I am facing an issue of a rattling/grinding noise from engine left/lower side particularly in warm engine. Car is Suzuki cultus with 3-cylinder non-efi G10 engine and running on petrol. Inside cabin while driving it feels like exhaust leak noise when accelerating but noise from open engine bay is like metal grinding noise. I feel it more when I put my ear close to the timing belt cover. One mechanic said it is from crank while one said it is from piston rod. I want to avoid unnecessary trials by mechanics and wish to have a proper diagnosis first. I have uploaded the video showing engine noise. Please have a look and advise. Thanks in advance.


  • Locate the noise by using a long screwdriver as a stethoscope or get a stethoscope.
    – Solar Mike
    Commented Dec 3, 2021 at 9:03
  • Can you please guide where on engine should I put stethoscope more specifically? Commented Dec 3, 2021 at 9:53
  • Put the stethoscope all over the engine until you find where the noise is :-)
    – Rory Alsop
    Commented Dec 7, 2021 at 19:42

1 Answer 1


The knocking sound (if that is the sound you are talking about) is likely coming from the inside of the engine. To properly diagnose the exact wear that is causing the noise will require some dismantling of the engine. It will be impossible to say that it is crank wear or piston rod wear without some dismantling.

You may be able to locate more precisely the location of the noise by getting the car on a lift to listen underneath, but I can’t see anyone being willing to guarantee which part is at fault without dismantling.

Depending on the design of the car, it may be possible to just remove the sump (oil pan) and look for play in the components, but on some cars even doing that can be a fairly big job.

I think that a ‘proper diagnosis’ is going to cost money, which will require a mechanics time.

By the time a mechanic has dismantled the engine to diagnose the issue, there should be no ‘trials’ necessary. They should be able to tell you exactly which components need replacing.

If the noise is coming from the bottom of the engine, you may find that it would be cheaper to just have a second hand engine fitted than repair the original.

  • Thanks very much for your kind advice. Appreciate it! Commented Dec 3, 2021 at 10:39

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