Trimmer stripping top spark plug thread

[TIDY]

Ok guys my old Husky 325HS99x trimmer has been an absolute belter for 10 years, just recently it started to strip the thread off a spark plug where the HT cap fits on. If i use a spark plug with the resistor on top the resistor ends up coming off and stuck into the HT cap, making the HT cap not fit properly (wobbles instead of tight)

 

Ive tried using a spark plug without a resistor and then replacing the HT cap for the correct one and then it strips the top thread on the spark plug. Using NGK plugs and HT caps so not cheap crap. Any ideas its been doing it for a good few months now, starts to thread after a few big trimming jobs!

 

Photo of resistor stuck in HT cap "again"

[openspaceman]

1 hour ago, TIDY said:

Ok guys my old Husky 325HS99x trimmer has been an absolute belter for 10 years, just recently it started to strip the thread off a spark plug where the HT cap fits on. If i use a spark plug with the resistor on top the resistor ends up coming off and stuck into the HT cap, making the HT cap not fit properly (wobbles instead of tight)

 

Ive tried using a spark plug without a resistor and then replacing the HT cap for the correct one and then it strips the top thread on the spark plug. Using NGK plugs and HT caps so not cheap crap. Any ideas its been doing it for a good few months now, starts to thread after a few big trimming jobs!

 

Photo of resistor stuck in HT cap "again"

Are you sure the screw on piece at the top of the plug is not retained on the spring in the cap and you just need a new plug and screw top?

 

Edited July 2, 2019 by openspaceman

[TIDY]

That's exactly what's happened.. the thing is it keeps happening... I'm wondering why? and has it happened to anybody else on any of their tools.

[openspaceman]

38 minutes ago, TIDY said:

That's exactly what's happened.. the thing is it keeps happening... I'm wondering why? and has it happened to anybody else on any of their tools.

How hard are you doing the screw top?

 

When you replace it with a new plug ask for the NGK equivalent with a solid top.

[TIDY]

I screw it tight (its usually tight from the box) i didnt know that you could get a plug with a solid top, i thought they were all screw on jobbys. I will look next time i get one thanks.

[htb]

Had a MS260 that used to do that to the spark plugs didn't matter how tight you did the ferrule up, tried loctite no difference.

[openspaceman]

3 hours ago, TIDY said:

I screw it tight (its usually tight from the box) i didnt know that you could get a plug with a solid top, i thought they were all screw on jobbys. I will look next time i get one thanks.

I wonder if a dealer like @GardenKit can advise if there is a solid tip equivalent for that BPM7A?

[Ratman]

Have you tried another brand of plug? Or just used and refit NGK only.

[TIDY]

I've always used NGK plugs on all my tools and never had a problem.

[Ratman]

Only a suggestion as to try and rule it out thats all.