Guesses? Severe piston slap = high wear metals?

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6,235
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Kalifornia Kollective
There is one other factor - tightness of wrist pin fit. Some pistons are tight on the pin cold. So as the rod angle varies, they rock against the cylinder wall. Once the piston is up to op temp, the wrist pin is freer in the piston bore and the skirts do not bang into the wall. As mentioned, some of the noise makers will run 200,000 miles ...
 

irv

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2,186
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Oshawa, Ont. Canada
My 09 5.3 Sierra engine was replaced somewhere around 8,000 km's, maybe less, due to a cylinder being out of round. It clacked like it was a diesel and was noticeable the most at startup but could also clearly be heard when it was hot. Lifters were tried first, then 4th cylinder wrist pin then finally a brand new short block. It leaked oil after somewhere so with that and all the other issues this pos Sierra had, I got rid of it and am now driving a Ram. I was GM for years and years but will not even look at one, nor, if someone paid me to drive one, I still wouldn't. The headaches I went through with that truck, an LTZ no less, was enough for me to give up entirely on GM trucks! mad
 

Gasbuggy

Thread starter
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PA
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.
2003+ the 5.3 had a change to stop/reduce piston slap, as noted. You should be fine until very high mileage. I've run two cans of Seafoam through the intake of this truck and 30 gallons of fuel treated with Techron Concentrate Plus.
 
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wv
Originally Posted By: Gasbuggy
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.
2003+ the 5.3 had a change to stop/reduce piston slap, as noted. You should be fine until very high mileage. I've run two cans of Seafoam through the intake of this truck and 30 gallons of fuel treated with Techron Concentrate Plus.
Been awhile since i saw it.. but here is the bulletin i had vague memories from. https://gm.oemdtc.com/5917/01-06-01-028c-engine-knock-on-cold-start-1999-2016-chevrolet-cadillac-gmc "This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall." Yeah im a 2003 guy..the previous guys have different issues.
 

irv

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2,186
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Oshawa, Ont. Canada
Originally Posted By: krismoriah72
Originally Posted By: Gasbuggy
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.
2003+ the 5.3 had a change to stop/reduce piston slap, as noted. You should be fine until very high mileage. I've run two cans of Seafoam through the intake of this truck and 30 gallons of fuel treated with Techron Concentrate Plus.
Been awhile since i saw it.. but here is the bulletin i had vague memories from. https://gm.oemdtc.com/5917/01-06-01-028c-engine-knock-on-cold-start-1999-2016-chevrolet-cadillac-gmc "This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall." Yeah im a 2003 guy..the previous guys have different issues.
That article was written in April of 2016 and covers this problem from 1999 until 2016. Was this issue finally fixed in 2016 or is it still present in 2018?
 

4WD

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17,049
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Texas
Originally Posted By: irv
Originally Posted By: krismoriah72
Originally Posted By: Gasbuggy
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.
2003+ the 5.3 had a change to stop/reduce piston slap, as noted. You should be fine until very high mileage. I've run two cans of Seafoam through the intake of this truck and 30 gallons of fuel treated with Techron Concentrate Plus.
Been awhile since i saw it.. but here is the bulletin i had vague memories from. https://gm.oemdtc.com/5917/01-06-01-028c-engine-knock-on-cold-start-1999-2016-chevrolet-cadillac-gmc "This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall." Yeah im a 2003 guy..the previous guys have different issues.
That article was written in April of 2016 and covers this problem from 1999 until 2016. Was this issue finally fixed in 2016 or is it still present in 2018?
New gen L83 has piston oil jets … mine is quiet at startup and smooth & quiet on the road …
 

irv

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2,186
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Oshawa, Ont. Canada
[/quote] That article was written in April of 2016 and covers this problem from 1999 until 2016. Was this issue finally fixed in 2016 or is it still present in 2018? [/quote] New gen L83 has piston oil jets … mine is quiet at startup and smooth & quiet on the road … [/quote] Good to hear. cheers Are the engines still dogs or have they also improved that? My buddy purchased a 17, I believe, but possibly an 18 and he said it was night and day different than his last one. I haven't driven it to see for myself, but I have no reason not to believe him. I hated my 09 5.3! Worst, ill powered engine I have ever owned in any vehicle. mad http://www.gm-trucks.com/forums/topic/61445-2000-w53-acts-like-a-dog-off-the-line/ http://www.silveradosierra.com/vortec-5-3l-v8/a-very-sluggish-5-3-t14142.html
 
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Michigan
My 2002 LS1 Camaro has had piston slap since I bought it new. I was pretty disgusted with it, and thought "OK, I've got a 36,000 miles warranty, I'm gonna drive it like I stole it, then bring it back for a new engine at 35,000." I thrashed it mercilessly at autocrosses and track days for 2 years, and the cold start slap never did get worse. So I didn't worry about going through the warranty without replacing the engine. Now at 263,000 miles, it still behaves as it did when it was new. Once it warms up, the engine doesn't have any mechanical noises. But it burns oil now, and I have retired it from track days after accumulating ~200 hours of track time in 15 years. The oil consumption didn't become unacceptable until it had over 240k on it. One thing I found that helped the cold start piston slap was to rev the engine to 1700 rpm instead of letting it idle. The slap noise would go away. Then once the engine got to operating temperature, it ran silently at idle. I ran a lot of different oils in it, but none of them had any effect on the piston slap.
 
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Mahzurrah!
We have a 2000 Lumina with slap so loud I can easily hear it inside the house when my son starts it in the driveway. Has been that way for as long as I can remember and we have owned it since 2004. No apparent issues that I can tell and it happily still plugs along at 191k now. Like A Harman mentioned it still runs very smooth and quiet once warmed up. No oil seems to make any difference.
 
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Hudson, NH
My 06 6.0 suffered from startup piston slap pretty bad 70k ago. I tried most quality syns on the market to see if that would help. Some were better than others, but that slap was still annoying. Against better judgement I tried the Lucas honey trick, because so many say claim it works. That turned a slap into a 20 second jackhammer! The Lucas experiment got me thinking about startup flow. Next oil change I used a different filter that was less efficient and had better flow. Used the same oil brand as not to introduce another variable. Wow, the slap was reduced to the point I don't even notice it anymore. Even when its 0f or below. So, in my case the best way to reduce piston slap was increase the flow at startup. And the oil filter was as important, maybe more important than the oil. Suffer from piston slap? get rid of the high efficiency filter and rely on a quality oil with good cleaning and suspension properties.
 
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11,467
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Florida, Cape Coral
Some manufactures get away with sloppy engineering, poor design and loose tolerances. We get statements like "1,000 miles per quart of oil is normal or Piston slap is normal on that engine" If I get a new engine that uses excessive oil or has excessive piston slap or?, I will raise heck and try to get a different vehicle. Ed
 
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5,670
Location
Fort Worth, Texas
Originally Posted By: irv
Are the engines still dogs or have they also improved that? My buddy purchased a 17, I believe, but possibly an 18 and he said it was night and day different than his last one. I haven't driven it to see for myself, but I have no reason not to believe him. I hated my 09 5.3! Worst, ill powered engine I have ever owned in any vehicle. mad http://www.gm-trucks.com/forums/topic/61445-2000-w53-acts-like-a-dog-off-the-line/ http://www.silveradosierra.com/vortec-5-3l-v8/a-very-sluggish-5-3-t14142.html
Could have got the top of the line engine like you did with your Ram? The VVT/Flex fuel 6.2L L9H would have served you well! The option cost right around $1000 over the base 5.3L.
 

wwillson

Staff member
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3,906
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Naperville, IL
Originally Posted By: 4WD
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
Yeah, I ran 15w-40, 5w-40, and even Red Line 0w-20. There was no appreciable difference in noise with any of the oils.
 
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1,714
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Toronto
Whatever causes the slap in GM engines, they seem to want it- or at least are willing to sanction it. There's been talk about GM reducing the piston pin offset for the LS series to reduce friction losses from the 'thrust loading' against the cylinder, combined with short skirt pistons. The 60 degree V6s also have warm up noise which I'm beginning to suspect is piston slap rather than valve clatter.
 

OVERKILL

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Originally Posted By: PeterPolyol
Whatever causes the slap in GM engines, they seem to want it- or at least are willing to sanction it. There's been talk about GM reducing the piston pin offset for the LS series to reduce friction losses from the 'thrust loading' against the cylinder, combined with short skirt pistons. The 60 degree V6s also have warm up noise which I'm beginning to suspect is piston slap rather than valve clatter.
I already mentioned what causes it earlier wink
 
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Toronto
Sorry I didn't see. I get too excited to respond to threads sometimes laugh Not sure if I totally agree that it's due to manufacturing processes resulting in sloppier clearances though. Plenty of engines, specific engines, suffer slap. Honda 4 cyls are ready examples- not sure if their manufacturing process leads them to wide ranging clearances but as horrible as slap sounds, it doesn't hurt. The piston expansion was a good point. It's why many OEs choose high-silicon hypereutectic metallurgy for their pistons, which controls contraction/expansion. Downside is that it makes for a more brittle piston- less tolerant to severe detonation- but not exactly a problem for grocery getters and commuters. Why would some engines like the LS and several series of Honda engines have such disagreeable NVH/chronic piston slap? Most engines never slap at all and aren't exactly cracking pistons or losing power to thrust
 

OVERKILL

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Originally Posted By: PeterPolyol
Sorry I didn't see. I get too excited to respond to threads sometimes laugh Not sure if I totally agree that it's due to manufacturing processes resulting in sloppier clearances though. Plenty of engines, specific engines, suffer slap. Honda 4 cyls are ready examples- not sure if their manufacturing process leads them to wide ranging clearances but as horrible as slap sounds, it doesn't hurt. The piston expansion was a good point. It's why many OEs choose high-silicon hypereutectic metallurgy for their pistons, which controls contraction/expansion. Downside is that it makes for a more brittle piston- less tolerant to severe detonation- but not exactly a problem for grocery getters and commuters. Why would some engines like the LS and several series of Honda engines have such disagreeable NVH/chronic piston slap? Most engines never slap at all and aren't exactly cracking pistons or losing power to thrust
Short pistons/short skirts. Examples with forged pistons are even louder, FWIW, because of the greater expansion/contraction when compared to a hypereutectic. I wish I had some here to show you, but if you compare an old Ford 302 piston (an engine that never slapped as far as I'm aware, even with forged pistons) to a Modular, of which there have been examples that have slapped, you can readily see the rather massive difference in piston height. Now of course the older engines had hand-fit pistons/bores too, but even on the "el cheapo" cast slug non-HO versions, which didn't get the factory balanced rotating assemblies and I assume far less attention to detail on piston-to-bore clearance than their forged-slug HO siblings, they were not noisy because of the piston height. Just going to short pistons doesn't make noise. That's why not all examples slap. But short pistons in conjunction with wide piston-to-bore clearance will make noise. It's a cumulative result. Some stock pictures which may help: Stock 302HO piston/rod: Stock 4.6L piston/rod (not in the best of shape but conveys the difference): Stock GM LS1 piston/rod:
 
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Toronto
Look at the 'offset' on that 4.6 piston LOL Boost? Yea agree it's definitely not just short skirtage responsible for it, check this stock shortie I have NEVER in over 15 years heard piston noise from one of these engines, ever. Hyper pistons, adequate offset and a decent 1.85:1 rod/stroke ratio probably helps
 
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