I broke my spark plug, advice needed

[sidecarnutz]

Wow, only a cheap Guzzi owner would consider welding a plug back together to re-use it.   

[Huzo]

Wow, only a cheap Guzzi owner would consider welding a plug back together to re-use it.   

Guzzi’s that come to the Southern Hemisphere, have left hand threads...

[SIR REAL ED]

In 50 years of changing spark plugs in all manner of engines, road, race, car, motorcycle, power products, including aircraft and Jet engines (ignitors) I've never used a torque wrench and never had any issue whatsoever. Once the crush washer has fully compressed you're close to what you need however a lot of engines also use a tapered plug seat and those need extra caution and "feel"
I acknowledge the position that not everyone is a practiced at installing plugs as I am but honestly the variation people come across in specific plug torque recommendations is quite worrying. The engine manufacturer wants one spec the plug manufacturer another, it's not just here in the bike world but the automotive is the same, constant debate over plug torque settings. makes me glad I leave the torque wrench out of it.
I can give one piece of advice for people with respect to cars mainly. A lot of cars have a plug change schedule of every 80,000klm or so. That's too long in my view. Not because the plug itself is degraded (fine wire platinum plugs will do the mileage ok) but it's too long to leave the plug installed in the head with regards to the threads. Fifty thousand KLMs max for me so I avoid thread issues in aluminium heads. Pulling them at 75k and listening to them in the first turn and a half enough times has convinced me to shorten the change period no matter what the plug and engine manufacturer tells me the life is. 

Ciao

That is sound advice.

Same here.  I've never used a torque wrench on anything other than head bolts.  Since I grew up working on ancient junk (tractors and construction equipment that should have been scrapped long ago), that had  no PM/TLC in years or decades.  Never-sieze on spark plugs and lug bolts became a must.  Might be several years before either are touched again.  Obviously the reduced friction means the fastener is under a higher tensile load, but, the long term insurance against corrosion is well worth it.

 

[sickora]

Some Ford V8s have a history of plugs breaking. There is a special tool available to extract the shell. Most repair shops have them. I sold a couple of them when I worked at a NAPA store.
kk

I saw those tools when I was looking up online if the auto stores near me had the extracters in stock.Ford Triton engines I think?

[bmc5733946]

I also had a widely varied career working on a lot of different things and agree with having seldom used a torque wrench on spark plugs. I have however used one religiously on lug nuts and lug bolts since the 1970s because I have seen problems. Lubrication of lug bolts and nuts is done to manufacturers specification because lubing or not lubing can cause serious problems, broken studs, loose wheels etc.. I worked on a lot of things that had washers that were trapped on the lug nut lubing the interface between washer and nut was recommended but nut the threads. If those studs or nuts were lubed it almost guaranteed the wheel would be coming loose even if torqued properly. YMMV

Brian

[Moparnut72]

I saw those tools when I was looking up online if the auto stores near me had the extracters in stock.Ford Triton engines I think?

Yup, the Triton engines. I think the threads protruded into the combustion chamber and got cruded up and bound up causing the plug to break. One of my race outboards had similar setup, but the plugs were taken out regularly for checks so no problems.
kk

[Tom]

I use torque wrenches like other have state.  Usually on fasteners that hold things together and not on spark plugs.

I do use the human torque wrench settings on the ratchet handle.  Full fist for large bolts, thumb w/index & middle finger for mid size and thumb w/index finger for small bolts.  YMMV.  No full arm strength except on the large ones and what they're tightening on. 

Takes some practice and pay attention on the last 1/4 turn of the bolt etc.