My engine (Ford Escape Hybrid 2006) has gotten noticeably louder over the years. Not to the point that I'm concerned, but it has gotten me wondering why exactly engine noise gets worse with time. I've heard about piston slap, but if that's not occurring then what else? Do the belts get louder? Bearings? I am just curious.

  • What part get's louder? Just the general engine noise? I mean, if there is fiberglass in the muffler, this could deteriorate as well. Sep 27, 2015 at 17:28

1 Answer 1


I take it that you're referring to the noise of the engine in the engine bay rather than the exhaust.

I'm personally still amazed by the number of parts that go together to form an engine (and a car in general). Over time of course, almost all of these parts will wear. Serpentine belts will wear. Non OEM air intakes can be very loud (modifications are often not wife-acceptable). Timing belts will wear and extend, putting camshaft timing out. Timing chains will also do the same, creating more noise especially if the tensioner is not working properly.

In my experience, most of the noise is usually generated by the valvetrain. It tends to go out of adjustment over time and will be the noisiest when it is cold - which is usually when you decide to inspect the engine. I would check to see whether your vehicle requires a valve adjustment if it seems excessively noisy. I rebuilt an inline six cylinder Ford engine once and the valvetrain went completely off 2 weeks later. The noise was incredibly loud when driving it.

  • Thanks, this is exactly what I was asking. So I would guess though that a moderate increase in valvetrain noise is no need for concern?
    – dbq
    Sep 30, 2015 at 0:25
  • Correct. And usually it will be on cold starting that the noise will be at it's loudest - cars will often 'tick' before they warmup. I would check the maintenance schedule for your car and see what they recommend. Also if you're chasing peak power and economy, you also might want to get an adjustment if the noise seems to have increased over time.
    – timbo
    Sep 30, 2015 at 1:55
  • Does this apply to only motor engines? What kind of motor would start making more noise over time? AC, DC, brushless,brushed, induction, etc..?
    – blue_ego
    Jun 4, 2022 at 12:30

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