Alright, car is a 2000 SS with 66k miles. Problem is the engine sounds like there is something like excessive piston slap or a bad lifter (Although I don't really know what that would sound like for the first 5-10 minutes of opperation. I was used to this sound (But a little quieter in my LT1) in the winter but it lasts longer in the LS1 and it is way louder. I do not think it is an exhaust manifold leak, it is louder in the car than standing with the hood open It is most pronounced between 1200 and ~2400 when bogging it to launch in first gear. I just have visions of pistons scorring the walls. Any explanation would be greatly appreciated. PS oil is 10W30 normal.

 

Well this doesnt help you but mine does the same thing but only when it is extremely cold. I did notice it more when I did the throttle body bypass, but that may have just been whe it got cold out.

 

Honestly I dont know much about the Ls1 engines, but I would hazard a guess that a lifter isnt pumping up very quickly. Do you have an oil pressure guage? how does it look?
CoryM

 

Sounds like piston slap to me, I've got it too. Its very common in LS1s. My car sound like a diesel until it's been at operating temp (210deg F) for a couple of minutes. Oh yeah, for some reason the noise is louder inside of the car. GM says it's normal for LS1 cars (it's not, it's due to an over bored cylinder<s>), most techs agree it's not that damaging (the LS1s aluminum block transmits sound better so it makes the slap sound worse than it really is). They suggest keeping an eye on oil consumption as it is a sympton of ring flutter which can be a bigger problem. Do a search on "LS1" and "piston slap". I've seen many threads here and at LS1.com. Hope the info. helps.

 

Thank you very much I was getting really paranoid after finding major debris in my MAF screen, and rust flakes in the oil. Talk about buyers regret Yeah, it does sound as bad as a diesel it is really disconcerting. Thanks for all your replys. Hey, how would I find out if a lifter were not pumping up? Even a slow lifter should fill in under a minute I would think.

 

That would be piston slap, common on ls1 motors.

 

Our GM trucks experience the same problems after about 50K miles. Carbon build up on the pistons and cold engine intensifies the piston slap problem. Our mechanics use the following procedure recommended by a local chevy dealer. Pull each plug and squirt a libel amount of carbon cleaner into cylinder, replace plugs and let stand overnight. DO NOT START OR RUN ENGINE FOR 4-6 HOURS AFTER PROCEDURE.

 

Thanks IrishJim what is this carbon cleaner? Anybody else done this? It sounds a little scarry and I don't know if its worth it to get rid of a little noise. Oppinions would be greatly appreciated.

 

Just drive the car already!

Even if you have scored cylinder walls, you're not gonna fix it till it gets really bad anyway. But the noise you have is a standard feature with almost all LS1's. Welcome to the club. Your lifters are fine. If you got the air filter in fine, that's not a problem anymore either. Worry about something you can actually do something about.

Drive the car already!

 

Ive also heard about the carbon deposit thing, but ive never sparayed anything into the cylinders...yet. sounds like a sound idea. other than that, the carbon buildup is because the pcv system cant get rid of the crap fast enough. I was told to put a 2002 z06 pcv valve on and it should remedy the problem. Supposedely, there was a recaall on some ls1/vortec4.8, 5.3, and 6.0's where they did this mod. I changed mine the other day for 3 bucks and change. The old one looked fine and wasnt clogged or anything. the new z06 pcv doesnt have any moving parts that i can hear, it just has a little hole in the end, kinda weird, but ill see if it helps.

 

I dont think aluminum expands as much as cast iron, so the pistons would expand more than the engine block when they heat up, so maybe the knocking is because the pistons are actually a little bit smaller than the bore upon start up. The noise goes away when it expands and stops rattling around.

My idea,
Joey

Ps- its good to finally be back on this site. I sold my Firebird almost a year ago and havent really been back here, but I want to get another F-body one day.

 

Aluminum expands more than iron, and thats part of the problem. The stock forged Alum Hypers and over-bored cylinders dont help things, but its still got *****, so i wont complain too much.

 

Robvas, my thought exactly. Man my stock LT1 sounded a lot better with the SLP SS take off. Will the SLP 2 ON the left do a good job to bring the LS1 up to LT1 standards? What mufler only can I get for this car, I don't have the coin for a cat back now.