Why do some car engines make a ticking sound when you shut them off, and some cars don’t?

My last car made very little ticking noise whenever you stopped the engine. My new one sounds like someone is making popcorn under the hood after you turn the car off. Same thing with lawn mowers, I have one that makes little noise after you stop it, and another which ticks a lot. 

Why the difference between engines and what causes it?

7 Answers

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  • 1 month ago

    Metal heats up and expands and makes a slight noise and you can't hear it with the engine running. But when you shut the engine off, then you hear it cooling back down. It's normal.

  • M.
    Lv 7
    1 month ago

    It's the exhaust system that is doing that.  The closer to the engine the hotter it gets.  Just in a few minutes the thin metal of the exhaust system sheds hundreds of degrees and therefore contracts. 

    The engine isn't making the noise.  It's not as hot and loses heat much more slowly than the exhaust system. 

    -Engine overhaul mechanic and general automotive mechanic since 1972

  • 1 month ago

    Metal ticks like that as it cools off from being very hot.

  • 1 month ago

    You're hearing the contraction of various parts as they cool. It can vary from car to car according to different engines, different materials, different methods of fixing, tightness of fittings and so on.

    Had a car once where the exhaust would give a resounding "clang" about 5 minutes after switching off, presumably when the contraction reached the point where the exhaust would move in its fittings.  One day out of curiosity I slackened all the fixings and hangings and retightened them.  It never did it again.  Just one of those things.

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  • Anonymous
    1 month ago

    you must be living in a hot desert area

    like Arizona where the temperature

    is may be 40 deg C

    the metal parts in the engine are contracting

    and cooling hence the tick tick sound

    i

  • Anonymous
    1 month ago

    Different engines, different parts, different materials, etc etc etc.

  • 1 month ago

    It is relatively sudden of cooling engine and exhaust parts.  Since engines and exhausts are different, they may tick differently.  It is not a problem.

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