C5 piston slap?
 

Hey guys I know its been beat to death here but i was wondering if anyone has a noise like mine. I have a 2000 c5 with the ls1, as far as i know its all stock engine wise. Has 107k miles. I get a tick at idle on cold starts, and it ticks pretty loud between 1000-2000 rpm for the first 5 to 10 minutes under any kind of load other than a constant speed. Once the engine reaches full temp it quiets down but is still noticeable with the windows up.

I found two loose spark plugs and was hoping that was the issue but it made no difference surprisingly. I have tried seafoam in the oil and intake, no difference. Castrol 0w40, no difference. Pulled valve covers and inspected everything visually and made sure rockers were tight. Checked all exhaust manifold bolts too.

The noise is not awful, but it sure is annoying. If i roll the windows down I cant hear it while driving but id still like to quiet it down if possible. Maybe its just an ls engine thing. Any ideas?

Honestly if the car is running fine, it's nothing to worry about. Theses are loud motors, not very refined. Could continue playing with oil weights, or get a louder exhaust. Longtubes give you enough valve-train noise you probably won't be able to hear it anymore.

Haha right on. The car does run good, and it has a "catback"/axle back exhaust so it is a little louder than stock. Im sure the noise doesnt hurt anything its just annoying and hard to accept. And i imagine it will make it harder to sell someday.

Have you compared the noise to other C5s? Could be a lazy lifter, fuel injector, or just normal. Without hearing it in person, it is hard to diagnose.

Piston slap typically isn't heard once the engine is at operating temps.

No, I havent compared to other c5's. I honestly dont anyone else locally that has one. If i run into one at a car show or something ill have to listen to it and compare. The noise definitely gets quieter after 5 or 10 minutes but never completely goes away. Only reason i dont think its a lifter is it is more dependent on load. It sounds pefectly normal until you accelerate in the 1000-2000 rpm range. Can only be heard at idle and blipping the throttle when its cold.

not my video, but his engine sounds very similar to mine. Mine is worse under load though. Mine starts a few seconds after starting the engine like his also.

Sounds like mine as well. If that's all it is, don't worry. If you get a hard metal on metal tick, then its time to investigate.

Well im glad im not the only one, guess I'll just leave the targa top out and the windows down so i cant hear it haha.

Does it sound like this a few mins after cranking?

https://youtu.be/4VLl_xAKSHU

Yes that is about how mine sounds warming up from a cold start. Quiets down as it warms up but i can always here it from 1500-2000 like they mentioned in the comments.

That is exactly how mine is. After cranking it takes a min or so to start tapping and will do that until it warms up and then will quiten down at idle but between 1500-2000 rpms you can hear it pretty good. I'd love to know what it is.

I would love to know too. I bought the car about a month ago and it has always made the noise. I figured id try to find the source and if i cant I'll just live with it. Car runs great and is alot of fun to drive!

Mine runs great too, no codes or anything. I bought my car with shorty headers already on it and from what I remember it never made that noise then. I had long tube headers put on awhile back then dyno tuned and it was after that I noticed the sound and it has done it every cold start since. I dont know if I damaged something while on the dyno or what but from the ppl Ive had look at it most think it is a lifter.

My 03 Silverado and 04 Vette have both been singing me the LS1 Piston Slap song since day one....Still singing to this day with no problems what so ever.

Piston slap on an LS motor is very common and doesn't cause any damage that I'm aware of but the noise in both mine and his videos is not piston slap I do not believe

Liftter noise is something most have to live wiht on LSx motors.
Mine started doing it about a month from taking delivery, with 180k sometimes it sounds like its coming apart, other days not so much

Using Dino oil made a huge difference in the noise, plain old 10/30 or 10/40 does the trick. Think all the syn I used was wasted money.

I may throw some cheap Dino oil just to see what kind of sound difference it makes on mine but I don't think I could use it regularely.

I might try rotella t4 10w30 next time just to see if it makes a difference. Ive heard good results with fino oil in the ls engines.

Let me know the results