Piston Slap

[KGMtech]

I can't understand how Korean car companies can still have engines failing so frequently, the basic concept is over 100 years old ! The root cause of these failures are not with new technologies, they are in the basic mechanics and raw materials from what read.

When North American engineers dissected Honda engines 30+ years ago, they didn't find hyper exotic designs, they saw good quality raw materials, durable design, elements of inspired design, good assembly methods.... but basically nothing that could not be replicated by any OEM.

I know the Koreans have a justified long standing hatred of Japanese, but for this hate to prevent them learning from the best is stupid stubbornness - presuming I'm not over-simplifying this situation.

 

[ABN_CBT_ENGR]

I can't understand how Korean car companies can still have engines failing so frequently, the basic concept is over 100 years old ! The root cause of these failures are not with new technologies, they are in the basic mechanics and raw materials from what read.

I know the Koreans have a justified long standing hatred of Japanese, but for this hate to prevent them learning from the best is stupid stubbornness - presuming I'm not over-simplifying this situation.

I have wondered the same. The physics and basic design has not changed since the first piston. The tools of design are the same I was trained on and use ( they may have the latest greatest but that's more bell and whistle).

I can only deduce that they are pushing too many envelopes too hard but that's only a guess.

 

[Job]

They dont machine engines at their operating temperature. It must be quite an engineering and testing process to have a hot engine especially aluminum keep clearances at temperature similar to when cold. Chrysler made the slant six in aluminum too, didnt work out either apparently, like the American Motors aluminum six. The Buick aluminum v8 was good though.

 

[ABN_CBT_ENGR]

They dont machine engines at their operating temperature. It must be quite an engineering and testing process to have a hot engine especially aluminum keep clearances at temperature similar to when cold.

What they do is test and calculate the coefficients of expansion for the materials then based on the mass and geometry calculate the fixed reference point ( all parts of that piston do not expand equally in dimension or time and its not perfect in circularity OR cylindricity- 2 GD&T things to look for)

Then its machined accordingly

 

[Jetronic]

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.

Had a 2012 i30 in with a non working ABS a few weeks ago - the connector showed signs of sparking and smelled burned. No recalls here yet

 

[OilUzer]

when or if there is physical contact e.g. till the engine warms up ... use oils with good chunks of moly. It will not solve the problem but it will run much smooooother!

Maybe that's why ester or moly are expensive because they are smooth operator!

btw, we have 2 Hyundai one with over 220K and the other 96K miles and both engines sound very smooth. Both purchased new and seen regular and relatively shorter oci based on what I read on bitog.
the 2005 (220K+) has a little tick tick at cold starts for about 20 seconds with certain oils but in general very quiet.

 

[CKN]

Then there are the Silverado 5.3's w/piston slap.....

 

[OilUzer]

Then there are the Silverado 5.3's w/piston slap.....

My v8 Tundra with very low mileage sounds like a diesel or typewriter. Talk about noise! Not sure if it will last 200K. I may try Amsoil or Red Line next time to quiet the baby down! Moly pacifier. lol

 

[Blinker]

GM had piston slap in a wide range of its engines but it didn’t affect the durability of the engine. The LSx engines almost all have it, some of the 3.1/3.4 V6 and 2.2 Ecotec have it to a lesser degree. The Toyota 3.5 V6 has piston slap as well. All of these engines have it but the engines live long, fruitful lives

The Hyundai piston slap ends up destroying the cylinder bores. It’s anyone’s guess why the Hyundai engines have this problem. To my knowledge I thought piston slap was mainly in the 1.8 and 2.0 Nu engine family.

 

[RDY4WAR]

My 2002 Tahoe has had piston slap since it rolled off the dealer lot. It now has 269k miles and per the compression and leakdown tests conducted at 250k miles, it still has less than 3% variance in compression between cylinders and less than 5% leakdown. It also does not consume any excessive amount of oil (~0.5 qt at 7500 miles) so based on that anecdotal evidence, I don't see piston slap as a problem. Mine only does it when cold with ambient temps at ~50*F or lower, and it quiets down within ~30 seconds.

 

[Jetronic]

GM had piston slap in a wide range of its engines but it didn’t affect the durability of the engine. The LSx engines almost all have it, some of the 3.1/3.4 V6 and 2.2 Ecotec have it to a lesser degree. The Toyota 3.5 V6 has piston slap as well. All of these engines have it but the engines live long, fruitful lives

The Hyundai piston slap ends up destroying the cylinder bores. It’s anyone’s guess why the Hyundai engines have this problem. To my knowledge I thought piston slap was mainly in the 1.8 and 2.0 Nu engine family.

As a hyundai mech, I have seen some engines with huge clearances between bore and piston. But those engines weren't of the types mentioned above and we didn't lift the head because of the pistons. These were Kappa engines and had coolant leaks from the headgasket to the outside

 

[ZeeOSix]

GM had piston slap in a wide range of its engines but it didn’t affect the durability of the engine. The LSx engines almost all have it ...

My Z06 with the LS7 has slight piston slap for the first couple minutes after a cold start. You could hear it almost instantly go away after the engine warmed half way up. Once fully warm it was pretty quiet except for some valve train noise which is normal on that engine.

 

[ragtoplvr]

for low friction everyone went to short pistion skirts. Tolerances needed to get tighter. I see folks starting the car, and tearing out like a bat out of hell even in cold weather, that is never good as oil is thick and bore tolerance may be less depending on metallurgy. There just is not much safety margin on short skirt pistons. Couple that with poor quality control and quality management, and culture. Some go boom.

Rod

 

[RDY4WAR]

I never let mine warm up fully before leaving but it doesn't too terribly cold here. It was 28*F the other morning, and I let it idle just until the rpm settled down some which was maybe 30-40 seconds. I do take it easy on it when driving until I at least see the temp gauge bump. When driving, I notice the oil temp will reach 160*F before the coolant does. When idling, it's the other way around.

 

[CKN]

First of all-I own a Hyundai and a Silverado. I made the "piston slap" comment about the 5.3's because I know it's a fairly common issue. So-when a Hyundai does it-it's a weakness, when a 5.3 does it-it's by design. Just another day on BITOG.

 

[Trav]

Positive GM comments will get you labeled a heretic. LOL

 

[Jetronic]

I never let mine warm up fully before leaving but it doesn't too terribly cold here. It was 28*F the other morning, and I let it idle just until the rpm settled down some which was maybe 30-40 seconds. I do take it easy on it when driving until I at least see the temp gauge bump. When driving, I notice the oil temp will reach 160*F before the coolant does. When idling, it's the other way around.

Does you car have a heat exchanger between the oil and coolant circuits? Or any type of oil cooler?

If it's cold enough that the windows might get damp on the inside, I wait until the coolant is hot enough to keep the windscreen clear. This is typically more of an issue when temps hover around 32F and less when it stays below 32 day and night.

 

[4WD]

My 2002 Tahoe has had piston slap since it rolled off the dealer lot. It now has 269k miles and per the compression and leakdown tests conducted at 250k miles, it still has less than 3% variance in compression between cylinders and less than 5% leakdown. It also does not consume any excessive amount of oil (~0.5 qt at 7500 miles) so based on that anecdotal evidence, I don't see piston slap as a problem. Mine only does it when cold with ambient temps at ~50*F or lower, and it quiets down within ~30 seconds.

My 2010 was the last one I had that slapped a bit after startup … my 2017 & 2018 5.3L’s = nope, quiet … even running BITOG water for oil …

 

[RDY4WAR]

Does you car have a heat exchanger between the oil and coolant circuits? Or any type of oil cooler?

If it's cold enough that the windows might get damp on the inside, I wait until the coolant is hot enough to keep the windscreen clear. This is typically more of an issue when temps hover around 32F and less when it stays below 32 day and night.

No, the oil has no external cooling neither through the radiator nor separate. It's interesting to observe because when driving casually on these country roads at steady part throttle and 1500 rpm, the oil temp will increase steadily staying 15-20*F above the coolant temp until ~180*F where the oil will level off. The coolant temp will catch and surpass the oil at 180*F on it's way to the thermostat opening and levels off at ~205*F. Once the coolant becomes higher than the oil temp, the oil temp will slowly start increasing again and eventually pass the coolant temp until it levels off again at ~220*F.

 

[Blinker]

First of all-I own a Hyundai and a Silverado. I made the "piston slap" comment about the 5.3's because I know it's a fairly common issue. So-when a Hyundai does it-it's a weakness, when a 5.3 does it-it's by design. Just another day on BITOG.

What we are trying to say is that the GM piston slap is a non issue. The engines run a very long time with no ill effect. Piston slap on the Hyundai’s appears to be a death sentence for that engine.