Cylinder head spark plug hole repair

I have a kohler k161 engine that appears to have 2 heilacoils. When I removed the spark plug one was on the plug. Closer examination showed another in the head. Has anyone encountered this before? Seems like to put a new plug in I would have to install a new coil on the new plug. Or I could clean the old plug and leave it in. Thanks for any help on this!
 
The issue is more heat control than convenience. The helicoils change the heat transfer from the head to the plug shell. Making the plug maybe two ranges hotter than marked. Not good on an air cooled engine. Go with Teddy's idea of welding and tapping, or a new head. Jim
 
Some people like this option. Heli coils on spark plugs are way down the list.
https://www.timesert.com/
 
Being as you have a failed precious repair I am not sure this would even work.
http://www.timesert.com/html/bigsert.html
 
A heli-coil repair goes in the hole, in this case, the head, not on the bolt, or spark plug. If you re-use that plug, you need to get the insert off of there and throw it away. Have you tried to screw that plug, or any other plug, back in the hole to see if it holds? I assume when you say it looks like two inserts in the hole, one was farther in? Maybe it's too far in for the plug to catch? With a hole that big, it's not too difficult to remove an old insert, and install a new one.
 
Never heard of a Helicoil inside a Helicoil.

I can't imagine how that would even be possible as a Helicoil thread is an odd size.

I would look for a new or used head unless they are hard to find or expensive.

Trying to fix it will be time consuming, expensive, and have a risk of failure factor.
 
Thanks for the replies guys. I might try an 18mm plug that has similar reach. Also there is a parts tractor the head could be used from.
 
HeliCoil -- now named Stanley Engineered Fastening -- sells "Twinsert" inserts that are used to repair a stripped-out hole that was tapped for a standard wound-wire insert. Once the Twinsert insert is installed, a standard insert is installed within it. I don't know when the Twinsert insert was first put on the market, but I learned about them thirty-some years ago from a mentor who claimed he'd been using them for decades.

It should be self-evident, but Twinsert inserts require taps and insertion tools sized for Twinserts.

I don't know if HeliCoil sells Twinsert inserts to repair sparkplug holes, but I generally prefer thread repair inserts made of solid stock for sparkplug use . . . and have found EZ-Lok sparkplug inserts to both be easy to install and work well.
 
Take the plug with the heli-coil stuck on it , put some red loctite on it wait over night then unscrew the plug from engine.
 
Kind of a common thing for old aluminum headed Kohlers.I had one in a Wheelhorse that would do what yours is doing,usually once a summer.I would just put a new insert in with Locktite and go some more.A few years ago I found I could buy a good head and a gasket off ebay for $30.delivered.New ones were $40.I wonder how much I spent on inserts over the 25 years or so I patched it.I would buy a tube of inserts,use one,and not be able to find it the next year when it happened again.
 
So I guess I got it wrong. Heilicoil is in head and threaded repair sleeve is on plug. I will try Loctite on a new sleeve in heilacoil.
 
What I did on the last one I came across that had a previous repair that failed: (And it was on a Kohler) I tapped the head for pipe thread. I think 3/8 pipe but may have been 1/2"pipe. Then I took the that size pipe bushing, tapped the center to 18mm to fit the sparkplug threads and screwed it into the head. Then put the plug back in the threaded hole in the bushing. It worked.
 
K161 engine should use a Champion J8 plug, 14 mm. Never had any luck with Heilicoils, I'd drill and retap threads to 18 mm and install a Champion D-10 plug. I did that on a K301 30 years ago and ran it for ten years till I sold it.
 

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