Dear friends

I have a rotax 914 and in my last inspection I couldn't remove one of the spark plugs (it was me who put them in, initially turning easily by hand and finishing with a torque of 20 Nm).

I've tried with the engine cold, hot (very hot), going back and forth several times, but there's a lot of resistance and then I'm afraid of breaking the spark plug or what would be worse, breaking the threads on the head.

I've tried liquid degreaser too, without success.


I was suggested to put light penetrating oil (which one??) overnight and try again the next day.


What do you suggest me??


Thank You,



Marcelo from Brazil

  • Re: Hard remove Spark Plug

    by » one year ago

    I had the same thing happen to me a few years ago. I snapped the plug off at the base with the plug wrench. I then used an easy out to remove the base, no harm done.

    Thank you said by: Marcelo G Martins

  • Re: Hard remove Spark Plug

    by » one year ago

    Whatever you do, don't damage the thread as it is not permitted to fit a helicoil in these heads.

    Can you use a boroscope to look through the exhaust valve to see what it looks like on the inside?

    It is easy to remove the cylinder head, could you then take it to a machine shop where they can extract the plug safely without damaging the head?

  • Re: Hard remove Spark Plug

    by » one year ago

    Try it while the motor is warm. Try shocking it by tapping the nut portion of the plug. Place a piece of heavy pipe or modified socket over the porcelain and onto the nut and tap with a hammer then remove. I’ve had success removing head bolts with this method. Reinstall with the thermal paste.

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