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/

 

[mikeyss]

Thank you, and I'm sorry my video does kinda suck hearing it. I will pop the hood this weekend and get a video. I am leaning towards this being valve train/lifter noise. It runs strong, and idles smooth. I should get the drivers side rear manifold bolt fixed, that also could be what I'm hearing.

The noise I'm hearing is kind of like yours, not as bad though.

 

[Derick]

I should get the drivers side rear manifold bolt fixed, that also could be what I'm hearing.

The noise I'm hearing is kind of like yours, not as bad though.

That certainly could be it. More revs = more vibration of the motor and if the manifolds aren't properly secured to the motor, well you can get all sorts of noise. I had to have new manifolds put on last year, and had at least 2 broken studs.

 

[mikeyss]

I was finally able to get another video of the noise that made me start this thread. I am leaning towards the noise being a bad lifter. If that's the case, I guess I'll just have to replace the lifters and upgrade to a BTR cam

 

[Kraig]

While you have the heads off for the cam swap, replace that broken exhaust stud and I bet the noise isn’t there when you put it back together.

 

[mikeyss]

The broken bolt is on the driver's side rear, and surprisingly there is a very small amount of soot around it. It just looks like normal dirt. The noise is coming from the passenger side. I may rob my exhaust clamp thing from my 05 Tahoe (it also has the same broken bolt) and clamp it on to see if the noise changes. I am waiting to get that broken bolt out for when I get ARH longtubes.

 

[Derick]

Sooooooooooooo, take off the torque converter cover and see if it gets louder. That sounds exactly like mine did as my torque converter starting to kick it. Do you get a weird vibration/noise inside at high rev shifts?

 

[mikeyss]

Sooooooooooooo, take off the torque converter cover and see if it gets louder. That sounds exactly like mine did as my torque converter starting to kick it. Do you get a weird vibration/noise inside at high rev shifts?

I haven't noticed any vibrations, but it does sound like the noise is in the torque converter area. I'm going to pop off the cover and check the noise, as well as make sure the flywheel is ok. It just started doing this not too long ago, and it also feels like I have a U-Joint going out. When I press the gas, there is a weird binding type feel, it feels like a bad u-joint but maybe it is torque converter related.