ok, I know what piston slap is but how bad is it really. Some say normal, some say horrible. WHich one is it, just need some feedback from the people who know it best.

 

Depends on how much the pistons are undersize. Remember what's happening, the pistons is bangging against the sides of the cylinder. Go to that www.pistonslap.com site and look at some of the pics. The real problems happen when the coating on the piston skirts wears off, scoring the cylinder walls.

 

Piston slap is basically made up name for a normal noise during operation of our LSX motors. I have been in the business since these motors came out and have NEVER seen an engine need replacing for anything even remotely related to "piston slap". The IDIOTS that made, follow and believe the crap on the pistonslap.com website are friggin morons and should "piston slapped" across the face. These motors are among the strongest and most problem free motors GM has ever built and we should be proud to have them powering our cars. They may be a little noisy, but they are bad a$$ motors. Don't believe the crap from the morons who feed you the piston slap line cause they don't know what they are talking about. Just another way to bash GM for something that is not perfect in their world.

 

These piston slap posts (and web site) were driving me nuts so I went out and checked my '01 C5 (15,600 miles) and my '02 Suburban (40,056 miles). These are some of the primary years affected from what I read. Started both from cold and ran for 5+ minutes each and past warm up. Happy to say that I did not hear anything out of the ordinary, and never have. Both of these cars have had ZERO mechanical problems, and NO excessive oil useage. I do change my oil at 3,000 miles religiously, and do all interval service requirements. I also change all other fluids every 15,000 miles to be on the safe side. I am very happy with these cars and intend to keep them for at least another few years. Also have an '04 Infinity M45, '04 Subaru WRX (modified), and an '03 VW Jetta turbo.

I agree that some people need to get a good Piston Slap.

 

I have learned to live with my piston slap. It only occurs during warm up 130-180 degrees

 

I have learned to live with the slap on my 2000 Vert. Although annoying, engine runs great and no oil consumption problems. I can see how this problem alarms many as I have heard many a GM engine with this noise and it can be un nerving. You ought to hear the high mileage engines if you want to hear some noise, however no problems with the engine. I go to many a auto auction and when a GM car or truck comes in the door, all bidders listen to the engines and just say piston slap and go ahead and bid on the vehicle and go on their merry way. Unless you engines are using oil or are excessively noisy when hot, and learn to live with it, just the GM beast, however I do believe they need to fix the problem.

 

My 2000 Camaro SS never has had any noise like that, but my 01 C5 does. About 3-5 minutes after starting it it goes away and runs great. Never goes through any oil either although the SS does.

 

Thanks Fellas, I was just curious, and appreciate all of the reponses.

 

my 02 does it as well and i only have 7k on it.after reading all these other posts i beleve now that its normal and just going to ignore it.

 

Regardless of what you have read piston slap is completely harmless and is actually beneficial in a performance engine. The only way you can get pistons to run quiet is to run with .0005 to .0015 clearance. This will result in a quiet engine but the resulting friction soaks up horsepower like a sponge. Performance engines need greater than .0015 piston to bore clearance to make power but you are starting to get in the noise region with clearances around .002. Years ago our typical "Cup" racing pistons raced .0075-.008 clearance in an 800 HP engine. Our pistons have seen a lot of development work since then and the clearances we run now are tighter than we used before but even the pistons we use now would still be extremely noisy in a street engine. The wobbling pistons reported on pistonslap.com is pretty funny. Soccer moms probably worry when they read this stuff though.

Greg

 

Piston to Bore Clearance for KB Performance Pistons were dyno tested at wide open throttle with .0015", .0020", .0035" and .0045" piston-to-bore clearance. After 7-1/2 hours, the pistons were examined and all looked as new, except the tops had normal deposit color. Even with 320 degrees oil temperature, the inside of the piston remained shiny and completely clean. Excess clearance has been shown to be safe with KB pistons (no reported cracks in four years). The added skirt stiffness of the KB pistons reduces piston rock, even if it is set up loose. Loose KB pistons over .0020" do make noise. As they get up to temperature they still make noise because they have very restricted expansion rate and do not swell up in the bore. Our hypereutectic alloy not only expands 15% less, it insulates the skirts from combustion chamber heat. A short term Hp improvement can be had by running additional piston clearance because friction is reduced. To obtain actual piston diameter, measure the piston from skirt to skirt level with the balance pad. See The Special Clearance Requirements for KB Pistons.

 

My piston slap got fixed when I added headers and GHL exhaust

 

What I don't like is that my engine has piston slap on only one cylinder. That means that piston to bore clearance is not the same on all cylinders, like over .002 on one and under .002 on the rest. If it's done for increased power by GM, then it should be the same on all.
How come most other manufacturers don't have this noise, and GM does?

 

D,

You will never want to take a stock short block out and put a micrometer to parts and the block. The spec's are all over the place and the cylinders are all different sizes. Its frankly really embarrassing.

Even some so called good internet built motors here are truly pathedic. How fast can we slap them together seems to be the moto for most.

B

 

I'm not saying that GM doesn't have an issue with piston slap, I am saying it is blown out of proportion relative to the seriousness of the problem. The noise probably bothers many folks more than it does the engine. The cylinder you have that is noisy probably contributes more power than the others do. Factory engine building is pretty good when compared to most of the stuff that is available out there. Generally a rebuild by a typical local rebuilder will not last as long as the factory build did.

 

I agree with Greg. This is why I prefer to buy crate motors vs having a local shop rebuild an existing block. Even a fairly local head shop that was nationally known reworked an engine that always ran hot and produced pitiful horsepower. Factory V-8s from the big three are pretty darn reliable.

 

2000 FRC here, 6 yrs, 37,000 miles. Stock LS1, No "piston slap" noise, no oil consumption, no noise when clutch is not depressed when shutting off, no nothing!

 

Ill bet a $1.00 the LS2 and LS7 doesnt have piston slap

 

That is exactly what I did to cure mine.
Piston slap? what piston slap?

 

The people who claim this is "normal" and perfectly ok amaze me. I didn't shell out $50k on a new vehicle to have it sound like a clapped out Yugo within 7k miles. My 04 vette has a serious case of the clap and I'm NOT happy!

If this was a design feature, the engineers should be shown the door. There is no way you can BS your way out of this problem.

There is NOTHING normal about a knocking, tapping, clapping, ticking engine, especially one in GM most expensive auto.

Is it a lack of quality control? Is it poor judgment in using that piston design? You can bet on this bit of info, my next new car will NOT be a GM's product.

My current stable of cars include the 04 Vette, 02 DeVille, 85 GMC, 85 Fiero, 85 Grand Prix(with a 95 LT1) and no piston slap in the older vehicles.

Every time I fire up the Vette, Cats scatter, Birds take flight and neighbors stare in shock and horror.

Maybe you're happy with this lack of quality, I most certainly am not. As far as knowing what I'm "talking" about, I've earned a living working in a machine shop, building and repairing engines of all types. A piston slap in a street machine would be considered a failed engine.