Guesses? Severe piston slap = high wear metals?

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2,699
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PA
My 2002 Yukon XL has thee worst cold piston slap of any 5.3 I've ever heard. And I've owned and drove many. Random citizens with likely no car knowledge whatsoever turn and stare when I fire it up and drive off. I'm sure the neighbors are confused because my driveway looks like James Bond lives here but half the time I'm rolling out in something that sounds like it's about to blow up. It has the charm of a rod knock but it is merely piston slap. Piston slap so bad it throws the knock sensors off for the first 30 seconds if it's below freezing. I bought it in the summer so I didn't get fully acquainted with the severity until this winter. I changed the clean Jiffy Lube oil when I bought it and put in MaxLife 10w30. It hardly has burned a drop of oil in 5000 miles, burns rubber though. I'll probably change it at 7k. No complaints for a $1500 beater that was maintained and had newer tires, brakes, and cooling system. Anyone want to throw a guess on if wear metals will be higher with this condition? I can't see how it wouldn't. I mean, something is smashing into something every time I cold start it. You can still lightly hear it when it's fully warmed up.
 
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43,677
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'Stralia
As an engineer, piston slap tells me that things aren't operating correctly. Things that should be happening in a slappy engine are: * Higher, irregular loading of points on the piston skirts (more wear) * higher scyclic loading including impact on the skirts (high cycle fatigue) * cocking of the piston rings (reduced seal and wear). But the things seem to typically live lives that see out the chassis and running gear, so like the other compromises that OEMs make "not ideal" is not the same as "about to blow up.
 

4WD

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17,046
Location
Texas
I thought guys like short skirts. The worst I had was a 2004 Yukon … about 10 seconds after start up and done= after we put 130k trouble free on the unit … saw it around town for a few years after. BiL put 400k on his and the motor never failed … it did it …Some have called the polymer coating a band aid … but they are not wearing out prematurely … My 2010 has a tiny amount at start up … the 2017 is just a very quiet motor, period. You could experiment with various oils and see what happens … http://www.autos.ca/auto-tech/auto-tech-noisy-engine-it-might-be-piston-slap/
 
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1,196
Location
San Antonio, TX
10W-40 MaxLife would probably be better. It'd give you more film thickness on the cylinder wall. More film thickness might offer a better cushion between the piston and cylinder wall.
 
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1/2 hr N.E. of Detroit
Originally Posted By: Gasbuggy
My 2002 Yukon XL has thee worst cold piston slap of any 5.3 I've ever heard. And I've owned and drove many. Random citizens with likely no car knowledge whatsoever turn and stare when I fire it up and drive off. I'm sure the neighbors are confused because my driveway looks like James Bond lives here but half the time I'm rolling out in something that sounds like it's about to blow up. It has the charm of a rod knock but it is merely piston slap. Piston slap so bad it throws the knock sensors off for the first 30 seconds if it's below freezing. I bought it in the summer so I didn't get fully acquainted with the severity until this winter. I changed the clean Jiffy Lube oil when I bought it and put in MaxLife 10w30. It hardly has burned a drop of oil in 5000 miles, burns rubber though. I'll probably change it at 7k. No complaints for a $1500 beater that was maintained and had newer tires, brakes, and cooling system. Anyone want to throw a guess on if wear metals will be higher with this condition? I can't see how it wouldn't. I mean, something is smashing into something every time I cold start it. You can still lightly hear it when it's fully warmed up.
I wouldn't do 7K OCIs using semi-synthetic on a 16 year-old vehicle. Many semi-synthetics only have around 25-30% synthetic oil in the jug.
 
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Southeast Texas
Originally Posted By: Gasbuggy
No complaints for a $1500 beater that was maintained and had newer tires, brakes, and cooling system.
SAE 30wt. in winter, SAE 40wt. rest of the year.
 
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7,504
Location
FL, USA
I don't think I have ever heard or read of piston slap killing an engine. I know my previous Accord slapped from the time I got it at 97K miles to when I traded around 140K. I know its not the same miles as yours but again, no issues with mine.
 

4WD

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17,046
Location
Texas
Originally Posted By: gregk24
I don't think I have ever heard or read of piston slap killing an engine. I know my previous Accord slapped from the time I got it at 97K miles to when I traded around 140K. I know its not the same miles as yours but again, no issues with mine.
Internet is full of things https://m.youtube.com/watch?v=fwe7qxu10sU
 

4WD

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17,046
Location
Texas
Originally Posted By: mjk
Since it really owes you nothing, and the 5.3 will outlast the body, throw in a quart of Lucas and see if that quiets it. coffee coffee
No ~ Slick 50 dude
 

wwillson

Staff member
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Naperville, IL
My 5.3L 2002 Suburban had loud piston slap for the first couple minutes after startup. I did several oil samples, which are posted here, and the wear metals were always low. The piston slap didn't seem to cause accelerated wear, just the annoying knocking.
 
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Location
Sunny Florida
We have had many GM V8 "slappers" over the years. Never any issues other than some annoyance. Our worst slapper was sold with over 500k miles on it, doesn't seem to hurt longevity at all...
 

4WD

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17,046
Location
Texas
Originally Posted By: wwillson
My 5.3L 2002 Suburban had loud piston slap for the first couple minutes after startup. I did several oil samples, which are posted here, and the wear metals were always low. The piston slap didn't seem to cause accelerated wear, just the annoying knocking.
Didn’t you run like a 15w40 Delvac ? I’m finding on that or Delvac 1 5w40 there is really little difference at startup
 
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In the shop
Originally Posted By: SteveSRT8
We have had many GM V8 "slappers" over the years. Never any issues other than some annoyance. Our worst slapper was sold with over 500k miles on it, doesn't seem to hurt longevity at all...
Yep, we sold our 2010 5.3 v-8 plow truck Chevy 2500 reg cab 4x4 with 279,xxx on it and it had this piston slap and nothing but Safety Kleen 5w30 DEXOS oil
 

4WD

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17,046
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Texas
So with a good 15” subwoofer both you and the neighbors will not notice the piston slap …
 
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5,339
Location
Southeast Texas
Originally Posted By: Linctex
20% oil capacity with Lucas Oil "stabilizer" Yes, it's thick snake oil - but it will help quite a bit.
Why not just use thicker oil in the first place? I suggested "SAE 30wt. in winter, and SAE 40wt. in rest of the year". I would rather have that than Lucas anything.
 
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2,584
Location
wv
I read alot about this when i got my 2003 with the 5.3..mine doesnt have it but i put the information in the memory bank in case it did. I also did a top end clean just in case it was in the works of happening. Piston Slap in this GM engine is caused by carbon buildup on the top rings. You should do a Fuel Injection cleaning and Top end cleaning to reduce/remove the carbon buildup. There are GM TSBs on it. What I did- I used the Mopar Combustion Chamber Cleaner and also did the Redline SI-1 fuel injection cleaner. My vehicle was maintained well and had oil changes at least every 5K miles the oil never got black until I did the above.. So find a product you like for Top End Cleaning and a powerful fuel injection cleaner- run top tier gas and find a high detergent oil and see if that helps.
 

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46,185
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Ontario, Canada
Originally Posted By: krismoriah72
I read alot about this when i got my 2003 with the 5.3..mine doesnt have it but i put the information in the memory bank in case it did. I also did a top end clean just in case it was in the works of happening. Piston Slap in this GM engine is caused by carbon buildup on the top rings. You should do a Fuel Injection cleaning and Top end cleaning to reduce/remove the carbon buildup. There are GM TSBs on it. What I did- I used the Mopar Combustion Chamber Cleaner and also did the Redline SI-1 fuel injection cleaner. My vehicle was maintained well and had oil changes at least every 5K miles the oil never got black until I did the above.. So find a product you like for Top End Cleaning and a powerful fuel injection cleaner- run top tier gas and find a high detergent oil and see if that helps.
That's carbon knock, these are two separate phenomena. Piston slap is excessive clearance between the piston and cylinder wall when cold that allows the piston to "rock" in the bore. The sound is the piston and skirt literally slapping against the side of the bore as the rod angle changes. It goes away as the engine warms and the piston expands to take up the slack. GM's method of dealing with this was to put a low-friction coating on the skirts like other manufacturers had already done. This doesn't eliminate the issue, but it does significantly quiet it. Until the coating wears off of course, LOL. Piston slap came to fruition as a byproduct of bulk-fit pistons and short skirts, which were implemented to reduce frictional power loss and increase fuel economy. "Back in the day" pistons and bores were hand-fit. IIRC, you had boxes of pistons of various size deviations from stock due to manufacturing variance and the same happened when the block was bored. These were matched up to give a reasonably good fit. With bulk-fit, which was implemented due to a supposed tightening of manufacturing tolerances, it is exactly what it sounds like, a batch of eight pistons go into a freshly bored block and there will be varying degrees of tightness between those pistons and the bores. Particularly loose examples like the OP's are an inevitable byproduct of this process and as such, really make a ton of noise. Others are perfectly quiet at the other end of the spectrum. Carbon knock, which is what you are thinking of, is a build-up of carbon on the piston top and the quench area of the chamber that eventually smack each other making a knocking sound. This can be cleaned up via the process you've described.
 
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