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Replacing Sparkplug Helicoil

Bavafa

Well Known Member
I was wondering if anyone has removed a sparkplug Helicoil and know of any tricks or definite steps to avoid.

I need to remove and replace my Helicoil and can grab one end of it with a needle nose pliers. I don't think it can be unscrewed that way but I am hoping it can be unwind and pull it without breaking it.
 
I messed up a helicoil on a diesel engine preheat probe. I was able to grab the top coil with needle nose pliers and twist it inward and pull up. It came out in one piece easily. A spark plug helicoil might be stronger and tougher. You might want to google how to do it or go on a helicoil site. Good luck.
 
There’s a special helicoil and a special tool required to the the job. The ATS website explains this.

https://aircraft-tool.com/shop/detail.aspx?id=4260-18&AspxAutoDetectCookieSupport=1

When I did it, I bought a few helicoils and borrowed/rented the tool from a local aircraft engine overhaul shop. Because of the expense, a typical A&P isn’t going to have one of these tools. Also, when breaking off the tang, use needle nose Vise-Grips. With regular needle nose pliers, there’s the threat of dropping the tang into the cylinder.

I’m pretty sure there’s a service bulletin somewhere, but I haven’t been able to locate it.

Good luck!
 
Jerry and JDeanda,
Thank you both for chiming in. I have read the SI 1034A and in the process of getting the tool and the oversized Helicoil. I am hoping for some actual experience of doing it. The two specific area that I like to get more info on is
1- pulling the existing Helicoil out
2- How hard to bang on the staking tool to drive those serrated teeth in. My fear, maybe unfounded, by banging on the stake tool to mess up the first thread.

@Jerry,
I have the SI 1034A and if you want it, I can e-mail it to you.
 
Be careful but diligent cleaning out the aluminum threads. Last time I did a spark plug it was pretty fouled and nasty. Once I chased the threads and cleaned it up, the coil went in uneventfully. I used thread locker on the new coil also. Didn't want it moving around.
 
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