Stripped Spark Plug Hole Thread Repair??

[benjiboo 174]

Ok folks, so it appears that either I or the previous owner of my C-160 torqued the spark plug down too tight and now the threads have pulled out and is now stripped. I have found a source (another member) to get another head but am also very interested in repairing this one. What methods do you guys use? The local lawn mower repair shop tells me it takes a 'special' type of heli-coil to repair it but cannot explain the difference so I'd prefer to do this on my own instead of dealing with the secretive repair man. So whats the best way to go about this repair?

[sorekiwi 761]

Autoparts stores sell helicoil kits to repair spark plug threads. 

 

The kit will include the special tap and an insertion tool, and sometimes the right size drill bit for enlarging the hole.  They come in several different sizes to suit the various sizes of spark plug.

[TT-(Moderator) 1,147]

I use the Empi 00-4013-0 shouldered inserts designed for air-cooled VW engines.

The combination reamer/tap is a little expensive, but once you have it you have it.

The inserts are about $6 for 4.

[953 nut 57,896]

Check with your NAPA store, if they do any engine work they would have the tool to put in a helicoil and may let you use it or do the job for a resonable fee.

[benjiboo 174]

Ok folks, So I went down to NAPA and got the proper heli coil kit to fix the stripped threads. Got it home, took the head off and went to work. It worked like a charm and was able to salvage the head so I put it back on, put the plug back in and wah-la......started right up with out hesitation. That was a lot easier than I had anticipated. Groovy,.....back in business, Bring on the snow. Lol.

[chazm 413]

Don't ya love it when a plan comes together   

 

 

chasm 

[illinilefttackle 399]

Ok folks, So I went down to NAPA and got the proper heli coil kit to fix the stripped threads. Got it home, took the head off and went to work. It worked like a charm and was able to salvage the head so I put it back on, put the plug back in and wah-la......started right up with out hesitation. That was a lot easier than I had anticipated. Groovy,.....back in business, Bring on the snow. Lol.

Good Job- but don't forget to re-torque your head bolts after a few minutes running time & a cool down-Al

[specialwheelhorse 174]

Very durable, been used in aircraft industry for years, all aluminum had

heli-coil inserts, been used for years. I used to work at United Aircraft Products

many years back and I can remember the lady's that worked there, most of them set at a bench

and inserted H-Cs all day long or lock-wired.

JIM

Edited December 21, 2013 by specialwheelhorse

[benjiboo 174]

Retorque the head bolts........check. I ran it somewhere around 20-30min. and then let it cool completely and then retorqued everything up. The helicoil appeared to be made of better material than the head itself, so hopefully I shouldn't have to ever do this again. If I do...... I suppose (provided I can get the helicoil out) I can just redo the repair job with another coil.

[shorts 182]

You don't need to remove the head, if you put heavy grease on the tap to catch the chips, also use a shop vacuum with a reducer hose to help keep the chips out of the engine. use a good pair of needle nose pliers to break off and remove the drive tang in the SS insert

[ol550 830]

You don't need to remove the head, if you put heavy grease on the tap to catch the chips, also use a shop vacuum with a reducer hose to help keep the chips out of the engine. use a good pair of needle nose pliers to break off and remove the drive tang in the SS insert

 

Another thing to keep the chips out is to position the engine with the exhaust valve just as it starts to open

and blow air in the exhaust to blow the chips out.  Use this a lot on Ford engines.

[953 nut 57,896]

 

You don't need to remove the head, if you put heavy grease on the tap to catch the chips, also use a shop vacuum with a reducer hose to help keep the chips out of the engine. use a good pair of needle nose pliers to break off and remove the drive tang in the SS insert

 

Another thing to keep the chips out is to position the engine with the exhaust valve just as it starts to open

and blow air in the exhaust to blow the chips out.  Use this a lot on Ford engines.

 

 

  You would be blowing the air in while the tap is being used, right?   

[ol550 830]

That would be correct.  Don't forget eye safety!!! 

[shorts 182]

I would do everything in my power to keep from getting the chips in the engine but blowing out the cylinder thru the exhaust would be a good safety measure when you are done tapping the hole

[JC 1965 1,532]

Ok folks, So I went down to NAPA and got the proper heli coil kit to fix the stripped threads. Got it home, took the head off and went to work. It worked like a charm and was able to salvage the head so I put it back on, put the plug back in and wah-la......started right up with out hesitation. That was a lot easier than I had anticipated. Groovy,.....back in business, Bring on the snow. Lol.

 

 

 

 How do you know which kit to purchase ? Do you take the spark plug to the auto parts store to determine which kit you need ?   I assume they have different sizes,  right ?   

[benjiboo 174]

 

Ok folks, So I went down to NAPA and got the proper heli coil kit to fix the stripped threads. Got it home, took the head off and went to work. It worked like a charm and was able to salvage the head so I put it back on, put the plug back in and wah-la......started right up with out hesitation. That was a lot easier than I had anticipated. Groovy,.....back in business, Bring on the snow. Lol.

 

 

 

 How do you know which kit to purchase ? Do you take the spark plug to the auto parts store to determine which kit you need ?   I assume they have different sizes,  right ?   

 

Yes, that is what I did. It turned out to be a 14x1.25mm thread.