Question about over torquing spark plugs by at least 11 ft lbs?

Hello everyone, I have a 2012 subaru impreza. I wanted to change the spark plugs so I looked for the torque spec for this car and I got a range of answers starting from 8.9 to 20 ft lbs, I tightened them to 20 ft lbs because I didnt want the spark plug to blow out but now I worry that its too tight. worst case , I over torqued them by 11 ft lbs. Is over torquing by that much big deal?

Update:

Thank you to all who answered

6 Answers

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  • 10 months ago
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    Not a big deal. In the days of cast iron cylinder heads lots of people, even professionals, simply "snugged" them in. It was not unusual to fight to get plugs out.

    Aluminum cylinder heads don't stand up well to repeated overtorquing but this once is already part of the head's history. 11 ft-lbs shouldn't be a big deal. According to your details the question should have been "...by as much as 11 ft-lbs...." rather than "at least." Many engines have 25 ft-lb specs.

    For those who have the infamous Ford Triton engines with the long reach plugs it is a whole different thing. Proper torque with antiseize is the only way those may ever come out intact again.

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  • 10 months ago

    If you put anti seize compound on the threads, 20 ft Lbs isn't going to lock up the plugs and they will come out when you need. I usually torque to 14 ft Lbs. Go to the library and look in a Chilton's manual for your car if you want the right answer.

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  • 10 months ago

    Just leave them and drive. If you loosen them up and tighten them to a lesser torque setting the crush washers may not seal tot he heads.

    Source(s): Mitsubishi Master Tech
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  • 10 months ago

    The biggest problem now is they might be hard to get out, and the loger you leave them in the higher the risk they may damage the trhreads on the way out. I would consider loosening and retorquing to proper spec.

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  • 10 months ago

    If they are already torqued in, and the car runs, you likely don't have a problem.

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  • 10 months ago

    yes it is.

    overtorque them and they can push down into the combustion chamber more than expected and damage the treads for the plugs

    when they are too far in it will smash the top of the plugs causing physical damage.

    over tighten them to 31 ft lbs and you are going to cause serious damage to the car.

    most likely requiring the threads to be redone and new spark plug models bought. depending on the damage you might need to replace pistons or cylinder head

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