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spark plug threads stripped in al. cyl block


berky's Avatar
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Join Date: Dec 2007
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12-02-07, 03:37 PM   #1  
spark plug threads stripped in al. cyl block

I am working on a Troy Bilt string trimmer which has blown out the spark plug. The threads are stripped in the aluminum cylinder block. Can they be drilled out and a heli coil inserted?? If so, where can I get parts & instructions?

 
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CAMINO KID's Avatar
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12-02-07, 03:46 PM   #2  
yes you can get a helicoil to fix this but the tap to cut the threads is expensive for this low priced unit. Your best bet is to take it to a shop for then to tap and insert a helicoil. Most auto part stores have the necessary tools and helicoils if you really want to invest the money.

 
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12-03-07, 03:25 AM   #3  
Hopefully you understand that you must disassemble the entire trimmer's engine to do this service! You cannot take the chance of getting filings in the combustion chamber when performing the service.

 
CAMINO KID's Avatar
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12-04-07, 05:12 PM   #4  
I have been using the heavy wheel bearing grease on the tap and have not lost an engine yet in over 40 years as the cuttings stick to the tap. Wipe any excess grease and cuttings away from the hole. As cheap as these trimmers go for you can almost buy new unit for the price of the repair kit with the necessary taps. The units i use have a cutter on the tap that enlarges the hole and taps for the helicoil at the same time.

 
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12-05-07, 02:20 AM   #5  
Camino, have you seen or tried Recoil brand inserts and insert kits? I like them better than Heli-coil brand, check them out if you get the chance. Among other places, you can find them at Fastenal stores.

 
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12-08-07, 10:02 AM   #6  
I can't say that I have seen the Recoil brand inserts. Will have to stop at the Fasinal outlet and warehouse here to look at them. I did have a different style come into the shop that had a solid threaded insert piece that had backed out of the orginal redo that was about 18 mm in size. It took some doing, but managed to get the insert back into the head and staked it with a center punch in several places to keep it in place and not back out when the plug was removed. One thing about Helicoils is that you do not make the hole that much bigger than that other insert.

 
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