Save A Thread Blown Out! Larger Thread Repair Needed

When a Save-A-Thread insert fails, it can leave the spark plug hole in your engine significantly larger than its original size. This scenario often requires more robust repair solutions, such as the 389XL Triple Oversize Thread Repair Kit. Here's a comprehensive guide on how to tackle this issue effectively.

Understanding the Problem Spark plug threads can become damaged or stripped due to various reasons, including cross-threading, over-tightening, or the failure of previous repair attempts. When a Save-A-Thread insert, which is commonly used for quick fixes, fails, it often enlarges the spark plug hole beyond what standard repair kits can handle. This is where the 389XL kit comes into play, offering a last-ditch solution to restore the functionality of your engine without the need for a costly cylinder head replacement.

About the 389XL Triple Oversize Thread Repair Kit 

The 389XL kit is specifically designed for situations where the spark plug hole has become excessively large due to failed repairs. Unlike temporary fixes from parts stores, this kit provides a permanent type repair:

• Design: This kit uses one insert per hole, which is larger than those in the standard 38900 kit. It includes a guide for precise alignment, ensuring the insert is installed correctly.
• Compatibility: It's particularly suited for Ford engines (4.6, 5.4, and 6.8 liter) but may be used in other applications where the spark plug hole has become oversized.
• Material: The inserts are made from a high-quality steel alloy, offering durability and resistance to the high temperatures of engine operation.

Step-by-Step Guide to Repair 1. Preparation:

• Using the cylinder leak tester provided to ensure valves are closed, will eliminate the possibility of damaging the valves with tooling. This also isolates the cylinder which allows drebris removal with compresses air before the job is completed.

2. Assessment:

• Check the diameter of the existing hole with a caliper or drill bit. If it's larger than 0.678 inches (approximately 17.20mm), the 389XL kit is your solution.

3. Reaming:

• Use the reamer provided in the kit to clean out the damaged threads/material. This step cleans the hole making it cylindricak and allows it to accept fresh threads.

4. Tapping:

• Thread the hole with the tap from the kit. This creates new threads to accommodate the larger insert. Use cutting oil to ease the process and reduce the risk of breaking the tap.

5. Insert Installation:

• Make sure threads are clean and dry. Apply a thread locker (like Loctite) to the insert's threads for added security.
• Screw the insert into the newly tapped hole using the installation tool provided. Ensure the insert is flush with the surface of the cylinder head.

6. Final Check:

• Clean out any residual chips or debris from the cylinder using compressed air or a vacuum tool.

7. Testing:

• Replace the spark plug and tighten to the updated specifications.
• Start the engine and monitor for leaks or misfires, which could indicate a poor seal or misalignment. Clear any trouble codes that were set due to misfire.

Tips for Success:

• Precision: Always align the installation tools correctly to avoid further damage.
• Cleanliness: Ensure no metal shavings remain inside the cylinder, as they could cause severe engine damage.
• Use the Right Tools: The kit comes with specialized tools; using generic tools might not yield the same results.

Conclusion Using the 389XL Triple Oversize Thread Repair Kit is an effective way to preserve an engine that has suffered from a failed Save-A-Thread insert. This repair not only saves time and money compared to replacing the cylinder head but also ensures that your vehicle can return to reliable service. Remember, while this kit provides a robust solution, it's crucial to follow each step meticulously to guarantee a successful repair. We include tips which answers common questions we've had over the years.

At Wise Auto Tools, we’ve been selling thread repair products since 2005. If you need a thread repair kit, or if you’re unsure which thread repair kit is right for your project, use our application lookup tool, fill out our “Contact Us” form, or call us at 800-734-8665. We’re here to help you get the job done right the first time.