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Debate: Torquing spark plugs to spec vs. the old ugga-dugga method
I always went by feel on spark plugs until last month when a 777 engine threw a code from a loose one I did. My old timer coworker says he's never used a torque wrench on them in 40 years, but the manual says 16 ft-lbs exactly. Which side are you on for routine jobs like this?
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adam_lewis2d ago
Taylor's right about under-torque being the bigger problem. I went the other direction once and ugga-dugga'd a plug so hard it cracked the porcelain, then spent a Saturday fishing ceramic bits out of the cylinder. My torque wrench now lives in the toolbox right next to my 'hey that feels tight enough' brain, but the wrench usually wins the argument.
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taylor_young3d ago
Read a while back that most DIY spark plug failures come from under-torque not over-torque, so I'd lean toward the spec.
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the_ryan3d ago
Yeah I was guilty of going too light on them for years. Thought I was being careful but ended up with a plug backing out on the highway once. That was a fun tow truck bill. Ever since then I just use a torque wrench every single time and never had a problem. The spec is there for a reason even if it feels tight.
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