Part# 08-13859
MFR Model# 2-52


18mm long Heli-Coil aviation grade spark plug inserts.
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Worked fine.

Melvin D Verified Purchase


August 24, 2022

This is the real deal for aircraft engines, but dont think you can just thread it in easily. Use the Helicoil insertion tool AFTER youve carefully run the Helicoil stepped tap, with lots of aluminum cutting fluid or grease on it, through the spark plug hole, repeatedly until it theres little resistance to turning it. MAKE SURE THE PISTON IS NEAR THE BOTTOM! Put the coil in the insertion tool with about one thread of the coil exposed and hold the tool inner shaft and outer sleeve so the exposed coil is wrapped tightly to the inner shafts threads. Get the tool centered on the hole and square with it (do this more by feel than sight). Then slowly rotate the entire tool without allowing the coil to loosen from the threads on the inner shaft. It will probably take many tries, so be patient, its never easy with airplanes. Dont be afraid of removing the coil from the tool and starting over, just be very careful with the coil so you dont distort it or break the tang off. Once the coil gets threaded into the cylinder, hold the outer sleeve and turn the inner shaft until the coil clears the outer sleeve, then screw the coil so the end of it is about one thread inside the hole. Unscrew the inner shaft from it and inspect. If it looks good, use a long needle nose pliers to grab the end of the tank and wiggle it in and out about 1/16 until it work hardens and breaks off. DONT DROP IT INSIDE THE CYLINDER! Then you need the staking tool to drive the serrated end of the coil into the cylinder head, to lock it in place. Otherwise, it will screw out with the sparkplug the next time you remove one. USE SPARKPLUG THREAD LUBE (black liquid) AND A FRESH OR ANNEALED WASHER WHENEVER INSTALLING A SPARKPLUG! Silver anti-seize goop is NOT sparkplug lube...

Gelston A Verified Purchase


February 10, 2022

The low reviews on this page come from not knowing how to insert the helicoil. The helicoil looks too big, but with a special tool, it is inserted into the cylinder with a bit of spring tension so that when you pull the tool out it is wedged in there.

Amos C
August 11, 2021

Fit perfectly. Understanding how the installation tool works is critical! I used a NAPA Balkamp 18-1.50mm spark plug thread repair kit P/N 770-3066.

Thomas S
April 20, 2021

Size .5mm off. Material possibly to thick. Could not use. Might work for non-aircraft use.

Songbird A
March 16, 2021

We ordered an 18 mm helicoil for a Lycoming engine. The Helicoil came in a bag labeled 18 mm but definitely was not 18 mm. it measured more than 20 mm on the ID. We had an additional 2 days down time on this engine while we procured the correct helicoil.

Bill H
September 30, 2019


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: What material is this heli-coil insert made from? Is it brass?

Per Vendor: 08-13859 is made of stainless steel. Brass cannot be used on Aircraft Engines as the temperature would melt the brass in an Aircraft Engine.

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