Spark Plug Thread Repair, Solid Insert vs Heli-coil

[Turd Furgeson]

Hey Guys,

I picked up a carving bar setup off marketplace from a guy yesterday who mentioned he couldn't get it to work on his 445 which I also have. The more I talked to him the more I realized he just lost interest after his saw broke. He cross threaded the spark plug and stripped the threads and I dragged the saw home too.

I have a bunch of Briggs and Stratton spark plug thread repair kits from a thrift store. These are the coil type, I've only done this once before to a Quad 4 engine about 10 years or so back and at that time I used a solid insert type repair and it held up great the whole time I had the car.

I'd prefer the solid insert, but I have the coil kits already. Have any of you had any issues with the coil type repairs on spark plugs? Should I use red loctite or permatex ultra copper on the OD of the coil?

Thanks!

TF

 

[huskyboy]

Hey Guys,

I picked up a carving bar setup off marketplace from a guy yesterday who mentioned he couldn't get it to work on his 445 which I also have. The more I talked to him the more I realized he just lost interest after his saw broke. He cross threaded the spark plug and stripped the threads and I dragged the saw home too.

I have a bunch of Briggs and Stratton spark plug thread repair kits from a thrift store. These are the coil type, I've only done this once before to a Quad 4 engine about 10 years or so back and at that time I used a solid insert type repair and it held up great the whole time I had the car.

I'd prefer the solid insert, but I have the coil kits already. Have any of you had any issues with the coil type repairs on spark plugs? Should I use red loctite or permatex ultra copper on the OD of the coil?

Thanks!

TF

Jb weld on the outside of the helicoil/insert. You never want it to come outta there again lol. Just make sure the insert/helicoil is slightly below the sealing surface of the plug washer. Or else you’ll have a leaky plug and you’ll chase your tail trying to figure out why the saw has a airleak.

 

[legdelimber]

Before installing it, Check your insert coil length against the spark plug thread length.
Just my old fading opinion here, but, I think they should be the same length.
I used to see the coil type inserts get backed out of the hole when the spark plug threads had carbon buildup on the end of the threads.

I wasn't the installer, just a wrench fumbler trying to fix things afterwards. So I have no idea of what tools & skill or knowledge level the installers had.

 

[Mastermind]

Before installing it, Check your insert coil length against the spark plug thread length.
Just my old fading opinion here, but, I think they should be the same length.
I used to see the coil type inserts get backed out of the hole when the spark plug threads had carbon buildup on the end of the threads.

I wasn't the installer, just a wrench fumbler trying to fix things afterwards. So I have no idea of what tools & skill or knowledge level the installers had.

Good advice.

 

[Turd Furgeson]

Thank for the idea about JB weld. That should hold it in place.

I originally liked the idea of making the insert the same length as the plug, but then I thought about it a bit. If the coil is the same length as the plug, it means it would stick out into the cylinder, I wonder if the unsupported coils could fatigue at some point and break off in the engine... I would think the JB weld would have enough holding power to stay in place even if there is some carbon built up on the plug...

 

[legdelimber]

shoot, some days you just gotta roll with what you got!
It's always "a learning opportunity" the elders said to me when I was younger.

 

[Stump Shot]

Thank for the idea about JB weld. That should hold it in place.

I originally liked the idea of making the insert the same length as the plug, but then I thought about it a bit. If the coil is the same length as the plug, it means it would stick out into the cylinder, I wonder if the unsupported coils could fatigue at some point and break off in the engine... I would think the JB weld would have enough holding power to stay in place even if there is some carbon built up on the plug...

It would have to be a high temperature version to work.
Myself, I use a high temp red loctite to hold coils in. A wait time is necessary as to not "lock" your plug or fastener in.

 

[Carhartt]

I have the solid ones. The thread tool isn't cheap. If you aren't ever going to use it again it wld be an expensive concept. I use Stihl Dirko on the back of my threads and never had any problems. Now the solid threads have a crimp groove with teeth in them that set into the cylinder for holding bite.

 

[Stevetheboatguy]

Use a ton of these to repair plug holes that have been ham fisted. Hold up very well. The Napa kit is a smaller od. The pt kit is larger and works on most that have been previously "repaired"

Steven