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Discussion Starter · #1 ·
Can someone please explain to me what this is, and how bad is it for your engine?
 

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I'll go out on a limb and give this one a shot...

Piston slap is when the piston skirt is suddenly forced against the cylinder wall during high piston loading conditions. The rings act as a fulcrum point for the pivot to occur and the small end of the rod and the wrist pin produce the load to push the piston slightly sideays in the bore. It's usually a problem with excessive piston-to-bore clearances associated with forged aluminum pistons that 'grow' alot when heated. The clearance have to be wider when cool to allow room for heat growth (expansion).

Somebody add to this, I'm sure its not complete....

Herb
 

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Discussion Starter · #3 ·
Thanks for the info, im hoping this is NOT my case but as my luck would have it, its probably worse.
 

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My motor has the Piston slap but is only noticed after I start it. I usually let it run for a few mins before I take off and it goes away.
 

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Discussion Starter · #5 ·
99BlackBeast said:
My motor has the Piston slap but is only noticed after I start it. I usually let it run for a few mins before I take off and it goes away.
Is this on a built engine? Mine did the same thing, when I started it , sounded like a diesel truck, and did get better as the truck heated up. Does this hurt any of your performance?
 

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I'll speak in generic terms because "piston slap" happens at different times for different reasons.

My motor has the Piston slap but is only noticed after I start it.
Piston slap in this case is actually normal and quite a number of Gen 2 owners experience this. Me included.

In a ambient condition (the colder the worse it is) the dimensional gap between the piston and the cylinder wall is big enough that the piston "slaps" against the cylinder. As the piston warms up it expands and the noise goes away. This gap has now become small enough that no perceivable noise is heard. (a very common experience on "forged" pistons)

It's really nothing to awful bad or to get upset about. It's just life.

Now having said all that, A fully synthetic oil that's a little thicker on the cold end will get rid of it. (I use 10w-30 Mobil 1 and it's quite now) ;)

Rich
 

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Discussion Starter · #7 ·
Thanks for the great info as always. When can I start using synthetic oil in my engine, I have heard not until around 5k miles?
 

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I started around 5k miles on mine. I first went to 5w-30 mobil and it got somewhat quieter. A week later I switched to 10w-30 and been that way for the additional 25k miles since. I even start / run mine in 0 degree weather with no problems at all.

I'd say if your over 2k miles you'll be ok switching over to full synthetic. You wanna give all the moving parts a little time/wear to seat properly.

Rich
 

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Hmmmm....I might have to try a little thicker oil like you suggest. My motor also has a slight piston noise during cold startup that goes away within about 2-3 minutes.
Thanks for the Tip [smilie=fingersx.gif]
 

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I first got mine at 500 miles, my first oil change. Once I drained the factory oil and put in the Motorcraft 5W-20 you could hear it. As was stated after 5 – 10 minutes of warm up it basically went away.

When I switched to Mobil One full synthetic (5W-30) at 1,500 miles it was much less noticeable at start up so it sounds like a 10W-30 would help even more…
 

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silverbolt01 said:
99BlackBeast said:
My motor has the Piston slap but is only noticed after I start it. I usually let it run for a few mins before I take off and it goes away.
Is this on a built engine?  Mine did the same thing, when I started it , sounded like a diesel truck, and did get better as the truck heated up.  Does this hurt any of your performance?
No it is a stock motor
 

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Discussion Starter · #12 ·
I am going to change my oil this week (if I get my truck back again) and I will put 5w30 in her for the next 500 miles. Thanks all
 
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