Sounds like a piece of plastic against a fan blade, or cards in bike spokes. Running fine though.

Happens when the car is idling/parked and becomes louder when accelerating.

Began hearing the sound much more quietly and intermittently prior to oil change in September. Over the last week (potentially more, it is hard to hear when driving with the AC/HEAT on so I may not have noticed) it has become very loud.

Seems to lessen when I maintain speed with no change in acceleration or deacceleration. Braking does not seem to lessen it, although I'm not yet 100% sure of that. Braking in neutral was no change; not sure of in motion.

White vapor-like smoke from tailpipe when accelerating. Disappears quickly. (possibly normal?)

Had oil and filter changed (was full at time of change) and tires rotated in September. Also replaced 2 tires in September. Replaced battery around September as well. Brake shoes and drums replaced last fall. Seems to be running fine besides the sound. Has always had a small power steering fluid leak (can't remember details but had it looked at once in 2013 and some work I don't remember done; it does alright if I just add power steering fluid every few months).

Had a check engine light on prior to battery replacement in August/September. Had it checked and the code ran something for oxygen sensor. Guy cleared the code for me and it showed once after, then never again. Had issues years ago (2013 or 2014) with it failing inspection due to oxygen sensor code/gas cap. Replaced the gas cap and passed inspection, was fine for several years.

Video of sound when parked: https://youtu.be/9nRsD50WXlA (open hood)

Video of accelerating in neutral: https://youtu.be/2thxJbKDM38 (closed hood)

  • Just based purely on sound and that it becomes worse with acceleration, I'm inclined to suggest a knocking rod - a connecting rod has broken and is now flopping around in the cylinder. But, that is a worst case scenario. Has there been any loss of power? Smoke from the tail pipe? Does the sound ever not present itself? If so, when? A little more info could go a long way! – NFeutz Nov 26 '17 at 4:44
  • To be clear: a broken rod would destroy the engine in short order - how long has this issue persisted? – NFeutz Nov 26 '17 at 5:34
  • 1
    Heard it very quietly 2 months ago when checking out the car as the battery died, but didnt pay much mind to it. Battery was around five years old so no surprise, had it replaced and no power problems since. Sound has become more noticeable over the last week, although I might have missed it prior as it's easily covered by the AC/heat when driving. No smoke I am aware of, but I can double check tomorrow. The sound lessens when I'm driving at a solid speed without any change in acceleration or de-acceleration, but I'm not sure if it ever completely vanishes. I don't think so. – zkr Nov 26 '17 at 6:26
  • Does the sound change at all based on transmission gear, or only engine speed? – NFeutz Nov 26 '17 at 6:33
  • I don't know how to tell this. If you explain, I can find out tomorrow. – zkr Nov 26 '17 at 6:43

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