Piston slap

[mikeyss]

My 09 L9H has always had the 'normal' piston slap noise that goes away when warmed up. However, as of the last few months, even after it's warmed up, I can still faintly hear it. Oil pressure is good, 25-30psi at idle, and 38-42psi while driving. It seems around 2k RPM is when I hear it most. Can it be lifters/cam starting to go bad? I do have one manifold bolt broken off on the rear drivers side, but I don't think that's what I'm hearing.

 

[PG01]

My 09 L9H has always had the 'normal' piston slap noise that goes away when warmed up. However, as of the last few months, even after it's warmed up, I can still faintly hear it. Oil pressure is good, 25-30psi at idle, and 38-42psi while driving. It seems around 2k RPM is when I hear it most. Can it be lifters/cam starting to go bad? I do have one manifold bolt broken off on the rear drivers side, but I don't think that's what I'm hearing.

Mikey maybe you can grab a sound clip?
Ive always believed that the earlier ls engine was prone to piston slap. I think the ‘newer ls’s’ was more llifter noise but if you have a known broken bolt i think you’re hearing exhaust. Imo. But im no mechanic...

 

[mikeyss]

I will get a video or sound clip soon. I should also note that I have around 150k miles on it.

 

[Derick]

I definitely misdiagnosed piston slap too....definitely grab some audio. If it is lifter noise, or perhaps as an all around suggestion, I'd run a quart of trans fluid in your next oil change. Helped quiet down my motor immensely, and only cost a few bucks. The kreen I bought was like 30+.

 

[mikeyss]

My phone audio sucks, I will try tomorrow to get another clip. I didn't have the windows down so my mic didn't pick up the sound.

 

[mikeyss]

I rarely use manual mode nor rev it out like this, but it's the only way to hear the noise I'm talking about. It's hard to hear, but around 22 second mark you can definitely hear the clatter type noise.

 

[thompsoj22]

IMO, piston slap should be most audible at an idle or subtle revving and than dropping back to idle. Are you sure the sound you are hearing isnt some type of exhaust resonance? Mine does the slap mostly at idle, 6.2 L92 130k miles. It is absolutely more pronounced at an idle with valvoline 5/30 as opposed to mobil one 5/30. another 1000 miles and im back to mobil one for the life of the vehicle.

 

[PG01]

I can’t really hear it but im old. Sorry mikey. At idle under hood cold start do you hear it? Or is it more at temp driving around or all the time?

 

[Derick]

I put my ear buds in and I couldn't hear a thing that sounded off. Do you only hear it while driving? Piston slap/lifter tick/other engine noises are usually heard while stopped. Pop the hood, rev it via the throttle body if you need to, but my guess, again not hearing anything, would be that if you hear things its further down the drivetrain. Torque converter, trans, differential, etc.

 

[Derick]

So again, I also misdiagnosed piston slap...so here's a rundown of those two common noises. Again these are stopped, and at idle.

When the motor is cold and you start, you hear a ticking but stops within 20 seconds give or take.....thats piston slap. I forget the root cause of it, but Chevy has officially written it off as a regular operating noise.

When the motor is warm, you hear a cyclical ticking, and it may or may not go away with rev.....that's likely lifter tick. You might be able to bring it back from the brink w/ some engine cleaning options. I tried the gunk engine flush, I tried trans fluid, and I tried kreen. Now admittedly, the kreen was the last to go in, so the other stuff did most of the work. If you feel like your noise fits this description, I'd replace a qt of oil with plain ole ATF at your next oil change. It's another high quality oil with LOTS of detergents. I ran mine for about 1k miles and then changed the oil. I think out of all the treatments I went through, that was the most effective, and also the cheapest. My motor is quiet, and smooth as butter now. A huge leap from where it was.

Check out my engine noise thread and see if the first video seems familiar.

https://www.tahoeyukonforum.com/posts/1314542/