Is This Piston Slaping Sound?

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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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TumblrDucks

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You may notice piston slap more inside the car than out. And as described earlier, sounds almost like a light rod knock. How many miles you have on this engine?
Thanks for the comment. This car has a recall on connecting rod bearings and I took it to the dealer, they checked and told me nothing is wrong, I guess I can rule out that?
 
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Thanks for the comment. This car has a recall on connecting rod bearings and I took it to the dealer, they checked and told me nothing is wrong, I guess I can rule out that?
Best thing for those engines is to run a good 30w oil. 5w-30or 10w. that recall consisted of tuning the knock sensor to the frequency of rod bearing noise, which, incidentally, is caused by piston rocking in its bore enough to wear the rod bearings. Some engines will run forever, some won’t. I’ve had one engine fail to consumption, the rest were running perfect with high mileage on them When sold/traded. Like I daid, when your inside the car, thats when it seems the best able to hear a knock. I’d say as long as it’s running fine, your using a good 30 grade oil, changing at no more than 5k intervals, press on with pride, and don’t lose any sleep. If it comes around, you’ll know it. You never stated how many miles are on this engine?
 

TumblrDucks

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Best thing for those engines is to run a good 30w oil. 5w-30or 10w. that recall consisted of tuning the knock sensor to the frequency of rod bearing noise, which, incidentally, is caused by piston rocking in its bore enough to wear the rod bearings. Some engines will run forever, some won’t. I’ve had one engine fail to consumption, the rest were running perfect with high mileage on them When sold/traded. Like I daid, when your inside the car, thats when it seems the best able to hear a knock. I’d say as long as it’s running fine, your using a good 30 grade oil, changing at no more than 5k intervals, press on with pride, and don’t lose any sleep. If it comes around, you’ll know it. You never stated how many miles are on this engine?
Add my mileage in the first post, it's around 88600. Appreciate your analysis & advice! : D
 
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I'm hearing a background 'thud' below all the valvetrain/injector racket......
Maybe yours are just collapsing now & that thud disappears once fully warmed?
Had an ancient '74 VW bus with tired pistons, it would slap at cold idle, and run pretty smooth once it was fully warmed up.
It could be that. Unless your audio is from a hot engine, in that case ?????? I hear they tend to run fine but eventually a piston skirt can bust off.
 
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Add my mileage in the first post, it's around 88600. Appreciate your analysis & advice! : D
Well, you still have warranty if it blows up. Even after 100K in most cases. You are most welcome.

Edit. If you are still concerned, take it to a dealer and have them check it, that way, its on record of a possible issue, and that can carry it out beyond warranty. That guy in the video you put up has a longer one on the engine teardown and he goes into depth and shows the damage on the engine internals. Pretty good video.
 
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I hear a sound, behind all the injector, valvetrain, & timing chain noise, that sounds an awful lot like main bearings. Deeper & heavier than rod knocks (which are most noticable at high RPM, steady or just releasing throttle when hot), & piston slap (which normally happens cold & disappears in a few minutes of driving) which is higher pitched. Like somebody above said, try going with thicker oil, maybe even 40 grade as a test & see if the deep thud disappears. I'm glad I was never crazy enough to buy a Hyundal!
 

TumblrDucks

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I'm hearing a background 'thud' below all the valvetrain/injector racket......
Maybe yours are just collapsing now & that thud disappears once fully warmed?
Had an ancient '74 VW bus with tired pistons, it would slap at cold idle, and run pretty smooth once it was fully warmed up.
It could be that. Unless your audio is from a hot engine, in that case ?????? I hear they tend to run fine but eventually a piston skirt can bust off.
Maybe I should ask a mechanic to take the cylinder head off and see what kind of surprise I get. It sounds like this in past five years……
 
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that recall consisted of tuning the knock sensor to the frequency of rod bearing noise, which, incidentally, is caused by piston rocking in its bore enough to wear the rod bearings.
This simply is not true. The Theta II does not have a known history for piston slapping, I have yet to hear one with piston slap. The bearings fail for other reasons. Also, piston slap generally isn’t hard on bearings. If it was then we would have seen numerous piston slapping GM and Toyota engines with failed bearings.

Now, the Hyundai Nu engine family suffers from piston slap (Hyundai recently issued an extended warranty regarding this) but they rarely spin the bearings.
 
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Maybe I should ask a mechanic to take the cylinder head off and see what kind of surprise I get. It sounds like this in past five years……
usually the piston slap will disappear if you disable the spark to the cylinder with the collapsed skirt, once there's no power stroke the sound will lessen or disappear. Easy with an old classic with a distributor, I'm sure your noise could be checked unplugging a coil pack or three........
no need for serious surgery.
 
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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:

Sounds like a normal noisy Hyundai to me. Try some 5w-40 it massively reduces the clacking.
 
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This simply is not true. The Theta II does not have a known history for piston slapping, I have yet to hear one with piston slap. The bearings fail for other reasons. Also, piston slap generally isn’t hard on bearings. If it was then we would have seen numerous piston slapping GM and Toyota engines with failed bearings.

Now, the Hyundai Nu engine family suffers from piston slap (Hyundai recently issued an extended warranty regarding this) but they rarely spin the bearings.
Look up Hyundai Service Campaign 953 for the rod bearing recall. As for slapping, while yes, more common in the NU engines, most notably the 1.8L, the 2.0 L had slapping issues as well, and the 2.0L is a theta 2 engine, not an NU.
 

Astro14

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The clacking sounds like cold valve train tick, and the usual injector nose. It goes away as the engine warms and the valve train clearance is reduced.
 
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