Piston Slap

[Scout1]

Out of pandemic boredom I've been watching a lot of YouTube videos on engine teardowns. I noticed a lot of Hyundai engines seem to have pretty severe piston slap issues. When they remove the pistons the skirts on one side are horribly worn/scraped up and so is the cylinder bore. I know a lot of engines have piston slap and most folks seem to think it's not harmful as it goes away when the engine warms up. But on these Hyundai's it definitely looks to be harmful.

Does this level of cylinder/piston skirt wear come from owners letting the oil level go low? Or is it just the piston design and if so, what about the design is bad? I can see they have a very short skirt, but so do my Hondas I think... The tear down videos I've been seeing include both the 2.4 and 1.8 engines. I don't want to start a Hyundai hate thread, I've never owned one but I'm just curious about what I've been watching.

 

[AutoMechanic]

I haven’t seen any of the videos it’s probably them letting it run low on oil. If it was a bad design you would probably hear more about it.

 

[atikovi]

Install a set of these pistons. A little pricey though.

 

[Mainia]

Out of pandemic boredom I've been watching a lot of YouTube videos on engine teardowns. I noticed a lot of Hyundai engines seem to have pretty severe piston slap issues. When they remove the pistons the skirts on one side are horribly worn/scraped up and so is the cylinder bore. I know a lot of engines have piston slap and most folks seem to think it's not harmful as it goes away when the engine warms up. But on these Hyundai's it definitely looks to be harmful.

Does this level of cylinder/piston skirt wear come from owners letting the oil level go low? Or is it just the piston design and if so, what about the design is bad? I can see they have a very short skirt, but so do my Hondas I think... The tear down videos I've been seeing include both the 2.4 and 1.8 engines. I don't want to start a Hyundai hate thread, I've never owned one but I'm just curious about what I've been watching.

I copy and pasted my post from another thread.

My opinion is the problem with Hyundai/Kia is bad metallurgy choice, and going 100% all into "The Korean Way" = "Put your head in the sand, and keep plugging along, all while doing nothing to change or find the problem". The worst of all engines is the 2.0 and 2.4, The Theta 2. . Another model engine was the "Nu", the 1.8 and 2.0 liter motor that had this issue of destroying itself too. The 1.6 and 1.6T Gamma motor is one of their better motors. A 10 year Hyundai mechanic said "If you don't see a side of a piston skirt in the oil pan by 6,000 miles, you wont have a problem with the 1.6 and 1,6T motor." (with the exception of weak connecting rods in the 2013/14 Veloster Turbo that has been over/badly tuned...BOOM!). The Global Engine Alliance was a joint venture between Chrysler, Mitsubishi Motors, and the Hyundai Motor Company for developing a line of shared 4-cylinder engines. The initial design of the engine block and cylinder head was handled by Hyundai. However, each manufacturer configured their variants of the initial design differently based on their needs. In 2009, Chrysler bought out Mitsubishi and Hyundai's stake in the joint-venture; however, each company retained rights to build the engines. It was said by Hyundai, that they had an issue with leaving crankshaft machining metal scraps in the oil passageways for 2-3 years on the 2.0 and 2.4 liter motors. Well how does this correlate into 9 years of what appears to be bad piston metallurgy and bad crank and rod bearing metallurgy choice. Chrysler and Mitsubishi used their choice of piston, crank, and bearing metallurgy, along with their choice of oil pump design AFTER the disbandment of the engine alliance in 2009. After 10 + years of Hyundai/Kia beating it's head against the wall, and nothing changed with their horrendous choice of metallurgy, all coming from a world wide behemoth of a metals company. "The Irony". These 10+ years I have not heard of the other manufactures engines destroying themselves like Hyundai's have. It has been said 14% to 16% of all Hyundai/Kia motors will destroy themselves, sometimes as many as three times in one car. Many with Hyundai OEM oil filters on them, since many privater shops will use Hyundai OEM filters to protect themselves. I don't think it is the filter. Too many live a long life with every different filter known to man. My wife had a 2013 Elantra GT 1.8 where at 14,000 miles, and a life of 3,000 miles oil changes ( short tripper 3 miles to work) of SuperTech full synthetic and Mobil . The motor destroyed itself with scuffed and brutally galled piston skirts where the metal went into the lifters from oil filter bypass startups and took the lifters out and gave it the CLASSIC "Hyundai Tick of Death". One of the key problems a Hyundai/Kia CAN be born with. https://en.wikipedia.org/wiki/Galling I now use the Fram Titanium filter because I question if the tiny holes in the Fram TG/XG that COULD create foam vs the larger easy flowing holes in the base plate of the new Titanium. Again just a hunch that I am going to go with as a Hail Mary opinion of hope. Ha Ha. My hypothesis is, it is not the filter or the machining chips, I think it is metallurgy engine part choice. That's from my research into the matter, just my opinion. .

 

[aquariuscsm]

I'm guessing crappy engine design.

 

[Mainia]

Hyundai has publicly stated it has spent 3 billion on just rebuilding bad engines and another 2 billion on other problems like the ABS controller corrosion fire starter that finally has been recalled in the past year, and recently expanded. It goes back to 2012 model year.

 

[CourierDriver]

Just let honda build the engines and put them in those darn Hyvndais,,problem solved,imho

 

[pbm]

The 2.0 'BETA' engine in our 2008 Elantra has been bullet proof....It's not particular about oil (the OM allows SJ oil from 5w20 to 10w30). It isn't particularly high tech but it seems that 'technology' often has 'teething pains' where the customer is the laboratory (ie: GDI).

OT: I mentioned in another recent post that I'm currently running QS synthetic SJ rated 5w30 that was made in 1998 in this car....Obviously I don't believe that properly stored oil has a shelf life.

 

[JT20]

I was going to make a thread about JDM engines but maybe we can segway/parallel.

If Piston Slap gets bad enough you'll be looking for another engine...

Why would someone choose a JDM engine?

 

[Donald]

I assume the cracked piston skirts in Jeep 4.0 engines is an extreme case of piston slap. I am told its cylinder wear and rings being too close together.

 

[JT20]

I assume the cracked piston skirts in Jeep 4.0 engines is an extreme case of piston slap. I am told its cylinder wear and rings being too close together.

This also seems to be the case on EJ25s from Subaru.

Bore too big.. Cylinder wall too thin (an EJ20 is actually a stronger motor, and opinions differ on if an EJ22 is good or not.) In the case of the Subaru, I believe it comes down to the thickness of the wall between it and the water jacket.

 

[ABN_CBT_ENGR]

Does this level of cylinder/piston skirt wear come from owners letting the oil level go low? Or is it just the piston design and if so, what about the design is bad?

No, in basic terms, it has nothing to do with oil- it boils down to not just the design but the physics behind it.

Everything with a piston has a degree of piston free motion in degrees of freedom along the axis. ( engines, compressors, pumps, hydraulics and even syringes)- if there is a tolerance/clearance between the 2 parts, there will be the freedom to move.

Whether that freedom of movement makes physical contact is one thing but then it moves to how much contact (in terms of cycles and force) as to how significant it is.

Its not just one item that contributes to it. Some of them are the clearances, surface finish, coefficient of expansion of the materials, combustion forces and location of those forces, mass of components/balance, geometry and many more. That scale can be tipped in many ways and almost an infinite number of combinations.

It all eventually boils down to the law of diminishing returns.

For any given design and material selection- there will come a point where there is nothing more to be gained from tweaking parameters and bad things will start happening in very short order. Given standards that must be met and individual companies efforts- these ceilings are being tested every day.

Some wont make it - some will barely make it and some will manage it but all will experience it.

 

[JT20]

No, in basic terms, it has nothing to do with oil- it boils down to not just the design but the physics behind it.

Everything with a piston has a degree of piston free motion in degrees of freedom along the axis. ( engines, compressors, pumps, hydraulics and even syringes)- if there is a tolerance/clearance between the 2 parts, there will be the freedom to move.

Whether that freedom of movement makes physical contact is one thing but then it moves to how much contact (in terms of cycles and force) as to how significant it is.

Its not just one item that contributes to it. Some of them are the clearances, surface finish, coefficient of expansion of the materials, combustion forces and location of those forces, mass of components/balance, geometry and many more. That scale can be tipped in many ways and almost an infinite number of combinations.

It all eventually boils down to the law of diminishing returns.

For any given design and material selection- there will come a point where there is nothing more to be gained from tweaking parameters and bad things will start happening in very short order. Given standards that must be met and individual companies efforts- these ceilings are being tested every day.

Some wont make it - some will barely make it and some will manage it but all will experience it.

You mean like blow-by.. It is always there, even on any engine, just how much it is noticed is the issue?

 

[ABN_CBT_ENGR]

You mean like blow-by.. It is always there, even on any engine, just how much it is noticed is the issue?

Exactly, its there and always will be but it and its effect has been managed/reduced until the engine mechanically wears to a certain point.

Same with piston off axis movement leading to eventual touching ( technically "slapping" is a type of touching but not the only type)

 

[JT20]

Exactly, its there and always will be but it and its effect has been managed/reduced until the engine mechanically wears to a certain point.

Same with piston off axis movement leading to eventual touching ( technically "slapping" is a type of touching but not the only type)

I just remember it was explained to me.. Even a Ferrari Enzo engine has blow-by. They all do. It just varies between Miniscule to messing up a PCV valve and blowing smoke out the exhaust. But it is there.

Any engine. (Any engine with valves lol)

 

[Trav]

A lot of it has to do with piston to bore clearance, get it a little loose at time of assembly and it will slap.
This has been a problem with automated assembly for a long time now, pistons years ago were all measured and fit by hand, the people doing the work knew how to use measuring tools and get a nice fit.

Today it is different, it is hard to find qualified workers, most are OJT off the street and could no more read a micrometer than Egyptian hieroglyphics so some manufacturers make every engine with a bore that measures X and every piston that measures Y and theoretically they should all fit. In reality they all fit in the holes but not much better.

 

[ABN_CBT_ENGR]

hard to find qualified workers, most are OJT off the street and could no more read a micrometer than Egyptian hieroglyphics

oh, so true

 

[Donald]

No, in basic terms, it has nothing to do with oil- it boils down to not just the design but the physics behind it.

Everything with a piston has a degree of piston free motion in degrees of freedom along the axis. ( engines, compressors, pumps, hydraulics and even syringes)- if there is a tolerance/clearance between the 2 parts, there will be the freedom to move.

Whether that freedom of movement makes physical contact is one thing but then it moves to how much contact (in terms of cycles and force) as to how significant it is.

Its not just one item that contributes to it. Some of them are the clearances, surface finish, coefficient of expansion of the materials, combustion forces and location of those forces, mass of components/balance, geometry and many more. That scale can be tipped in many ways and almost an infinite number of combinations.

It all eventually boils down to the law of diminishing returns.

For any given design and material selection- there will come a point where there is nothing more to be gained from tweaking parameters and bad things will start happening in very short order. Given standards that must be met and individual companies efforts- these ceilings are being tested every day.

Some wont make it - some will barely make it and some will manage it but all will experience it.

Some shouldn't have made like GM's attempt to take a gas engine block and make a diesel engine out of it for Cadillac back in the 1980s? (If I remember correctly.)

 

[ABN_CBT_ENGR]

Some shouldn't have made it like GM's attempt to take a gas engine block and make a diesel engine out of it for Cadillac back in the 1980s? (If I remember correctly.)

I remember them too- another example of the same point.

 

[Job]

My dad bought a new 1962 Rambler station wagon with the aluminum version of the reliable cast iron six. It drank so much oil he used to just use the bulk oil they used to sell in glass bottles at stations. I remember we always were getting oil and gas at the same time. Aluminum is not as forgiving to design as cast iron. Can't just put liners in the bores and call it a day, Maybe too much adolescence and desire to produce cars fast let down their testing and qc programs on those particular engine series. Probably all the staff involved with the problem had to kill themselves. No wait, that's Japan.