Piston Slap

[Skud]

Hi All,

Since it's been cold in the mornings I've noticed what sounds like piston slap on every cold start. It does go away after the truck warms up and it's more noticeable when the truck is in gear with my foot on the brake or as I'm accelerating (under load). Here is a video that I took. I've got the truck in reverse and I'm just slightly giving it a bit of gas.

Thoughts?

EDIT: Better video in post #8.

 

[Fatherof3]

Hi All,

Since it's been cold in the mornings I've noticed what sounds like piston slap on every cold start. It does go away after the truck warms up and it's more noticeable when the truck is in gear with my foot on the brake or as I'm accelerating (under load). Here is a video that I took. I've got the truck in reverse and I'm just slightly giving it a bit of gas.

Thoughts?

It doesn’t sound like piston slap to me . Sounds more like a small exhaust leak .

 

[Sleeper]

Hi All,

Since it's been cold in the mornings I've noticed what sounds like piston slap on every cold start. It does go away after the truck warms up and it's more noticeable when the truck is in gear with my foot on the brake or as I'm accelerating (under load). Here is a video that I took. I've got the truck in reverse and I'm just slightly giving it a bit of gas.

Thoughts?

Agree with fatherof3. Bad manifold gasket, broken manifold bolts or cracked manifold. Search those and you will find a lot of issues.

 

[silver billet]

There are 2 different sounds there. The higher pitched tick/squeaking is from the injectors and is "normal", every hemi is noisy like that.

There is also a lower pitched sound, "knocking", that definitely sounds like piston slap to me as well, piston slap will also go away when the engine heats up. I don't know what to suggest there, try change your oil, put in a high quality synthetic. Some guys on the other forum are saying to try a thinner oil in the winter, but if you're already running 5w-20 then definitely don't run anything thinner than 0w-20, you can get away with 0w in cold winter months where it is well below freezing. Doing so WILL void your warranty if you get engine problems later on and they find out you're not running 5w-20.

 

[kapinallinen2]

My 1997 5.4 Expedition developed piston slap when cold around 160k miles, engine kept on going.
Our 2000 Grand Cherokee six banger did the same around 230k miles, couple months later the #6 piston skirt came apart.
That does not sound like piston slap to me.

 

[Jeffjad]

I just had a cracked manifold and this doesn't sound like an exhaust leak....I agree with @silver billet, try changing oil and tapping will prob go away.

 

[Skud]

Thanks for the input everyone. I’ll try to get a better video. The sound is pretty clear in my original video and in person but a lot of the fidelity was lost on the YouTube conversion.


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[Skud]

OK - here is a better video.

0:28 - I put the truck in reverse with my foot on the brake and the noise starts. It gets louder when I put more load on the engine as well as when the RPMs drop.
1:00 - It can be heard pretty clearly.
1:27 - I put the truck in park and the noise go away. Put it back in reverse and it comes back. I do this a couple times.

 

[DSN46]

OK - here is a better video.

0:28 - I put the truck in reverse with my foot on the brake and the noise starts. It gets louder when I put more load on the engine as well as when the RPMs drop.
1:00 - It can be heard pretty clearly.
1:27 - I put the truck in park and the noise go away. Put it back in reverse and it comes back. I do this a couple times.

I definitely hear it. It does sound like piston slap to me (I had it in a GM 5.3). Tell us, how many miles are on your truck? If still under warranty, this is something I would show to a dealership tech and at the very least get it documented. Good luck and keep us informed as to what you do!

 

[Skud]

I definitely hear it. It does sound like piston slap to me (I had it in a GM 5.3). Tell us, how many miles are on your truck? If still under warranty, this is something I would show to a dealership tech and at the very least get it documented. Good luck and keep us informed as to what you do!

It's a 2019 Limited with ~22,000 miles.

 

[My1stHemi]

I get that sound in my rig as well, and I have always run Shell Rotella Gas Truck Oil (Synthetic 5w-20) 29,303miles. April 2019 Build Date.

 

[kapinallinen2]

That does kinda sound like piston slap. IMO it should not go away when you shift to park (exhaust manifold leak does behave like that)
This Vortec sounds like my Triton did.

 

[Skud]

I'm going to take it in. I don't think an engine with 22,000 miles on it should have this amount of slap. Honestly, my 2002 Mustang with a fully forged stroker and extra PTW clearance for the boost has less slap.

 

[DSN46]

I'm going to take it in. I don't think an engine with 22,000 miles on it should have this amount of slap. Honestly, my 2002 Mustang with a fully forged stroker and extra PTW clearance for the boost has less slap.

Let us know what you find out!

 

[Billy James]

I'll be following this one; my truck pretty much sounds exactly the same.

 

[Skud]

Stopped in at a dealer this week. Showed them the video and they could definitely hear it.

Was told that a “low RPM knock is pretty normal for the hemi”. If I wanted to book it in to be looked at then they could get me in sometime in April.




So it begins.


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[dork17]

Stopped in at a dealer this week. Showed them the video and they could definitely hear it.

Was told that a “low RPM knock is pretty normal for the hemi”. If I wanted to book it in to be looked at then they could get me in sometime in April.




So it begins.


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Hey, hoping to revive this old thread! Did you ever find out what this noise was about? Experiencing the exact same thing with mine.

 

[SD Rebel]

Hey, hoping to revive this old thread! Did you ever find out what this noise was about? Experiencing the exact same thing with mine.

Me as well, just noticed it recently. Only under load when cold, goes away after about 1 mile.

 

[gunsnfunz]

Has anybody figured this out my truck with only 29k has been doing it for awhile now identical to this and can’t get any answers

 

[SD Rebel]

Has anybody figured this out my truck with only 29k has been doing it for awhile now identical to this and can’t get any answers

From what I understand it's normal. The pistons are sized a little smaller due to expansion and once it gets up to temp, they stop doing it as they expand to fill the cylinder walls. It was probably happening for me since the beginning, but since I always drive with music on, I never noticed until recently. If you hear the sound only on first cold operations, and goes away when warmed up, it's probably not an issue.

Drove in another truck, a friends who said hers didn't do it. Guess what, it does it, she just wasn't "tuned" to the sound to bother her. Some people aren't sensitive to the "pistol slap" sound and simply don't notice it, especially if it goes away quickly. For me, it's gone after about 1 mile of driving, or about 170F on the coolant.

Note - I can only here it under light throttle, not at idle during, during initial cold start.