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Can't help ya, Sorry.
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Discussion Starter #1
Is anyone experiancing piston slap at start up? I noticed it the other day. I've never noticed it before on other cars I've owned and was told by a friend that it was a trait of the LS1 to slap until it warmed up. He told me not to worry but I do.

The next question: Should I wait until the car warms at idle before I drive? I've always been a turn the key and count to 10 kind of guy..

This is the first thing about the car that has me really concerned.
 

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Captain Thread Killer returns
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sxty8goats said:
Is anyone experiancing piston slap at start up? I noticed it the other day. I've never noticed it before on other cars I've owned and was told by a friend that it was a trait of the LS1 to slap until it warmed up. He told me not to worry but I do.

The next question: Should I wait until the car warms at idle before I drive? I've always been a turn the key and count to 10 kind of guy..

This is the first thing about the car that has me really concerned.
I hear that, I guess that is what I hear.....like a nocking noise. I do notice that it does go away. I am slightly worried but I keep reading where everyone says its normal so I tend not to worry as much anymore. Maybe someone with some real good tech. knowledge will be able to give us a good answer once and for all.
 

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The pistons are supposed to be redesigned for this model year (technically I believe it was mid-year 2002 when it was fixed) and not have piston slap. How loud is it? The valve train seems pretty loud on these cars - but the piston slap is a loud knocking - almost like a diesel or a motor that has spun a bearing.
Dan
 

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May I quote you on that?
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I've also noticed that the valve train is not the quietest thing in town. I like to give it a couple of minutes at idle before I drop it in gear. Gets the oil circulating, gives me time to buckle up, twiddle the radio, etc.
 

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Knight Errant
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Oh yeah...

sxty8goats said:
Is anyone experiancing piston slap at start up? I noticed it the other day. I've never noticed it before on other cars I've owned and was told by a friend that it was a trait of the LS1 to slap until it warmed up. He told me not to worry but I do.

The next question: Should I wait until the car warms at idle before I drive? I've always been a turn the key and count to 10 kind of guy..

This is the first thing about the car that has me really concerned.
This is the noise I described some time back from the midline of the engine. Car sounds like it has full floating piston pins. Mine tapers off when the heat in the engine evens out, very gradually. It is RPM dependent. I know what lifters sound like...the truck has solids... ;) Lately, it has been more than 15 minutes for the noise to taper off. I give it a ten minute warm up and move out. This problem was supposed to be 'cured' in these engines by relocating the piston pins. Either it didn't, or I have the old style piston.
It is NOT a good thing, sooner or later it will end up camming the piston skirts or unevenly wearing the cylinder bores. Part of the problem is generated by the high Rod Aspect ratio these engines run. The old 400 small block, when hot rodded, had a similar issue until the aftermarket off centered the piston pin hole in the piston.
 

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Can't help ya, Sorry.
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Discussion Starter #6
I'm pretty sure it isn't valve train noise. That tends to sound more like a tapping, this sounds more like a quiet disieling. I too thought they were susposed to have eliminated this in 2002. I wonder if the land of Oz's engines were the last to see the fix? My car was built 11/03.
It does taper off as the engine heats but it is not gone until the temp levels off.
 

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Well, well

Gee, where have I heard this before? See the previous thread on piston slap:

http://www.ls1gto.com/forums/showthread.php?t=508

GM's 2002 "improvements" notwithstanding, it appears that the LS1 design continues to be prone to piston slap. Starting in 2002, a design change added a new oil scraper ring, reduced the piston-to-bore clearance tolerance, and added a teflon coating on the piston skirt to prevent scuffing due to the the tighter clearances. As I understand it, these changes were introduced primarily to address complaints about high oil consumption. A side benefit was supposedly elimination of piston slap due to the tighter piston-to-cylinder wall tolerances. It now appears that GM was well aware that cold start piston slap would never be eliminated due to a flaw in the engine's basic design, as evidenced by this extract from page 6-37 in the Helm's Manual:

"Important: A cold piston knock which disappears in 1.5 minutes should be considered acceptable. A cold engine knock usually disappears when the specific cylinder's secondary ignition circuit is grounded out during diagnosis." (No s--t; if there's no combustion force against the piston, the piston skirt shouldn't be driven against the cylinder wall).

Take a look at the website mentioned in the thread, pistonslap.com. I know that most of the complaints on that site involve GM trucks ("Like A Knock"); nevertheless, there are many other sites that talk about this problem with LS-1-equipped Camaros, Firebirds, and Corvettes. I guess I could live with slight cold temperature knocking (even though I've never had a car that did that, including other aluminum block/head/piston engines operated at very low starting temperatures). My main concern is that if it's doing it now, with very low mileage on the engine, it's probably only going to get worse with additional use. I have a hard time believing that metal-to-metal contact in the cylinder bore is no big deal. Engine longevity notwithstanding, that deep, powerful exhaust note is going to lose some of it's charm if it's drowned out by the sound of a diesel up front.
 

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Well, given that there are very few people experiencing this noise, I would be worried about something different, and more serious, going on. I have no knocking / slapping noise - cold or otherwise - other than valvetrain noise. I heard 3 other cars start up after sitting quite a while a couple of weekends ago and none of them had anything that sounded vaguely like a piston slap.
Also, the motors aren't assembled in Oz, it's either Mexico or Canada - I can't remember which.
Dan
 

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May I quote you on that?
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If I recall correctly, CMNT experiences mild cold piston slap on his LS1 Camaro. He would probably be a good person to ask. I don't remember him being overly concerned about it.
 

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mistermike said:
If I recall correctly, CMNT experiences mild cold piston slap on his LS1 Camaro. He would probably be a good person to ask. I don't remember him being overly concerned about it.
Yeah, I think you're right...perhaps I'm being an alarmist about it, but there's so much hype out there that it's hard to tell what's a problem and what's not. In any case, I thought that it had been eliminated.
 

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Snagging your fish!!!
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DANSLS1 said:
Also, the motors aren't assembled in Oz, it's either Mexico or Canada - I can't remember which.
Dan
I believe it is St. Catherines, Ontario Canada. I think. :D
 

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the cold knocking noise is common here in aus, I'm not sure I know of a car that doesnt do it eventually, to a degree. also many reports of it coming back after rebuilds. i have 2 ls1's in the garage and they both do it. it's been an issue down here in the media and forums etc.
 

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Can't help ya, Sorry.
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Discussion Starter #13
I know that the engines are built in hocky town and shipped to Oz, I was just pondering that they may have been shipped there in 2002 and the stock hadn't been depleted by the time they built my car..
I really don't think it is valve train noise. Would bumping up to a 5w-40 oil help to lessen the sound/ protect the engine?
 

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2004 GTO IBM/Blue m6
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sxty8goats said:
Is anyone experiancing piston slap at start up? I noticed it the other day. I've never noticed it before on other cars I've owned and was told by a friend that it was a trait of the LS1 to slap until it warmed up. He told me not to worry but I do.

The next question: Should I wait until the car warms at idle before I drive? I've always been a turn the key and count to 10 kind of guy..

This is the first thing about the car that has me really concerned.
I haven't noticed anything out of the ordinary yet. My '02 WS6 had it BAD which was the biggest reason I wanted to get rid of it. I hope GM has fixed the problem, but its not like they are going to do anything about it if they haven't fixed it.
 

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GTOholic
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If the noise is as dramatic as others have described, then I must assume I do NOT experience piston slap. I do not hear any "knocking" or "diesel" sounds when I cold start my car. Even the valve train sounds are "acceptable" based on my limited experience. Now that I'm paranoid again, I will listen more carefully this evening when I start the car.
 

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Knight Errant
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Engine rattle

Guys, mine didn't do it new. It started shortly after the first oil change at 500 miles. The first time was the third day after the oil change, it sat for two days without being driven (rain). When it fired up, it was really bad for about 15 seconds, then it softened and went away in about 30 seconds. At first blush I suspected a malfunctioning anti-drainback valve in the oil filter, but It is DEFINITELY piston noise. I do not beat the car (doughnuts, burnouts, or bounce off the limiter), but I did let it do it's thing trying to find the best launch (I did finally) and do an occasional WOT through the gears off a ramp onto an empty road to clean the carbon out. I've got 2,062 miles now, and it is worsening slowly and getting longer to recede. Now if it sits parked for a few hours, like it did at F1 yesterday, it does it on startup.

Take a short piece of steel brake or fuel line if you have it, and a piece of vacuum hose. Join them together, use the hose end for your ear, and search by the plugs for the noise with the metal end against the block, heads, etc. like using a stethoscope. Then listen for the valve train at the covers. (DON'T GROUND OUT A COIL)! Or you'll light up your life for sure!...;>)
 

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Discussion Starter #17
OG that sounds exactly like my situation. Nothing until after the first oil change @ 600 miles. I don't beat the car, I did bounce off of the rev-limiter once. I don't melt the tires, they have spun but I tend to back down on the throttle when that happens.

I have to run it by the dealership to fix a bit of a scratch they put on my bumper. I'll ask them what they think but I am not hopeful as they have been less than corpative in the service department.
 

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Knight Errant
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Service

sxty8goats said:
OG that sounds exactly like my situation. Nothing until after the first oil change @ 600 miles. I don't beat the car, I did bounce off of the rev-limiter once. I don't melt the tires, they have spun but I tend to back down on the throttle when that happens.

I have to run it by the dealership to fix a bit of a scratch they put on my bumper. I'll ask them what they think but I am not hopeful as they have been less than corpative in the service department.
I'll get a fair assessment off John, the Service manager at Joseph's. Will post.
 

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Discussion Starter #19
ya know, If this was any other consumer product besides a car I could just pop on back to the dealer and get another one that wasnt' broke.

I may be paranoid but I still hear it a bit when the car is warmed up. And it is getting worse when it is cold.
 

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Piston slap is a big issue but GM hanging tough

GM has put alot of poeple thru a lot of agony on piston slap. Now extended warranties are no longer covering it if it goes away. We are now talking all GM engines. It usually starts 5000-15000 miles and may have some relationship with normal types of carbon buildup. but if it goes away in a coupel of minutes, GM will not do anything about it. 2 things to comment on. First, I ahve seen some of our trucks with the noise for 80K miles and has not changed in any way. Have seen a 5.3L rtuck engine with several hundred thousand miles that did have piston slap since new, and had no wear. Could still see the cross cuts and no lip at the top. I do not think there is a concern in terms of wear and longevity as a result of piston slap. those customers expressing their concern to consumer relations were being given an extended warranty on the engine at no charge. Do not know if this is still going on. but the concern I have is potnetial affects on resale. time will tell. I am sure this noise is much louder with our friends in the Northern part of the country. Our southern friends may not even know what it is since temperature does have influence on the noise. If you hear it, I would recommend you have it docuemnted with the dealership and consumer relations. As far as I know, the lawyers who chase this kind of thing are not having all the successes as some might think.
dms
 
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