insert procedure for Caterpillar 3406 using LS-8704.

LS-8704 Caterpillar 3406 bolt hole thread insert procedure step-by-step

By Blog Admin • January 15, 2026 • Posted in Products, Diesel Tools

This 12-phase procedure uses the LS-8704 insert to repair stripped bolt holes in Caterpillar 3406 block decks. Ensures secure threading for gasket sealing and engine integrity without full block replacement.

Introduction: Essential Bolt Hole Repair for CAT Engines

Proper bolt hole threads in CAT 3406 decks maintain gasket seal. The LS-8704 insert restores stripped holes, avoiding block replacement—critical for cost-effective repairs.

Phase 1-3: Block Preparation & Inspection

Remove head and inspect holes – Note stripping
Clean deck surface – Use solvent/brushes
Measure hole depth – Ensure insert fit
Drill/tap for outside thread – 7/8" x 16 TPI
Prepare LS-8704 insert – Apply loctite

Phase 4-6: Insert Installation

Thread insert into hole – Hand start
Torque to seat – 50–60 ft-lbs
Verify flush – No protrusion
Clean inside threads – Tap 3/4" x 16 TPI
Test bolt fit – Smooth threading
Repeat for all holes – Consistent

Phase 7-9: Reassembly

CRITICAL: LS-8704 Insert Setup

Install new gasket – Align holes
Position head – Guide pins
Torque bolts sequence – To spec
Check for gaps – Even seal
Reinstall components – Torque all
Document per hole – Torque values

Phase 10-12: Testing & Finalization

Refill fluids/prime – Check levels
Start idle test – Monitor leaks
Road test load – Verify no issues
Final torque re-check – After run-in
Update logs – Note insert used

Critical Safety Warnings: Insert Procedure

MUST AVOID THESE FATAL ERRORS:

❌ Never skip measurement – Wrong fit fails ($1K+)
❌ Never over-torque – Strips new threads
❌ Never unclean – Contam ($2K+)
❌ Never uneven seat – Leaks
❌ Never omit loctite – Loose insert
❌ Never reuse bolts – Weak hold
❌ Never skip test – Hidden leaks
❌ Never ignore PPE – Tool risks

Professional Repair Documentation

Service Phase	Documentation Required	Complete?
Pre-Service	Hole inspection, depth measures	□
Installation	Torque applied, seating notes	□
Reassembly	Bolt torque sequence, gasket check	□
Testing	Leak/pressure results	□
Final Approval	Signature, warranty log	□

Why LS-8704 Outperforms Standard Repairs

Risky Standard Methods:

❌ Helicoil → Weak hold ($1K+ leaks)
❌ Machining → Expensive
❌ 2–4 hour delays → Labor losses
❌ Poor fix → Overheat
❌ No insert → Block fail

LS-8704 Advantages:

✅ Precision threads
✅ Bulk pricing
✅ 50% faster
✅ Sealing secure
✅ Protects $6,000–$12,500
✅ Durable length
✅ Gasket hold
✅ Repeatable

Repair Professionally. Secure CAT Blocks. Enhance Durability.

Get LS-8704 – $56.00

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