Spark Plug Insert Repair

MFK

New member
Hello

What is the normal procedure for repairing a threads in the head for a spark plug? I recently purchased a Top Kart kadet with a Animal engine and I discovered I was getting a compression leak pass the plug. It looks like someone tried to repair it with a steel insert but they installed it crooked so it doesn't look like the crush washer on the plug is making a seal. Or is this normal plug angle from the factory? What are my option?

Should you use a steel insert on a aluminum head?






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Might work to use a spot facing tool with a pilot that an alum. piece can be made to the i.d. size of the hole and then the cutter can align the top surface with the hole. Not a counter bore tool but a wider spot facer.
 
like jack said your only option is to spot face it. old school it via dremel or replace head.
have you tried 2 sealing washers
 
You may find that some high temp orange permatex on the threads may do the trick.
 
I was considering using a dremel to carefully clean up the area so I wouldn't have to remove the head. The spot facing is a good idea as well I will see if I can get some or make some tooling to use with my mill. If all else fails can, I use my tig welder to build up the damaged aluminum, drill and tap for the plug? I wasn't sure if the head would warp while tig welding.
 
The one time I tried that on my Mac, when I was using a CHT, I found that CHT temps went out of sight. I attributed this to the fact that the plug contact was with the steel of the insert, rather than the aluminum of the head. Steel doesn't transfer heat is good as aluminum. I just through the head away.
 
Well I was able to extract the HeliCoil Sav-A-Thread Spark Plug Insert the previous owner installed. I was surprised I usually don't have that kind of luck. Im going to buy a new insert and install it and see how that works.
I was suppose to take the kart out for my daughter for the first time today so hopefully I can get it repaired soon. Thanks for your advice
 
best of luck. Curious how you got it out musta been pretty loose or your pretty good:)
jimbos trick then new head.
 
Go to any auto parts store, get a spark plug thread repair kit, which will include a heli-coil type insert, and follow instructions.
It's very simple.
 
I have tried the helicoil style and the metal insert style. Sooner or later they will leak and/or gaul your spark plug. It might be a quick fix, but you are better off replacing the head.
 
I have tried the helicoil style and the metal insert style. Sooner or later they will leak and/or gaul your spark plug. It might be a quick fix, but you are better off replacing the head.

I agree. I tiried with a flathead but wasn´t very happy with the result. I think next time I won´t even try. A head is not so expensive. JMO
 
The insert type will never leak IF INSTALLED correctly.
Putting on a new head tho, is always a good idea....rather than repair on oldy.
 
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