I have a 2011 Hyundai Sonata Hybrid for 5 years with ~88600 miles on it, after learning about how poorly these Theta II engines were built I start paying more attention on it. Every morning I can hear some kind of ticking/knocking sound during cold start, especially in winter.
The sound reduce a lot when idling hot and disappears when driving on the road. 3000 miles on full-synthetic based HM oil, no visible consumption.
Attachment above is engine idling sound recorded by phone in a cold start scenario, I can hear weak knocking blended in the idle. does it sound like piston slaping? What should I do about it?
PS: Piston slap sound found on YouTube, it sounds similar so I made this post to double check:
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