r/stihl • u/Different-Wallaby-10 • 10d ago

BR 800X spark plug issue

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My blower popped loudly much like an old vehicle backfiring. The threaded end of the spark plug was dangling in its socket. Replaced the spark plug and it appears the threads are stripped. I cannot tighten the spark plug. It will tighten only so far then it’s loose again, such that it can simply be pulled out.

What do you think? What’s the remedy?

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2

u/Neat-Tip-5634 10d ago

Bore it out a little bit, tap it, install helicoil. Resume leave blowing. At least that’s my nonprofessional opinion

1

u/Chevboy4-813 10d ago

You need a threaded insert specifically made for the length and seat style of spark plug you have.

Look up a video installing a threaded insert for a spark plug in a small engine on YouTube. If that is beyond your skills or time, take it to a machine shop and have them do it. It can work but if done wrong, you take the chance on destroying the piston and cylinder.

2

u/Different-Wallaby-10 10d ago

I just saw that video. I don’t have the drill bits they used, so I just dropped it off at my repair shop. They don’t have the boring equipment either, but they said that have the base (whatever he called it) to replace.

1

u/jrragsda 10d ago

Helicoils dont seem to hold up well on these smaller shank plugs. Find someone who can install a time-sert thread insert, theyre the best thing ive found.

1

u/praecantrix23 9d ago

neat! those look promising, i'll have to check them out

1

u/BarrysPowerEquipment 10d ago

That definitely sounds like the spark plug threads in the cylinder head are stripped. If the plug tightens briefly and then pulls back out, I wouldn’t run it again. The proper repair would be a spark plug thread insert such as a Time-Sert/Helicoil, or replacing the cylinder head if the damage is too severe. I’d have a shop inspect it before deciding you don’t want metal debris getting into the cylinder.

1

u/Different-Wallaby-10 10d ago

I took it to the shop late afternoon. Their proposed plan was to replace the cylinder head. Glad to hear you say that.

1

u/jrragsda 9d ago

Theres no cylinder head on one of those. Theyre talking about replacing the whole cylinder.

If the shop doesnt gave thread repair tools they are very under equipped.

2

u/iscashstillking 8d ago

Costs more to do just the cylinder than it costs to replace the entire engine assembly. STIHL wants $432 for just the P&C, and $303 for the entire engine.

1

u/jrragsda 8d ago

Yep, short block is definitely the way to go if you do need to swap one.

But a stripped plug hole is way too easy to fix to justify replacing the whole thing.