New LS1 Owners - Newbie Tech - Piston slap or lifter noise on cold startup

Hi all,

Ive got this cold start noise and Im trying to determine if its piston slap or lifters. I know its hard to diagnose over a audio file, although I might get some ideas.
Seems to be more apparent now its alot colder at night.

Ive run Penrite HPR10 and Castrol Magnatec both resulting in similar noises at a cold startup.
The noise practically goes away after about 3-5 minutes.

http://www.youtube.com/watch?v=Kcicg0xnLcs

Sounds like piston slap to me. Lifters usually make more of a "ticking" noise.

It sounds a little different than my piston slap does, but if it goes away after 3-5 minutes, it should just be piston slap. If it was a failing lifter I doubt it would go away like that.

mine does the same thing on cold start

Same thing here. A few min and its gone. Been like that for the 70k I have put on the car.

It doesn't sound like a lifter to me either. Have you tried a mechanics stethoscope? You can get them fairly cheap and sometimes it will help pinpoint the noise.

loose rocker.....but even if its not...you can always order

some new ls7 lifters
new rockers (or just tighten it down a little bit)
and use some real oil ( royal purple race or mobil 1)

take a screwdriver and put it on the valvecovers and see if you can pinpoint if its coming from the left or right side and remove those valvecovers and you may very well find that ticking. depending on what size rockers you need I have some good ones off my 41k mile ls1 laying around with bolts

did you ever figure out what this noise was? I just picked up a 2001 z28 for dirt cheap cause it has this noise

My car made the same exact noise, turned out to be pistons slap.

I've owned 2 camaro's both of which had a cold knock sound... They go away after driving like 200 feet... I also knew other friends who had the same problem. I honestly believe its normal for most ls1's lol. I've seen a 2002 with 5k miles with the same problem when i was at a car show i just think its natural man. Dont think it's much to worry about. But its deffently annoying...

I don't mean to hijack this thread, but mine does not go away it does get quieter when warm, but still very noticeable, especially while returning to idle from no load reving, and also with a stethoscope it is dominant on the timing chain cover behind the water pump, I've pulled the valve covers and everything is tight, I will be checking for a bent pushrod next............

I have a similar sound, though mine is not in a rythme like yours. Im pretty sure mine is piston slap. I just start my car and turn the radio up so I dont have to listen to it because it is really annoying.

Pretty sure almost every ls1 makes this noise.

Both of my ls1 fbodies made this noise and went away as the cars warmed up.

Piston slap, piston slap, piston slap, if it goes away after a few minutes, just forget about it and dont worry. Mines been doing it for two years. Still running strong and healthy

What if, as in my case, it does not go away, and can always be heard? with a stethoscope it is dominant on the timing chain cover behind the water Pump, all belts removed still does it? Again Sorry for the hijack

piston slap, cant garauntee it but mine does it first start in the morning then once its near operating temp(1/4) its all good and doesnt do it till the next morning

I've owned 2 camaro's both of which had a cold knock sound... They go away after driving like 200 feet... I also knew other friends who had the same problem. I honestly believe its normal for most ls1's lol. I've seen a 2002 with 5k miles with the same problem when i was at a car show i just think its natural man. Dont think it's much to worry about. But its deffently annoying...

2000 5.3L here in a Suburban, on cold starts (50deg ambient), if I let it idle for 30-40 seconds, I don't hear anything when pulling away from the driveway. But if I fire it up, put it in gear, back out, and hit the gas, it's loud as heck. Back off and it quiets down. Like Kyle said it only lasts a few hundred feet. This engine has 180K on it, owned since 172K.

My mother in law has a 2000 5.3L Silverado and that truck has 220K on it and it has never made the piston slap sound, ever, and she goes 8K-10K between conventional oil changes.

As a valet attendant in late 2003, I cold started a 5.3L 2003 Tahoe in the garage and it knocked pretty loud all the way to the stop sign before the hotel's main driveway, about 600 feet. It ticked a bit like a sewing machine while I waited for traffic to clear. Then when I pulled away from a stop, it just stopped being noisy. Truck had 4K miles on it. Was whisper quiet 200 feet later by the time I got to the front door.

I think it's a normal LS engine sound. I also think it can be exacerbated by harder driving and infrequent oil changes during the first year or so of operation. People these days don't believe a new car has to be broken in and they ride hard the day it comes off the lot. :mad:

the piston expands when hot, that's why it goes away or gets quieter. Just thought you guys should know. basically it means the clearance between your pistons and block is a bit off. but not much because its able to expand the pistons to the point where the noise is reduced or completely removed.

I have had my 02 for 2 years and it does the same thing on a cold start. I used a mechanics stethoscope and it does NOT sound like it is coming from the valves lifters or rockers. I agree it is piston slap as it is a fairly well know issue with LS1's. I use Mobile 1 mainly because it lubes better on start up because it doesn't drain off after setting. i don't think I have seen it discussed here is that my manual says to use 5w30 and the oil filler plug says to use 0w30, I only recently noticed the difference on the plug so I may try 0w30 the next time I change oil to see if it has any effect on how long I get the noise on startup.

If it starts and goes away it is piston slap, if it starts and gets seemingly worse it is more than likely lifters. Neither will leave you stranded at first sign but should be addressed. The LS1 with the common "piston slap" issues are very over sized when originally built. We have been measuring them for a few years and on a rebuild most come apart .004-.006" over in spots. That is a BIG #. you get a lot of piston rock until you get some heat in it. I wouldn't loose sleep over it if it has just started but start looking into a permanent fix before it becomes a problem that can not be resolved with an oversized piston or basic short block.