How do you check if your spark plug threads are bad?

I would like to know the most non-invasive method of checking this and also the most cheapest way to check this.

  • Are you experiencing any physical or audio symptoms such as, the spark plug seems loose or when it's idling you can hear air pulses. As much additional info as you can put and someone will always ask, what's the make/model/year, so you may as well jam that in there. You'll definitely get a better response if you jam as much data in there as you can. Thanks! Dec 11, 2015 at 18:13
  • cant hear spark plugs being loose. not sure what you mean by air pulses... hisses? no hisses.
    – Zero
    Dec 20, 2015 at 20:08

1 Answer 1


Remove your spark plug wire primary leads. Spray the area around the spark plug with soapy water. Crank or run the engine and see if bubbles are formed. Perform this action with the engine cold and only run it for a little bit.

You didn't mention what car make model year you have. If the plugs are exposed on the sides of the heads the soapy water shouldn't cause any problems. If the plugs are recessed into the tops of the heads then be sure to blow the water out before removing the plug.

  • thats a good simple way. I can probably use the leak checking spray too right?
    – Zero
    Dec 20, 2015 at 20:09

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