Stripped spark plug threads.

[woodyman]

I picked up an extra cylinder a few months ago on,well it don't matter where.Now that I am ready to do some work on it I see the threads are stripped for the spark plug.Am I screwed or can it be fixed.Thanks,woodyman.

 

[Dan_IN_MN]

I picked up an extra cylinder a few months ago on,well it don't matter where.Now that I am ready to do some work on it I see the threads are stripped for the spark plug.Am I screwed or can it be fixed.Thanks,woodyman.

The threads can be repaired with a coil. Probably best to take it to a shop. The coil is cheep. The drill, tap, and insert tool is around $35.00-$55.00.

 

[w8ye]

Typically a automotive machine shop is equipped to do this for you.

Some better chain saw shops can probably do it also.

As was already stated, the tap and inserting tool plus the several coils in the kit make it expensive to just do one for yourself but to take the head to a shop that does this work, the price is reasonable.

 

[woodyman]

I thought about putting a heli-coil in but I read somewhere that it would loosen up over time on a chainsaw.I will give a couple places a call tomorrow and see what I can find out.Thanks for the help guys.

 

[Jacob J.]

A heli-coil properly done is a strong repair. The problem is, most people don't have the patience and fine touch it takes to do it right. When you get right down to it really, there's a lot of ham-handed, ham-brained people in the world.

I had a 272 that had a heli-coil spark plug repair I did myself and I ran it for many years. It's still in service. A timber faller buddy of mine is running an 066 with a heli-coil spark plug thread that was done in 1995.

 

[RVALUE]

I just bought a thread chaser. I sure don't think (hope) it cost $ 55.

I guess $ 5. (hope)

 

[ttyR2]

Heli-coil's are great, but I'd prefer a solid insert for fixing a sparkplug hole, like this:

Some small engine places have similar items.

 

[jason6586]

Heli-coil's are great, but I'd prefer a solid insert for fixing a sparkplug hole, like this:

Some small engine places have similar items.

I only use the solid inserts like the pic's above. I wouldn't use a heli-coil for anything. When I use the solid ones I actually apply a thin coat of JB Weld Quick right before installation and it is a better than new fix because it a solid steel thread. Good Luck!

 

[ttyR2]

Found the brand, Timesert. http://www.timesert.com

I wouldn't use anything to bond them when installing to fix a spark plug. You'll really mess up the heat flow out of the plug.

 

[w8ye]

At one time, some automotive engines with aluminum heads came from the factory with Heli Coil inserts in the plug threads

 

[chrisoppie]

Harborfreight sells a two sided/size thread restorer for short money. Guy at my shop has one and says it works well for small engine alum. heads. Good luck

 

[SkippyKtm]

A heli-coil properly done is a strong repair. The problem is, most people don't have the patience and fine touch it takes to do it right. When you get right down to it really, there's a lot of ham-handed, ham-brained people in the world.

I had a 272 that had a heli-coil spark plug repair I did myself and I ran it for many years. It's still in service. A timber faller buddy of mine is running an 066 with a heli-coil spark plug thread that was done in 1995.

I agree with JJ, Its all in the skill of the installer!

I only use the solid inserts like the pic's above. I wouldn't use a heli-coil for anything. When I use the solid ones I actually apply a thin coat of JB Weld Quick right before installation and it is a better than new fix because it a solid steel thread. Good Luck!

Helicoil makes a SOLID insert just for the purpose of restoring spark plug threads:
Amazon.com: Helicoil 5334-14 Save-A-Thread Thread Repair Kit M14 x 1.25: Automotive
They are of similar design to the timesert brand. I've been using 'em for years with no problems. Some people tend to use the word Helicoil to describe a threaded insert, when its really a brand, not an object, kinda like using the word kleenex to describe a facial tissue.

At one time, some automotive engines with aluminum heads came from the factory with Heli Coil inserts in the plug threads

They're actually stronger than the original, when done right!

 

[rob066]

I havent had to fix stripped spark plug holes. But I have an 066 that I helicoiled the bolts that hold the cylinder on. The cylinder hasnt budged in 3 years. I use this saw often for firewood.

 

[heimannm]

This topic has been discussed before. There are several different companies offering varieites of solid inserts for spark plug repairs. I have a set (don't remember the manufacurer) that comes with the tap for cleaning up the threads, then once the insert is installed you use another tool to swage the knurled portion of the insert to the cylinder head to lock it in place.

Done correctly, any of the repairs available (Heli-coil, Timsert, etc.) will make a fine repair.

Mark

 

[ironman_gq]

Heli-coil make a solid insert kit that comes with the tap/ream tool and the expander to anchor the insert. I did a cylinder with it a while back and it has worked great. I think the kit was around $50 at NAPA which is cheaper than what the shop wanted to put a coil in it, Now that I have the tools I just need to get the right inserts if I ever have to do it again, the inserts arent too spendy so I think I came out ahead.

 

[Fred482]

I have several thread repair installation kits in the shop. The problem seems to be, I never have enough or the correct size. It's a tool dealer's bonanza, they love me!

I watched a procedure done on one of the popular TV truck shows recently, dealing with the Ford truck "broken spark plug, damaged thread" syndrome. They advised using the correct special tool(s) for this because of the different expansion-contraction rates of the dissimilar metals of the cylinder head and the popular inserts. They had some special inserts, designed expressly for the aluminum Ford head, same metal spec. They say tests indicate the inserts, properly sized and installed are as strong or stronger than the original threads.

The keys were, proper tools, proper procedures, grease on the tool to catch the chips, etc. The pilot for lining up the reamer looked well designed and fairly easy to use. They used a one-piece solid base replacement spark plug to prevent the tip from breaking off in the future. The problem seems to stem from long (100,000 mile) service intervals.

Good idea if it saves a head! :msp_wink:

 

[Jacob J.]

If your saw cylinder spark plug threads are even too far gone for a Time-sert or other solid repair, you can always move up to an 18mm small block Chevy plug. I did that before in an 066 and it worked well.

 

[Simonizer]

Heli-coil make a solid insert kit that comes with the tap/ream tool and the expander to anchor the insert. I did a cylinder with it a while back and it has worked great. I think the kit was around $50 at NAPA which is cheaper than what the shop wanted to put a coil in it, Now that I have the tools I just need to get the right inserts if I ever have to do it again, the inserts arent too spendy so I think I came out ahead.

I have used these as well to save a cylinder. Very good product. Have not had any failures and have probably used 30-40 over the years. Key is to take extra time to get the tap exactly straight and to use a t-handle not a ratchet to drive the tap. You get torque without a net force in any direction that way. A few drops of Relton A-9 on the tap makes for a nice finish on the threads for the insert to go into. Also better to hit the flaring punch 10X at a medium force than once hard and drive it right through the top of the cylinder. Saw a heavy-duty mechanic do that to a saw once lol.

 

[nmurph]

I agree with JJ, Its all in the skill of the installer!


Helicoil makes a SOLID insert just for the purpose of restoring spark plug threads:
Amazon.com: Helicoil 5334-14 Save-A-Thread Thread Repair Kit M14 x 1.25: Automotive
They are of similar design to the timesert brand. I've been using 'em for years with no problems. Some people tend to use the word Helicoil to describe a threaded insert, when its really a brand, not an object, kinda like using the word kleenex to describe a facial tissue.

They're actually stronger than the original, when done right!

Yep....if JJ says it, it is good enough for 99.99% of the people on this board.

 

[Polish hammer]

Hey I know this is super old but I have a 461 that the helicoil keeps coming out and now the cylinder is stripped so I was thinking of drilling and tapping to bigger size what spark plug did you use?

If your saw cylinder spark plug threads are even too far gone for a Time-sert or other solid repair, you can always move up to an 18mm small block Chevy plug. I did that before in an 066 and it worked well.